U.S. patent number 3,905,355 [Application Number 05/422,129] was granted by the patent office on 1975-09-16 for system for the measurement, display and instrumental conditioning of electromyographic signals.
Invention is credited to Joseph Brudny.
United States Patent |
3,905,355 |
Brudny |
September 16, 1975 |
System for the measurement, display and instrumental conditioning
of electromyographic signals
Abstract
A plurality of electrical contacts are applied to human beings
to detect muscle [i.e. electromyographic, or E.M.G.] activity at
various points of the body. Each of the multiplicity of resultant
signals are amplified, filtered, rectified and converted to a pulse
train. These pulse trains are integrated over programmable time
periods and the multiplicity of integrated signals representative
of muscle activity may be displayed on a multiplicity of output
devices including audio and visual. In addition means are included
to represent a reference signal corresponding to willful E.M.G.
activity. This instrument is useful to provide exteroceptive
signals to human beings whose proprioceptive mechanisms have been
damaged by disease or other causes. By these means alternate neural
pathways may be used to train or retrain human beings to proper
willful activity and/or restoration of function.
Inventors: |
Brudny; Joseph (New york,
NY) |
Family
ID: |
23673513 |
Appl.
No.: |
05/422,129 |
Filed: |
December 6, 1973 |
Current U.S.
Class: |
600/546; 128/908;
128/905 |
Current CPC
Class: |
A61B
5/389 (20210101); A61B 5/7242 (20130101); A61B
5/301 (20210101); Y10S 128/908 (20130101); Y10S
128/905 (20130101) |
Current International
Class: |
A61B
5/0488 (20060101); A61B 5/0428 (20060101); A61B
5/0402 (20060101); A61B 005/04 () |
Field of
Search: |
;128/1R,2N,2R,2S,2.1A,2.1B,2.1M,2.1P,2.1R,2.1Z,419R,2.6B,2.6G
;340/407,279 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Pfeiffer et al., "Medical and Biological Engineering," Vol. 8, No.
2, March, 1970, pp. 209-211..
|
Primary Examiner: Kamm; William E.
Attorney, Agent or Firm: Mencher; Alexander
Claims
I claim:
1. An apparatus for obtaining and displaying muscle activity at a
multiplicity of points on the human body, said device
comprising:
a multiplicity of electrode sets adapted to be in contact with the
skin, each of said electrode sets including two or more
electrodes,
input means for receiving signals from said multiplicity of
electrode sets,
amplification means for the amplification of said signals, full
wave rectification means for said amplification of said signals for
each of said multiplicity of signals representative of muscle
activity,
conversion means for the conversion of said multiplicity of said
full wave rectified signals into pulse signals whose frequency is
proportional to said full wave rectified signals, the latter being
representative of muscle activity,
isolation means connected to said conversion means by which said
multiplicity of pulse signals is converted into a multiplicity of
light signals,
a multiplicity of detection means associated with the multiplicity
of light signals by which said light signals are converted into
electrical pulses proportional to the repetition of said
multiplicity of light signals,
a multiplicity of integration means including multi-point switching
means connected to said multiplicity of detection means wherein a
multiplicity of muscle signals is integrated by summation of the
multiplicity of pulses produced by said multiplicity of detection
means,
feedback means connected to said multiplicity of integration means
wherein a multiplicity of signals subject to normal recognition by
the normally functioning human senses are produced therefrom, said
feedback means comprising:
a multiplicity of scale adjustment means wherein said integration
may be adjusted in relation to the frequency of said pulses
representative of muscle activity wherein the total number of
accumulated pulses representative of the integrated muscle signal
may be adjusted by insertion of said pulses into said multi-point
switching means of said multiplicity of integration means,
a multiplicity of storage means by which the multiplicity of
accumulated pulses associated with the said multiplicity of
integration means may be stored for predetermined periods of time,
such storage means retaining a continuous representation of the
multiplicity of rectified muscle signals,
programming means whereby the contents of the multiplicity of
storage means may be periodically changed and whereby the contents
of said multiplicity of integration means may be initiated at zero,
thereby preparing them for accumulation of pulses representative of
muscle activity during a subsequent time period,
a multiplicity of conversion means whereby the said number of
pulses stored in said multiplicity of storage means is converted
therefrom into a voltage proportional to said number of pulses,
display means connected to any of the said multiplicity of storage
means whereby the contents of said multiplicity of storage means
may be displayed on a digital display device,
oscilloscope means including a cathode ray tube connected to said
second mentioned multiplicity of conversion means whereby the
voltage or signal from any and all of the said second mentioned
multiplicity of conversion means may be displayed on said
oscilloscope means as a continuous trace on the cathode ray tube of
said oscilloscope means,
adjustable reference means connected to said cathode ray tube,
comparison means connected to any of said second mentioned
multiplicity of conversion means wherein the signals from any of
the second mentioned multiplicity of conversion means may be
compared to said adjustable reference means, said comparison means
producing signals proportional to the difference between the
signals of said second mentioned multiplicity of conversion means
and said adjustable reference means, and signals indicative of when
said adjustable reference means is larger or smaller than the
signals from said second mentioned conversion means,
audio means whereby the intensity of a tone may be adjusted in
accordance with the output signal of the comparison means, such
audio means being selected so as to be put at its maximum intensity
when the signal from said second mentioned conversion means is
larger than said adjustable reference means, or when the signal
from said second mentioned multiplicity of conversion means is
smaller than said adjustable reference means, or whose intensity is
proportional to the difference between said reference means signal
and the signal from said second mentioned multiplicity of
conversion means.
2. A device as in claim 1 wherein said adjustable reference means
comprises:
an independent source of variable electrical voltage settable in
magnitude so as to be representative of equivalent muscle activity
and connected to said cathode ray tube to be displayable thereon as
a continuous trace simultaneously with any of the signals of said
second mentioned multiplicity of conversion means thereby providing
a means for human beings to compare the signals from said second
mentioned multiplicity of conversion means with said adjustable
reference means representative of willful muscle activity.
Description
BACKGROUND OF INVENTION
This invention relates generally to the field of electronic
computers, of a type employed for converting biological signals,
from human beings but not restricted exclusively to such use, to a
variety of sensory display modes including visual and auditory.
The invention further contemplates a system for providing a
combined diagnostic sensory display of muscular proprioceptive
signals and a therapeutic comparative co-sensor display of
continuous and willful muscular exteroceptive signals for
differentiation of said signals by the subject and includes the
steps of converting said proprioceptive signals into a continuous
sensory-recognizable form thereby inducing exteroceptive signals
and converting said exteroceptive signals for modifying said
continuous sensory-recognizable form so that the subject can judge
the difference in the respective signals as a measure of
therapeutic accomplishment.
In the past there have been various forms of apparatus constructed
for diagnostic purposes, known as Electromyograph, for detection of
electrical signals from the muscle. These devices are normally
confined to laboratories only, are being used purely for diagnostic
purposes and have little or no use in therapy.
There have been also in the past various forms of apparatus
constructed for purposes of feedback of E.M.G. activity to
subjects. Such apparatus have been used for teaching subjects
relaxation of muscle activity. These devices failed uniformly to
provide the necessary accuracy of time integration variables,
failed to provide simultaneous display of more than one of muscles
being examined, failed to provide built in features of instrumental
learning, e.g. reference signal concept, failed to provide
oscilloscopic displays of integrated muscle electrical
activity.
In summary, the present available various apparatus failed to
provide multiplicity of detection and display and multiplicity of
therapeutic applications present in the proposed system.
In human beings mechanical output (work) is achieved as a result of
a willful self-generated signal delivered to the sensory motor
cortex from proprioceptive signals originating in muscles. In such
instances the desire to produce work or motion is converted to an
electrochemical signal which causes the contraction of certain
appropriate muscle fibers and the relaxation of other appropriate
muscles resulting in motion. The intensity of such muscle activity
is transmitted back (by electrochemical means) to the brain or
central nervous system where these intensity signals are compared
to the signal. Any discrepancies are used to modulate or alter the
contraction and relaxation of the muscles so as to bring the
original stimulus and the resultant motion into conformity. This
continuous process results in smooth motion. In humans afflicted
with disease of physical impairment the intensity or presence of
the muscle activity signals which are compared to the stimulus
(referred to as proprioceptive feedback) may be altered in such a
way as to prevent proper motion.
SUMMARY OF THE INVENTION
The present disclosure relates to a device which will detect
signals originating in the muscles, convert these signals into a
form where the human being may detect them using visual and/or
auditory senses rather than proprioceptive feedback, and thus
permit proper comparison of the muscle response and motion
stimulus.
It is among the principal objects of the present invention to
provide an improved means for detecting and displaying biological
signals from a multiplicity of biological sources in order to
provide exteroceptive feedback to the organism for the smooth
control of muscle action. Without such exteroceptive feedback,
muscle action may be either spastic, paretic or otherwise
impaired.
Yet another object of the invention lies in instantaneous display
of units representative of muscle activity at any given time. These
units can be recorded for the purpose of diagnosis, charting
progress of recovery, prognosis, and collection of scientific data
in research.
Another object of the invention lies in the provision of means for
encoding and displaying a multiplicity of biological signals
directly in units which are representative of muscle activity
rather than arbitrary units which must be interpreted by the
organism.
Yet another object of the invention lies in the provision of a
multiplicity of displays from the multiplicity of biological muscle
sources such that one source may be displayed in a visual mode
while a second source may be displayed in an auditory mode.
Still another object of the present invention lies in the inclusion
of a signal (herein called reference) by which a willful biological
muscle activity may be represented in a variety of modalities. This
reference can be used to provide exteroceptive information to the
organism which is representative of its own willful biological
muscle activity.
A further object of the present invention lies in the use of a
representation of an organism's willful muscle activity (the
reference) to do work in conjunction with a display of the signals
from each of a multiplicity of muscles to provide means by which
the organism may learn to produce smooth control of muscles which
are otherwise impaired.
Yet another object of the present invention lies in the provision
by which the difference between the representation of an organism's
willful muscle activity and signals generated by the organism's
muscles may be displayed in a variety of modalities.
These objects as well as other incidental ends and advantages will
more fully appear in the progress of the following disclosure and
be pointed out in the appended claims.
Before entering into a detailed consideration of the structural
aspects of the disclosure, the following discussion is believed
apposite.
Electrochemical activity within a biological organism originating
in muscle tissue may be detected either by inserting needle
electrodes into the muscles or by placing suitable metal electrodes
at the tissue-electrode interface. These signals consist of a time
varying electrical intensity. They are generally larger and more
frequent in occurrence when the muscle is contracted and they are
smaller and less frequent in occurrence when the muscle is relaxed.
In order to obtain a measure of the amount of work the muscle is
doing, a computation of the work associated with the muscle
activity is performed. This is accomplished by integrating the time
varying muscle signal intensity. However, as the muscle signal may
vary above and below some reference line, the integral computation
may produce a zero result while in fact considerable work is being
done. Thus to measure the effective work the time varying muscle
signal is first rectified. That is, the time varying intensities
are made unidirectional in extent. This resultant signal is then
integrated. Since the integral represents the area under the
varying intensity signal and the electrical representation of the
intensity has units of volts, the resultant unit of muscle activity
is the volt-second. The intensities as detected in muscle tissue
are generally much smaller than 1 volt. Generally these signals are
in microvolts (10 .sup..sup.-6 volts). Thus the usual unit of
muscle activity is the microvolt-second.
Integration of the rectified muscle signal can be performed by
accumulating the effect of the varying intensity over a period of
time. This can be accomplished by storing a charge in a capacitor.
The current producing the charge can be made proportional to the
muscle intensity. Another method of integrating the muscle signal,
as depicted in the drawings and discussed herein, is to convert the
muscle intensity into a sequence of electrical pulses. The
frequency of these electrical pulses is proportional to the
intensity of the muscle signal. These pulses may then be stored or
accumulated in an electronic (or other) counter. The number of
pulses counted in a given time interval is the equivalent of the
integral of the rectified muscle signal.
BRIEF DESCRIPTION OF DRAWINGS
With the foregoing discussion in mind, reference may now be had to
the accompanying drawings, in which:
FIG. 1A is a schematic diagram of the entire device, showing two
channels feeding to a central computer and display.
FIG. 1B is a schematic diagram showing, in somewhat more detail,
the circuitry of a single channel of the device of FIG. 1A.
FIG. 1C is a schematic diagram showing, in somewhat more detail,
the circuitry of the central computer and display of FIG. 1A.
FIG. 2 is a schematic wiring diagram showing one channel of a two
channel transducer.
FIG. 3 is a schematic wiring diagram showing a programmer.
FIG. 4 is a schematic wiring diagram showing a digital
integrator.
FIG. 5 is a schematic wiring diagram showing display driver,
reference source control, and recorder driver.
FIG. 6 is a schematic wiring diagram showing a comparator tone
generator, and proportionality amplifier.
DESCRIPTION OF PREFERRED EMBODIMENT
As can be seen in FIG. 1A the device comprises broadly: a system of
electrodes 1; a system of transducers 2 (including, per FIG. 1B, a
pair of pre amps 5, gain adjust amps 6, half wave rectifiers 7,
summers 8, and voltage to frequency converters 9); a system of opto
isolators 3; and a central computer and display 4.
Inviting attention to FIGS. 1A, 1B, and 1C showing the preferred
embodiment of the invention, electromyographic, or E.M.G., muscle
signals from the electrode sets 1 associated with each of two or
more channels (FIG. 1A) are first amplified, then integrated (FIG.
1D), and finally converted to electrical pulses whose frequency is
proportional to the intensity of the muscle signals. These pulses
are then fed to a central computer and display (4 in FIG. 1A),
where the number of pulses counted in a predetermined time interval
is employed to provide a display (visual, auditory, and/or record)
of a measure of the muscle activity. This display gives immediate
information to the subject regarding his own muscle activity.
In keeping with another aspect of the invention, a reference
signal, generated by a reference source or control (41 in FIG. 1C),
may be established which corresponds to a willful biological muscle
activity. This reference signal is then available for comparison
with the display from the muscle signals in any of several
predetermined modes. Thus, for example, by appropriate setting of
the scope display select switch 36 and/or the mode switch 46 (FIG.
1C), as will be detailed subsequently, the actual display presented
to the subject may correspond to the difference (or another
predetermined relationship) between the muscle signal display and
the reference signal display. By way of illustration, the subject
may hear a sound only when his muscle signal exceeds the reference
signal, or only when the muscle signal is less than that of the
reference, or a sound which varies (either in pitch or intensity)
in proportion to the difference between the two signals.
Alternatively or simultaneously, the subject may be shown either or
both displays, or only the difference between such displays.
To obtain electrical pulses of a frequency proportional to the
intensity of muscle signals, a set of three electrodes associated
with each amplification channel (FIG. 1A) is affixed to the
subject. Electrical signals from each set are amplified, rectified,
and integrated, and then converted to pulses having a frequency
proportional to the intensity of the muscle signal (FIG. 1B).
Detailed operation of the device may be followed by considering
elements shown in FIG. 1B and FIG. 1C. In FIG. 1B, (one transducer
is shown) the muscle signals are detected by induction into a
system of electrodes 1 including individual electrodes 1A, 1B, and
1C. These signals are amplified in pre-amp 5. Further amplification
is made in gain adjust amp. 6. Gain adjust amp. 6 also limits the
frequency of occurrence of the signal to be within limits
encountered in biological organisms. Half wave rectifier 7 converts
all excursions of one polarity into excursions of the opposity
polarity. Summer 8 combines the one directional excursions from
half wave rectifier 7 and the bidirectional signal excursions from
gain adjust amp. 6 in such a manner as to produce one directional
signals from summer 8. The voltage to frequency converter 9
converts the intensity of the signal into a repetition of pulses
whose frequency is proportional to the intensity of the signals
coming from summer 8. The pulses from voltage to frequency
converter 9 drive opto isolator 3. Opto isolator 3 upon receiving a
pulse from voltage to frequency converter 9 will convert the
electrical pulse to a light pulse. This light pulse can be
transmitted to central computer and display 4. Thus, there is no
wire connection between transducer 2 and central computer and
display 4. This eliminates any hazard to the biological organism
which might result from currents flowing in such a wire connection.
Energy for the transducer is supplied by batteries 10. The voltage
from these batteries is adjusted in power supply regulator 11 to a
point where they are suitable for the elements of the transducer
2.
The light signals from opto isolator 3 are received in a light
detector 12 shown in FIG. 1C. The detector 12 is an element of
integrator 13. The detector 12 converts the light signals from opto
isolator 3 into electrical pulses. The output of detector 12 is a
repetitive sequence of pulses proportional in frequency to the
rectified muscle signal intensity. When these pulses are summed up
in counters 14, 15, 16, 17 and 18 under the control of full scale
switch 19, and signals from programmer 20, the integral of the
rectified muscle signal results.
The integrator 13 accepts these electrical pulses, collects them in
a series of counters (16, 17, 18) during a preselected time period
(shown in Table 1, below), transfers the count to a series of store
elements (29, 30, 31), resets the counters to zero, and presents
the stored count to a digital display 44. To understand how
integrator 13 is controlled, consider the operation of programmer
20. Programmer 20 includes oscillator 21. Oscillator 21 produces a
4 Hz repetitive signal. This frequency of the oscillator signal is
divided in half using FF 22 (flip flop). The output of FF 22 is
further divided in half using FF 23. The output of FF 23 is again
divided in half using FF 24. The output of FF 24 is divided by 5
using counter 25. Counter 26 directly divides the output of FF 23
by 5. The outputs of oscillator 21, FF 22, FF 23, FF 24, counter 25
and counter 26 have periods in accordance with Table 1.
TABLE 1 ______________________________________ ELEMENT PERIOD
______________________________________ OSCILLATOR 21 0.25 secs. FF
22 .5 secs. FF 23 1 sec. FF 24 2 secs. COUNTER 25 10 secs. COUNTER
26 5 secs. ______________________________________
These frequencies appear at integration time switch 27. One of
these signals is selected from integration time switch 27 as the
time interval over which the pulses representing the rectified
muscle signal intensity are to be accumulated. This time signal
passes to store one shot 28. Store one shot 28 produces a momentary
signal for each repetition of the signal selected by integration
time switch 27. When this occurs the count stored in counters 16,
17 and 18 of integrator 13 is transferred into store 29, 30, and 31
respectively.
Store elements 29, 30, and 31 taken together can accumulate a
maximum of 999 pulses and a minimum of 000 pulses. The actual
number of counts accumulated will depend on the rectified muscle
intensity which produces pulses from detector 12 and the
interaction of full scale switch 19 and counters 14 and 15. When
store one shot 28 produces a signal which transfers the accumulated
counts from counters 16, 17, and 18 into store 29, 30, and 31, a
signal is also transmitted to reset one shot 32. This produces a
momentary signal immediately after the momentary signal produced by
store one shot 28. Thus store one shot 28 and reset one shot 32
both produce a momentary signal at each repetition of the signal
controlled by integration time switch 27. The store one shot 28
signal precedes the signal produced by reset one shot 32. The
momentary signal produced by reset one shot 32 restores the
accumulated count stored in counters 14, 15, 16, 17, 18 to zero.
This occurs after the accumulated count of counters 16, 17, and 18
has been transferred to stores 29, 30 and 31. Stores 29, 30, and 31
thus contain the number of counts accumulated by counters 16, 17
and 18 for the preceding period of time which has been selected by
integration time switch 27. Each repetition of the time period
selected by integration time switch 27 causes the stores 29, 30 and
31 to be updated from counters 16, 17, and 18 and causes counters
14, 15, 16, 17, and 18 to be reset.
It was noted above that the number of counts accumulated in
counters 16, 17 and 18 in a time period selected by integration
switch 27 depends on the number of counts being generated by
detector 12, full scale switch 19 and counters 14 and 15. To see
how this comes about make reference to Table 2.
TABLE 2 ______________________________________ Full Scale Switch
Counter Driven 19 scale setting by Detector 12
______________________________________ 3 (0-999) 14 2 (0-99.9) 15 1
(0-9.99) 16 ______________________________________
When full scale switch 19 is set to position 3 this corresponds to
a full scale count of 999 microvolts of integrated rectified muscle
signal. At the same time that the detector 12 is driving counter 14
(for full scale switch 19 scale setting 3) the full scale switch 19
also connects counter 14 to counter 15 and counter 15 to counter
16. If the original muscle signal had been 100 microvolts, as an
example, the detector 12 would produce a pulse repetition of 1,000
Hz. For scale setting 3 of full scale switch 19 counters 14, 15,
16, 17, and 18 are arranged to count 10 pulses and produce a carry
to the next counter as they return to 0 (from 9).
Suppose that integration time switch 27 selects 1 second
integration time. In 1 second detector 12 would produce 10,000
pulses. This would be counted in counters 14, 15, 16, 17, and 18.
After 1 second, counter 18 would have 1 count and counters 17, 16,
15 and 14 should each have 0 counts. When the counts of counter 18,
17, and 16 are transferred to stores 31, 30 and 29 at the end of 1
second these elements (the stores) would then store a 1 in store
31; a zero in store 30, and a zero in store 29. If store 31 is
interpreted as the most significant digit of the integral of
rectified muscle signals, store 30 as the next most significant
digit, and store 29 as the least significant digit, then the number
100 would appear in these stores. The number 100 is the indication
that 100 microvolts existed for 1 second. Had integration time
switch 27 selected 2 seconds, 20,000 pulses would have been
produced by detector 12. The count in stores 31, 30, and 29 would
be 200 after 2 seconds and this would correspond to an integral of
200 microvolt seconds. Thus stores 31, 30, and 29 contain a number
which is the value of the integrated rectified muscle signal
directly in microvolt-seconds. Other arrangements of full scale
switch 19 and integration time switch 27 similarly produce the
exact integral value in stores 31, 30, and 29, directly in
microvolt second units when multiplied by the setting on
integration time switch 27.
For various modes of display an analog signal rather than a digital
signal is required. Such an analog signal, having a magnitude
proportional to the integrated rectified muscle signal fed to the
integrator 13 (FIG. 1C), is thus available for driving a scope
display 39, a loud speaker 48, and/or an external analog recorder
(via an amplifier 34).
The outputs of stores 31, 30 and 29 drive digital to analog
converter 33. This device produces an electrical output which is
proportional to the number stored in stores 31, 30, and 29 at all
times. The output of digital to analog converter 33 is thus an
electrical signal (voltage) proportional to the integrated
rectified muscle signal. The output of digital to analog converter
33 drives among other things amp. 34. Amp 34 adjusts the output of
digital to analog converter 33 such that the output of amp. 34 is
suitable for recording on a graphic or other recording device.
As noted previously, one of the display modes is the presentation
of results on a scope 39. In keeping with this feature, controls
are provided to allow the scope 39 to display any two of the
preselected signals (i.e., from channel 1, from channel 2, and from
the reference). To this end:
The output of digital to analog converter 33 also controls amp. 35.
The output of amp. 35 is connected to scope display select switch
36. Amp. 37 and amp. 38 are also connected to scope display select
switch 36. The scope display select switch 36 controls the signals
which appear on scope display 39. The scope display select switch
36 controls which two signals appear on scope display 39. Scope
display 39 is capable of displaying two signals as they can vary
with time. The time base of scope display 39 is adjustable with
sweep speed select 40. Control of the signals to be displayed is
accomplished according to Table 3.
TABLE 3 ______________________________________ Position of Scope
Signals Displayed on Display Select Switch Scope Display 39 36
Channel 1 Channel 2 ______________________________________ 1 Output
of inte- Reference grator 13 via signal 41 digital to ana- via amp.
38 log converter 33 and amp. 35 2 Output of inte- Reference grator
42 via signal 41 amp. 37 via amp. 38 3 Output of inte- Output of
grator 13 via integrator digital to ana- 42 via log converter amp.
37 33 and amp. 35 ______________________________________
Scope display 39 will display either the output of the channel 1
integrator 13 and a reference signal determined by reference
control 41, or the output of channel 2 integrator 42 and the
reference signal determined by reference control 41, or the output
of both channel 1 integrator 13 and channel 2 integrator 42. The
elements of channel 2 integrator 42 are identical in configuration
to the elements of integrator 13 (channel 1). Amp. 42A provides an
identical function to amp. 34.
The outputs of stores 31, 30, and 29 (and the corresponding
elements of channel 2 integrator 32) in addition to controlling the
digital to analog converter 33 are connected to display select
switch 43. Display select switch 43 controls the number to be
displayed on digital display 44. When channel 1 integrated output
is displayed on digital display 44 the outputs of stores 31, 30,
and 29 are transferred to digital display 44 by display select
switch 43. When channel 2 integrated output is displayed on digital
display 44 the outputs of the stores in integrator 42 (channel 2)
are transferred to digital display 44 by display select switch
43.
The remaining elements shown in FIG. 1C including channel select
switch 45, comparator 49 (per FIG. 6, a Schmitt trigger
discriminator 236), amp. 50, amp. 51, mode switch 46, tone
generator 47 and speaker 48, are arranged to produce an audible
tone which provides another modality to display the relation
between a multiplicity of muscle sources and a signal
representative of the willful stimulus produced by a human being.
Channel select switch 45 receives signals from digital to analog
converter 33, an element of integrator 13, and from the
corresponding digital to analog converter element of integrator 42.
These inputs are voltages which are equivalent to the rectified
integrated muscle signals. Channel select switch 45 determines
which of these signals is to produce the audible tone. The signal
selected by channel select switch 45 passes to amp. 50. A second
input to amp. 50 is the reference signal produced by reference
control 41. Amp. 50 produces a signal which is proportional to the
difference between the integrated rectified muscle signal from
channel select switch 45 and reference control 41. The larger the
difference between the integrated rectified muscle signal and the
reference signal, the greater the output of amp. 50. Comparator 49
receives the same inputs as amp. 50. Comparator 49 however produces
either a zero signal or a larger intensity signal depending on the
relative conditions of its input signals. If the integrated
rectified muscle signal is smaller than the reference the
comparator 49 produces its full magnitude output. Its output is not
proportional to the difference but rather is present in its
entirety as long as the integrated rectified muscle signal is
smaller than the reference. If the integrated rectified muscle
signal is equal to or larger than the reference, the comparator 49
will produce a zero signal. Amp. 51 inverts the sense of the
comparator 49 signals. Thus the output of amp. 51 has no output
when the integrated rectified muscle signal is smaller than the
reference and has full output when the integrated rectified muscle
signal is equal to or greater than the reference. A mode switch 46
determines which signal will pass to the tone generator 47. The
signal passing to the tone generator is selected in accordance with
Table 4.
TABLE 4 ______________________________________ Mode Switch 46
Signal Passing to Setting Tone Generator 47
______________________________________ Off Zero Proportional Output
of amp. 50 Decrease Output of comparator 49 Increase Output of amp.
51 ______________________________________
Tone generator 47 (i.e., a variable oscillator as shown in detail
in FIG. 6) produces an output which is proportional to its input.
The output of tone generator 47 drives speaker 48. Depending on the
position of mode switch 46, speaker 48 will produce a tone in
either of the following areas: a high intensity tone only when the
integrated rectified muscle signal is equal to or greater than the
reference, a high intensity tone only when the integrated rectified
muscle signal is smaller than the reference, a tone whose intensity
is proportional to the difference between the integrated rectified
muscle signal, or no tone when the mode switch 46 is set in the OFF
position.
Exemplary circuit details for specific components and wiring for
the system of FIGS. 1A, 1B, 1C are contained in FIGS. 2 through 6
inclusive. For convenient reference, nomenclature and numbering
within the two groups of figures have been maintained. FIG. 2 is a
schematic wiring diagram showing on channel of a two channel
transducer. Signals from electrodes attached to a human subject are
received by the pre amp 5 at resistors 52 and 53. These resistors
together with the electrode capacitances of transistors 54 and 55
provide for attenuation of communication signals which might be
induced in the signal leads. Transistors 54 and 55 are arranged to
detect the difference between the two signal electrodes. Resistors
60, 61 and 62 act as biasing elements for transistors 54 and 55.
Transistors 56 and 57 are arranged to amplify the output of
transistors 54 and 55. Resistors 65 and 66 are bias elements along
with resistors 68 and 69 for transistors 58 and 59. Transistors 58
and 59 serve to isolate transistors 56 and 57 from the remainder of
the network. Resistors 70 and 71 and capacitors 72 and 73 serve to
limit the lower repetition frequency of the incoming signals such
that variations below 10 Hz will not be amplified. Capacitor 63 and
variable capacitor 64 serve to compensate for high frequency
signals which may be present in both input leads. Variable resistor
67 compensates for common signals which may be present in both
signal leads (the so called "Common mode signal"). Signals from the
emitter of transistor 58 (via resistor 74) and the emitter of
transistor 59 (via resistor 80) are coupled to transistors 77 and
78. These transistors provide additional amplication of the
difference between incoming signals from the electrodes
amplification Resistors 115A and 79 bias the transistors 77 and 78.
Transistor 76 isolates transistors 77 and 78 from the remainder of
the network. The output of the emitter of transistor 76 is coupled
through capacitors 82 and 83 to the gain adjust amp. 6. The
components up to resistor 84 in the signal path comprise the
pre-amp 5. From the pre amp 5, signals are fed to a gain adjust amp
6 for amplitude control. Operational amplifier 86 (for example Type
776, Fairchild) with variable resistor 90 and resistor 84 comprise
the means by which adjustments in the signal path may be
accomplished. Capacitor 91 in conjunction with the aforementioned
elements provides limits in the high frequency variation of the
signal. Resistor 87 is a bias element and resistor 88 is an
impedance compensation element.
The output of the gain adjust amp. 6 is transmitted via resistor 92
to the half wave rectifier 7 and via resistor 101 to the summer 8.
When the output of gain adjust amp 6. is negative, operational
amplifier 94 (Type 776, Fairchild) in conjunction with rectifiers
97 and 98, resistor 99, resistor 92, and biased resistors 95 and
96, produce zero volts at the junction of rectifier 98 and resistor
99 (the output of half wave rectifier 7). When the output of gain
adjust amp. 6 is positive the output of half wave rectifier 7 is
negative and of equal extent. The outputs of gain adjust amp. 6
(via resistor 101) and half we rectifier 7 (via resistor 100) are
combined in summer 8.
Summer 8 produces the full wave-rectified version of the output of
gain adjust amp. 6 in the following manner. When the output of gain
adjust amp. 6 is negative, zero volts appear at the output of half
wave rectifier 7. Thus resistor 100 sums zero current into the
junction of resistors 101 and 100. Resistor 101 sums a current
proportional to the negative signal at the output of gain adjust
amp. 6. The output of summer 8 at the junction of operational
amplifier 103 (Type 776, Fairchild) and resistor 104, is a voltage
which is positive (operational amplifier 103 inverts the polarity
of the current summed into resistors 101 and 100) and proportional
to the sum of the voltages at the outputs of gain adjust amp. 6 and
half wave rectifier 7. Two currents flow in resistors 101 and 100.
The current in resistor 101 is proportional to the positive
excursion of the output of gain adjust amp. 6. The current in
resistor 100 is negative in direction. This is so because half wave
rectifier 7 has inverted the signal from gain adjust amp 6.
Resistor 101 and 100 are in the ratio of 2 to 1. The output of
operational amplifier 103 is proportional to the sum of the
currents flowing in resistors 101 and 100. The output of
operational amplifier 103 is positive as it was for the case when
the output of gain adjust amp. 6 was negative. The output of
operational amplifier 103 is thus a full wave rectified signal
proportional to the output of gain adjust amp. 6. Resistors 102,
105, and 106 bias the op amp 103.
The output of summer 8 is coupled via variable resistor 107 to
voltage to frequency converter 9, which includes a voltage to
frequency converter 109 (Type 4701, Teledyne). Variable resistor
107 adjusts the full scale frequency of voltage to frquency
converter 109 while variable resistor 108 adjusts the absolute
value of the low frequency operation of voltage to frequency
converter 109. The output of voltage to frequency converter 109
consists of pulses whose repetition rate is proportional to the
output of summer 8.
The pulse signals from the voltage to frequency converter 9 are
coupled via resistor 110 to transistor 111, which delivers a pulse
of current via resistor 112 to a light emitting diode 113 of opto
isolator 3. Light from light emitting diode 113 is coupled (without
wires) to photo transistor 114. Photo transistor 114 converts light
pulses into electrical current flow and it forms part of detector
12 of the integrator 13 (or integrator 42 for the other transducer
channel).
FIG. 3 is a schematic diagram of the programmer 20 of FIG. 1C.
Transistor 118 in conjunction with resistors 115 and 116 and
capacitor 117 oscillates at a frequency of 4 Hz. The output pulses
are coupled via resistor 120 to transistor 121. Resistor 119 biases
the transistor 118. Transistor 121 amplifies the pulses from
transistor 111 and couples the amplified pulses via resistor 122 to
integrated circuit 122A. Integrated circuit 122A contains 4 flip
flops and associated gates arranged to act as a counter of 10.
Integrated circuit 122A (Type 7490) divides the pulse repetition
frequency of the pulses coming from transistor 121 by a factor of
10.
Integrated circuit 123 (Type 7473) consists of two flip flops, with
each one able to divide its input by a factor of 2. Signals from
integrated circuit 122A drive integrated circuit 123. Two outputs
are available from integrated circuit 123. Each consists of pulses
whose repetition rate is 1/2 and 1/4 respectively that of the
output of integrated circuit 122A. The output of the second flip
flop of integrated circuit 123 is coupled to two integrated
circuits, namely 125 and 124 (each Type 7490). Integrated circuit
125 (i.e., counter 26 of FIG. 1C) consists of flip flops and gates
arranged to divide incoming reptition rates by 5 while integrated
circuit 124 consists of flip flops and gates arranged to divide
incoming repetition rates by factors of 2 (i.e., flip flop 24 of
FIG. 1C) and 5 (counter 25 of FIG. 1C). The outputs of the various
integrated circuits are coupled to the integration time switch 27
according to Table 5.
TABLE 5 ______________________________________ Integrated Circuit
Pulse Period of Output (secs.)
______________________________________ 122A .25 123 .5, 1 124 2, 10
125 5 ______________________________________
Integrated circuit 129 (Type 7400) receives pulse signals from the
integration time switch 27 via capacitor 128. Capacitor 128
differentiates the signal with resulting positive excursions being
conducted to the power supply via diode 132. Negative excursions of
pulse signals produced by capacitor 128 cause gates in integrated
circuit 129 to be turned from a normally on state to a normally off
state. This signal is coupled to two places. It is coupled to
integrated circuit 137 where it is amplified and transmitted to
store elements 31, 30 and 29.
The negative excursions of signals through capacitor 128 are
restored to their normal level in a time determined by capacitor
128 and resistor 126 and variable resistor 127. Variable resistor
127 in conjunction with resistor 126 and capacitor 128 determine
the duration of time during which the gates of integrated circuit
129 will remain cut off. This momentary signal in addition to being
coupled to integrated circuit 137 (Type SP357, Signetics) is
coupled via capacitor 136 to other gate elements in integrated
circuit 129. A similar differentiation of signal takes place via
capacitor 136; resistors 135, 133, 130 and diode 134. The resultant
signal is a momentary signal occurring after the signal initiated
by the signal from integration time selector switch 27. This
momentary signal is coupled to integrated circuit 137 where it is
amplified and transmitted to the counter elements 14, 15, 16, 17
and 18 of integrator 13 and the corresponding elements of
integrator 42.
Detailed circuitry for the digital integrator 19, the counters
14-18, the stores 29-31 and the digital to analog converter 33
(i.e., 153) of FIG. 1C is shown in FIG. 4.
FIG. 4 is a schematic wiring diagram showing a digital integrator
included in digital integrator 13 (or 42). An input sequence of
pulses representative of rectified muscle signal intensity is
transmitted from photo transistor 114 to resistor 138. The
combination of diodes 139 and 140 prevents muscle signals from
causing a false pulse. Resistors 141 and 142 are bias elements for
transistor 143. Transistor 143 amplifies the pulses which are
transmitted to integrated circuit 144 Type 7400. This also
amplifies the pulse signals and transmits them to the full scale
switch 19.
Integrated circuits 145, 146, 147, 148 and 149 that is, counters
14, 15, 16, 17, and 18 of FIG. 1C; each Type 7490 are combinations
of flip flops and gates arranged to produce 10 states whose binary
code represents the decimal digits 0 through 9. Upon returning from
state 9 to state 0, a carry signal is produced. Thus integrated
circuits 145, 146, 147, 148, and 149 can be connected in serial
order according to the position of full scale switch 19. The serial
sequence of counting can be seen in Table 6.
TABLE 6 ______________________________________ Setting of Full
Scale Serial arrangement of integrated Switch 19 Circuits 145, 146,
147, 148 and 149 ______________________________________ 1 (0-9.9)
147 - 148 - 149 2 (0-99.9) 146 - 147 - 148 - 149 3 (0-999) 145 -
146 - 147 - 148 - 149 ______________________________________
The first element indicated in each line of the Table 6 is the
element driven by the pulses originating in integrated circuit 144.
Integrated circuits 150, 151, and 152 (i.e., stores 31, 30, 29,
respectively, of FIG. 1C; each Type 7475) are arrangements of flip
flops which can store a 4 bit binary code upon command. These
elements store the binary coded decimal number which appears in
elements 147, 148 and 149. The code is stored in 150, 151 and 152
upon command from store one shot 28. Integrated circuit 153 (Type
DAC 372-12 BCD, Hybrid Systems Corp.) is a digital to analog
converter. This receives signals from store elements 152, 151 and
150 and proviides an analog representation of this binary coded
decimal input at its output. Variable resistors 154 and 155 adjust
the output voltage when the input is a binary coded representation
of 000 and when the input is a binary coded representation of
999.
FIG. 5 is a schematic wiring diagram showing, in more detail,
elements of FIG. 1C, including display drivers (i.e., amps 35, 37,
38), a reference source (i.e., reference control 41), and recorder
drivers (amps 34 and 42A). Amp. 34 receives signals from the
digital to analog converter 33. These are attenuated in resistor
154 and variable resistor 155 to cause them to be suitable for
controlling either graphic recorders or magnetic tape recorders.
Integrated circuit 157 and resistor 156 are used to provide a
compatible driver for the various recording apparatus.
Amp. 42A is identical in function to amp. 34. Resistors 158, 159,
and 160, and operational amplifier 161 perform identical functions
as corresponding elements 154, 155, 156 and 157.
Amp. 35 receives signals from digital to analog converter 33.
Resistors 174 and 175 suitably attenuate the signal such that for
maximum input voltage from digital to analog converter 33 the
deflection of the cathode ray tube electron beam observed on the
scope display 39 is adjacent to a mark indicating full scale.
Resistors 172 and 173 suitably attenuate the signal from digital to
analog converter 33 (FIG. 1C) such that for zero signal from
digital to analog converter 33 the deflection of the cathode ray
tube electron beam observed on the scope display 39 is adjacent to
a mark indicating zero signal. Operational amplifiers 177 and
resistor 176 provide coupling means to scope display 39.
Amp. 37 includes elements 178, 179, 180, 181, 182 and 183 whose
function is analogous to corresponding elements in amp. 34. Amp. 37
provides the same function for channel 2 signals that amp. 35
provides for channel 1 signals.
Reference control 41 provides an adjustable voltage representative
of willful muscle signal from zero to full scale. Variable resistor
170 and fixed resistor 169 attenuate the supply voltage in
accordance with the setting of resistor 170. This signal is
transmitted to operational amplifier 171 which in combination with
resistor 168 provides an output voltage with low equivalent source
impedance. In addition to being transmitted to comparator 49 and
amp. 50, the output of reference control 41 is transmitted to amp.
38. Amp. 38 contains elements 162, 163, 164, 165, 166 and 167 which
function in an entirely analygous manner to the corresponding
elements of amp. 35.
FIG. 6 is a schematic wiring diagram showing further details of
FIG. 1C, including a proportionality amplifier 50, a comparator
236, and a tone generator 47. Signals representing the integrated
rectified muscle signal are coupled via channel select switch 45 to
resistor 185. Signals from the reference source 41 are coupled to
resistor 184. These signals are combined using operational
amplifier 188 (Type 741), and resistors 186 and 187.
The output of operational amplifier 188 consists of the difference
between the integrated rectified muscle signals and the reference.
The amount of this difference is coupled via diode 190 and resistor
191 to the mode switch 46 (FIG. 1C) where it will drive the tone
generator 47 when the mode switch 46 is set to proportional
control. In addition, the output of operational amplifier 188 is
coupled via resistor 189 to a Schmitt trigger circuit 236. This
circuit determines when the reference signal is greater or less
than the integrated rectified muscle signal and produces two
different output voltages for the two conditions. This is
accomplished using resistors 189, 192, 193, and 195, diodes 196,
197, 198 and 199 and operational amplifier 194 (Type 741).
Resistors 192 and 193 provide hysteresis in the operation of the
network.
The output of the Schmitt trigger 236 is coupled via resistor 200
to an amplifier consisting of transistor 202 and resistor 201. The
output of transistor 202 produces its maximum output when the
reference is larger than the integrated rectified muscle signal and
produces its minimum output when the reference is smaller than the
integrated rectified muscle signal. In addition to transmitting
this signal to the mode switch 46 the signal is coupled via diode
203 to another amplifier comprised of resistors 204, 206, and 208,
diode 205, and transistor 207. These elements combine to invert the
conditions at the output of transistor 202 in such a way that the
output of transistor 207 will be a maximum when the output of
transistor 202 is a minimum and the output of transistor 207 will
be a minimum when the output of transistor 202 is a maximum. The
output of transistor 207 is coupled to mode switch 46.
Tone generator 47 accepts signals from the mode switch 46. It
accepts signals from either resistor 191, transistor 202, or
transistor 207 or ground (when the mode switch 46 is in the off
position) depending upon the position of mode switch 46. The signal
is transmitted to the base of transistor 222. Transistor 222 and
associated elements resistor 223 and resistor 221 act to isolate
the mode switch 46 signal from the remainder of the network.
A tone is generated in the following manner. Resistor 209,
capacitor 210, transistor 212, resistor 211 and resistor 213
combine to produce oscillations at a suitable audio frequency
(1,600 Hz as an example). The pulses produced at Base 1 of
transistor 212 are amplified in transistor 214 in association with
resistor 215. The resultant amplified pulses are coupled to
integrated circuit 216 (Type 7473). Integrated circuit 216 consists
of flip flops which divide the incoming pulse train by a factor of
two. Thus the output pulses consist of square waves whose frequency
is 1/2 the incoming frequency (800 Hz for example). The outputs of
integrated circuit 216 drive transistor 218 and 220 via resistors
217 and 218. Transistors 218 and 220 act as switches which either
short the signals found at resistors 224 and 225 (when transistors
218 or 220 are closed) to ground or allow the signals found at
resistors 224 and 225 to pass to resistors 226 and 227 (when
transistors 218 or 220 are opened). The signals passing through
resistors 226 and 227 are either zero (when transistors 218 or 220
are closed) or allow the signal originating at transistor 222 to
pass to the operational amplifier 230. Since transistors 218 and
220 are driven from a flip flop in integrated circuit 216, they are
turned on and off at different times. When transistor 218 is open,
transistor 220 is closed and vice versa.
The combination of the operation of transistors 220 and 218 causes
operational amplifier 230 and resistors 226, 227, 228 and 229 to
act as an amplifier whose gain changes from negative to positive as
transistors 220 and 218 are switches from on to off. The
combination of transistors 218 and 220 and resistors 226, 227, 228,
and 229 and operational amplifier 230 acts as a modulator of the
signal present at the emitter of transistor 222. The magnitude of
the signal at the output of operational amplifier 230 is
proportional to the signal from the mode switch 46 and has a
frequency determined by the oscillator transistor 212 and
integrated circuit 216 (800 Hz for example). This signal (the
output of operational amplifier 230) drives variable resistor 231.
This adjusts the volume of the tone produced by speaker 48. The
signal from the variable resistor or volume control, 231 is coupled
to an amplifier consisting of transistors 232, 234, and 235 and
resistor 233. The output of this amplifier (the junction of the
emitters of transistors 234 and 235) drives speaker 48.
Uses:
the normal sensory motor performance in health, is a closed loop
servomechanism with continuity of sensory feedback control and with
multisensory integration.
Any sizable deficit in the flow of afferent proprioceptive sensory
information (feedback) will result in disturbance of skilled motor
performance. Such disturbance is seen in a variety of neuromuscular
disorders due to injury or disease, e.g., stroke, cerebral palsy,
dystonia.
The proposed system, reflecting instantaneously the functional
state of involved muscles and delivered to the central nervous
system through intact sensory organs of vision and hearing, has
been found of considerable therapeutic significance.
The proposed system is utilizing the known plasticity of central
nervous system which is the perceptual mechanism that can deal with
information supplied by structures not previously concerned with
the analysis of a particular modality of sensory information.
The proposed system allows for substitution for the defect in the
servomechanism of volitional movements through integration of
substitute signals (exteroceptive instead of proprioceptive).
The proposed system is reestablishing the integrity of sensory
motor interaction and is allowing for learning of a new pattern of
voluntary movements.
These new patterns of voluntary movement become permanently
retained through processes of learning after the withdrawal of
instrumental learning.
The uses of the proposed system will be of considerable therapeutic
significance in treatment of many neuromuscular disorders, due to
injury or disease, where there are clinical signs of decreased or
absent sensory feedback from the muscles.
* * * * *