Encephalolexianalyzer

• US 5,840,040 A
• Filed: 12/18/1992
• Issued: 11/24/1998
• Est. Priority Date: 12/18/1992
• Status: Expired due to Fees

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Dowla, Farid U., Altschuler, Eric L.
• Primary Examiner(s): Tucker, Guy V.
• Application Number:
  US07/993,050
• Time in Patent Office: 2,167 Days
• Field of Search: 128/731, 128/732, 600/545, 600/544
• US Class Current: 600/545
• CPC Class Codes: A61B 5/374 Detecting the frequency distribution of signals, e.g. detecting delta, theta, alpha, beta or gamma waves
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: G06F 3/015 Input arrangements based on nervous system activity detection, e.g. brain waves [EEG] detection, electromyograms [EMG] detection, electrodermal response detection

Abstract

The encephalolexianalyzer uses digital signal processing techniques on electroencephalograph (EEG) brain waves to determine whether or not someone is thinking about moving, e.g., tapping their fingers, or, alternatively, whether someone is actually moving, e.g., tapping their fingers, or at rest, i.e., not moving and not thinking of moving. The mu waves measured by a pair of electrodes placed over the motor cortex are signal processed to determine the power spectrum. At rest, the peak value of the power spectrum in the 8-13 Hz range is high, while when moving or thinking of moving, the peak value of the power spectrum in the 8-13 Hz range is low. This measured change in signal power spectrum is used to produce a control signal. The encephalolexianalyzer can be used to communicate either directly using Morse code, or via a cursor controlling a remote control; the encephalolexianalyzer can also be used to control other devices. The encephalolexianalyzer will be of great benefit to people with various handicaps and disabilities, and also has enormous commercial potential, as well as being an invaluable tool for studying the brain.

Claims

1. Method of producing a communication or control signal using the mu wave from the brain of a person, comprising:

monitoring the mu wave from the brain of the person;

producing changes in the mu wave by performing movement or movement rehearsal by the person of a particular body part or parts of the person to attenuate the mu wave of the person in a selected pattern from the value of the mu wave when the person is neither moving nor thinking of moving;

measuring said mu wave attenuation from the brain of the person caused by movement or movement rehearsal of said body part or parts of the person;

converting said measured mu wave attenuation to a communication or control signal by signal processing the measured mu wave to obtain a power spectrum and comparing the peak power spectrum value to a predetermined threshold value.

2. Method of claim 1 wherein the mu wave is monitored and mu wave attenuation is measured by placing a pair of electrodes on the central region of the scalp, one on each side of the head, in a position to measure the mu wave and measuring a voltage difference between the electrodes.

3. Method of claim 2 wherein the electrodes are placed substantially over the motor cortex.

4. Method of claim 3 wherein the electrodes are placed substantially at the standard EEG C₃ and C₄ electrode positions.

5. Method of claim 4 wherein a first level of mu wave blocking is measured by movement or movement rehearsal of a finger or hand, and a second level of mu wave blocking is measured by movement or movement rehearsal of another body part.

6. Method of claim 1 wherein the mu wave attenuation is measured in about the 8-13 Hz range.

7. Method of claim 1 wherein the predetermined threshold value is obtained by measuring the mu wave (a) when the person is neither moving nor thinking of moving a body part, and (b) when the person is either moving or thinking of moving a body part;

determining the power spectrum of the mu waves from (a) and (b); and

selecting a value between the power spectrum from (a) and (b).

8. Method of claim 1 wherein the body part is a finger.

9. Method of claim 1 further comprising selectively attenuating the mu wave for time intervals of varying length by movement or movement rehearsal of said length to produce a control signal having a sequence of time intervals of different lengths.

10. Method of claim 1 wherein mu wave attentuation is measured by placing a pair of electrodes on the central region of the scalp, one on each side of the head and measuring a voltage signal from each electrode, and further comprising differentiating movement or movement rehearsal of a body part from the left and from the right side of the body.

11. Method of claim 1 wherein mu wave attentuation is measured by placing a plurality of electrodes at different positions of the scalp and measuring a voltage signal from each electrode, and further comprising differentiating different parts of the body.

12. Method of claim 11 wherein the plurality of electrodes is more than two and different degrees of mu wave attenuation are measured as a result of movement or movement rehearsal of one body part while consciously thinking about relaxing another body part.

13. Method comprising:

placing a pair of electrodes substantially over the motor cortex of a person'"'"'s scalp, one on each side of the head;

taking an EEG by measuring a voltage difference signal between the two electrodes;

taking a Fast Fourier Transform (FFT) of the voltage difference signal;

obtaining the power spectrum P=|FFT|² of the voltage difference signal;

comparing the peak value of the power spectrum of the new wave in the 8-13 Hz range to a baseline value to determine whether the person is either (a) neither moving nor thinking of moving a body part, or (b) either moving or thinking of moving a body part;

producing a binary control signal by changing between (a) and (b).

14. Method of claim 13 wherein the baseline is established by taking an EEG of the person (a) at rest, when the person is neither moving nor thinking of moving a body part, and (b) in movement, when the person is either moving or thinking of moving a body part;

taking a Fast Fourier Transform (FFT) of the EEG waves in (a) and (b);

obtaining a peak value of the power spectrum of the new wave from the FFT in the 8-13 Hz range; and

selecting a threshold value of the peak value of the power spectrum which differentiates (a) from (b).

15. Method of claim 14 wherein the body part is a finger.

16. Method of claim 13 wherein the electrodes are placed substantially at the standard EEG C₃ and C₄ electrode positions.

17. Method of producing a communication or control signal by an unaided person, comprising:

monitoring the mu wave from the brain of the person;

determining whether the mu wave is above or below a single threshold value, wherein values above the threshold correspond to the person at rest, when the person is neither moving nor thinking of moving a body part of the person, and values below the threshold correspond to movement, when the person is either moving or thinking of moving a body part of the person;

producing changes above and below the single threshold value by alternating between (a) neither moving nor thinking of moving a body part of the person and (b) either moving or thinking of moving a body part of the person,

producing a binary communication or control signal from the changes of the mu wave above and below the threshold value.

18. Method of claim 17 wherein the threshold value is determined by measuring (a) a maximum value produced by neither moving nor thinking of moving a body part of the person, and (b) an attenuated value produced by either moving or thinking of moving a body part of the person, and selecting a threshold value between values (a) and (b).