U.S. patent application number 13/847785 was filed with the patent office on 2016-10-20 for optical tissue interface method and apparatus for stimulating cells.
The applicant listed for this patent is The Board of Trustees of the Leland Stanford Junior University. Invention is credited to Alexander Aravanis, Karl Deisseroth, Jaimie M. Henderson, M. Bret Schneider, Feng Zhang.
Application Number | 20160303396 13/847785 |
Document ID | / |
Family ID | 40509181 |
Filed Date | 2016-10-20 |
United States Patent
Application |
20160303396 |
Kind Code |
A9 |
Deisseroth; Karl ; et
al. |
October 20, 2016 |
Optical Tissue Interface Method and Apparatus For Stimulating
Cells
Abstract
In one example, a system electrically stimulates target cells of
a living animal using an elongated structure, a modulation circuit
and a light pathway such as provided by an optical fiber
arrangement. The elongated structure is for insertion into a narrow
passageway in the animal such that an end of the elongated
structure is sufficiently near the target cells to deliver
stimulation thereto. The modulation circuit is for modulating the
target cells while the elongated structure is in the narrow
passageway, where the modulation circuit is adapted to deliver
viral vectors through the elongated structure for expressing light
responsive proteins in the target cells. The light pathway is used
for stimulating the target cells by delivering light to the
light-responsive proteins in the target cells.
Inventors: |
Deisseroth; Karl; (Stanford,
CA) ; Aravanis; Alexander; (San Diego, CA) ;
Zhang; Feng; (Cambridge, MA) ; Schneider; M.
Bret; (Portola Valley, CA) ; Henderson; Jaimie
M.; (Stanford, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
The Board of Trustees of the Leland Stanford Junior
University |
Palo Alto |
CA |
US |
|
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Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20130289669 A1 |
October 31, 2013 |
|
|
Family ID: |
40509181 |
Appl. No.: |
13/847785 |
Filed: |
March 20, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12185624 |
Aug 4, 2008 |
9238150 |
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13847785 |
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11651422 |
Jan 9, 2007 |
8926959 |
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12185624 |
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11459636 |
Jul 24, 2006 |
8906360 |
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11651422 |
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12041628 |
Mar 3, 2008 |
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12185624 |
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60953920 |
Aug 3, 2007 |
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60701799 |
Jul 22, 2005 |
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60904303 |
Mar 1, 2007 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61N 2005/0651 20130101;
A61K 41/0057 20130101; C12N 2710/10043 20130101; A61K 48/0058
20130101; A61N 5/0601 20130101; A61N 5/062 20130101; C12N
2710/16643 20130101; A61K 48/0083 20130101; C12N 7/00 20130101;
A61K 36/05 20130101; A61N 2005/063 20130101; A61K 38/16 20130101;
A61K 48/005 20130101; A61N 5/0622 20130101 |
International
Class: |
A61N 5/06 20060101
A61N005/06 |
Claims
1.-13. (canceled)
14. An arrangement, comprising: an elongated structure inserted
into a narrow passageway in an animal for modulating of the
activity of electrically-excitable cells and for actively growing
light-gated ion channels or pumps in the membrane of a nerve cell
located at a selected target within the body, and a light source
for directing at least one flash of light upon the light-activated
ion channels or pumps so as to modulate functions of the target
cells or of surrounding cells.
15. A system for electrically stimulating target cells of a living
animal in vivo, the system comprising: an elongated structure for
insertion into a narrow passageway in the animal such that an end
of the elongated structure is sufficiently near the target cells to
deliver stimulation thereto; means for delivering a viral vector
through the elongated structure, wherein the viral vector comprises
a nucleotide sequence encoding a light responsive polypeptide, a
modulation circuit for modulating the target cells while the
elongated structure is in the narrow passageway, and an optical
fiber arrangement for stimulating the target cells by delivering
light to the light-responsive polypeptide in the target cells.
16. The system of claim 15, wherein electrically stimulating target
cells of a living animal includes one of optogenetic excitation and
optogenetic stabilization.
17. A system for electrically stimulating target neurons in a brain
in vivo via the skull, the system comprising: an elongated
structure having two ends and a passage extending between the ends,
wherein the elongated structure is sufficiently small for insertion
through the skull and into the brain, a mount to secure the
elongated structure to the skull; a reservoir to hold a composition
comprising a viral vector comprising a nucleotide sequence encoding
a light responsive polypeptide; a delivery device to move the
composition comprising the viral vector from the reservoir through
the passage and to the target neurons; and an optical fiber
light-delivery arrangement including optical fiber for insertion
through the passage and a light generator for sourcing light
through the optical fiber to stimulate the target neurons and to
activate said light-responsive polypeptide expressed in the target
neurons, wherein light delivered through the optical fiber
illuminates an area of the brain in which the target neurons are
located.
18. The system of claim 15, comprising a composition comprising the
viral vector.
19. The system of claim 18, wherein the viral vector comprises a
nucleotide sequence encoding a light-activatable polypeptide having
at least about 95% amino acid sequence identity to a ChR2
polypeptide, wherein the nucleotide sequence is operably linked to
a target cell type-specific promoter.
20. The system of claim 17, wherein the reservoir comprises a
composition comprising a viral vector comprising a nucleotide
sequence encoding a light responsive polypeptide.
21. The system of claim 20, wherein the viral vector comprises a
nucleotide sequence encoding a light-activatable polypeptide having
at least about 95% amino acid sequence identity to a ChR2
polypeptide, and wherein the nucleotide sequence is operably linked
to a target cell type-specific promoter.
22. The system of claim 20, wherein the viral vector is an
adeno-associated virus vector or a lentivirus vector.
23. The system of claim 17, wherein the elongated structure is a
cannula.
24. The system of claim 17, wherein the elongated structure is a
catheter.
25. The system of claim 17, wherein at least a portion of the
system is implantable.
26. The system of claim 20, wherein the viral vector comprises a
nucleotide sequence encoding a halorhodopsin.
Description
RELATED PATENT DOCUMENTS
[0001] This patent document claims the benefit, under 35 U.S.C.
.sctn.119(e), of U.S. Provisional Patent Application Ser. No.
60/953,920, entitled Optical Tissue Interface Method and Apparatus
for Stimulating Cells and filed on Aug. 3, 2007; this patent
application, including the Appendix therein, is fully incorporated
herein by reference.
[0002] This patent document also claims priority, as a CIP under 35
U.S.C. .sctn.120, to the following patent documents which are also
individually incorporated by reference: U.S. patent application
Ser. No. 11/651,422 (STFD.150PA), filed on Jan. 9, 2007 and
entitled, System for Optical Stimulation of Target Cells), which is
a CIP of U.S. patent application Ser. No. 11/459,636 (STFD.169PA),
filed on Jul. 24, 2006 and entitled, Light-Activated Cation Channel
and Uses Thereof, which claims the benefit of U.S. Provisional
Application No. 60/701,799 (STFD.169P1), filed Jul. 22, 2005; and
U.S. patent application Ser. No. 12/041,628 (STFD.165PA), filed on
Mar. 3, 2008 and entitled, Systems, Methods And Compositions For
Optical Stimulation Of Target Cells, which claims the benefit of
U.S. Provisional Application No. 60/904,303 (STFD.165P1), filed on
Mar. 1, 2007.
FIELD OF THE INVENTION
[0003] The present invention relates generally to systems and/or
methods for stimulating target cells optically and more
particularly to an optical neural interface, system and method for
delivery of genetic modifiers and optical stimulus to target
cells.
BACKGROUND AND OVERVIEW
[0004] The stimulation of various cells of the body has been used
to produce a number of beneficial effects. One method of
stimulation involves the use of electrodes to introduce an
externally generated signal into cells. For example, in connection
with electrode-based brain stimulation techniques, the distributed
nature of neurons may be responsible for a given mental process.
Also, different types of neurons reside close to one another such
that only certain cells in a given region of the brain may be
activated while performing a specific task. Not only do
heterogeneous nerve tracts move in parallel through tight spatial
confines, but the cell bodies themselves may exist in mixed,
sparsely embedded configurations. This distributed manner of
processing is an issue in attempts to understand canonical order
within the Central Nervous System (CNS), and can make
neuromodulation a difficult therapeutic endeavor. Due to this
architecture of the brain, there are issues concerning use of
electrode-based stimulation which is relatively indiscriminate with
regards to the underlying physiology of the neurons that they
stimulate. Instead, physical proximity of the electrode poles to
the neuron is often the single largest determining factor as to
which neurons will be stimulated.
[0005] Electrode placement and mechanical stability can also be an
important influence on the effectiveness of electrode stimulation
since location often dictates which neurons will be stimulated, and
flawed location/stability can result in lead migration of the
electrodes from the targeted area. Moreover, after a period of time
within the body, electrode leads frequently become encapsulated
with glial cells, raising the effective electrical resistance of
the electrodes, and hence the electrical power delivery required to
reach targeted cells. Compensatory increases in voltage, frequency
or pulse width, however, may spread electrical current and result
in increases in unintended stimulation of additional cells.
[0006] In connection with work by the named inventor(s) of this
patent document, recently discovered techniques allow for
stimulation of cells resulting in the rapid depolarization of cells
(e.g., in the millisecond range). One method of stimulus uses
photosensitive bio-molecular structures to stimulate target cells
in response to light. For instance, light activated proteins can be
used to control the flow of ions through cell membranes. Ion
channels and ion pumps are cell-membrane proteins that control the
transport of positively or negatively charged ions (e.g., sodium,
potassium and chloride) across the cell membrane. Ion channels play
an important part of various animal and human functions including
signaling and metabolism. Using optically responsive ion channels
or pumps to facilitate or inhibit the flow of positive or negative
ions through cell membranes, the cell can be briefly depolarized,
depolarized and maintained in that state, or hyperpolarized.
Neurons are an example of a type of cell that uses the electrical
currents created by depolarization to generate communication
signals (i.e., nerve impulses). Other electrically excitable cells
include skeletal muscle, cardiac muscle, and endocrine cells.
[0007] Various techniques can be used to control the depolarization
of cells such as neurons. Neurons use rapid depolarization to
transmit signals throughout the body and for various purposes, such
as motor control (e.g., muscle contractions), sensory responses
(e.g., touch, hearing, and other senses) and computational
functions (e.g., brain functions). Thus, the control of the
depolarization of cells can be beneficial for a number of different
purposes, including (but not limited to) psychological therapy,
muscle control and sensory functions. For further details on
specific implementations of photosensitive bio-molecular structures
and methods, reference can be made to "Millisecond-Timescale,
Genetically Optical Control of Neural Activity", Nature
Neuroscience 8, 1263-1268 (2005). This reference discusses use of
blue-light-activated ion channel channelrhodopsin-2 (ChR2) to cause
calcium (Ca++)-mediated neural depolarization, and is fully
incorporated herein by reference. Other applicable light-activated
ion channels include halorhodopsin (NpHR), in which amber light
affects chloride (Cl-) ion flow so as to hyperpolarize neuronal
membrane, and make it resistant to firing.
SUMMARY
[0008] Various aspects of the invention address the above-discussed
issues and others as would become apparent from the discussion that
follows.
[0009] According to one embodiment, the present invention is
directed to a system for electrically stimulating targeted
excitable cells of a living animal using light to alter the
electrical behavior of the cells.
[0010] According to one embodiment, a system electrically
stimulates targeted excitable cells of a living animal by using an
elongated structure, a modulation circuit and a light pathway such
as provided by an optical fiber arrangement. The elongated
structure is for insertion into a narrow passageway in the animal
such that an end of the elongated structure is sufficiently near
the target cells to deliver stimulation thereto. The modulation
circuit is for modulating the target cells while the elongated
structure is in the narrow passageway, where the modulation circuit
is adapted to deliver viral vectors through the elongated structure
for expressing light responsive proteins in the target cells. The
light pathway is used for stimulating the target cells by
delivering light to the light-responsive proteins in the target
cells.
[0011] According to another embodiment, a method electrically
stimulates target cells of a living animal in vivo. An elongated
structure is inserted into a narrow passageway in the animal such
that an end of the structure is sufficiently near the target cells
to deliver stimulation thereto. While the elongated structure is in
the narrow passageway, viral vectors are delivered through the
elongated structure for expressing light responsive proteins in the
target cells. After delivering the viral vectors, an optical fiber
is inserted through the elongated structure. The target cells are
stimulated by using the optical fiber to deliver light to expressed
light responsive proteins in the target cells.
[0012] According to one embodiment, an elongated structure is
inserted into a narrow passageway in an animal for modulating of
the activity of electrically-excitable cells. Growth of light-gated
ion channels or pumps is induced in the membrane of a nerve cell
located at a selected target within the body. At least one flash of
light is directed upon the light-activated proteins so as to
modulate the function of the target or surrounding cells.
[0013] According to one embodiment, an arrangement is implemented
with an elongated structure inserted into a narrow passageway in an
animal for modulating of the activity of electrically-excitable
cells and for actively growing light-gated ion channels or pumps in
the membrane of a nerve cell located at a selected target within
the body. A light source is used for directing at least one flash
of light upon the light-activated proteins so as to modulate the
function of the target or surrounding cells.
[0014] According to one embodiment, a system electrically
stimulates target cells of a living animal in vivo. The system
includes an elongated structure for insertion into a narrow
passageway in the animal such that an end of the elongated
structure is sufficiently near the target cells to deliver
stimulation thereto. A modulation circuit is included for
modulating the target cells while the elongated structure is in the
narrow passageway, the modulation circuit including means for
delivering viral vectors through the elongated structure for
expressing light responsive proteins in the target cells. An
optical fiber arrangement is included for stimulating the target
cells by delivering light to the light-responsive proteins in the
target cells.
[0015] According to one embodiment, a system electrically
stimulates target neurons in a brain in vivo via the skull. The
system has an elongated structure having two ends and a passage
extending between the ends. The elongated structure is sufficiently
small for insertion through the skull and into the brain. A mount
secures the elongated structure to the skull. A reservoir holds
viral vectors for expressing at least one of ChR2 and NpHR in the
target cells. A delivery device moves the viral vectors from the
reservoir through the passage and to the target neurons. An optical
fiber light-delivery arrangement includes an optical fiber for
insertion through the passage and a light generator for sourcing
light through the optical fiber to stimulate the target cells and
to activate the at least one of ChR2 and NpHR expressed in the
target cells. The light delivered through the optical fiber
illuminates an area of the brain in which the target neurons are
located.
[0016] The above summary is not intended to describe each
illustrated embodiment or every implementation of the present
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The invention may be more completely understood in
consideration of the detailed description of various embodiments of
the invention that follows in connection with the accompanying
drawings, in which:
[0018] FIGS. 1A and 1B are diagrams of respective arrangements for
application to mammalian skulls, each arrangement including an
optical neural interface according to an example embodiment of the
present invention;
[0019] FIG. 2 is a flow chart showing one example of a method for
optically targeting cells in a selected patient, according to the
present invention;
[0020] FIG. 3A shows a diagram of test setup involving mouse
whisker deflection, consistent with an example embodiment of the
present invention;
[0021] FIG. 3B shows detected whisker deflection relative to the
stimulating light, consistent with an example embodiment of the
present invention;
[0022] FIG. 3C shows detected whisker deflection with and without
CHR2 and with and without stimulating light, consistent with an
example embodiment of the present invention;
[0023] FIG. 4A shows electrode-based cell stimulation; consistent
with an example embodiment of the present invention;
[0024] FIG. 4B illustrates optical stimulation of
genetically-targeted cells, consistent with an example embodiment
of the present invention;
[0025] FIG. 5 shows an example of an optical neural interface used
for neural stimulation of the brain, according to an example
embodiment of the present invention;
[0026] FIG. 6 shows an example of an optical neural interface used
for endocardial stimulation of the heart; according to an example
embodiment of the present invention;
[0027] FIG. 7 shows an example of an optical neural interface used
for epicardial stimulation of the heart; according to an example
embodiment of the present invention;
[0028] FIGS. 8a through 8e illustrate cell recordings that were
obtained from a ChR2+ layer 5 motor neuron in acute brain slices
that were prepared and processed according to the present
invention;
[0029] FIGS. 9A and 9B are graphs showing the effective light
transmission/intensity for tissue penetration, as may be useful in
connection with estimating expected tissue volume that is activated
optical neural interfaces implemented and used in accordance with
the present invention; and
[0030] FIGS. 10A, 10B, 10C and 10D are diagrams showing the
effectiveness of evoking whisker deflections as it relates to,
optical neural interface implanted and tested in mice according to
the present invention.
[0031] While the invention is amenable to various modifications and
alternative forms, specifics thereof have been shown by way of
example in the drawings and will be described in detail. It should
be understood, however, that the intention is not to limit the
invention to the particular embodiments described. On the contrary,
the intention is to cover all modifications, equivalents, and
alternatives falling within the spirit and scope of the
invention.
DETAILED DESCRIPTION
[0032] The present invention is directed to practical application
of a variety of optically-based stimulus systems, and the invention
has been found to be particularly suited for use in systems and
methods dealing with stimulation of target cells using a cannula (a
tube for insertion into a body cavity or into a duct or vessel) to
deliver optically responsive genetic modifiers and optical stimulus
to target cells. While the present invention is not necessarily
limited to such applications, various aspects of the invention may
be appreciated through a discussion of various examples using this
context.
[0033] Recently discovered techniques allow for stimulation of
cells resulting in the rapid depolarization of cells (e.g., in the
millisecond range). Such techniques can be used to control the
depolarization of cells such as neurons. Neurons use rapid
depolarization to transmit signals throughout the body and for
various purposes, such as motor control (e.g., muscle
contractions), sensory responses (e.g., touch, hearing, and other
senses) and computational functions (e.g., brain functions). Thus,
the control of the depolarization of cells can be beneficial for a
number of different biological applications, among others including
psychological therapy, muscle control and sensory functions. For
further details on specific implementations of photosensitive
bio-molecular structures and methods, reference can be made to the
above-referenced patent documents by Karl Deisseroth et al., which
are fully incorporated herein by reference. These references
discuss use of blue-light-activated ion-channel channelrhodopsin-2
(ChR2) to cause calcium (Ca++)-mediated neural depolarization.
Other applicable light-activated ion channels include, for example,
halorhodopsin (NpHR) in which amber light affects chloride (Cl-)
ion flow so as to hyperpolarize aneuronal membrane, and make it
resistant to firing.
[0034] Certain aspects of the present invention are directed to
stimulating target cells via optogenetic excitation and/or to
optogenetic stabilization. Optogenetic excitation refers to a
combined optical and genetic approach that increases the
depolarization rate of the targeted cell population. While not
necessarily limited to this application (or agent), one approach to
achieving such increases involves expression of ChR2 in targeted
cells, and blue light, emitted for example, from a surgically
implanted hardware device, is flashed to trigger depolarization.
Optogenetic stabilization refers to a combined optical and genetic
approach that decreases the depolarization rate of the targeted
cell population. One approach to achieving such decreases is to
cause NpHR to be expressed in targeted cells. Yellow light emitted
for example, from a surgically implanted hardware device, is
provided to hyperpolarize the membrane and prevent depolarization.
Optogenetic stabilization is not necessarily limited to any
particular genetic agent and may apply to other appropriate
optogenetic agents as well as to variations on the delivery of
light thereto.
[0035] Consistent with one example embodiment of the present
invention, a system is implemented for providing in vivo stimulus
(e.g., via optogenetic excitation and/or to optogenetic
stabilization) to target cells. The system provides an elegant
solution for both modifying the target cells to be optically
responsive and stimulating the target cells optically. One end of a
cannula may be stereotactically or otherwise guided near the target
cells. Viral vectors or other cell modifiers are inserted through
the other end of the cannula to modify the target cells to be
optically responsive. The cannula is then used to guide an optical
delivery device, such as fiber optics, to the same site that the
viral vectors were delivered. Optical stimulus is provided to the
target cells using the optical delivery device. Generally, these
and other applications are discussed herein in the context of live
animals; however, other applications (e.g., postmortem or
otherwise) are also envisioned.
[0036] For the delivery of light to photo-sensitive neurons and
other cell types, there are several different possible light
sources, each having its own benefits with respect to power,
wavelength, heat production, optical coupling, size, and cost. A
few example light sources include, but are not limited to, lasers
(gas, crystal, and solid-state) and light-emitting diodes (LEDs).
Optical fibers have many properties that make them beneficial for
the delivery of light deep within tissue such as the brain. They
are thin, light-weight, flexible, and transmit light with
negligible loss over short distances. In addition to single optical
fibers, fiber bundles or arrays of optical fibers can be useful for
light delivery depending on the size and location of the tissue
targeted. For some applications direct light delivery an LED may be
preferred. For example, treatment of cortical brain tissue or heart
tissue LED illumination may be efficacious.
[0037] In one embodiment, a system that includes a power supply,
control circuit, light source, and light conduit, could be
implanted. This can be useful for minimizing infection and
improving patient convenience. In order to facilitate such
implantation, the light source/housing/power supply "box" can be
designed on the order of the largest current neurostimulators. The
supply box can also be designed to either be rechargeable or to
have a long battery life (e.g., 3 years or more).
[0038] According to one embodiment of the presenting invention, an
implantable cylindrical structure (e.g., a cannula or a cathether)
includes multiple parallel fibers terminating around the
circumference of a cylindrical structure, over a span of several
millimeters. This allows for "steering" of light to various
portions and allows intensity control by activation of more or
fewer fibers. Such multiplexing of light through multiple fibers
can also be useful for spatial control of light delivery.
[0039] One such device can be reinforced for protection of the
light guides so as to survive clumsy handling by surgeons and the
bending/buckling stresses encountered inside a mobile animal/human
body. In one instance, the device can be arranged with optical
connectors that allow replacement of the light guide.
[0040] One such device may also be arranged to facilitate the
integration of electrical recording with optical stimulation. In a
particular instance this is accomplished using different
populations of fibers, and an electrical recording component which
could either be an array of microelectrodes (a la
Cyberkinetics/Utah) or larger macroelectrodes to record local field
potentials.
[0041] According to another embodiment, microfluidic integration
can be useful, given the potential need for "booster" injections of
vector. This can be particularly useful for delivery mechanisms
that require periodic delivery, such as adenovirus-based delivery.
According to one embodiment of the present invention, the cannula
may be fixed to a skull (mammalian or otherwise) using adhesive, or
other suitable attachment mechanisms, prior to the delivery of the
(ChR2/NpHR) solution. This can be useful for maintaining the
location for the end of the cannula located near the target cells
during the entire procedure. The solution may be administered
directly through the cannula or through a separate deliver lumen or
tube that may be inserted through the cannula. The first lumen may
be subsequently removed and fiber optics or a lens and mirror
arrangement may be inserted into the lumen.
[0042] As applied to human skull and a rat skull, FIGS. 1A and 1B
provide an overview of an optical neural interface, in accordance
with the present invention. FIGS. 1A and 1B illustrate similar
optical neural interfaces which are mounted on a mammalian skull,
showing an optical fiber guide, optical fiber inserted in the
guide, and blue light transmitted to the cortex. As discussed in
more detail below, optical neural interfaces, have a wide variety
of applications for studies and treatment of a wide variety of
functions and disorders. These functions and disorders are
typically associated with specific neurons or anatomic
locations.
[0043] FIG. 1A illustrates examples of several example anatomic
locations for interventions in accordance with the methods herein
described. An MRI image or patient 100 is shown in cross-sectional
plane 110. Brain 140 contains numerous regions to which the methods
detailed herein describe. As representative examples, five such
anatomical regions and associated applications are illustrated.
Brain region 115 depicts Brodmann Area 25, a depression treatment
target as described below. Brain region 120 is the genu of the
anterior cingulate, and a target for drug addiction treatment as
described below. Brain region 125 is the prefrontal cortex, and a
target for conditions including depression, as described below.
Brain region 130 is anterior cingulate and corresponds with
Brodmann Area 24, which is a target for pain disorders, as well as
OCD and depression as described below. Brain region 135 is
posterior cingulate gyms, and is one of the targets for Alzheimer's
disease, as described below.
[0044] In the specific case of the rat (FIG. 1B), two weeks prior
to testing, a lentivirus carrying the ChR2 gene is fused to mCherry
under control of the CaMKII.alpha. promoter as injected through the
fiber guide. FIGS. 1B(i) and 1B(ii) show a schematic of the
stimulated region with the optical fiber tip flush with the fiber
guide and blue light illuminating the deeper layers of motor
cortex. Only glutamatergic pyramidal neurons that are both in the
cone of illumination and genetically ChR2+ will be activated to
fire action potentials. FIG. 1B(iii) shows the rat with the optical
neural interface implanted, and showing blue light transmitted to
target neurons via the optical fiber. FIG. 1B(iv) is a close-up
view of the optical neural interface showing fiber guide attached
with translucent cranioplastic cement. Note that no scalp or bone
is exposed. FIG. 1B(v) is a low-power mCherry fluorescence image of
an acute brain slice showing the rat motor cortex after removal of
the optical neural interface. The edge of the potential space
created by the fiber guide is demarcated with a dashed line.
Numerous mCherry+ neurons around the distal end of the fiber guide
are present. The scale bar is 250 .mu.m. FIG. 1B(vi) is a
high-power image of mCherry+ neurons at the edge of the fiber guide
potential space, showing membrane-localized fluorescence
characteristic of ChR2-mCherry fusion protein expression.
[0045] As an example, FIG. 2 outlines a set of basic steps for one
method that may be used in connection with the embodiments of the
present invention. In step 205, the patient is selected or
diagnosed as having a functional disorder of electrically-excitable
cells, from a large number of possibilities, including those
described herein. As part of this process, the neural circuitry,
physiological feedback loops and associated mechanism of the
disorder may be considered. In step 210, an applicable optogenetic
approach is selected for the specific functional disorder. For
example, in the case that the primary source of the problem is a
hypoactive cell population, the selected approach might be an
optogenetic excitation stimulation method to stimulate underactive
cells, or the selected approach might be an optogenetic
stabilization stimulation method to suppress another group of cells
that serves to inhibit the underactive cells. In step 215 the
targeted anatomy that corresponds with the known disease state and
treatment strategy is identified within the actual patient. This
may be done, for example, by direct visualization such as an open
craniotomy or endoscope placement, or accomplished via functional
imaging modalities such as functional magnetic resonance imaging
(fMRI) and positron emission tomography (PET), and registered to
the patient via surgical image guidance systems as are known in the
art (for example, the StealthStation.TM. by Medtronic Navigation,
of Louisville, Colo.). In step 220 a gene for light-sensitive ion
channels or pumps, such as ChR2 or NpHR, is surgically applied to
the appropriate anatomical location. As described in the
above-referenced patent documents (by Karl Deisseroth et al.), for
example, for use in the brain, injections of lentiviruses can be
used to selectively express the Channelrhodopsin-2 (ChR2) protein
in excitatory neurons. ChR2 is a genetically expressible,
light-activated cation channel which has been previously developed
for use in mammals, that can give rise to nontoxic, light-driven
stimulation of CNS neurons on a timescale of milliseconds, allowing
precise quantitative coupling between optical excitation and
neuronal activation. The genetic specificity is achieved by using a
transcription promoter that is specific to excitatory neurons
(CamKII.alpha.). Using this method ChR2 is expressed in excitatory
neurons and not inhibitory neurons or glial cells.
[0046] In step 225, the light-pulsing hardware is surgically
inserted and, optionally implanted. An example of such light
pulsing hardware can include an optical fiber coupled to a light
source such as a laser diode or LED (as in FIG. 1). The target
cells are then illuminated via the fiber coupled light source. An
example of such an optical neural interface (ONI) is used to
activate ChR2 in an intact animal brain. The interface consists of
an optical fiber guide stereotactically mounted to the skull with
an optical fiber inserted through the guide. The fiber guide is
composed of a cannula embedded in a mounting pedestal. For viral
transduction of neurons, the fiber guide serves as an injection
cannula to deliver the viral vector to the motor cortex. Then
following expression of ChR2, the cannula is used to guide the
optical fiber to the correct location, positioning the tip so the
light beam is registered with the ChR2+ neurons. By using the same
cannula for viral delivery and positioning of the optical fiber,
the system ensures that the light beam is correctly registered to
the ChR2+ neurons. A rat with the ONI implanted can have blue light
transmitted to the ChR2+ neurons. The fiber guide can be attached
with cranioplastic cement and an optical fiber inserted into the
guide.
[0047] Steps 225 and 220 may be performed in either order, or in an
integrated concurrent or simultaneous fashion, and are hence shown
on the same vertical level of FIG. 2, in accordance with
previously-disclosed methods (see e.g., Zhang, F., L. P. Wang, E.
S. Boyden, and K. Deisseroth, "Channelrhodopsin-2 and optical
control of excitable cells", Nat Methods, 2006. 3(10): p. 785-92;
and Aravanis, A. M. et al. An Optical Neural Interface In Vivo
Control of Rodent Motor Cortex with Integrated Fiberoptic and
Optogenetic Technology. Journal of Neural Engineering, 2007, as
well as the above-mentioned patent documents. In step 230 the
stimulation device is turned on, as also described in the
above-mentioned documents.
[0048] Various implementations of the present invention would
activate or affect difference volumes of tissue. Larger volumes of
activation could be important in other settings, for example in
large-scale neural prosthetic applications. However, measurements
and calculations are believed to give rise to a lower limit on
volume of tissue activatable with the ONI. Neurons at higher
physiological temperatures are believed to be more excitable than
those in in vitro experiments in which light power requirements
were quantitatively measured. Moreover, while optical fiber can be
made relatively thin (e.g., 1.27 mm), enlarging the fiber markedly
enlarges the volume of tissue activated (e.g., 20 mm.sup.3 for a 1
mm diameter optical fiber).
[0049] As an example demonstration of the effectiveness of the
present invention as generally applicable to mammalian specimens,
the present invention has been applied to control the respective
motor functions of various species including, for example, rats and
mice. Specifically, by applying the invention to a rat vibrissal
motor cortex, whisker movements are evoked as shown in FIG. 3. Also
in connection with the present invention, it has been discovered
that pulsed blue light delivered via the optical neural interface
repeatedly evokes whisker deflections in the rat of up to
10.degree.. The mean number of whisker deflection events during
stimulation is significantly higher in the ChR2+ rats than in the
ChR2- control rats (p<0.05).
[0050] In accordance with the present invention, FIGS. 3a, 3b and
3c illustrate a specific optical neural interface as demonstrated
to optically control the motor output of a rat. FIG. 3a is a
schematic of a whisker movement measurement arrangement using
optical neural interface to activate rat vibrissal motor cortex:
the blue laser diode was coupled to a 200 .mu.m multi-mode
silica-core optical fiber. The fiber was directed at the motor
cortex using the implanted fiber guide. Blue light (473 nm) was
transmitted to the vibrissal motor cortex via the optical fiber.
Whisker movements were measured magnetically; a magnetic particle
was attached to the contralateral C2 vibrissa and a
magnetoresistive sensor was placed near the particle. Changes in
the voltage were amplified electronically and recorded to a
computer. The signal was high-pass filtered at 10 Hz to remove
low-frequency drift. FIG. 3b shows whisker activity in a ChR2+ rat
in response to a 20 s continuous pulse of blue light. The scale
bars are 5.degree. and 5 s. FIG. 3c shows rat mean whisker activity
pre-stimulus, intra-stimulus, and post-stimulus. The mean number of
whisker twitching events was significantly greater in the ChR2+
rats (lentivirus injected through the fiber guide, n=2) than in the
ChR2- rats (vehicle injected through fiber guide, n=2),
*p<0.05.
[0051] Relative to electrode-based cell stimulation as illustrated
in FIG. 4a, FIG. 4b illustrates optical stimulation of
genetically-targeted cells. FIG. 4b shows ChR2 expression to a
specific neuron population. In this example, ChR2 expression is
specific to the excitatory CaMKII.alpha.-expressing cortical neuron
population. Thus, one embodiment of the optical neural interface is
particularly useful for activating the specific target cells
without affecting other cells (e.g., activating excitatory cortical
neurons and not other cell types such as inhibitory neurons or
glial cells). Embodiments of the present invention also allow for
the use of both electrical and optical stimulation.
[0052] FIG. 5 shows an example of an optical neural interface (ONI)
device for optically stimulating target cells 502. Cannula 506 is
inserted through the skull 504 of the patient. This can be done
using a variety of surgical procedures, such as a sterotatic
surgery. Once cannula 506 is properly positioned, genetic modifiers
are introduced to target cells 502 through cannula 506.
Subsequently, a light deliver mechanism 508 uses cannula 506 to
deliver light to the target cells. In a specific example, light
delivery mechanism 508 includes an optical fiber that is inserted
through cannula 506. Another implementation uses a combination of
mirrors and/or lens elements to direct light to the target
cells.
[0053] Control 510 may modify the properties of the optical pulses
(e.g., frequency, intensity and duration). In a particular
embodiment, control 510 includes one or more lasers that generate
light at a frequency that corresponds to the optical properties of
the target cells. For instance, cells modified with ChR2 have been
shown to respond to light corresponding to wavelengths around 400
to 900 nm, and more particularly, to wavelengths of about 470 nm.
In addition to providing or controlling the wavelength of the
light, the power and temporal characteristics of the light may also
be controlled. By varying the intensity or power of the light, the
strength of the reaction from the target cells 502 may be varied
accordingly. Due to diffusion of the light within the tissue, the
intensity of the light generally reduces as the distance from the
light source increases. Thus, by increasing the intensity of the
light the amount of tissue receiving enough light to activate the
light responsive channels or pumps can be increased.
[0054] According to a specific embodiment of the present invention,
the optical stimulus may be directed at specific target area(s)
within the target tissue. In one instance, micro-Electro-Mechanical
Systems (MEMS) or servo controlled oscillating mirrors can be used
to direct the optical stimulus at a specific location or stimulus
point. The stimulus point can be further focused using an objective
lens. In a particular embodiment, a scanning microscopy technique,
such as laser scanning confocal microscopy, is used to direct the
light toward the desired stimulus point. In this manner, light may
be scanned across the target cells. The effectiveness and/or
results of stimulus at each location within the scan can be
monitored and used to determine the most desirable treatment. In
another instance, a specific target cell area may be targeted or
certain portions of the target cells may be stimulated in a
specific sequence.
[0055] According to another embodiment of the present invention,
the cannula may be inserted near various nerves or muscles. In a
particular example of such a use, the cannula may be inserted near
various portions of the conduction system of the heart. As an
example, the cannula may be inserted near the sinoatrial node (SA)
of a patient who exhibits cardiac pacing abnormalities, such as
tachycardia and bradycardia. The stimulus may then be used to
increase the heart rate (for bradycardia), decrease the heart rate
(for tachycardia) or otherwise control the heart rate. Pacing the
heart using externally generated electrical pulses (e.g., from
electrical contacts) may produce unwanted capture characteristics,
such as long QRS waves, and may also suffer from increasing voltage
thresholds due to anodal blocking. Optical stimulus may be
particularly useful for generating a pseudo-intrinsic pulse (e.g.,
a pulse voltage that originates from an action potential rather
than an electrical contact).
[0056] In various embodiments, the cannula may be implemented with
at least a portion of the cannula that is flexible. For instance,
the cannula may function as a catheter that can be inserted through
veins or arteries and into the heart. A fixation device may be
included to attach one end of the cannula near the target cells.
For further details on catheter devices and their use in cardiac
applications, reference may be made to U.S. Pat. No. 4,559,951 to
Dahl et al. and entitled "Catheter Assembly," which is fully
incorporated herein by reference.
[0057] FIG. 6 shows an example of an optical neural interface used
for endocardial stimulation of the heart; according to an example
embodiment of the present invention. The genetic modifiers are
guided to the desired location using the cannula 602. The cannula
602 is guided into the heart through various techniques, such as
those used in connection with the implantation of electrical pacing
systems. For instance, the cannula can be fed through one of
several veins or arteries into the desired atrium or ventricle of
the heart. In a specific example, the cannula is fed into the right
atrium to a location near the SA 604. The cannula maybe affixed to
(or near) the SA using tines, a screw, barbs or other suitable
attachment mechanisms. The genetic modifiers can then be delivered
to the target neural cells within the SA. Fiber optics is then
inserted through cannula 602 and optical stimulus may then be used
to pace or otherwise control the heart.
[0058] FIG. 7 shows an example of an optical neural interface used
for epicardial stimulation of the heart; according to an example
embodiment of the present invention. The cannula 702 is surgically
implanted near or into the epicardial (exterior wall) of the heart
to allow for stimulus of the target cells 706. The genetic
modifiers and optical stimulus are delivered via the inner lumen
704 of the cannula 702. In some instances, the use of optical
stimulus in place of other stimulus methods, such as electrical
stimulus via electrodes, may result in distinct stimulus
characteristics. For instance, electrical conductivity of tissue
often does not correspond to optical diffusion characteristics,
electrical stimulus may be difficult to direct, and optical
diffusion does not necessarily correspond to electrical fields and
current flow.
[0059] While the invention is not so limited, various aspects of
the invention may be better understood in the context of specific
embodiments of the invention. According to one such embodiment, a
solid-state laser diode that can be pulsed with millisecond
precision and that outputs 20 mW of power at 473 nm is coupled to a
lightweight, flexible multimode optical fiber that is about 200
.mu.m in diameter. Specific targeting of ChR2 in excitatory cells
in vivo may be accomplished using the CaMKII.alpha. promoter. Under
these conditions, the power density of light exiting the fiber
(e.g., around 380 mW/mm) has been found to be sufficient for
driving excitatory neurons in vivo and control motor cortex
function in intact rodents. For animals with naturally occurring
all-trans-retinal (ATR) in sufficient quantities, such as mammals,
no exogenous chemical cofactor is needed.
[0060] The in vivo tissue may produce significant attenuation of
the laser intensity. Notwithstanding, a power density of light
exiting the fiber end at 380 mW/mm.sup.2 is believed to be
sufficient to excite ChR2+ neurons within millimeters of the fiber
end.
[0061] A specific embodiment of the present invention may be
explained in connection with the following methodology as conducted
on mammalian subjects. Rats (male Wistars, 250-350 g) and mice
(female C57/BL6, 25-30 g) were anaesthetized by i.p. injection (90
mg ketamine and 5 mg xylazine per kg of rat body weight). A
concentrated lentivirus solution was stereotactically injected into
the rat motor cortex (anteroposterior=-1.5 mm from bregma;
lateral=1.5 mm; ventral=1.5 mm) using an ONI device. For
electrophysiological experiments, 2 weeks post-injection, 250 .mu.m
cortical slices were prepared in ice-cold cutting buffer (64 mM
NaCl, 25 mM NaHCO.sup.3, 10 mM glucose, 120 mM sucrose, 2.5 mM KCl,
1.25 mM NaH.sub.2PO.sub.4, 0.5 mM CaCl.sub.2 and 7 mM MgCl.sub.2,
equilibrated with 95% O.sub.2/5% CO.sub.2) using a vibratome (VT
1000 S; Leica). After a recovery period of 30 min in cutting buffer
at 32-35.degree. C., slices were gently removed to a recording
chamber mounted on an upright microscope (DM LFSA, Leica) and
continuously perfused at a rate of 3-5 ml/min with carbonated ACSF
(124 mM NaCl, 3 mM KCl, 26 mM NaHCO.sup.3, 1.25 mM
NaH.sub.2PO.sub.4, 2.4 mM CaCl.sub.2, 1.3 mM MgCl.sub.2, 10 mM
Glucose), ventilated with 95% O.sub.2/5% CO.sub.2.
[0062] Motor cortex slices were visualized by standard transmission
optics on an upright fluorescence microscope (DM LFSA; Leica) with
a 20.times., 0.5 NA water immersion objective. mCherry expressing
cells located about 10-30 .mu.m below the surface of the slice were
visualized with a TXRED filter set (TXRED 4040B, exciter 562 nm,
dichroic 530-585 nm, emitter 624 nm; Semrock). Images were recorded
with a cooled CCD camera (Retiga Exi; Qimaging).
Electrophysiological recordings in neurons were performed. For
instance, membrane currents were measured with the patch-clamp
technique in the whole cell voltage-clamp configuration using Axon
Multiclamp 700B (Axon Instruments) amplifiers. Pipette solution
consisted of (in mM): 97 potassium gluconate, 38 KCl, 6 NaCl, 0.35
sodium ATP, 4 magnesium ATP, 0.35 EGTA, 7 phosphocreatine and 20
HEPES (pH 7.25 with KOH). Pipette resistance was 4-8 M.OMEGA.. To
obtain an estimate of the resting potential, the membrane potential
at the time of establishing the whole cell configuration was
recorded. pClamp 9 software (Axon Instruments) was used to record
all data. For ChR2 activation, blue light pulses were generated
using the DG-4 high-speed optical switch with a 300 W xenon lamp
(Sutter Instruments) and a GFP filter set (excitation filter
HQ470/40X, dichroic Q495LP; Chroma). The light pulses were
delivered to the slice through a 20.times. objective lens (NA 0.5;
Leica) yielding a blue light power density of 10 mW/mm.sup.2,
measured with a power meter (1815-C; Newport). Electrophysiological
experiments were performed at room temperature (22-24.degree.
C.).
[0063] Light transmission measurements were conducted with acute
brain slices from a 300 g rat and a 30 g mouse. Brain slices of
thicknesses between 200 .mu.m and 1 mm were cut in 0-4.degree. C.
sucrose solution using a vibratome (Leica; VT1000S). The brain
slices were then placed in a Petri dish containing the same sucrose
solution over the photodetector of a power meter (ThorLabs; S130A).
The tip of a 200 .mu.m optical fiber (BFL37-200; Thorlabs) coupled
to a blue diode laser (473 nm, Crystal Laser) was mounted on a
micromanipulator and then positioned over the cortical tissue in
the slice, normal to the slice and detector. The tip was submerged
into the solution and moved to 1 mm above the tissue surface. Blue
light from the diode laser was delivered to the tissue via the
optical fiber and a measurement of the total light power was
recorded from the power meter. The fiber tip was then translated
horizontally, so that a blank measurement without tissue present
could be taken. For each slice, 1 measurement was taken from each
hemisphere. For each tissue thickness value, 2 different slices
were cut and measured. Transmission fraction was calculated as the
power with tissue present divided by the power with no tissue
present. Transmission of light through the brain slices was modeled
using the Kubelka-Munk model for diffuse scattering media,
T=1/(Sx+1), where T is transmission fraction, S is the scatter
coefficient per unit thickness, and x is the thickness of the
sample. The model assumes that the sample is a planar, homogeneous,
ideal diffuser, and illuminated on one side with diffuse
monochromatic light. The model further assumes that reflection and
absorption are constant over the thickness of the sample. To
further simplify the model, it was also assumed that no absorption
occurs. This assumption is based on previous in vivo and in vitro
data showing that in mammalian brain tissue, transmission loss from
scattering is much greater than loss from absorption for
wavelengths ranging from 400 to 900 nm. Best fit values for S were
11.2 mm.sub.-1 for mouse and 10.3 mm.sub.-1 for rat. The
relationship of power density to tissue penetration distance was
estimated by taking the product of the measured transmission
fraction (remaining light not scattered or absorbed) and the
calculated fractional decrease in power density due to the conical
geometry of emitted light at a given distance in the absence of
tissue scattering and absorption. The geometric decrease in power
density with distance from the fiber end x was calculated using the
NA (0.37) of the optical fiber, I(x)/I(o)=y.sup.2/((Sx+1)(x+
y).sup.2), (geometric component only) where
y = r ( n NA ) 2 - 1 , ##EQU00001##
r is the diameter of the optical fiber, and n is the index of
refraction of grey matter (e.g., 1.36). The complete expression for
power density taking into account both the scattering and geometric
losses is
I ( x ) I ( o ) = y 2 ( Sx + 1 ) ( x + y ) 2 . ##EQU00002##
[0064] Surgeries were performed under aseptic conditions. For
anesthesia, ketamine (90 mg/kg of rat body weight; 16 mg/kg of
mouse body weight) and xylazine (5 mg/kg of rat body weight; 5
mg/kg of mouse body weight) cocktail was injected i.p. The level of
anesthesia was carefully monitored and maintenance doses of
anesthesia were given as needed. Fur was sheared from the top of
the animal's head and the head was placed in a stereotactic
positioning rig. A midline scalp incision was made and a
1-mm-diameter craniotomy was drilled: (rat: anteroposterior=-1.5 mm
from bregma, lateral=1.5 mm); (mouse: anteroposterior=-1 mm from
bregma, lateral=1 mm). A fiber guide (C313G; Plastics1) was then
inserted through the craniotomy to a depth of 1.5 mm in the rat and
1.3 mm in the mouse. Three skull screws (00-96X3/32; Plastics1)
were placed in the skull surrounding the fiber guide pedestal, and
cranioplastic cement (Ortho-Jet; Lang Dental) was used to anchor
the fiber guide system to the skull screws. After 30 minutes, the
free edge of the scalp was brought to the base of the cranioplastic
cement using sutures (3-0 silk; Ethicon) and tissue adhesive
(Vetbond; 3M). A 2 .mu.L aliquot of concentrated lentiviruses in
solution (described above) was slowly injected through the fiber
guide using an internal cannula (C313I; Plastics1) over 5 minutes.
After waiting 10 more minutes for diffusion of the lentivirus, the
internal cannula was withdrawn, and a dummy cannula (C313G;
Plastics1) was inserted to keep the fiber guide open.
[0065] The animals were lightly anesthetized with a 50% dose of the
ketamine and xylazine cocktail described above. For these
experiments animals were kept in only a lightly sedated state,
where whisker deflections spontaneously occurred, as heavier
sedation abolished both spontaneous and evoked responses and with
no sedation the spontaneous activity was so vigorous it obscured
any evoked activity. Whiskers contralateral to the fiber guide
implantation were trimmed to 1 cm in length, and a 1 mg rare-earth
magnetic particle (neodymium-iron-boron; Magcraft) was attached to
the C2 vibrissa. The head was then placed in a stereotactic rig
with minimal pressure applied. To measure whisker movement, a
magnetoresistive sensor (HMC1001; Honeywell) was mounted on a
micromanipulator and moved near the magnetic particle. The signal
was amplified (410; Brownlee) and recorded to a computer. Signals
were high-pass filtered at 10 Hz to remove low-frequency drift
arising from head movement and breathing. Stimulation of ChR2+
neurons was accomplished using a multimode optical fiber (NA 0.37)
with a 200 .mu.m silica core (BFL37-200; Thorlabs) coupled to a 473
nm diode pumped laser (20 mW output power uncoupled; Crystal
Laser). The measured power density emanating from the fiber was 380
mW/mm.sup.2. The distal end of the fiber was polished and the
jacket was stripped; the fiber was inserted into the fiber guide
and advanced until flush with the fiber guide end. The animal was
then allowed to habituate to the setup. Experiments were initiated
once spontaneous whisker twitches greater than 0.5.degree. were
present. During an experimental sweep, 30 s of pre-stimulus data,
20 s of intra-stimulus data (20s pulse of blue light), and 30 s of
post-stimulus data were recorded.
[0066] Three weeks after photo stimulation, a subset of mice were
anesthetized with ketamine/xylazine and sacrificed by transcardial
perfusion with ice cold 4% paraformaldehyde (PFA) in phosphate
buffered saline (PBS). Extracted brains were incubated overnight in
4% PFA/PBS and for 48 hours in 30% sucrose/PBS. 40 .mu.m sections
were cut on a Leica freezing microtome and stored in cryoprotectant
at 4.degree. C. For immunostaining, free-floating sections were
rinsed twice in Tris-buffered saline (TBS, pH 7.5) and blocked for
30 minutes in TBS++ (TBS/0.3% Triton X-100/3% Normal Donkey Serum
[NDS]). Both primary and secondary antibody incubations were
conducted overnight at 4.degree. C. in TBS++ with NDS reduced to
1%; sections were washed repeatedly in TBS after each antibody
incubation. Antibodies used were rabbit anti-dsRed (1:500,
Clontech), mouse anti-CaMKII.alpha. (1:200; Chemicon), mouse
anti-GAD67 (1:500, Chemicon), Cy3 donkey anti-rabbit (1:1000;
Jackson ImmunoResearch), and FITC donkey anti-mouse (1:1000,
Jackson). Stained sections were mounted under PVA-Dabco (Sigma).
Confocal images were acquired on a Leica TCS SP2 microscope.
[0067] One of skill in the art would recognize that these methods
may be used and modified to be applicable for various animals and
human uses. The optical neural interface (ONI) may be particularly
useful in functionally activating ChR2 in an intact animal. One
instance of the interface consisted of an optical fiber guide
stereotactically mounted to the skull with an optical fiber
inserted through the guide. The fiber guide is composed of a
cannula embedded in a mounting pedestal. For viral transduction of
neurons, the fiber guide can serve as an injection cannula to
deliver the viral vector to the motor cortex. Then, following
expression of ChR2, the cannula is used to guide the optical fiber
to the correct location, positioning the tip so the light beam is
registered with the ChR2+ neurons. By using the same cannula for
viral delivery and positioning of the optical fiber, the light beam
is correctly registered to the ChR2+ neurons.
[0068] Acute rat brain slices (2 weeks post-injection through the
fiber guide with lentivirus carrying the ChR2-mCherry fusion
protein) displayed large numbers of red-fluorescent layer 4, 5, and
6 neurons in motor cortex, revealing robust ChR2-mCherry
expression. As expected, and required for the optical interface to
function, the fluorescent neurons were located on the edge of the
potential space created by the fiber guide. At higher
magnification, the red fluorescence appeared to be preferentially
localized to the plasma membrane in these neurons, consistent with
previous observations of mCherry-ChR2 expression. This data
suggested that the targeted expression and spatial registration
functions of the cannula/fiber guide system could be suitable for
implementing an optical neural interface.
[0069] To confirm that functional ChR2 could be expressed in the
targeted excitatory motor neurons of layer 5 motor cortex,
lentivirus carrying the ChR2-mCherry fusion protein under the
control of an excitatory neuron-specific CaMKII.alpha. promoter was
stereotactically injected into rat vibrissal motor cortex, where
brain slices of the injected region made 2 weeks post-injection
showed the expected significant red fluorescence (mCherry) in the
deeper layers of the cortex. In these same slices, it was next
tested whether the level of ChR2 expression in these neurons and
with this promoter would be sufficient to induce the depolarizing
photocurrents required for action potential generation. Indeed,
whole cell recordings obtained from these ChR2+ layer 5 motor
neurons in acute brain slices showed robust spiking in response to
illumination with blue light (473 nm; 10 mW/mm.sup.2 generated by a
300 W xenon lamp and 20.times., 0.5 NA objective) (FIG. 8a). In
fact, the ChR2+ neurons were able to follow photostimulation trains
(10 ms pulses) at 5, 10 and 20 Hz, as shown in FIGS. 8a, 8b and 8c.
Moreover, the neurons generated an action potential for every light
stimulus; FIG. 8d shows that failures were never observed even over
multiple sustained trains of 10 Hz light pulses.
[0070] A fiber-coupled diode laser was evaluated for its ability to
evoke photocurrent induced action potentials. Whole cell recordings
were obtained from a ChR2+ layer 5 motor neuron in acute brain
slices prepared as in FIG. 8a-e, illuminated in this case not by
the xenon lamp and 20.times. objective, but by the polished end of
a 200 .mu.m multi-mode optical fiber. With the fiber tip placed 1
mm away from the microelectrode tip, the closest distance
practically achievable, the neuron perfectly followed a train of
photostimuli at 2 Hz (FIG. 8d). As the frequency increased beyond 2
Hz, there were an increasing number of failures, where the
photocurrents evoked were insufficient to depolarize the neuron to
the threshold of action potential generation. Since the light
intensity exiting the fiber end is quite high (.about.380
mW/mm.sup.2), the decrease in efficacy with fiber illumination at
higher frequencies is likely due to a rapid decrease in the
effective light intensity at significant distances distal to the
fiber tip. Presumably, ChR2+ neurons close to the fiber received a
higher light intensity and therefore followed action potential
trains more reliably.
[0071] The following discussion addresses various physical
processes and device parameters that may be used in determining the
volume of ChR2+ neurons that can be effectively photostimulated.
Such a volume should correspond to the brain volume in which the
light intensity achieved is greater than 1 mW/mm.sup.2, the minimum
intensity required for generation of ChR2-evoked action potentials.
The light intensity exiting the 200 .mu.m diameter optical fiber
tip is sufficiently intense to evoke action potentials (e.g.,
around 380 mW/mm.sup.2). For these experiments, the blue light used
for ChR2 activation (473 nm) is near the ChR2 peak absorption
wavelength, but brain tissue highly scatters and weakly absorbs
light at this wavelength. A direct measurement of the transmission
fraction of total transmitted blue light as a function of distance
through the rat and mouse cortical tissue was made. FIG. 9A shows
that after passing through 100 .mu.m of cortical tissue, total
transmitted light power was reduced by 50%, and by 90% at 1 mm.
Similar results were obtained in rat and mouse tissue, and both
sets of data corresponded very well with the Kubelka-Munk model for
diffuse scattering media, with best fit values for S of 11.2
mm.sup.-1 for mouse and 10.3 mm.sup.-1 for rat.
[0072] In addition to loss of light from scattering and absorption,
light intensity also decreases as a result of the conical spreading
of light after it exits the optical fiber. The light exiting the
multimode fiber is not collimated and spreads with a conical angle
of 32.degree. determined by the numerical aperture of 0.37. This
effect will reduce the power density of light, which may be a
relevant quantitative parameter for determining efficacy of ChR2
stimulation. FIGS. 9A and 9B show the effective light density or
intensity as calculated, taking into account the combined effects
of scattering, absorption, and conical spread. The relationship of
power density to tissue penetration distance was estimated by
taking the product of the measured transmission fraction (total
remaining light not scattered or absorbed) and the calculated
fractional decrease in power density due to the conical geometry of
emitted light at a given distance in the absence of tissue
scattering and absorption. Using these experimental observations
and calculations (e.g., FIG. 9B), the expected volume of tissue
activated by this implementation of the optical neural interface
was estimated. If effective ChR2-induced spiking is achieved at 1
mW/mm.sup.2, then with the current laser diode and fiber optic
technology the optical neural interface in principle will be
capable of evoking spiking in neurons at least up to 1.4 mm from
the fiber tip. This distance value, together with the measured
conical cross-section of 1 mm diameter at 1.4 mm from the fiber
tip, results in a total volume experiencing .gtoreq.1 mW/mm.sup.2
light intensity of .about.0.5 mm.sup.3. This volume represents a
substantial volume of brain tissue on the same order of magnitude
as features on the somatotopic maps on motor cortex, and indicated
to us that the optical design of the neural interface, in
combination with the previously tested genetic design, could
suffice to drive motor cortex function in the intact animal.
[0073] It was also tested whether the optical neural interface
could be used to control motor output. Having demonstrated that
functional ChR2 can be expressed in the deeper layers of vibrissal
motor cortex, it was believed that activation of these neurons
using the optical neural interface would cause detectable whisker
movements. Previous work has shown that electrical stimulation of
vibrissal motor cortex results in whisker deflections, and that
firing of even a single layer 5 or 6 motor neuron will evoke
deflections.
[0074] The laboratory rat is a widely used animal model for many
neurological and psychiatric diseases relevant to brain stimulation
work. However, mice are the ideal animal model for studying genetic
contributions to nervous system physiology and pathology, despite
the fact that mice can be more challenging for neural interface
work due to their much smaller size. Therefore, the optical neural
interfaces were also implanted and tested in mice. FIG. 10A shows
that, as in the rat, 20-second blue light pulses delivered with the
ONI evoked whisker deflections up to 20.degree.. FIG. 10B shows
that the mean number of deflections during the stimulus period was
significantly higher in the ChR2+ mice than in the ChR2- mice
(p<0.05). FIGS. 10C and 10D show that the amplitude of the
whisker deflections demonstrated an increase during the stimulus
period when compared with pre-stimulus period (p<0.05).
Together, these data demonstrate successful implementation of an
optical neural interface.
[0075] Confirmation of whether a select genetically defined set of
neurons were in fact being stimulated via this integrated optical
and genetic technology was obtained by employing
immunohistochemistry to verify that ChR2 was expressed specifically
in the excitatory cortical pyramidal neurons, as hypothesized from
the use of the glutamatergic, neuron-specific, CaMKII.alpha.
promoter to drive ChR2 expression. Fixed brain sections of injected
animals were immunostained as floating sections with an antibody
for dsRed to label ChR2-mCherry, along with antibodies for either
CaMKII.alpha. or glutamate decarboxylase (GAD67), a GABA-producing
enzyme that is specifically expressed in inhibitory interneurons.
Representative confocal images of ChR2/CaMKII.alpha. and ChR2/GAD67
immunostaining were taken for confirmation purposes. Nearly all of
the ChR2-positive cells in the cortex also expressed CaMKII.alpha.,
and almost none expressed GAD67. Thus, ChR2 expression was specific
to the excitatory CaMKII.alpha.-expressing cortical neuron
population. One embodiment of the optical neural interface may be
particularly useful for activating the specific target cells
without affecting other cells (e.g., activating excitatory cortical
neurons and not other cell types such as inhibitory neurons or
glial cells).
[0076] Many human applications of the present invention require
FDA-approval prior to their use. For instance, human use of gene
therapy may require such approval. However, similar gene therapies
in neurons (nonproliferative cells that are non-susceptible to
neoplasms) are proceeding rapidly, with active, FDA-approved
clinical trials already underway involving viral gene delivery to
human brains. This is likely to facilitate the use of various
embodiments of the present invention for a large variety of
applications. The following is a non-exhaustive list of a few
examples of such applications and embodiments.
[0077] Addiction is associated with a variety of brain functions,
including reward and expectation. Additionally, the driving cause
of addiction may vary between individuals. According to one
embodiment, addiction, for example nicotine addiction, may be
treated with optogenetic stabilization of small areas on the
insula. Optionally, functional brain imaging--for example
cued-state PET or fMRI--may be used to locate a hypermetabolic
focus in order to determine a precise target spot for the
intervention on the insula surface.
[0078] Optogenetic excitation of the nucleus accumbens and septum
may provide reward and pleasure to a patient without need for
resorting to use of substances, and hence may hold a key to
addiction treatment. Conversely, optogenetic stabilization of the
nucleus accumbens and septum may be used to decrease drug craving
in the context of addiction. In an alternative embodiment,
optogenetic stabilization of hypermetabolic activity observed at
the genu of the anterior cingulate (BA32) can be used to decrease
drug craving. Optogenetic stabilization of cells within the arcuate
nucleus of the medial hypothalamus which contain peptide products
of pro-opiomelanocortin (POMC) and
cocaine-and-amphetamine-regulating transcript (CART) can also be
used to decrease drug addiction behavior. For further information
in this regard, reference may be made to: Naqvi N H, Rudrauf D,
Damasio H, Bechara A. Damage to the insula disrupts addiction to
cigarette smoking. Science. 2007 Jan. 26; 315(5811):531-534, which
is fully incorporated herein by reference.
[0079] Optogenetic stimulation of neuroendocrine neurons of the
hypothalamic periventricular nucleus that secrete somatostatin can
be used to inhibit secretion of growth hormone from the anterior
pituitary, for example in acromegaly. Optogenetic stabilization of
neuroendocrine neurons that secrete somatostatin or growth hormone
can be used to increase growth and physical development. Among the
changes that accompany "normal" aging, is a sharp decline in serum
growth hormone levels after the 4.sup.th and 5.sup.th decades.
Consequently, physical deterioration associated with aging may be
lessened through optogenetic stabilization of the periventricular
nucleus.
[0080] Optogenetic stabilization of the ventromedial nucleus of the
hypothalamus, particularly the pro-opiomelanocortin (POMC) and
cocaine-and-amphetamine-regulating transcript (CART) of the arcuate
nucleus, can be used to increase appetite, and thereby treat
anorexia nervosa. Alternatively, optogenetic stimulation of the
lateral nuclei of the hypothalamus can be used to increase appetite
and eating behaviors.
[0081] Optogenetic excitation in the cholinergic cells of affected
areas including the temporal lobe, the NBM (Nucleus basalis of
Meynert) and the posterior cingulate gyrus (BA 31) provides
stimulation, and hence neurotrophic drive to deteriorating areas.
Because the affected areas are widespread within the brain, an
analogous treatment with implanted electrodes may be less feasible
than an opto-genetic approach.
[0082] Anxiety disorders are typically associated with increased
activity in the left temporal and frontal cortex and amygdala,
which trends toward normal as anxiety resolves. Accordingly, the
affected left temporal and frontal regions and amygdala may be
treated with optogenetic stabilization, so as to dampen activity in
these regions.
[0083] In normal physiology, photosensitive neural cells of the
retina, which depolarize in response to the light that they
receive, create a visual map of the received light pattern.
Optogenetic ion channels can be used to mimic this process in many
parts of the body, and the eyes are no exception. In the case of
visual impairment or blindness due to damaged retina, a
functionally new retina can be grown, which uses natural ambient
light rather than flashing light patterns from an implanted device.
The artificial retina grown may be placed in the location of the
original retina (where it can take advantage of the optic nerve
serving as a conduit back to the visual cortex). Alternatively, the
artificial retina may be placed in another location, such as the
forehead, provided that a conduit for the depolarization signals
are transmitted to cortical tissue capable of deciphering the
encoded information from the optogenetic sensor matrix. Cortical
blindness could also be treated by simulating visual pathways
downstream of the visual cortex. The stimulation would be based on
visual data produced up stream of the visual cortex or by an
artificial light sensor.
[0084] Treatment of tachycardia may be accomplished with
optogenetic stimulation to parasympathetic nervous system fibers
including CN X or Vagus Nerve. This causes a decrease in the SA
node rate, thereby decreasing the heart rate and force of
contraction. Similarly, optogenetic stabilization of sympathetic
nervous system fibers within spinal nerves T1 through T4, serves to
slow the heart. For the treatment of pathological bradycardia,
optogenetic stabilization of the Vagus nerve, or optogenetic
stimulation of sympathetic fibers in T1 through T4 will serve to
increase heart rate. Cardiac disrhythmias resulting from aberrant
electrical foci that outpace the sinoatrial node may be suppressed
by treating the aberrant electrical focus with moderate optogenetic
stabilization. This decreases the intrinsic rate of firing within
the treated tissue, and permits the sinoatrial node to regain its
role in pacing the heart's electrical system. In a similar way, any
type of cardiac arrhythmia could be treated. Degeneration of
cardiac tissue that occurs in cardiomyopathy or congestive heart
failure could also be treated using this invention; the remaining
tissue could be excited using various embodiments of the
invention.
[0085] Optogenetic excitation stimulation of brain regions
including the frontal lobe, parietal lobes and hippocampi, may
increase processing speed, improve memory, and stimulate growth and
interconnection of neurons, including spurring development of
neural progenitor cells. As an example, one such application of the
present invention is directed to optogenetic excitation stimulation
of targeted neurons in the thalamus for the purpose of bringing a
patient out of a near-vegetative (barely-conscious) state.
Consistent with the flow chart of FIG. 2 and other embodiments
discussed herein, an elongated delivery structure is inserted into
a narrow passageway of the patient's skull for inducing growth of
light-gated ion channels or pumps in the membrane of targeted
thalamus neurons. These modified neurons are then stimulated, e.g.,
via optics which may also gain access by the same passageway, by
directing a flash of light thereupon so as to modulate the function
of the targeted neurons and/or surrounding cells. For further
information regarding appropriate modulation techniques (via
electrode-based treatment) or further information regarding the
associated brain regions for such patients, reference may be made
to: Schiff N D, Giacino J T, Kalmar K, Victor J D, Baker K, Gerber
M, Fritz B, Eisenberg B, O'Connor J O, Kobylarz E J, Farris S,
Machado A, McCagg C, Plum F, Fins J J, Rezai A R. Behavioral
improvements with thalamic stimulation after severe traumatic brain
injury. Nature. Vol 448. Aug. 2, 2007 pp 600-604.
[0086] In an alternative embodiment, optogenetic excitation may be
used to treat weakened cardiac muscle in conditions such as
congestive heart failure. Electrical assistance to failing heart
muscle of CHF is generally not practical, due to the
thin-stretched, fragile state of the cardiac wall, and the
difficulty in providing an evenly distributed electrical coupling
between an electrodes and muscle. For this reason, preferred
methods to date for increasing cardiac contractility have involved
either pharmacological methods such as Beta agonists, and
mechanical approaches such as ventricular assist devices. In this
embodiment of the present invention, optogenetic excitation is
delivered to weakened heart muscle via light emitting elements on
the inner surface of a jacket surround the heart or otherwise
against the affected heart wall. Light may be diffused by means
well known in the art, to smoothly cover large areas of muscle,
prompting contraction with each light pulse.
[0087] Optogenetic stabilization in the subgenual portion of the
cingulate gyms (Cg25), yellow light may be applied with an
implanted device. The goal would be to treat depression by
suppressing target activity in manner analogous to what is taught
by Mayberg H S et al., Deep Brain Stimulation for
Treatment-Resistant Depression. Neuron, Vol. 45, 651-660, Mar. 3,
2005, 651-660, which is fully incorporated herein by reference. In
an alternative embodiment, an optogenetic excitation stimulation
method is to increase activity in that region in a manner analogous
to what is taught by Schlaepfer et al., Deep Brain stimulation to
Reward Circuitry Alleviates Anhedonia in Refractory Major
Depression, Neuropsychopharmacology 2007 1-10, which is fully
incorporated herein by reference. In yet another embodiment the
left dorsolateral prefrontal cortex (LDPFC) is targeted with an
optogenetic excitation stimulation method. Pacing the LDLPFC at
5-20 Hz serves to increase the basal metabolic level of this
structure which, via connecting circuitry, serves to decrease
activity in Cg 25, improving depression in the process. Suppression
of the right dorsolateral prefrontal cortex (RDLPFC) is also an
effective depression treatment strategy. This may be accomplished
by optogenetic stabilization on the RDLPFC, or suppression may also
be accomplished by using optogenetic excitation stimulation, and
pulsing at a slow rate--1 Hz or less, improving depression in the
process. Vagus nerve stimulation (VNS) may be improved using an
optogenetic approach. Use of optogenetic excitation may be used in
order to stimulate only the vagus afferents to the brain, such as
the nodose ganglion and the jugular ganglion. Efferents from the
brain would not receive stimulation by this approach, thus
eliminating some of the side-effects of VNS including discomfort in
the throat, a cough, difficulty swallowing and a hoarse voice. In
an alternative embodiment, the hippocampus may be optogenetically
excited, leading to increased dendritic and axonal sprouting, and
overall growth of the hippocampus. Other brain regions implicated
in depression that could be treated using this invention include
the amygdala, accumbens, orbitofrontal and orbitomedial cortex,
hippocampus, olfactory cortex, and dopaminergic, serotonergic, and
noradrenergic projections. Optogenetic approaches could be used to
control spread of activity through structures like the hippocampus
to control depressive symptoms.
[0088] So long as there are viable alpha and beta cell populations
in the pancreatic islets of Langerhans, the islets can be targeted
for the treatment of diabetes. For example, when serum glucose is
high (as determined manually or by closed loop glucose detection
system), optogenetic excitation may be used to cause insulin
release from the beta cells of the islets of Langerhans in the
pancreas, while optogenetic stabilization is used to prevent
glucagon release from the alpha cells of the islets of Langerhans
in the pancreas. Conversely, when blood sugars are too low (as
determined manually or by closed loop glucose detection system),
optogenetic stabilization may be used to stop beta cell secretion
of insulin, and optogenetic excitation may be used to increase
alpha-cell secretion of glucagon.
[0089] For treatment of epilepsy, quenching or blocking
epileptogenic activity is amenable to optogenetic approaches. Most
epilepsy patients have a stereotyped pattern of activity spread
resulting from an epileptogenic focus Optogenetic stabilization
could be used to suppress the abnormal activity before it spreads
or truncated it early in its course. Alternatively, activation of
excitatory tissue via optogenetic excitation stimulation could be
delivered in a series of deliberately ansynchronous patterns to
disrupt the emerging seizure activity. Another alternative involves
the activation of optogenetic excitation stimulation in GABAergic
neurons to provide a similar result. Thalamic relays may be
targeted with optogenetic stabilization triggered when an abnormal
EEG pattern is detected.
[0090] Another embodiment involves the treatment of
gastrointestinal disorders. The digestive system has its own,
semi-autonomous nervous system containing sensory neurons, motor
neurons and interneurons. These neurons control movement of the GI
tract, as well as trigger specific cells in the gut to release
acid, digestive enzymes, and hormones including gastrin,
cholecystokinin and secretin. Syndromes that include inadequate
secretion of any of these cellular products may be treated with
optogenetic stimulation of the producing cell types, or neurons
that prompt their activity. Conversely, optogenetic stabilization
may be used to treat syndromes in which excessive endocrine and
exocrine products are being created. Disorders of lowered
intestinal motility, ranging from constipation (particularly in
patients with spinal cord injury) to megacolan may be treated with
optogenetic excitation of motor neurons in the intestines.
Disorders of intestinal hypermotility, including some forms of
irritable bowel syndrome may be treated with optogenetic
stabilization of neurons that control motility. Neurogentic gastric
outlet obstructions may be treated with optogenetic stabilization
of neurons and musculature in the pyloris. An alternative approach
to hypomobility syndromes would be to provide optogenetic
excitation to stretch-sensitive neurons in the walls of the gut,
increasing the signal that the gut is full and in need of
emptying.
[0091] In this same paradigm, an approach to hypermobility
syndromes of the gut would be to provide optogenetic stabilization
to stretch receptor neurons in the lower GI, thus providing a
"false cue" that the gut was empty, and not in need of emptying. In
the case of frank fecal incontinence, gaining improved control of
the internal and external sphincters may be preferred to slowing
the motility of the entire tract. During periods of time during
which a patient needs to hold feces in, optogenetic excitation of
the internal anal sphincter will provide for retention. Providing
optogenetic stimulation to the external sphincter may be used to
provide additional continence. When the patient is required to
defecate, the internal anal sphincter, and then external anal
sphincter should be relaxed, either by pausing the optogenetic
stimulation, or by adding optogenetic stabilization.
[0092] Conductive hearing loss may be treated by the use of optical
cochlear implants. Once the cochlea has been prepared for
optogenetic stimulation, a cochlear implant that flashes light may
be used. Sensorineural hearing loss may be treated through optical
stimulation of downstream targets in the auditory pathway.
[0093] Another embodiment of the present invention is directed
toward the treatment of blood pressure disorders, such as
hypertension. Baroreceptors and chemoreceptors in regions such as
the aorta (aortic bodies and paraaortic bodies) and the carotid
arteries ("carotic bodies") participate the regulation of blood
pressure and respiration by sending afferents via the vagus nerve
(CN X), and other pathways to the medulla and pons, particularly
the solitary tract and nucleus. Optogentetic excitation of the
carotid bodies, aortic bodies, paraortic bodies, may be used to
send a false message of "hypertension" to the solitary nucleus and
tract, causing it to report that blood pressure should be
decreased. Optogenetic excitation or stabilization directly to
appropriate parts of the brainstem may also be used to lower blood
pressure. The opposite modality causes the optogenetic approach to
serve as a pressor, raising blood pressure. A similar effect may
also be achieved via optogenetic excitation of the Vagus nerve, or
by optogenetic stabilization of sympathetic fibers within spinal
nerves T1-T4. In an alternative embodiment, hypertension may be
treated with optogenetic stabilization of the heart, resulting in
decreased cardiac output and lowered blood pressure. According to
another embodiment, optogentic stabilization of
aldosterone-producing cells within the adrenal cortex may be used
to decrease blood pressure. In yet another alternative embodiment,
hypertension may be treated by optogenetic stabilization of
vascular smooth muscle. Activating light may be passed
transcutaneously to the peripheral vascular bed.
[0094] Another example embodiment is directed toward the treatment
of hypothalamic-pituitary-adrenal axis disorders. In the treatment
of hypothyroidism, optogenetic excitation of parvocellular
neuroendocrine, neurons in the paraventricular and anterior
hypothalamic nuclei can be used to increase secretion of
thyrotropin-releasing hormone (TRH). TRH, in turn, stimulates
anterior pituitary to secrete TSH. Converely, hyperthyroidism may
be treated with optogenetic stabilization of the provocellular
neuroendocrine neurons. For the treatment of adrenal insufficiency,
or of Addison's disease, optogenetic excitation of parvocellular
neuroendocrine neurons in the supraoptic nucleus and
paraventricular nuclei may be used to increase the secretion of
vasopressin, which, with the help of corticotropin-releasing
hormone (CRH), stimulate anterior pituitary to secrete ACTH.
Cushing syndrome, frequently caused by excessive ACTH secretion,
may be treated with optogenetic stabilization of the parvocellular
neuroendocrine neurons of supraoptic nucleus via the same
physiological chain of effects described above. Neuroendocrine
neurons of the arcuate nucleus produce dopamine, which inhibits
secretion of prolactin from the anterior pituitary.
Hyperprolactinemia can therefore be treated via optogenetic
excitation, while hypoprolactinemia can be treated with optogenetic
stabilization of the neuroendocrine cells of the arcuate
nucleus.
[0095] In the treatment of hyperautonomic states, for example
anxiety disorders, optogenetic stabilization of the adrenal medulla
may be used to reduce norepinephrine output. Similarly, optogenetic
stimulation of the adrenal medulla may be used in persons with need
for adrenaline surges, for example those with severe asthma, or
disorders that manifest as chronic sleepiness.
[0096] Optogenetic stimulation of the adrenal cortex will cause
release of chemicals including cortisol, testosterone, and
aldosterone. Unlike the adrenal medualla, the adrenal cortex
receives its instructions from neuroendocrine hormones secreted
from the pituitary and hypothalamus, the lungs, and the kidneys.
Regardless, the adrenal cortex is amenable to optogenetic
stimulation. Optogenetic stimulation of the cortisol-producing
cells of the adrenal cortex may be used to treat Addison's disease.
Optogenetic stabilization of cortisol-producing cells of the
adrenal cortex may be used to treat Cushing's disease. Optogenetic
stimulation of testosterone-producing cells may be used to treat
disorders of sexual interest in women: Optogenetic stabilization of
those same cells may be used to decrease facial hair in women.
Optogenetic stabilization of aldosterone-producing cells within the
adrenal cortex may be used to decrease blood pressure. Optogenetic
excitation of aldosterone-producing cells within the adrenal cortex
may be used to increase blood pressure.
[0097] Optogenetic excitation stimulation of specific affected
brain regions may be used to increase processing speed, and
stimulate growth and interconnection of neurons, including spurring
the maturation of neural progenitor cells as in Deisseroth et al.,
2004. Such uses can be particularly useful for treatment of mental
retardation.
[0098] According to another embodiment of the present invention,
various muscle diseases and injuries can be treated. Palsies
related to muscle damage, peripheral nerve damage and to dystrophic
diseases can be treated with optogenetic excitation to cause
contraction, and optogenetic stabilization to cause relaxation.
This latter relaxation via optogenetic stabilization approach can
also be used to prevent muscle wasting, maintain tone, and permit
coordinated movement as opposing muscle groups are contracted.
Likewise, frank spasticity can be treated via optogenetic
stabilization.
[0099] In areas as diverse as peripheral nerve truncation, stroke,
traumatic brain injury and spinal cord injury, there is a need to
foster the growth of new neurons, and assist with their integration
into a functional network with other neurons and with their target
tissue. Re-growth of new neuronal tracts may be encouraged via
optogenetic excitation, which serves to signal stem cells to sprout
axons and dendrites, and to integrate themselves with the network.
Use of an optogenetic technique (as opposed to electrodes) prevents
receipt of signals by intact tissue, and serves to ensure that new
target tissue grows by virtue of a communication set up with the
developing neurons, and not with an artificial signal like current
emanating from an electrode.
[0100] Obesity can be treated with optogenetic excitation to the
ventromedial nucleus of the hypothalamus, particularly the
pro-opiomelanocortin (POMC) and cocaine-and-amphetamine-regulating
transcript (CART) of the arcuate nucleus. In an alternative
embodiment, obesity can be treated via optogenetic stabilization of
the lateral nuclei of the hypothalamus. In another embodiment,
optogenetic stimulation to leptin-producing cells, or to cells with
leptin receptors within the hypothalamus may be used to decrease
appetite and hence treat obesity.
[0101] Destructive lesions to the anterior capsule and analogous
DBS to that region are established means of treating severe,
intractable obsessive-compulsive disorder 48 (OCD48). Such
approaches may be emulated using optogenetic stabilization to the
anterior limb of the internal capsule, or to regions such as BA32
and Cg24 which show metabolic decrease as OCD remits.
[0102] Chronic Pain can be treated using another embodiment of the
present invention. Electrical stimulation methods include local
peripheral nerve stimulation, local cranial nerve stimulation and
"subthreshold" motor cortex stimulation. Reasonable optogenic
approaches include optogenetic stabilization at local painful
sites. Attention to promoter selection would ensure that other
sensory and motor fibers would be unaffected. Selective optogenetic
excitation of interneurons at the primary motor cortex also may
provide effective pain relief. Also, optogenetic stabilization at
the sensory thalamus, (particularly medial thalamic nuclei),
periventricular grey matter, and ventral raphe nuclei, may be used
to produce pain relief. In an alternative embodiment, optogenetic
stabilization of parvalbumin-expressing cells targeting as
targeting strategy, may be used to treat pain by decreasing
Substance P production. The release of endogenous opiods may be
accomplished by using optogenetic excitation to increase activity
in the nucleus accumbens. In an alternative embodiment, when POMC
neurons of the arcuate nucleus of the medial hypothalamus are
optogenetically excited, beta endorphin are increased, providing
viable treatment approaches for depression and for chronic
pain.
[0103] Parkinson's Disease can be treated by expressing optogenetic
stabilization in the glutamatergic neurons in either the
subthalamic nucleus (STN) or the globus pallidus interna (GPi)
using an excitatory-specific promoter such as CaMKII.alpha., and
apply optogenetic stabilization. Unlike electrical modulation in
which all cell-types are affected, only glutamatergic STN neurons
would be suppressed.
[0104] Certain personality disorders, including the borderline and
antisocial types, demonstrate focal deficits in brain disorders
including "hypofrontality." Direct or indirect optogenetic
excitation of these regions is anticipated to produce improvement
of symptoms. Abnormal bursts of activity in the amygdala are also
known to precipitate sudden, unprompted flights into rage: a
symptom of borderline personality disorder, as well as other
conditions, which can benefit from optogenetic stabilization of the
amygdala. Optogenetic approaches could improve communication and
synchronization between different parts of the brain, including
amygdala, striatum, and frontal cortex, which could help in
reducing impulsiveness and improving insight.
[0105] The amygdalocentric model of post-traumatic-stress disorder
(PTSD) proposes that it is associated with hyperarousal of the
amygdala and insufficient top-down control by the medial prefrontal
cortex and the hippocampus. Accordingly, PTSD may be treated with
optogenetic stabilization of the amygdale or hippocampus.
[0106] Schizophrenia is characterized by abnormalities including
auditory hallucinations. These might be treated by suppression of
the auditory cortex using optogenetic stabilization. Hypofrontality
associated with schizophrenia might be treated with optogenetic
excitation in the affected frontal regions. Optogenetic approaches
could improve communication and synchronization between different
parts of the brain which could help in reducing misattribution of
self-generated stimuli as foreign.
[0107] Optogenetic stabilization of cells within the arcuate
nucleus of the medial hypothalamus, which contain peptide products
of pro-opiomelanocortin (POMC) and
cocaine-and-amphetamine-regulating transcript (CART) can be used to
reduce compulsive sexual behavior. Optogentic excitation of cells
within the arcuate nucleus of the medial hypothalamus which contain
peptide products of pro-opiomelanocortin (POMC) and
cocaine-and-amphetamine-regulating transcript (CART) may be used to
increase sexual interest in the treatment of cases of disorders of
sexual desire. In the treatment of disorders of hypoactive sexual
desire testosterone production by the testes and the adrenal glands
can be increased through optogenetic excitation of the pituitary
gland. Optogentic excitation of the nucleus accumbens can be used
for the treatment of anorgasmia.
[0108] The suprachiasmatic nucleus secretes melatonin, which serves
to regulate sleep/wake cycles. Optogenetic excitation to the
suprachiasmic nucleus can be used to increase melatonin production,
inducing sleep, and thereby treating insomnia. Orexin (hypocretin)
neurons strongly excite numerous brain nuclei in order to promote
wakefulness. Optogentetic excitation of orexin-producing cell
populations can be used to treat narcolepsy, and chronic daytime
sleepiness.
[0109] Optogenetic stimulation of the supraoptic nucleus may be
used to induce secretion of oxytocin, can be used to promote
parturition during childbirth, and can be used to treat disorders
of social attachment.
[0110] Like muscular palsies, the motor functions that have been
de-afferented by a spinal cord injury may be treated with
optogenetic excitation to cause contraction, and optogenetic
stabilization to cause relaxation. This latter relaxation via
optogenetic stabilization approach may also be used to prevent
muscle wasting, maintain tone, and permit coordinated movement as
opposing muscle groups are contracted. Likewise, frank spasticity
may be treated via optogenetic stabilization. Re-growth of new
spinal neuronal tracts may be encouraged via optogenetic
excitation, which serves to signal stem cells to sprout axons and
dendrites, and to integrate themselves with the network.
[0111] Stroke deficits include personality change, motor deficits,
sensory deficits, cognitive loss, and emotional instability. One
strategy for the treatment of stroke deficits is to provide
optogenetic stimulation to brain and body structures that have been
deafferented from excitatory connections. Similarly, optogenetic
stabilization capabilities can be imparted on brain and body
structures that have been deafferented from inhibitory
connections.
[0112] Research indicates that the underlying pathobiology in
Tourette's syndrome is a phasic dysfunction of dopamine
transmission in cortical and subcortical regions, the thalamus,
basal ganglia and frontal cortex. In order to provide therapy,
affected areas are preferably first identified using techniques
including functional brain imaging and magnetoencephalography
(MEG). Whether specifically identified or not, optogenetic
stabilization of candidate tracts may be used to suppress motor
tics. Post-implantation empirical testing of device parameters
reveals which sites of optogenetic stabilization, and which are
unnecessary to continue.
[0113] In order to treat disorders of urinary or fecal incontinence
optogenetic stabilization can be used to the sphincters, for
example via optogenetic stabilization of the bladder detrussor
smooth muscle or innervations of that muscle. When micturation is
necessary, these optogenetic processes are turned off, or
alternatively can be reversed, with optogenetic stabilization to
the (external) urinary sphincter, and optogenetic excitation of the
bladder detrussor muscle or its innervations. When a bladder has
been deafferentated, for example, when the sacral dorsal roots are
cut or destroyed by diseases of the dorsal roots such as tabes
dorsalis in humans, all reflex contractions of the bladder are
abolished, and the bladder becomes distended. Optogenetic
excitation of the muscle directly can be used to restore tone to
the detrussor, prevent kidney damage, and to assist with the
micturition process. As the bladder becomes "decentralized" and
hypersensitive to movement, and hence prone to incontinence,
optogenetic stabilization to the bladder muscle can be used to
minimize this reactivity of the organ.
[0114] In order to selectively excite/inhibit a given population of
neurons, for example those involved in the disease state of an
illness, several strategies can be used to target the optogenetic
proteins/molecules to specific populations.
[0115] For various embodiments of the present invention, genetic
targeting may be used to express various optogenetic proteins or
molecules. Such targeting involves the targeted expression of the
optogenetic proteins/molecules via genetic control elements such as
promoters (e.g. Parvalbumin, Somatostatin, Cholecystokinin, GFAP),
enhancers/silencers (e.g. Cytomaglovirus Immediate Early Enhancer),
and other transcriptional or translational regulatory elements
(e.g. Woodchuck Hepatitis Virus Post-transcriptional Regulatory
Element). Permutations of the promoter+enhancer+regulatory element
combination can be used to restrict the expression of optogenetic
probes to genetically-defined populations.
[0116] Various embodiments of the present invention may be
implemented using spatial/anatomical targeting. Such targeting
takes advantage of the fact that projection patterns of neurons,
virus or other reagents carrying genetic information (DNA plasmids,
fragments, etc), can be focally delivered to an area where a given
population of neurons project to. The genetic material will then be
transported back to the bodies of the neurons to mediate expression
of the optogenetic probes. Alternatively, if it is desired to label
cells in a focal region, viruses or genetic material may be focally
delivered to the interested region to mediate localized
expression.
[0117] Various gene delivery systems are useful in implementing one
or more embodiments of the present invention. One such delivery
system is Adeno-Associated Virus (AAV). AAV can be used to deliver
a promoter+optogenetic probe cassett to a specific region of
interest. The choice of promoter will drive expression in a
specific population of neurons. For example, using the
CaMKII.alpha. promoter will drive excitatory neuron specific
expression of optogenetic probes. AAV will mediate long-term
expression of the optogenetic probe for at least 1 year or more. To
achieve more specificity, AAV may be pseudotyped with specific
serotypes 1 to 8, with each having different trophism for different
cell types. For instance, serotype 2 and 5 is known to have good
neuron-specific trophism.
[0118] Another gene deliver mechanism is the use of a retrovirus.
HIV or other lentivirus-based retroviral vectors may be used to
deliver a promoter+optogenetic probe cassette to a specific region
of interest. Retroviruses may also be pseudotyped with the Rabies
virus envelope glycoprotein to achieve retrograde transport for
labeling cells based on their axonal projection patterns.
Retroviruses integrate into the host cell's genome, therefore are
capable of mediating permanent expression of the optogenetic
probes. Non-lentivirus based retroviral vectors can be used to
selectively label dividing cells.
[0119] Gutless Adenovirus and Herpes Simplex Virus (HSV) are two
DNA based viruses that can be used to deliver promoter+optogenetic
probe cassette into specific regions of the brain as well. HSV and
Adenovirus have much larger packaging capacities and therefore can
accommodate much larger promoter elements and can also be used to
deliver multiple optogenetic probes or other therapeutic genes
along with optogenetic probes.
[0120] Focal Electroporation can also be used to transiently
transfect neurons. DNA plasmids or fragments can be focally
delivered into a specific region of the brain. By applying mild
electrical current, surrounding local cells will receive the DNA
material and expression of the optogenetic probes.
[0121] In another instance, lipofection can be used by mixing
genetic material with lipid reagents and then subsequently injected
into the brain to mediate transfect of the local cells.
[0122] Various embodiments involve the use of various control
elements. In addition to genetic control elements, other control
elements (particularly promoters and enhancers whose activities are
sensitive to chemical, magnetic stimulation, or infrared radiation)
can be used to mediate temporally-controlled expression of the
optogenetic probes. For example, a promoter whose transcriptional
activity is subject to infrared radiation allows one to use focused
radiation to fine tune the expression of optogenetic probes in a
focal region at only the desired time.
[0123] According to one embodiment of the present invention, the
ONI device may be used in animal models of DBS, for example in
Parkinsonian rats, to identify the target cell types responsible
for therapeutic effects (an area of intense debate and immense
clinical importance). This knowledge alone may lead to the
development of improved pharmacological and surgical strategies for
treating human disease.
[0124] According to another embodiment of the present invention,
genetically-defined cell types may be linked with complex
systems-level behaviors, and may allow the elucidation of the
precise contribution of different cell types in many different
brain regions to high-level organismal functioning.
[0125] For further information, citations and background
information related to implementation of the above-discussed
embodiments, reference may be made to the following documents, each
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separated detection and stimulation electrodes. [0129] U.S. Pat.
No. 6,480,743 System and method for adaptive brain stimulation.
[0130] U.S. Pat. No. 6,473,639 Neurological event detection
procedure using processed display channel based algorithms and
devices incorporating these procedures. [0131] U.S. Pat. No.
6,161,045 Method for determining stimulation parameters for the
treatment of epileptic seizures. [0132] U.S. Pat. No. 6,134,474
Responsive implantable system for the treatment of neurological
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[0145] The various embodiments described above are provided by way
of illustration only and should not be construed to limit the
invention. Based on the above discussion and illustrations, those
skilled in the art will readily recognize that various
modifications and changes may be made to the present invention
without strictly following the exemplary embodiments and
applications illustrated and described herein. For example, such
modifications include combining teachings of the various patent
documents cited herein; including as just one example, combining
aspects of the teaching from the teachings of above-identified
application Ser. No. 11/651,422 entitled System for Optical
Stimulation of Target Cells (STFD.150PA). Such a combination
realizes many advantages expressly discussed in each of these
patent documents. Such modifications and changes do not depart from
the true spirit and scope of the present invention, which is set
forth in the following claims.
* * * * *