U.S. patent application number 10/978818 was filed with the patent office on 2005-06-30 for calibration systems and methods for neural interface devices.
Invention is credited to Branner, Almut, Caplan, Abraham H., Donoghue, John P., Flaherty, J. Christopher, Korver, Kirk F., Saleh, Maryam, Serruya, Mijail D..
Application Number | 20050143589 10/978818 |
Document ID | / |
Family ID | 34594943 |
Filed Date | 2005-06-30 |
United States Patent
Application |
20050143589 |
Kind Code |
A1 |
Donoghue, John P. ; et
al. |
June 30, 2005 |
Calibration systems and methods for neural interface devices
Abstract
A system and method for a neural interface system with integral
calibration elements may include a sensor including a plurality of
electrodes to detect multicellular signals, an interface to process
the signals from the sensor into a suitable control signal for a
controllable device, such as a computer or prosthetic limb, and an
integrated calibration routine to efficiently create calibration
output parameters used to generate the control signal. A graphical
user interface may be used to make various portions of the
calibration and signal processing configuration more efficient and
effective.
Inventors: |
Donoghue, John P.;
(Providence, RI) ; Flaherty, J. Christopher;
(Topsfield, MA) ; Serruya, Mijail D.; (Providence,
RI) ; Caplan, Abraham H.; (Cambridge, MA) ;
Saleh, Maryam; (Providence, RI) ; Korver, Kirk
F.; (Salt Lake City, UT) ; Branner, Almut;
(Salt Lake City, UT) |
Correspondence
Address: |
FINNEGAN, HENDERSON, FARABOW, GARRETT & DUNNER
LLP
901 NEW YORK AVENUE, NW
WASHINGTON
DC
20001-4413
US
|
Family ID: |
34594943 |
Appl. No.: |
10/978818 |
Filed: |
November 2, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60519047 |
Nov 9, 2003 |
|
|
|
Current U.S.
Class: |
552/650 |
Current CPC
Class: |
A61B 5/24 20210101; A61B
5/0006 20130101; G06F 3/015 20130101; G16H 40/40 20180101; G06F
19/00 20130101 |
Class at
Publication: |
552/650 |
International
Class: |
G01B 007/00 |
Claims
1-159. (canceled)
160. A neural interface system comprising: a sensor configured to
detect multicellular signals emanating from the central nervous
system of a patient, the sensor comprising a plurality of
electrodes for chronic detection of the multicellular signals; an
interface configured to receive the multicellular signals from the
sensor and process the multicellular signals to produce processed
signals, the interface being further configured to transmit the
processed signals to a controlled device; the controlled device
configured to receive the processed signals; and an integrated
calibration system configured to perform a calibration routine to
generate one or more calibration output parameters for use by the
interface to produce processed signals; wherein the calibration
routine is configured to be performed by an operator at least one
time during the use of the system.
161. The system of claim 160 wherein the sensor and the interface
are implanted in the patient.
162. The system of claim 160 wherein the controlled device is
implanted in the patient.
163. The system of claim 160 wherein the sensor and interface are
connected by one or more physical cables that include one or more
of the group consisting of: electrical wires and optical
fibers.
164. The system of claim 160 wherein at least one of the sensor and
the interface includes wireless transmission or receiving
capability.
165. The system of claim 160 wherein the sensor includes a
multi-electrode array.
166. The system of claim 160 wherein the sensor includes multiple
wires or wire bundle electrodes.
167. The system of claim 160 wherein the electrodes are configured
to detect one or more of the following types of multicellular
signals: neuron spikes, electrocorticogram signals, local field
potential signals and electroencephalogram signals.
168. The system of claim 160 wherein the electrodes are configured
to detect multicellular signals from clusters of neurons and
provide signals midway between single neuron and
electroencephalogram recordings.
169. The system of claim 160 wherein at least one of the electrodes
is configured to record a plurality of neurons.
170. The system of claim 160 wherein the interface includes an
element configured to amplify the multicellular signals.
171. The system of claim 160 wherein the interface includes a
processing unit external to the skull of the patient.
172. The system of claim 160 further comprising means for storing
the calibration output parameters in memory.
173. The system of claim 160 further comprising a monitor for
displaying signals received from the sensor.
174. The system of claim 160 further comprising a memory storage
module for storing information collected during the calibration
routine.
175. The system of claim 160 further comprising means for testing
calibration performance.
176. A neural signal processing unit comprising: an input port for
multiple neural signal input; and a graphical user interface
comprising: a display monitor for displaying information from
multiple individual neural signals; and an input device for
selecting graphical representations of neural signals and graphical
representations of parameter values on the display monitor, wherein
multiple neural signals are selected with the input device and
properties associated multiple individual neural signals are
changed simultaneously.
177. A method of calibrating a neural interface system, comprising:
providing a neural interface system comprising: a sensor configured
to detect multicellular signals emanating from the central nervous
system of a patient, the sensor comprising a plurality of
electrodes for chronic detection of the multicellular signals; 2p1
an interface configured to receive the multicellular signals from
the sensor and process the multicellular signals to produce
processed signals, the interface being further configured to
transmit the processed signals to a controlled device; and the
controlled device configured to receive the processed signals; and
calibrating the neural interface system to generate one or more
calibration output parameters for use by the neural interface
system to generate the processed signals.
178. The method of claim 177 wherein calibrating comprises: setting
a preliminary set of calibration output parameters; generating
processed signals to control the controlled device; measuring the
performance of the controlled device control; and modifying the
calibration output parameters.
179. The method of claim 177 wherein the step of calibrating is
performed with patient participation.
180. The method of claim 179 wherein the patient participation
includes using one or more cues from the following group: audio
cues, visual cues, olfactory cues, and tactile cues.
181. The method of claim 179 wherein the patient participation
includes the patient imagining multiple movements.
182. The method of claim 181 further comprising comparing the
multiple imagined movements to select the calibration output
parameters.
183. The method of claim 177 further comprising using one or more
calibration input parameters to determine the calibration output
parameters.
184. The method of claim 177 further comprising categorizing one or
more multicellular signals into three or more classifications for
further processing into the processed signal for transmission to
the controlled device.
186. The method of claim 177 further comprising storing the
calibration output parameters in memory.
187. The method of claim 177 further comprising displaying signals
received from the sensor on a display monitor.
Description
[0001] This application claims the benefit of priority under 35
U.S.C. .sctn. 119(e) of U.S. provisional application No.
60/519,047, filed Nov. 9, 2003.
DESCRIPTION OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to systems and methods for
calibrating neural interface devices, and, more particularly, to
calibration systems and methods for neural interface devices
employing mufti-electrode sensors for detecting neuronal
activity.
[0004] 2. Description of Related Art
[0005] Neural interface devices are currently under development for
numerous applications involving restoration of lost function due to
traumatic injury or neurological disease. Sensors, such as
electrode arrays, implanted in the higher brain regions that
control voluntary movement can be activated voluntarily to generate
electrical signals that can be processed by a neural interface
device to create a thought invoked control signal. Such control
signals can be used to control numerous devices including computers
and communication devices, external prostheses, such as an
artificial arm or functional electrical stimulation of paralyzed
muscles, as well as robots and other remote control devices.
Patient's afflicted with amyotrophic lateral sclerosis (Lou
Gehrig's Disease), particularly those in advanced stages of the
disease, would also be applicable to receiving a neural interface
device, even if just to improve communication to the external world
and thus improve their quality of life.
[0006] Early attempts to utilize signals directly from neurons to
control an external prosthesis encountered a number of technical
difficulties. The ability to identify and obtain stable electrical
signals of adequate amplitude was a major issue. Another problem
that has been encountered is caused by the changes that occur to
the neural signals that occur over time, resulting in a degradation
of system performance. Neural interface systems that utilize other
neural information, such as electrocorticogram (ECOG) signals,
local field potentials (LFPs) and electroencephalogram (EEG)
signals have similar issues to those associated with individual
neuron signals. Since all of these signals result from the
activation of large groups of neurons, the specificity and
resolution of the control signal that can be obtained is limited.
However, if these lower resolution signals could be properly
identified and the system adapt to their changes over time, simple
control signals could be generated to control rudimentary devices
or work in conjunction with more the higher power control signals
processed directly from individual neurons.
[0007] There is therefore a need for an improved neural interface
system which incorporate various novel elements needed to perform
an efficient and effective calibration routine which can identify
the optimal multicellular signals to be processed, and adjust for
the natural changes in those signals that occur over time.
Performance of the calibration routine at the outset and repeated
periodically throughout the life of the system would ensure a
sophisticated and effective control signal for the long term
control of an external device.
SUMMARY OF THE INVENTION
[0008] According to a first aspect of the invention, a neural
interface system is disclosed. The neural interface system collects
multicellular signals emanating from the central nervous system of
a patient and transmits processed signals to a controlled device.
The system comprises a sensor for detecting multicellular signals,
the sensor consisting of a plurality of electrodes. The electrodes
are designed to allow chronic detection of multicellular signals.
An interface is designed to receive the multicellular signals from
the sensor and process the multicellular signals to produce
processed signals. The processed signals are transmitted from the
interface to a controlled device. Integrated into the system is a
calibration routine, which generates one or more calibration output
parameters used by the interface to produce the processed signal.
The integrated calibration routine may be performed by an operator
at least one time during the use of the system.
[0009] The operator, a qualified individual in the use of the
calibration routine, utilizes calibration apparatus to generate the
calibration output parameters. The calibration apparatus can have
certain functions integrated into the interface of the system, or
may be a stand alone apparatus that communicates with the
interface. The calibration apparatus can be physically connected to
the interface via an electromechanical cable, or can communicate
via wireless technologies. The calibration routine can be performed
with or without patient involvement. Patient involvement may
include having the patient imagine particular events such as
imagined movement, memory recall, imagined states or other
imaginable events.
[0010] The controlled device of an exemplary embodiment is an
assistive device for a patient with a paralyzed or otherwise
reduced function due to traumatic injury or neurological disease.
In a preferred embodiment, the multicellular signals include, at a
minimum, neuronal spikes sensed with a mufti-electrode array
implanted in the motor cortex portion of the patient's brain.
[0011] In another aspect, the system includes one or more safety
checks regarding successful completion of the calibration routine.
For example, the operator is qualified by performing a mock
calibration utilizing data included in the calibration apparatus,
either synthetic data or previously recorded human data.
Alternatively or additionally, operator secured access is provided
preventing inadvertent or malicious changes in calibration being
performed by improper or unqualified individuals.
[0012] In still another aspect, multiple calibration routines are
embedded in the system. The multiple routines can be utilized for
comparative purposes, routines can be specific to a particular
controlled device and can differentiate an initial calibration from
subsequent calibration. In a preferred embodiment, multiple
calibration routines are performed, and a check is performed to
select the best performance. In one embodiment, specific
calibration routines are linked to specific controlled devices. In
still another embodiment, the neural interface system includes one
or more initial calibration routines, and one or more subsequent
calibration routines. The subsequent calibration routines have a
reduced number of steps resulting in reduced calibration duration,
and may utilize data captured from previous calibrations including
date from the initial calibration.
[0013] In some aspects, the calibration routine includes preset
limits for either input variables or output variables of the
calibration routine. In one embodiment, these limits are adjustable
by a subset of potential operators, such as only by the clinician.
This tiered approach offers the potential of both safe and
efficient calibration of the system, allowing less qualified
operators to make fine adjustments only.
[0014] In an aspect, certain parameters of the calibration, routine
are varied automatically based on the quality and quantity of
neural signals detected. An iterative process is created, to
efficiently select the best signals for processing based on the
patient and the requirements of the system, especially as they
relate to the requirements of the particular controlled device. For
example, particular targets for number of multicellular signals may
be linked with the specific controlled device intended for use. The
calibration routine can automatically readjust parameters based on
surpassing or underachieving the target signal amount, and
calibration repeated to select the most appropriate signals.
[0015] In some aspects, the calibration apparatus includes internal
safety checks for proper calibration. The system can check for
performance and other requirements, and if below a particular
level, the system can enter certain states. Such states may include
an alarm or warning condition, or a lockout condition wherein a
repeat calibration or other action is required prior to
transmitting the control signals to the controlled device.
[0016] According to another aspect of the invention, a method of
calibrating a neural interface system is disclosed. The method
includes providing a neural interface system for collecting
multicellular signals emanating from the central nervous system of
a patient and for transmitting processed signals to a controlled
device. The neural interface system includes a sensor for detecting
the multicellular signals. The sensor consists of a plurality of
electrodes that detect the multicellular signals. An interface
receives the multicellular signals from the sensor and processes
the signals to generate a processed signal which is sent to a
controlled device. The method further includes the performance by
an operator of a calibration routine, at least one time during the
use of the system. The calibration routine produces one or more
calibration output parameters to be used by the system to generate
the processed signals.
[0017] According to another aspect of the invention, a neural
signal processing unit is disclosed. The neural signal processing
unit comprises an input port for multiple neural signal input and a
graphical user interface. The graphical user interface includes: a
display monitor for displaying information from multiple individual
neural signals and an input device for selecting graphical
representations of neural signals and graphical representations of
parameter values on the display monitor. The multiple neural
signals can be selected with the input device and properties
associated multiple individual neural signals can be changed
simultaneously.
[0018] According to another aspect of the invention, another neural
signal processing unit is disclosed. The neural signal processing
unit comprises an input port for multiple neural signal input and a
graphical user interface. The graphical user interface includes: a
display monitor for displaying information from multiple individual
neural signals and an input device for selecting graphical
representations of neural signals and graphical representations of
parameter values on the display monitor. One or more neural signals
can be viewed automatically by selecting a graphical representation
of a specific parameter value.
[0019] According to another aspect of the invention, another neural
signal processing unit is disclosed. The neural signal processing
unit comprises an input port for multiple neural signal input and a
graphical user interface. The graphical user interface includes a
display monitor for displaying information from multiple individual
neural signals and an input device for selecting graphical
representations of neural signals and graphical representations of
parameter values on the display monitor. One or more neural signals
can have a parameter changed by moving the graphical representation
of the neural signal to the location of a graphical representation
of a specific parameter value or by moving a graphical
representation of a specific parameter value to a location of a
graphical representation of the neural signal.
[0020] Additional objects and advantages of the invention will be
set forth in part in the description which follows, and in part
will be obvious from the description, or may be learned by practice
of the invention. The objects and advantages of the invention will
be realized and attained by means of the elements and combinations
particularly pointed out in the appended claims.
[0021] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory only and are not restrictive of the invention, as
claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The accompanying drawings, which are incorporated in and
constitute a part of this specification, illustrate various
embodiments of the present invention, and, together with the
description, serve to explain the principles of the invention.
[0023] FIG. 1 illustrates a neural interface system consistent with
the present invention.
[0024] FIG. 2 illustrates an exemplary embodiment of a neural
interface system consistent with the present invention.
[0025] FIG. 3 illustrates another exemplary embodiment of a neural
interface system consistent with the present invention.
[0026] FIG. 4 illustrates an exemplary embodiment of a neural
signal processing unit consistent with the present invention.
[0027] FIG. 5 illustrates another exemplary embodiment of a neural
signal processing unit consistent with the present invention.
DESCRIPTION OF THE EMBODIMENTS
[0028] Reference will now be made in detail to the present
embodiments of the invention, examples of which are illustrated in
the accompanying drawings. Wherever possible, the same reference
numbers will be used throughout the drawings to refer to the same
or like parts.
[0029] Systems and methods consistent with the invention detect
neural signals generated within a patient's body and implement
various signal processing techniques to generate processed signals
for transmission to a device to be controlled. In one exemplary
environment, a neural interface system includes a calibration
routine which is implemented to ensure optimal, long term control
of the controlled device. Numerous preferred embodiments of
calibration routines are described, enabling the neural interface
system to efficiently work with various controlled devices, such as
prosthetic limbs, robots and robotic machinery, and computer
control devices. The various calibration routines described also
allow the neural interface system to be compatible with a broad
based patient population with varied level of neural signal
quality. Subsequent calibrations may be performed to adjust for
changes in signal quality and other changes, providing for
effective long term, or chronic use of the system. In other
exemplary embodiments, improved user interface systems are
described, allowing an operator to create processed signals in an
expeditious, efficient manner.
[0030] FIG. 1 shows a neural interface system 100 of implanted
components and components external to the body of a patient 500. A
sensor for detecting multicellular signals, such as a two
dimensional array of multiple protruding electrodes, may be
implanted in the brain of patient 500, in an area such as the motor
cortex. Alternatively, the sensor may include one or more wires or
wire bundles which include a plurality of electrodes. Patient 500
may be a patient with a spinal cord injury or afflicted with a
neurological disease that has resulted in a loss of voluntary
control of various muscles within the patient's body. The various
electrodes of the sensor detect multicellular signals, such as
neuron spikes which emanate from the individual neurons of the
brain. The sensor can be placed at one or more various locations
within the body of patient 500, such as at an extracranial site,
preferably in a location to collect multicellular signals directly
from the central nervous system. The sensor can be placed on the
surface of the brain without penetrating, such as to detect local
field potential signals, or on the scalp to detect
electroencephalogram (EEG) signals.
[0031] The sensor electrodes of system 100 can be used to detect
various multicellular signals including neuron spikes,
electrocorticogram signals (ECoG), local field potential signals,
etectroencelphalogram (EEG) signals and other multicellular
signals. The electrodes can detect multicellular signals from
clusters of neurons and provide signals midway between single
neuron and electroencephalogram recordings. Each electrode is
capable of recording a combination of signals, including a
plurality of neuron spikes.
[0032] As shown in FIG. 1, an interface may comprise first
interface portion 130A and second interface portion 130B. The
interface may receive the multicellular signals from the sensor and
perform various signal processing functions including but not
limited to amplification, filtering, sorting, conditioning,
translating, interpreting, encoding, decoding, combining,
extracting, mathematically transforming, and/or otherwise
processing those signals to generate a control signal for
transmission to a controlled device. The interface may comprise
multiple components as shown in FIG. 1, or a single component. Each
of the interface components can be implanted in patient 500 or be
external to the body.
[0033] In FIG. 1, controlled device 300 is a computer system, and
patient 500 may be controlling one or more of a mouse, keyboard,
cursor, joystick or other computer input device. Numerous other
controlled devices can be included in system 100, individually or
in combination, including but not limited to prosthetic limbs,
functional electrical stimulation (FES) devices and systems, robots
and robotic components, teleoperated devices, computer controlled
devices, communication devices, environmental control devices,
vehicles such as wheelchairs, remote control devices, medical
therapeutic and diagnostic equipment such as drug delivery
apparatus and other controllable devices applicable to patients
with some form of paralysis or diminished function, as well as any
device that may be better utilized under direct brain or thought
control.
[0034] The sensor is connected via a multi-conductor cable, not
shown, to first interface portion 130A which includes a
transcutaneous pedestal which is mounted to the patient's skull.
The mufti-conductor cable includes a separate conductor for each
electrode, as well as additional conductors to serve other
purposes. Various descriptions of the sensor and mufti-conductor
cable are described in detail in relation to subsequent figures
included herebelow.
[0035] First interface portion 130A may include various signal
conditioning elements such as amplifiers, fitters, and signal
multiplexing circuitry. First interface portion 130A is
electrically attached to second interface portion 130B via
intra-interface cable 140. Intra-interface cable 140, as well as
other physical cables incorporated into system 100, may include
electrical wires, optical fibers, other means of transmitting data
and/or power and any combination of those. The number of individual
conductors of intra-interface cable 140 can be greatly reduced from
the number of conductors included in the multi-conductor cable
between the implanted sensor and first interface portion 130A
through signal combination circuitry included in first interface
portion 130A. Intra-interface cable 140, as well as all other
physical cables incorporated into system 100, may include shielding
elements to prevent or otherwise reduce the amount of
electromagnetic noise added to the various neural signals,
processed neural signals and other signals carried by those cables.
In an alternative preferred embodiment, intra-interface cable 140
is replaced with a wireless connection for transmission between
first interface portion 130A and second interface portion 130B.
Wireless communication means, well known to those of skill in the
art, can be utilized to transmit information between any of the
components of system 100.
[0036] A qualified individual, operator 110, performs a calibration
of system 100 at some time during the use of system 100, preferably
soon after implantation of the sensor. As depicted in FIG. 1,
operator 110 utilizes calibration apparatus 115 which includes two
monitors, first calibration monitor 120a and second calibration
monitor 120b, along with calibration keyboard 116 to perform the
calibration routine. The software programs and hardware required to
perform the calibration can be included in the interface, such as
second interface portion 130B, or in a central processing unit
incorporated into calibration apparatus 115. Calibration apparatus
115 can include additional input devices, such as a mouse or
joystick, not shown. Calibration apparatus 115 can include various
elements, functions and data including but not limited to: memory
storage for future recall of calibration activities, operator
qualification routines, standard human data, standard synthesized
data, neuron spike discrimination software, operator security and
access control, controlled device data, wireless communication
means, remote (such as via the internet) calibration communication
means and other elements, functions and data used to provide an
effective and efficient calibration on a broad base of applicable
patients and a broad base of applicable controlled devices.
[0037] Operator 110 may be a clinician, technician, caregiver or
even the patient themselves in some circumstances. Multiple
operators may perform a calibration, and each operator may be
limited by system 100, via passwords and other control
configurations, to only perform specific functions. For example,
only the clinician may be able to change specific critical
parameters, or set upper and lower limits on other parameters,
while a caregiver or the patient, may not be able to access those
portions of the calibration procedure. The calibration procedure
includes the setting of numerous parameters needed by the system
100 to property control controlled device 300. The parameters
include but are not limited to various signal conditioning
parameters as well as selection of specific multicellular signals
for processing to generate the device control. The various signal
conditioning parameters include, but are not limited to, threshold
levels for amplitude sorting and filtering levels and
techniques.
[0038] The operator 110 may be required by system 100 to perform
certain tasks, not part of the actual calibration, to be qualified
and thus allowed to perform the calibration routine. The tasks may
include analysis of pre-loaded multicellular signals, either of
synthetic or human data, and may include previous data captured
from patient 500. The mock analysis can be tested for accuracy,
requiring a minimum performance for the calibration routine to
continue.
[0039] The calibration routine will result in the setting of
various calibration output parameters. Calibration output
parameters may consist of but are not limited to: electrode
selection, neural signal selection, neuron spike selection,
electrocorticogram signal selection, local field potential signal
selection, electroencephalogram signal selection, sampling rate by
signal, sampling rate by group of signals, amplification by signal,
amplification by group of signals, filter parameters by signal and
filter parameters by group of signals. In an embodiment, at least
one of the output parameters includes the selection of a subset of
multicellular signals to be processed by the interface to generate
the controlled device control signal. In an alternative embodiment,
the calibration output parameters can only be set within preset
limits. In another embodiment, the limits can be changed by any
operator, and in a preferred embodiment, only operators with
specific permissions, such as password controlled permissions, can
change the limits for individual parameters.
[0040] The calibration routine may be performed soon after sensor
implantation, and prior to control of controlled device 300. System
100 may include an internal lockout feature which prevents control
of any controlled device, prior to successfully completing a
calibration procedure. In the performance of the calibration
routine, the operator 110 can perform multiple calibrations and
compare results of each. Calibration routines may be performed on a
periodic basis, and may include the selection and deselection of
specific neural signals over time. The initial calibration routine
may include initial values, or starting points, for one or more of
the calibration output parameters. Subsequent calibration routines
may involve utilizing previous calibration output parameters which
have been stored in a memory storage element of system 100.
Subsequent calibration routines may be shorter in duration than an
initial calibration and may require less patient involvement.
Subsequent calibration routine results may be compared to previous
calibration results, and system 100 may require a repeat of
calibration if certain comparative performance is not achieved.
[0041] The calibration routine may include the steps of (a) setting
a preliminary set of calibration output parameters; (b) generating
processed signals to control the controlled device; (c) measuring
the performance of the controlled device control; and (d) modifying
the calibration output parameters. The calibration routine may
further include the steps of repeating steps (b) through (d). The
order of the steps may be altered, as necessary. Additionally or
alternatively, any of the steps (b) through (d) may be omitted.
[0042] In the performance of the calibration routine, the operator
110 may involve the patient 500 or perform steps that do not
involve the patient. The operator 100 may have patient 500 think of
an imagined movement, imagined state, or other imagined event, such
as a memory, an emotion, the thought of being hot or cold, or other
imagined event not necessarily associated with movement. The
patient participation may include the use of one or more cues such
as audio cues, visual cues, olfactory cues, and tactile cues. The
patient 500 may be asked to imagine multiple movements, and the
output parameters selected during each movement may be compared to
determine an optimal set of output parameters. The imagined
movements may include the movement of a part of the body, such as a
limb, arm, wrist, finger, shoulder, neck, leg, ankle, and toe, and
imagining moving to a location, moving at a velocity or moving at
an acceleration.
[0043] The calibration routine may include classifying the
multicellular signals into one or more of two groups: discrete data
and continuous data. Numerous factors can be analyzed from the
neural signals received such as firing rate, average firing rate,
standard deviation in firing rate and other mathematical analyses
of firing rate. Determining the maximum modulation of firing rate,
such as through the use of fano factor techniques, may be desirable
in selecting which neural signals to process, as well as which
imagined movement is generating the most useful signals. For
particular mathematical algorithms, such as linear filters used to
transform the selected multicellular signals into the controlled
device control signal, it may be desirous to have a minimum of
seven (7) neural signals for optimal device control.
[0044] The calibration routine will utilize one or more calibration
input parameters to determine the calibration output parameters. In
addition to the multicellular signals themselves, system or
controlled device performance criteria can be utilized. In order to
optimize the system, an iterative analysis of modifying the
performance criteria, based on the number of multicellular signals
that meet the criteria versus the optimal number of multicellular
signals to be included in the signal processing for the particular
controlled device, can be performed. Criteria can be increased or
decreased in the signal selection process during the calibration
procedure.
[0045] Other calibration input parameters include various
properties associated with the multicellular signals including one
or more of: signal to noise ratio, frequency of signal, amplitude
of signal, neuron firing rate, average neuron firing rate, standard
deviation in neuron firing rate, modulation of neuron firing rate
as well as a mathematical analysis of any signal property including
modulation of any signal property. Additional calibration input
parameters include but are not limited to: system performance
criteria, controlled device electrical time constants, controlled
device mechanical time constants, other controlled device criteria,
types of electrodes, number of electrodes, patient activity during
calibration, target number of signals required, patient disease
state, patient condition, patient age and other patient parameters
and event based (such as a patient imagined movement event)
variations in signal properties including neuron firing rate
activity.
[0046] The calibration routine may classify one or more
multicellular signals into three or more classifications for
subsequent selection for further processing into the processed
signal for transmission to the controlled device. The multiple
classifications can be completed in the initial portion of the
calibration routine, resulting in a count of each class of
available signal. Based on various requirements including the
requirements of the control device and applicable mathematical
transfer functions, signals can be selected from the most
appropriate classification, or a different number of classification
states can be chosen, and the signals may be reclassified in order
to select the most appropriate signals for optimal device
control.
[0047] It may be desirous for the calibration routine to exclude
one or more multicellular signals based on a desire to avoid
signals that respond to certain patient active functions, such as
non-paralyzed functions, or even certain imagined states. The
calibration routine may include having the patient imagine a
particular movement or state and, based on sufficient signal
activity such as firing rate or modulation of firing rate,
excluding that signal from the signal processing based on that
particular undesired imagined movement or imagined state.
Alternatively, real movement accomplished by the patient may also
be utilized to exclude certain multicellular signals emanating from
specific electrodes of the sensor.
[0048] Referring now to FIG. 2, system 100, according to another
exemplary embodiment of the invention, is shown. Patient 500 has
been implanted with sensor 200, preferably a multielectrode array
placed in the motor cortex of patient 500's brain, however any
arrangement of electrodes, such as wire electrodes, can be utilized
and placed anywhere that multicellular activity can be recorded.
The sensor 200 may be used to detect neuron spikes, or other
multicellular signals. The sensor 200 may detect multiple spikes
from a single electrode.
[0049] The sensor 200 is connected to first interfaces portion
130A, implanted within patient 500, via connecting cable 161. In a
preferred embodiment, sensor 200 includes at least eighty (80)
electrodes and connecting cable 161 is a multiconductor flexible
miniaturized cable including a conductor for each electrode, as
well as other conductors. Alternatively, sensor 200 may include
signal multiplexing circuitry allowing connecting cable 161 to
include less than eighty conductors. In another alternative, a
wireless connection could be integrated into sensor 200, sending
signals through the skull to first interface portion 130A. First
interface portion 130 is connected to second interface portion
130B, external to patient 500, via transcutaneous communication
means 160 which could be either an electromechanical miniaturized
cable designed to pass through the skin of the patient, or
preferably transcutaneous communication means 160 is a wireless
communication path accomplished by including wireless communication
transmit and receive technology in both first interface portion
130A and second interface portion 130B. In an alternative
embodiment, first interface portion 130A and second interface
portion 130B are combined into a single unit, and the combined
device may be implanted within patient 500, avoiding the need for
transcutaneous communication means 160.
[0050] The interface, including first interface portion 130A,
transcutaneous communication means 160, and second interface
portion 130B, receives the multicellular signals from sensor 200,
processes the multicellular signals to generate processed signals,
and transmits the processed signals to the controlled device. First
interface portion 130A may include various signal conditioning
elements such as amplifiers, filters and signal multiplexing
circuitry. Second interface portion 130B receives the modified
multicellular signals from the first interface portion 130A and
performs various signal processing functions including but not
limited to amplification, filtering, sorting, conditioning,
translating, interpreting, encoding, decoding, combining,
extracting, mathematically transforming and/or otherwise processing
those signals to generate a control signal for transmission to a
controlled device. Second interface portion 130B may include
various elements, functions and data to perform a calibration
routine, such as those functions not already included in
calibration apparatus 115. In a preferred embodiment, second
interface portion 130B includes a memory storage unit that stores a
complete history of all calibration information, which can be
recalled to perform repeat and/or subsequent calibrations.
[0051] Second interface portion 130B is connected to controlled
device 300 via controlled device cable 301. As described similarly
throughout, controlled device cable 301 could be replaced with
wireless communication means through the addition of wireless
transmission capability into second interface portion 130B and
wireless receiving capability into controlled device 300. In an
embodiment, both receive and transmit technologies are included in
both controlled device 300 and second interface portion 130B
allowing feedback from controlled device 300 to second interface
portion 130B to be used to improve system performance. Controlled
device 300 can be a number of controllable devices, including a
combination of controllable devices which are controlled by a
single or multiple control signals which are generated by the
second interface portion 130B. Lists of applicable controlled
devices 30 have been described hereabove.
[0052] Calibration apparatus 115 includes calibration monitor 120,
calibration keyboard 116 and calibration mouse 117. Calibration
apparatus 115 is attached to second interface portion 130B via
calibration connecting means 118, an electromechanical cable.
However, it should be appreciated that calibration connecting means
118 could be replaced with wireless communication means included in
calibration apparatus 115 and second interface portion 130B. The
operator, not shown, would utilize calibration apparatus 115 at
least one time in the calibration of system 100. The software
programs and hardware required to perform the calibration can be
included in the interface, such as second interface portion 130B,
or be included in a central processing unit incorporated into
calibration apparatus 115. Calibration apparatus 115 can include
additional input devices, such as a joystick, not shown.
Calibration apparatus 115 can include various elements, functions
and data including but not limited to: memory storage for future
recall of calibration activities, operator qualification routines,
standard human data, standard synthesized data, neuron spike
discrimination software, operator security and access control,
controlled device data, wireless communication means, remote (such
as via the internet) calibration communication means and other
elements, functions and data used to provide an effective and
efficient calibration on a broad base of applicable patients and a
broad base of applicable controlled devices.
[0053] In FIG. 3, system 100, according to still another exemplary
embodiment of the invention, is shown, wherein two separate
sensors, first sensor 200a and second sensor 200b are implanted in
patient 500. While both sensors 200a and 200b are show to be
located in brain 101 of patient 500, at least one of the sensors
may be placed in any location that can detect multicellular
signals. Each of sensors 200a and 200b is attached via connecting
cable 161 to central implant 135 which includes the interface
portion of system 100, as well as other elements such as a power
supply, wireless communication means, memory storage, central
processing unit, physiologic and other sensor input ports, control
signal output ports and other functions. Central implant 135 is
connected to various other implants including a series of implants,
implanted control devices 311 which could be Functional Electrical
Stimulation (FES) devices, other control devices, sensory devices,
or combination control and sensory devices. Also connected to
central implant 135 is an implanted drug infusion device, such as
implanted pump 310. The interface portion of central implant 135
may produce multiple control signals to control multiple devices
with different functions such as implanted controlled devices 311,
preferable an FES device, as well as a drug delivery device (e.g.,
implanted pump 310).
[0054] Also depicted in FIG. 3 is calibration apparatus 115 which
includes calibration monitor 120 and external equipment means 125,
preferably a central processing unit (CPU) including calibration
routine software and other computer hardware and software.
Alternatively, all calibration routine software and hardware can be
included in one or more components of system 100, such as the
interface included in central implant 135, and calibration
apparatus 115 simply include a monitor, input device and
communication means to transfer data with central implant 135.
Shown in FIG. 3, calibration apparatus 115 communicates with
central implant 135 via wireless communication, transcutaneous
communication means 160.
[0055] System 100 may include integrated memory storage for storing
any and all data collected during the calibration process. This
stored memory can be used for a number of functions including a
second calibration procedure performed off line and/or away from
the patient. This remote calibration, under different conditions,
may allow an enhanced calibration procedure to be performed on a
different time scale or with different equipment. If applicable,
the new calibration output parameters could be implemented at a
later date, either remotely or at the patent's site.
[0056] The calibration monitors described, such as calibration
monitor 120, can display information separately for each electrode,
as well as separately for each multicellular signal even if
multiple signals are received from a single electrode. Also
displayed can be the timing of patient events, such as the start
and stop of imagined motions, with time adjustable windows
surrounding the neural signal activity pre and post the time of the
patient event. These window times could be adjusted by the
operator. Real time and cumulative calibration information can be
displayed including spatial representations of data, such as that
relative to the geometric construction of an electrode array. For
ease of use, color schemes can accompany numeric output to indicate
various neural signal parameters such as firing rates of neuron
spikes. Alternatively or additionally, calibration apparatus 115
may include output devices in addition to calibration monitor 120,
such as audio devices or tactile devices, that can be used by the
operator or the patient during calibration. While searching for
multicellular signals with high firing rate, audio feedback may be
used to sort signals with the highest rates.
[0057] The interface of system 100 may be comprised of various
functions including an integrated neuron spike sorting function.
This sorting function may include a method of sorting that includes
setting a minimum signal amplitude threshold. The calibration
routine may be as automated as possible. Due to the critical nature
of these type of devices, it may be practical not to eliminate all
involvement of the clinician and appropriate healthcare
professionals. In an embodiment, the calibration routine of system
100 includes one or more automated calibration steps, and the
operator performs a limited, but critical function. Such critical
function may include one or more of: initiation of the calibration
routine, confirmation of acceptable completion of the calibration
routine, safety and/or performance check of the new calibration
output parameters, or other confirmatory step to prevent an adverse
event resulting from an improper automated calibration.
[0058] Numerous algorithms, mathematical and software techniques
can be utilized by the interface to create the desired control
signal. The interface may utilize neural net software routines to
map neural signals into desired device control signals. Individual
neural signals may be assigned to a specific use in the system. The
specific use may be determined by having the patient attempting an
imagined movement or other imagined state. For some applications,
the neural signals may be under the voluntary control of the
patient. The interface may mathematically combine various neural
signals to create a processed signal for device control.
[0059] Referring now to FIG. 4, a neural signal processing unit 600
is depicted for processing of neural signals. Neural signal
processing can include one or more of: amplifying, filtering,
translating, identifying, classifying, sorting, conditioning,
interpreting, encoding, decoding, combining, extracting, providing
analog representations, providing digital representations,
mathematically transforming and/or otherwise processing neural
signals. Neural signal processing unit (NSPU) 600 includes a
central processing unit (CPU) 601 which is attached to NSPU display
610, NSPU Mouse 650 and NSPU Keyboard 620. NSPU CPU 601 may include
all computer functions including hardware and software elements to
perform the neural signal processing. NSPU 600 includes an input
port 602 (e.g., sensor input port) which can be attached directly
to a multicellular signal sensor or to an intermediate device which
carries processed multicellular singles, such as amplified
multicellular signals. Additional input devices, such as a joystick
and output devices, such as a speaker, can be attached to NSPU CPU
601 to aid an operator in the use of the NSPU 600.
[0060] Displayed on NSPU display 610 are various windows of
information. NSPU channel list window 615 displays various channels
of information correlating to specific electrodes of a
multicellular signal sensor. Alternatively, each channel may
display a specific multicellular signal or a group of specific
electrodes or specific multicellular signals. Included in NSPU
channel list window 615 is information about all channels including
NSPU channel one information 616 and NSPU channel two information
617. NSPU digital output properties window 640 includes various
pieces of digital information associated with one or more channels.
NSPU analog output properties window 630 includes various pieces of
analog information associated with one or more channels. Also shown
on NSPU display 610 is NSPU display cursor 611, which is controlled
via NSPU mouse 650.
[0061] An operator, not shown, can select multiple channels of data
input, each representing a specific electrode, a specific
multicellular signal or a specific group of multicellular signals
or multiple electrodes. Multiple channels are selected, such as
NSPU channel one 616 and NSPU channel two 617, either with a
combination of keystrokes or use of the mouse 650's click function
or both. After selection of one or more channels, both NSPU digital
output properties window 640 and NSPU analog output properties
window 630 can display common properties between all channels
selected. The operator, utilizing either NSPU digital output
properties window 640 or NSPU analog output properties window 630,
or both, can set individual properties to a specific value. The
properties of multiple channels can then be changed to those values
simultaneously such as by clicking the "APPLY" function shown in
both windows, or via a particular keystroke on NSPU keyboard 620.
The selection of multiple channels, as well as the setting of the
specific property values, can be accomplished by using various
techniques employed in standard computer operating systems. After
the multiple channels are selected, the NSPU may allow rapid
changing of properties to specific selectable values, avoiding the
need to set each channel individually.
[0062] FIG. 5 shows an exemplary embodiment of a neural signal
processing unit (NSPU) 600 for processing of neural signals. Neural
signal processing can include one or more of: amplifying,
filtering, translating, identifying, classifying, sorting,
conditioning, interpreting, encoding, decoding, combining,
extracting, providing analog representations, providing digital
representations, mathematically transforming, and/or otherwise
processing neural signals. NSPU 600 includes a central processing
unit (CPU) 601 which is attached to NSPU display 610, NSPU Mouse
650 and NSPU Keyboard 620. NSPU CPU 601 may include all computer
functions including hardware and software elements to perform the
neural signal processing. Also shown on NSPU display 610 is NSPU
display cursor 611, which is controlled via NSPU mouse 650. Neural
signal processing unit 600 includes an input port 602 (e.g., sensor
input port) which can be attached directly to a multicellular
signal sensor or to an intermediate device which carries processed
multicellular singles, such as amplified multicellular signals.
Additional input devices, such as a joystick and output devices,
such as a speaker, can be attached to NSPU CPU 601 to aid an
operator in the use of the NSPU 600.
[0063] Displayed on NSPU display 610 are various windows of
information. NSPU Option One button 612 is a mouse clickable button
which allows the operator to view all channels. NSPU Option two 613
includes multiple clickable buttons that allow the user to select
various sampling rates. NSPU Option three 614 includes multiple
clickable button that allow the user to select various filtering
parameters. NSPU Channel List 615 displays a list of applicable
channels. In the embodiment of FIG. 5, the operator is provided
with a powerful graphical user interface to find channels that have
specific parameters and/or to easily change the parameters of
individual or groups of channels. The operator can pick a
particular parameter, such as a 500 S/sec sampling rate, and all
channels sampled at that rate will appear in NSPU Channel list 615.
Alternatively, a particular channel can be selected, and the
parameters associated with that channel will appear.
[0064] The graphical user interface allows easy setting of
parameters as mentioned above. The operator can use the mouse to
select and drag any channel or group of channels to the screen
location of a particular parameter value, and the channel will then
be set to that value. Alternatively, the operator can select and
drag any parameter value, or group of parameter values, to a screen
location of a particular channel and the channel will have its
parameter values automatically changed to those selected. It should
be appreciated that while FIG. 5 depicts sampling rate and filter
methods, any appropriate parameter value would be applicable to
this embodiment. It should also be appreciated, that numerous
methods of selecting channels utilizing, singly or in combination,
a mouse, computer keyboard, touch screen or other input device, can
be employed without departing from the spirit of the described
embodiment.
[0065] Other embodiments of the invention will be apparent to those
skilled in the art from consideration of the specification and
practice of the invention disclosed herein. It is intended that the
specification and examples be considered as exemplary only, with a
true scope and spirit of the invention being indicated by the
following claims.
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