## Method and apparatus for changing brain wave frequency

United States Patent | RE36,348
Carter , et al. | October 19, 1999

Method and apparatus for changing brain wave frequency

Abstract

A method for changing brain wave frequency to a desired frequency determines a current brain wave frequency of a user, generates two frequencies with a frequency difference of a magnitude between that of the current actual brain wave frequency and the desired frequency but always within a predetermined range of the current actual brain wave frequency, and produces an output to the user corresponding to the two frequencies. One apparatus to accomplish the method has a computer processor, a computer memory, EEG electrodes along with an amplifier, a programmable timing generator responsive to the computer processor for generating the two frequencies, audio amplifiers and a beat frequency generator driving a visual frequency amplifier.

Inventors: | Carter; John Leland (Harris County, TX); Russell; Harold Laverne (Galveston County, TX); Ochs; Len (Contra Costa County, CA)
Assignee: | Neurotrain L.C. (Galveston, TX)
Appl. No.: | 490116
Filed: | June 12, 1995

Related U.S. Patent Documents

| Patent No.: | Issued: | Appl. No.: | Filed:
Reissue of: | 05036858 | Aug 06, 1991 | 497426 | Mar 22, 1990

Current U.S. Class: | 600/545; 600/27
Intern'l Class: | A61B 005/04
Field of Search: | 128/731,732 600/26-28,545,544

References Cited

U.S. Patent Documents

3884218 | May., 1975 | Monroe | 600/28.
4191175 | Mar., 1980 | Nagle | 600/27.
4227516 | Oct., 1980 | Meland | 600/26.
4228807 | Oct., 1980 | Yagi et al. | 128/732.
4315502 | Feb., 1982 | Gorges | 600/27.
4334545 | Jun., 1982 | Shiga | 128/732.
4834701 | May., 1989 | Masaki | 600/28.
4883067 | Nov., 1989 | Knispel et al. | 128/732.
5241967 | Sep., 1993 | Yasushi et al. | 128/732.

Other References

Mind Power: Alpha, Radio Electronics, vol. 47, No. 7 pp. 36-39, 91 Jul. 1976, Gernsback Publications Inc., NY, NY.
Feeback Control of Amount and Frequency of Human Alpha Waves, Kobayashi et al., Jap. J. Medicene, vol. 14 No. 4 Aug. 1976.

Primary Examiner: Nasser; Robert L.
Attorney, Agent or Firm: Timmons; W. Thomas Timmons & Kelly

Parent Case Text

.Iadd.This application is a continuation of utility application Ser. No. 08/102,472 filed Aug. 5, 1993, abandoned. .Iaddend.

Claims

We claim:
1. A method for stimulating a user, comprising in combination the steps of:

- determining a desired brain wave frequency;
- determining a current brain wave frequency of the user;
- generating a first signal at a first frequency; generating a second signal at a second frequency
- .Iadd.creating a frequency difference between the first frequency and the second frequency
- .Iaddend.wherein the frequency difference .[.between the first and second signals.].
- is between the current brain wave frequency and the desired brain wave frequency and is within a predetermined range of the current brain wave
- frequency; and producing an output detectable by the user corresponding to the first and second signals to generate a beat signal equal to the frequency difference.

2. A method according to claim 1 further comprising:

- repeating the steps of determining a current brain wave frequency, generating a first signal,
- generating a second signal, and producing an output detectable by the user corresponding to the first and second signals to
- generate a beat signal equal to the frequency difference until the current brain wave frequency is within a predetermined range of the desired brain wave frequency,
  further comprising:
- maintaining the difference between the first and second frequencies substantially equal to the desired brain wave frequency for a predetermined amount of time;
- and changing the desired brain wave frequency to a second desired brain wave frequency and repeating the steps of determining a current brain wave frequency,
- generating a first signal, generating a second signal, and producing an output detectable by the user corresponding to the first and second signals
- to generate a beat signal equal to the frequency difference until the current brain wave frequency is within a predetermined range of the desired brain wave frequency.

3. A method according to claim 2 wherein the step of producing an output detectable by the user corresponding to the first and second signals to generate a beat signal equal to the frequency difference comprises sounding the first and second signals.

4. A method according to claim 2 wherein the second desired brain wave frequency substantially equals the original current brain wave frequency.

5. A method according to claim 1 further comprising:

- repeating the steps of determining a current brain wave frequency,
- generating a first signal, generating a second signal, and producing an output detectable by the user corresponding to the first and second signals
- to generate a beat signal .[.equal to.]. .Iadd.at
- .Iaddend.the frequency difference until the current brain wave frequency is within a predetermined range of the desired brain wave frequency,
  further comprising:
- maintaining the difference between the first and second frequencies substantially equal to the desired brain wave frequency for a predetermined amount of time;
- and producing no output detectable by the user for a second predetermined amount of time.

6. An apparatus for urging the brain wave frequency of a user toward a desired brain wave frequency, the apparatus comprising in combination:

- means for determining a current brain wave frequency of the user;
- means for generating a first signal at a first frequency;
- means for generating a second signal at a second frequency wherein .[.the.]. .Iadd.there is a .Iaddend.frequency difference between the first .Iadd.frequency .Iaddend.and .Iadd.the .Iaddend.second .[.signals.]. .Iadd.frequency and the frequency difference
- .Iaddend.is between the current brain wave frequency and the desired brain wave frequency and is within a predetermined range of the current brain wave frequency;
- and means for producing an output detectable by the user corresponding to the first and second signals to generate a beat signal .[.equal to.]. .Iadd.at .Iaddend.the frequency difference.

7. An apparatus according to claim 6 wherein the means for producing an output detectable by the user corresponding to the first and second signals to generate a beat signal .[.equal to.]. .Iadd.at .Iaddend.the frequency difference comprises means for sounding the first and second signals.
8. An apparatus for urging the brain wave frequency of a user toward a desired brain wave frequency, the apparatus comprising in combination: a computer processor; .[.a memory which can be written to and read from the computer processor;.] . means .Iadd.in communication with the computer processor .Iaddend.for determining a current brain wave frequency of the user.[., which communicates with the computer processor.].; a programmable timing generator .Iadd.operatively connected to and .Iaddend.responsive to the computer processor .[.and.]. .Iadd.for .Iaddend.generating a first signal at a first frequency and a second signal at a second frequency wherein .[.the.]. .Iadd.there is a .Iaddend.frequency difference between the first .Iadd.frequency .Iaddend.and .Iadd.the .Iaddend.second .[.signals.]. .Iadd.frequency and the frequency difference .Iaddend.is between the current brain wave frequency and the desired brain wave frequency and is within a predetermined range of the current brain wave frequency; .Iadd.and .Iaddend. means .Iadd.responsive to the programmable timing generator and .Iaddend.detectable by the user for producing an output corresponding to the first and second signals.
9. An apparatus according to claim 8 wherein the means detectable by the user is a means for sounding the first and second signals.
10. An apparatus according to claim 8 wherein the means detectable by the user comprises a means for generating a beat signal .[.equal to.]. .Iadd.at .Iaddend.the frequency difference .[.of the first and second signals.]..

11. An apparatus according to claim 10 wherein the means detectable by the user further comprises light means .Iadd.for visual detection by the user, .Iaddend.responsive to the means for generating a beat frequency. .Iadd.12. A method for stimulating a user, comprising in combination the steps of:

- determining a desired brain wave frequency;
- determining a current brain wave frequency of the user;
- generating a signal at a frequency between the current brain wave frequency and the desired brain wave frequency which is within a predetermined range of the current brain wave frequency;
- and producing an output detectable by the user at the signal frequency. .Iaddend..Iadd.13.
  A method according to claim 12 further comprising:
- repeating the steps of determining a current brain wave frequency,
- generating a signal at a frequency between the current brain wave frequency and the desired brain wave frequency which is within a predetermined range of the current brain wave frequency,
- and producing an output detectable by the user at the signal frequency until the current brain wave frequency is within a predetermined range of the desired brain wave frequency,
  further comprising:
- maintaining the signal frequency substantially equal to the desired brain wave frequency for a predetermined amount of time;
- and changing the desired brain wave frequency to a second desired brain wave frequency and repeating the steps of determining a current brain wave frequency,
- generating a signal at a frequency between the current brain wave frequency and the second desired brain wave frequency which is within a predetermined range of the current brain wave frequency,
- and producing an output detectable by the user at the signal frequency equal until the current brain wave frequency is within a predetermined range of the second desired brain wave frequency.
- .Iaddend..Iadd.14. A method according to claim 13 wherein the second desired brain wave frequency substantially equals the original current brain wave frequency.
- .Iaddend..Iadd.15. A method according to claim 12 further comprising: repeating the steps of determining a current brain wave frequency, generating a signal at a frequency between the current brain wave frequency and the desired brain wave frequency which is within a predetermined range of the current brain wave frequency, and producing an output detectable by the user at the signal frequency until the current brain wave frequency is within a predetermined range of the desired brain wave frequency,
  further comprising:
- maintaining the signal frequency substantially equal to the desired brain wave frequency for a predetermined amount of time;
- and producing no output detectable by the user for a second predetermined amount of time.
- .Iaddend..Iadd.16. An apparatus for urging the brain wave frequency of a user toward a desired brain wave frequency,
  the apparatus comprising in combination:
- means for determining a current brain wave frequency of the user;
- means for generating a signal at a frequency between the current brain wave frequency and the desired brain wave frequency which is within a predetermined range of the current brain wave frequency;
- and means for producing an output detectable by the user at the signal frequency.
- .Iaddend..Iadd.17. An apparatus for urging the brain wave frequency of a user toward a desired brain wave frequency,
  the apparatus comprising in combination:
- a computer processor; means in communication with the computer processor for determining a current brain wave frequency of the user;
- a programmable timing generator operatively connected to and responsive to the computer processor for generating a signal at a frequency which is between the current brain wave frequency and the desired brain wave frequency and is within a predetermined range of the current brain wave frequency; means responsive to the programmable timing generator and detectable by the user for producing an output at the signal frequency.
- .Iadd.18. An apparatus according to claim 17 wherein the means detectable by the user comprises light means for visual detection by the user, responsive to the signal frequency. .Iaddend.

Description

DESCRIPTION

1. Technical Field

The present invention relates generally to methods and apparatus for controlling brain wave frequencies.

The human brain produces detectable signals which vary in strength and frequency over time and from one part of the brain to another at any given time. Different frequencies are associated with different moods and changing abilities. A brain wave frequency of 13 hertz or higher is known as "beta-rhythm" and is normally associated with daily activity when all five sensory organs are functioning. A brain wave frequency of 8 to 13 hertz is known as "alpha-rhythm" and is often associated with a relaxed creative state. Brain wave frequencies of 4 to 8 hertz and 0.5 to 4 hertz are known as "theta-rhythm" and "delta-rhythm" respectively. Theta-rhythm is often found in adolescents with learning disorders, and delta-rhythm is typical of normal sleep. Researchers believe that externally creating brain wave frequencies associated with normal or desired behavior, such as externally creating delta-rhythm in someone who has a problem sleeping or alpha-rhythm in someone who has trouble learning, can help bring about such behavior.

2. Background Art

In the 1960's and early 1970's, Robert Monroe of the Monroe Institute of Applied Sciences explored the effects of sound on the brain and discovered that he could produce a driving or entrainment of brain waves. Dr. Gerald Oster, a biophysicist, also investigating the effects of sound on the brain, discovered that pulsations called binaural beats occurred in the brain when tones of different frequencies were presented separately to each ear. The beat frequency equals the frequency difference between the two tones. Both Monroe and Oster began using electronic oscillators to provide tones with frequency, purity and intensity that can be precisely controlled.

U.S. Pat. No. 3,884,218 to Robert A. Monroe shows a method for inducing sleep by amplitude modulating a pleasing sound with a delta-rhythm signal which is referred to as an "EEG sleep signal."

U.S. Pat. No. 4,191,175 to Nagle shows a method and apparatus for repetitively "producing a noise-like signal for inducing a hypnotic or anesthetic effect . . . " by creating frequency bursts of digital pulses which are then passed through a pink noise filter to get rid of frequencies above a certain cut-off. The resultant signal is then passed through a band pass filter and used to drive an audible signal source.

An apparatus for electrophysiological stimulation is shown in U.S. Pat. No. 4,227,516 to Meland et al. in which a first signal above the delta-beta frequency range is modulated by signal within that range and applied to electrodes on the forehead of a user.

A learning-relaxation device of U.S. Pat. No. 4,315,502 has both lights for pulsing signals and sound means for a pulsing sound signal as well as a control means which can individually vary the light and sound signals.

U.S. Pat. No. 4,834,701 to Masaki shows a device similar to those used by Monroe and Oster with first and second generators with frequencies above 16 hertz and a frequency difference of 4 to 16 hertz sounded to lower the brain wave frequency of a user.

An article entitled "Alpha Brain Waves & Biofeedback Training" in the December 1972 popular Electronics show a system which uses a person's own EEG signal to modulate a tone generator which, in turn, then drives a speaker heard by the same person. The device allowed a person to "hear" his or her own brain signals in an attempt to voluntarily control the frequency. A similar device which allows a person to "see" his or her own brain waves is shown in an article entitled "Mind Power: Alpha" in the July 1976 Radio-Electronics.

DISCLOSURE OF INVENTION

A method for stimulating a user according to the present invention includes first determining a desired brain wave frequency and then determining the actual current brain wave frequency of a user, allowing for the possibility that one user could have more than one brain wave frequency at the same time. First and second signals having first and second frequencies are then generated, the frequency difference being between the current brain wave frequency and the desired brain wave frequency, but also being within a certain range of the current brain wave frequency. An output corresponding to the first and second signals and detectable by the user is then produced. The output can be sound or light or even electrical current. The first and second signals can be combined first before sounding or can be presented separately to, one to each ear, with the resultant binaural beat.

The steps are repeated until the desired brain wave frequency is reached. The procedure then followed depends upon the particular situation. The desired frequency con be maintained for some predetermined period of time, after which a new desired frequency can be determined. One likely replacement for the desired frequency is the original brain wave frequency of the user as it was when the session began. Another possibility would be to take the user to a rest frequency between "work" sessions. Another possibility would be to generate no signal at all for a period of time.

A preferred form of an apparatus according to the present invention for urging the brain wave frequency of a user toward a desired frequency includes a computer processor, a memory which can be written to and read from the computer processor, means such as EEG electrodes attached to the head of the user along with an amplifier for determining a current brain wave frequency of a user, which means communicates with the computer processor, a programmable timing generator responsive to the computer processor, generating at least a first and a second signal, and means detectable by the user for producing an output corresponding to the first and second signals. The frequency difference between the first and second signals is between the current brain wave frequency and the desired brain wave frequency and is within a predetermined range of the current brain wave frequency.

These and other objects, advantages and features of this invention will be apparent from the following description taken with reference to the accompanying drawing, wherein is shown the preferred embodiments of thee invention.

BRIEF DESCRIPTION OF DRAWING

FIG. 1 is a block diagram representation of an apparatus according to the present invention for urging the brain wave frequency of a user toward a desired brain wave frequency.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring now to the drawing, an apparatus according to the present invention is represented generally by reference numeral 10. Apparatus 10 includes a computer processor such as microprocessor 12, memory 14 and 16 which can be written to or read from the microprocessor for storing programs and data, and means such as electrodes 18 and amplifier 20 for determining a current brain wave of a user 22. Electrodes 18 and amplifier 20 communicate with microprocessor 12 by through serial port 21. A programmable timing generator 24 is responsive to microprocessor 12 and generates a first signal at a first frequency on a first channel 26 and a second signal at a second frequency on a second channel 28. The frequency difference between the first and second signals is between the current brain wave frequency and the desired brain wave frequency and is within a predetermined range of the current brain wave frequency. First audio amplifier 30 along with right earphone 32 sounds the first signal to the right ear of the user, and second audio amplifier 34 along with left earphone 36 sounds the second signal to the left ear of the user.

The first and second signals are combined in beat frequency generator 38. The combined signal is then amplified by visual amplifier 40, yielding a beat signal equal to the frequency difference which is used to drive light goggles 42.

Keypad 44 and liquid crystal display 46 are conventional input and output devices, which together with Microprocessor 12 and memory 14 and 16 could form part of a personal or even a lap-top computer. Volume, brightness and balance controls 48 are used to adjust to the individual user and the purpose of the use.

It is now easy to see that a method according to the present invention for stimulating a user includes determining a desired brain wave frequency, then determining a current brain wave frequency of the user, then generating a first signal at a first frequency and a second signal at a second frequency, and then producing an output detectable by the user corresponding to the first and second signals to generate a beat signal equal to the frequency difference. The beat signal can be a binaural beat signal in the head of the user or an electronic beat signal. The steps are repeated until the desired frequency is reached or substantially reached.

One example for use of the present invention for a child experiencing problems in school which are not emotional would be:

original current brain wave frequency=10 Hz

gradually reduce to 5 Hz over 2 to 3 minutes

stay at 5 Hz for 10 to 15 minutes

back to 10 Hz for 2 to 3 minutes

1 minute with no signal

2 minutes at 18 Hz

1 minute with no signal

2 minutes at 10 Hz.

In one sense, such a use could be considered the mental equivalent of a programmable treadmill. Throughout the program illustrated, the signal caused from the frequency difference would be within 10 or 15 percent of the current actual.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

United States Patent | 3,951,134
Malech | April 20, 1976

Apparatus and method for remotely monitoring and altering brain waves

Abstract

Apparatus for and method of sensing brain waves at a position remote from a subject whereby electromagnetic signals of different frequencies are simultaneously transmitted to the brain of the subject in which the signals interfere with one another to yield a waveform which is modulated by the subject's brain waves. The interference waveform which is representative of the brain wave activity is re-transmitted by the brain to a receiver where it is demodulated and amplified. The demodulated waveform is then displayed for visual viewing and routed to a computer for further processing and analysis. The demodulated waveform also can be used to produce a compensating signal which is transmitted back to the brain to effect a desired change in electrical activity therein.

Inventors: | Malech; Robert G. (Plainview, NY)
Assignee: | Dorne & Margolin Inc. (Bohemia, NY)
Appl. No.: | 494518
Filed: | August 5, 1974

Current U.S. Class: | 600/544; 600/407
Intern'l Class: | A61B 005/04
Field of Search: | 128/1 C,1 R,2.1 B,2.1 R,419 R,422 R,420,404,2 R,2 S,2.05 R,2.05 V,2.05 F,2.06 R 340/248 A,258 A,258 B,258 D,229

References Cited

U.S. Patent Documents

2860627 | Nov., 1958 | Harden et al. | 128/2.
3096768 | Jul., 1963 | Griffith, Jr. | 128/420.
3233450 | Feb., 1966 | Fry | 128/2.
3483860 | Dec., 1969 | Namerow | 128/2.
3495596 | Feb., 1970 | Condict | 128/1.
3555529 | Jan., 1971 | Brown et al. | 128/2.
3773049 | Nov., 1973 | Rabichev et al. | 128/1.
3796208 | Mar., 1974 | Bloice | 128/2.

Primary Examiner: Kamm; William E.
Attorney, Agent or Firm: Darby & Darby

Claims

What is claimed is:

1. Brain wave monitoring apparatus comprising

- means for producing a base frequency signal,
- means for producing a first signal having a frequency related to that of the base frequency and at a predetermined phase related thereto,
- means for transmitting both said base frequency and said first signals to the brain of the subject being monitored,
- means for receiving a second signal transmitted by the brain of the subject being monitored in response to both said base frequency and said first signals,
- mixing means for producing from said base frequency signal and said received second signal a response signal having a frequency related to that of the base frequency, and
- means for interpreting said response signal.

2. Apparatus as in claim 1 where said receiving means comprises means for isolating the transmitted signals from the received second signals.

3. Apparatus as in claim 2 further comprising a band pass filter with an input connected to said isolating means and an output connected to said mixing means.

4. Apparatus as in claim 1 further comprising means for amplifying said response signal.

5. Apparatus as in claim 4 further comprising means for demodulating said amplified response signal.

6. Apparatus as in claim 5 further comprising interpreting means connected to the output of said demodulator means.

7. Apparatus according to claim 1 further comprising

means for producing an electromagnetic wave control signal dependent on said response signal, and

means for transmitting said control signal to the brain of said subject.

8. Apparatus as in claim 7 wherein said transmitting means comprises means for directing the electromagnetic wave control signal to a predetermined part of the brain.

9. A process for monitoring brain wave activity of a subject comprising the steps of

- transmitting at least two electromagnetic energy signals of different frequencies to the brain of the subject being monitored,
- receiving an electromagnetic energy signal resulting from the mixing of said two signals in the brain modulated by the brain wave activity and retransmitted by the brain in response to said transmitted energy signals, and,
- interpreting said received signal.

10. A process as in claim 9 further comprising the step of transmitting a further electromagnetic wave signal to the brain to vary the brain wave activity.

11. A process as in claim 10 wherein the step of transmitting the further signals comprises

- obtaining a standard signal,
- comparing said received electromagnetic energy signals with said standard signal,
- producing a compensating signal corresponding to the comparison between said received electrogagnetic energy signals and the standard signal, and
- transmitting the compensating signals to the brain of the subject being monitored.

Description

BACKGROUND OF THE INVENTION

Medical science has found brain waves to be a useful barometer of organic functions. Measurements of electrical activity in the brain have been instrumental in detecting physical and psychic disorder, measuring stress, determining sleep patterns, and monitoring body metabolism.

The present art for measurement of brain waves employs electroencephalographs including probes with sensors which are attached to the skull of the subject under study at points proximate to the regions of the brain being monitored. Electrical contact between the sensors and apparatus employed to process the detected brain waves is maintained by a plurality of wires extending from the sensors to the apparatus. The necessity for physically attaching the measuring apparatus to the subject imposes several limitations on the measurement process. The subject may experience discomfort, particulary if the measurements are to be made over extended periods of time. His bodily movements are restricted and he is generally confined to the immediate vicinity of the measuring apparatus. Furthermore, measurements cannot be made while the subject is conscious without his awareness. The comprehensiveness of the measurements is also limited since the finite number of probes employed to monitor local regions of brain wave activity do not permit observation of the total brain wave profile in a single test.

SUMMARY OF THE INVENTION

The present invention relates to apparatus and a method for monitoring brain waves wherein all components of the apparatus employed are remote from the test subject. More specifically, high frequency transmitters are operated to radiate electromagnetic energy of different frequencies through antennas which are capable of scanning the entire brain of the test subject or any desired region thereof. The signals of different frequencies penetrate the skull of the subject and impinge upon the brain where they mix to yield an interference wave modulated by radiations from the brain's natural electrical activity. The modulated interference wave is re-transmitted by the brain and received by an antenna at a remote station where it is demodulated, and processed to provide a profile of the suject's brain waves. In addition to passively monitoring his brain waves, the subject's neurological processes may be affected by transmitting to his brain, through a transmitter, compensating signals. The latter signals can be derived from the received and processed brain waves.

OBJECTS OF THE INVENTION

It is therefore an object of the invention to remotely monitor electrical activity in the entire brain or selected local regions thereof with a single measurement.

Another object is the monitoring of a subject's brain wave activity through transmission and reception of electromagnetic waves.

Still another object is to monitor brain wave activity from a position remote from the subject.

A further object is to provide a method and apparatus for affecting brain wave activity by transmitting electromagnetic signals thereto.

DESCRIPTION OF THE DRAWINGS

Other and further objects of the invention will appear from the following description and the accompanying drawings, which form part of the instant specification and which are to be read in conjunction therewith, and in which like reference numerals are used to indicate like parts in the various views;

FIG. 1 is a block diagram showing the interconnection of the components of the apparatus of the invention;

FIG. 2 is a block diagram showing signal flow in one embodiment of the apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings, specifically FIG. 1, a high frequency transmitter 2 produces and supplies two electromagnetic wave signals through suitable coupling means 14 to an antenna 4. The signals are directed by the antenna 4 to the skull 6 of the subject 8 being examined. The two signals from the antenna 4, which travel independently, penetrate the skull 6 and impinge upon the tissue of the brain 10.

Within the tissue of the brain 10, the signals combine, much in the manner of a conventional mixing process technique, with each section of the brain having a different modulating action. The resulting waveform of the two signals has its greatest amplitude when the two signals are in phase and thus reinforcing one another. When the signals are exactly 180.degree. out of phase the combination produces a resultant waveform of minimum amplitude. If the amplitudes of the two signals transmitted to the subject are maintained at identical levels, the resultant interference waveform, absent influences of external radiation, may be expected to assume zero intensity when maximum interference occurs, the number of such points being equal to the difference in frequencies of the incident signals. However, interference by radiation from electrical activity within the brain 10 causes the waveform resulting from interference of the two transmitted signals to vary from the expected result, i.e., the interference waveform is modulated by the brain waves. It is believed that this is due to the fact that brain waves produce electric charges each of which has a component of electromagnetic radiation associated with it. The electromagnetic radiation produced by the brain waves in turn reacts with the signals transmitted to the brain from the external source.

The modulated interference waveform is re-transmitted from the brain 10, back through the skull 6. A quantity of energy is re-transmitted sufficient to enable it to be picked up by the antenna 4. This can be controlled, within limits, by adjusting the absolute and relative intensities of the signals, originally transmitted to the brain. Of course, the level of the transmitted energy should be kept below that which may be harmful to the subject.

The antenna passes the received signal to a receiver 12 through the antenna electronics 14. Within the receiver the wave is amplified by conventional RF amplifiers 16 and demodulated by conventional detector and modulator electronics 18. The demodulated wave, representing the intra-brain electrical activity, is amplified by amplifiers 20 and the resulting information in electronic form is stored in buffer circuitry 22. From the buffers 22 the information is fed to a suitable visual display 24, for example one employing a cathode ray tube, light emitting diodes, liquid crystals, or a mechanical plotter. The information may also be channeled to a computer 26 for further processing and analysis with the output of the computer displayed by heretofore mentioned suitable means.

In addition to channeling its information to display devices 24, the computer 26 can also produce signals to control an auxiliary transmitter 28. Transmitter 28 is used to produce a compensating signal which is transmitted to the brain 10 of the subject 8 by the antenna 4. In a preferred embodiment of the invention, the compensating signal is derived as a function of the received brain wave signals, although it can be produced separately. The compensating signals affect electrical activity within the brain 10.

Various configurations of suitable apparatus and electronic circuitry may be utilized to form the system generally shown in FIG. 1 and one of the many possible configurations is illustrated in FIG. 2. In the example shown therein, two signals, one of 100 MHz and the other of 210 MHz are transmitted simultaneously and combine in the brain 10 to form a resultant wave of frequency equal to the difference in frequencies of the incident signals, i.e., 110 MHz. The sum of the two incident frequencies is also available, but is discarded in subsequent filtering. The 100 MHz signal is obtained at the output 37 of an RF power divider 34 into which a 100 MHz signal generated by an oscillator 30 is injected. The oscillator 30 is of a conventional type employing either crystals for fixed frequency circuits or a tunable circuit set to oscillate at 100 MHz. It can be a pulse generator, square wave generator or sinusoidal wave generator. The RF power divider can be any conventional VHF, UHF or SHF frequency range device constructed to provide, at each of three outputs, a signal identical in frequency to that applied to its input.

The 210 MHz signal is derived from the same 100 MHz oscillator 30 and RF power divider 34 as the 100 MHz signal, operating in concert with a frequency doubler 36 and 10 MHz oscillator 32. The frequency doubler can be any conventional device which provides at its output a signal with frequency equal to twice the frequency of a signal applied at its input. The 10 MHz oscillator can also be of conventional type similar to the 100 MHz oscillator herebefore described. A 100 MHz signal from the output 39 of the RF power divider 34 is fed through the frequency doubler 36 and the resulting 200 MHz signal is applied to a mixer 40. The mixer 40 can be any conventional VHF, UHF or SHF frequency range device capable of accepting two input signals of differing frequencies and providing two output signals with frequencies equal to the sum and difference in frequencies respectively of the input signals. A 10 MHz signal from the oscillator 32 is also applied to the mixer 40. The 200 MHz signal from the doubler 36 and the 10 MHz signal from the oscillator 32 combine in the mixer 40 to form a signal with a frequency of 210 MHz equal to the sum of the frequencies of the 200 MHz and 10 MHz signals.

The 210 MHz signal is one of the signals transmitted to the brain 10 of the subject being monitored. In the arrangement shown in FIG. 2, an antenna 41 is used to transmit the 210 MHz signal and another antenna 43 is used to transmit the 100 MHz signal. Of course, a single antenna capable of operating at 100 MHz and 210 MHz frequencies may be used to transmit both signals. The scan angle, direction and rate may be controlled mechanically, e.g., by a reversing motor, or electronically, e.g., by energizing elements in the antenna in proper synchronization. Thus, the antenna(s) can be of either fixed or rotary conventional types.

A second 100 MHz signal derived from output terminal 37 of the three-way power divider 34 is applied to a circulator 38 and emerges therefrom with a desired phase shift. The circulator 38 can be of any conventional type wherein a signal applied to an input port emerges from an output port with an appropriate phase shift. The 100 MHz signal is then transmitted to the brain 10 of the subject being monitored via the antenna 43 as the second component of the dual signal transmission. The antenna 43 can be of conventional type similar to antenna 41 herebefore described. As previously noted, these two antennas may be combined in a single unit.

The transmitted 100 and 210 MHz signal components mix within the tissue in the brain 10 and interfere with one another yielding a signal of a frequency of 110 MHz, the difference in frequencies of the two incident components, modulated by electromagnetic emissions from the brain, i.e., the brain wave activity being monitored. This modulated 110 MHz signal is radiated into space.

The 110 MHz signal, modulated by brain wave activity, is picked up by an antenna 45 and channeled back through the circulator 38 where it undergoes an appropriate phase shift. The circulator 38 isolates the transmitted signals from the received signal. Any suitable diplexer or duplexer can be used. The antenna 45 can be of conventional type similar to antennas 41 and 43. It can be combined with them in a single unit or it can be separate. The received modulated 110 MHz signal is then applied to a band pass filter 42, to eliminate undesirable harmonics and extraneous noise, and the filtered 110 MHz signal is inserted into a mixer 44 into which has also been introduced a component of the 100 MHz signal from the source 30 distributed by the RF power divider 34. The filter 42 can be any conventional band pass filter. The mixer 44 may also be of conventional type similar to the mixer 40 herebefore described.

The 100 MHz and 110 MHz signals combine in the mixer 44 to yield a signal of frequency equal to the difference in frequencies of the two component signals, i.e., 10 MHz still modulated by the monitored brain wave activity. The 10 MHz signal is amplified in an IF amplifier 46 and channeled to a demodulator 48. The IF amplifier and demodulator 48 can both be of conventional types. The type of demodulator selected will depend on the characteristics of the signals transmitted to and received from the brain, and the information desired to be obtained. The brain may modulate the amplitude, frequency and/or phase of the interference waveform. Certain of these parameters will be more sensitive to corresponding brain wave characteristics than others. Selection of amplitude, frequency or phase demodulation means is governed by the choice of brain wave characteristic to be monitored. If desired, several different types of demodulators can be provided and used alternately or at the same time.

The demodulated signal which is representative of the monitored brain wave activity is passed through audio amplifiers 50 a, b, c which may be of conventional type where it is amplified and routed to displays 58 a, b, c and a computer 60. The displays 58 a, b, c present the raw brain wave signals from the amplifiers 50 a, b, c. The computer 60 processes the amplified brain wave signals to derive information suitable for viewing, e.g., by suppressing, compressing, or expanding elements thereof, or combining them with other information-bearing signals and presents that information on a display 62. The displays can be conventional ones such as the types herebefore mentioned employing electronic visual displays or mechanical plotters 58b. The computer can also be of conventional type, either analog or digital, or a hybrid.

A profile of the entire brain wave emission pattern may be monitored or select areas of the brain may be observed in a single measurement simply by altering the scan angle and direction of the antennas. There is no physical contact between the subject and the monitoring apparatus. The computer 60 also can determine a compensating waveform for transmission to the brain 10 to alter the natural brain waves in a desired fashion. The closed loop compensating system permits instantaneous and continuous modification of the brain wave response pattern.

In performing the brain wave pattern modification function, the computer 60 can be furnished with an external standard signal from a source 70 representative of brain wave activity associated with a desired nuerological response. The region of the brain responsible for the response is monitored and the received signal, indicative of the brain wave activity therein, is compared with the standard signal. The computer 60 is programmed to determine a compensating signal, responsive to the difference between the standard signal and received signal. The compensating signal, when transmitted to the monitored region of the brain, modulates the natural brain wave activity therein toward a reproduction of the standard signal, thereby changing the neurological response of the subject.

The computer 60 controls an auxiliary transmitter 64 which transmits the compensating signal to the brain 10 of the subject via an antenna 66. The transmitter 64 is of the high frequency type commonly used in radar applications. The antenna 66 can be similar to antennas 41, 43 and 45 and can be combined with them. Through these means, brain wave activity may be altered and deviations from a desired norm may be compensated. Brain waves may be monitored and control signals transmitted to the brain from a remote station.

It is to be noted that the configuration described is one of many possibilities which may be formulated without departing from the spirit of my invention. The transmitters can be monostratic or bistatic. They also can be single, dual, or multiple frequency devices. The transmitted signal can be continuous wave, pulse, FM, or any combination of these as well as other transmission forms. Typical operating frequencies for the transmitters range from 1 MHz to 40 GHz but may be altered to suit the particular function being monitored and the characteristics of the specific subject.

The individual components of the system for monitoring and controlling brain wave activity may be of conventional type commonly employed in radar systems.

Various subassemblies of the brain wave monitoring and control apparatus may be added, substituted or combined. Thus, separate antennas or a single multi-mode antenna may be used for transmission and reception. Additional displays and computers may be added to present and analyze select components of the monitored brain waves.

Modulation of the interference signal retransmitted by the brain may be of amplitude, frequency and/or phase. Appropriate demodulators may be used to decipher the subject's brain activity and select components of his brain waves may be analyzed by computer to determine his mental state and monitor his thought processes.

As will be appreciated by those familiar with the art, apparatus and method of the subject invention has numerous uses. Persons in critical positions such as drivers and pilots can be continuously monitored with provision for activation of an emergency device in the event of human failure. Seizures, sleepiness and dreaming can be detected. Bodily functions such as pulse rate, heartbeat reqularity and others also can be monitored and occurrences of hallucinations can be detected. The system also permits medical diagnoses of patients, inaccessible to physicians, from remote stations.