Brain electrical activity analysis and mapping

• US 4,744,029 A
• Filed: 08/31/1984
• Issued: 05/10/1988
• Est. Priority Date: 08/31/1984
• Status: Expired due to Term

• Current Assignee: Bio-Logic SAS
• Original Assignee: Bio-Logic Systems Corporation (Natus Medical Incorporated)
• Inventors: Raviv, Gabriel, Raviv, Gil
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Jablon, Clark A.
• Application Number:
  US06/646,614
• Time in Patent Office: 1,348 Days
• Field of Search: 364/413, 364/415, 364/417, 128/731, 367/70
• US Class Current: 600/544
• 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 5/377 using evoked responses
• CPC Class Codes: A61B 5/7257 using Fourier transforms

Abstract

An apparatus for performing manipulation and analysis of data characteristic of brain electrical activity of a patient. Computer analysis is utilized to provide the most useful form of topographical maps and related data for evaluation of a patient by a user. The application can be operated as part of an integral unit or remote from the location where brain electrical activity signals are measured on the patient.

Threshold circuitry ensures that only signals meeting predetermined conditions are stored. A user modifiable digital filter allows for on-line analysis of changes in filter characteristics. A simultaneaous display of a plurality of topographical maps in visual summary format is presented. Readability is enhanced by showing only the color codes that actually appear in the topographical map. Montages can be created.

Claims

1. An apparatus for displaying a topographical map of brain electrical activity sensed by a plurality of electrode sensors disposed on a patient'"'"'s head, wherein said electrode sensors provide an associated plurality of input activity signals, said apparatus comprising

processing means responsive to said input activity signals for providing an amplified and digitized form of said plurality of input activity signals;

threshold means responsive to said amplified and digitized input activity signals for comparing a predetermined condition with said input activity signals and for activating the continuing measurement and storage of said amplified and digitized input activity signals responsive to having attained said predetermined condition;

means for storing said amplified and digitized input activity signals responsive to activation by said threshold means;

computer means for providing a video output responsive to said amplified and digitized input activity signals; and

means for displaying said topographical maps of said brain electrical activity responsive to said video output.

2. The apparatus as defined in claim 1 wherein said predetermined condition comprises a predetermined amplitude level, said threshold means comprising means for sensing an amplitude of said input activity signals and for comparing said amplitude with said predetermined amplitude level.

3. The apparatus as defined in claim 1 wherein said predetermined condition comprises a predetermined differential amplitude level, said threshold means comprising means for determining said differential amplitude of said input activity signals and for comparing said differential amplitude with said predetermined differential amplitude level.

4. The apparatus as defined in claim 1 wherein said predetermined condition comprises a predetermined frequency level, said threshold means comprising means for determining a frequency of said input activity signals and for comparing said frequency with said predetermined frequency level.

5. A distributed system for displaying a topographical map of brain electrical activity comprising:

input means for supplying an input signal responsive to a user input;

remote sensor means comprising;

(a) a plurality of electrode sensors disposed on a patient'"'"'s head for providing changeable amplitude sign input activity signals responsive to said brain electrical activity;

(b) processing means responsive to said input activity signals for providing an amplifed and digitized form of said input activity signals;

storage means for storing and outputting said amplified and digitized input activity signals;

means responsive to said input signal for storing a predetermined condition;

threshold means responsive to said amplified and digitized input acitvity signals for comparing said predetermined condition with said input activity signals and for activating the continuing measurement of said amplified and digitized input activity signals and storage in said storage means responsive to having attained said predetermined condition;

computer means for providing a video output responsive to said stored input activity signals; and

means for displaying said topographical map of said brain electrical activity responsive to said video output.

6. The apparatus as defined in claim 5 wherein said predetermined condition comprises a predetermined amplitude level and said threshold means comprises means for sensing an amplitude of said input activity signals and comparing said sensed amplitude with said predetermined amplitude level.

7. The apparatus as defined in claim 5 wherein said predetermined condition comprises a predetermined differential amplitude level and said threshold means comprises means for determining said differential amplitude of said input activity signals and comparing said differential amplitude with said predetermined differential amplitude level.

8. The apparatus as defined in claim 5 wherein said predetermined condition comprises a predetermined frequency level and said threshold means comprises means for determining a frequency of said input activity signals and comparing said frequency with said predetermined frequency level.

9. An apparatus for displaying a topographical map of brain electrical activity of a patient'"'"'s head comprising:

input means for supplying an input signal responsive to a user input;

a plurality of electrode sensors disposed on the patient'"'"'s head for providing input activity signals responsive to said brain electrical activity;

processing means responsive to said input activity signals for providing an amplified and digitized form of said input activity signals;

means responsive to said input signal for storing a predetermined condition;

threshold means responsive to said amplified and digitized input activity signals for comparing said predetermined condition with said input activity signals and for activating the continuing measurement and storage of said amplified and digitized input activity signals in said means for storing responsive to having attained said predetermined condition;

computer means for providing a video output responsive to said amplified and digitized input activity signals; and

means for displaying said topographical map of said brain electrical activity responsive to said video output.

26. The apparatus as defined in claim 9 wherein said storing means is further adapted to store said input activity signals for short time periods irregardless of the occurrence of said predetermined condition and upon occurrence of said predetermined condition said computer means permanently saving to said storing means said input activity signals occuring just before said predetermined condition.

10. A distributed system for displaying a topographical map of brain electrical activity remotely sensed by a plurality of electrode sensors disposed on a patient'"'"'s head, each of said plurality of electrode sensors adapted to provide a plurality of input activity signals and each said electrode sensor selectable as an active and a reference electrode sensor, said system further comprising;

processing means responsive to said input activity signals for providing an amplified and digitized form of said plurality of input activity signals and having a feature of interest included therein;

memory means for storing said amplified and digitized form of said input activity signals;

montage means responsive to said stored input activity signals for identifying said feature of interest in said stored signals by carrying out an iterative analysis of said stored input activity signals, said iterative analysis comprising selection of at least one said active electrode sensor and at least one said reference electrode sensor from said plurality of electrode sensors, forming a difference input activity signal by subtraction of said stored input activity signal for said active electrode sensor from said stored input activity signal associated with said reference electrode sensor, storing each of said difference input activity signals in said memory means, and outputting said stored difference input activity signals;

computer means for providing a video output responsive to said stored difference input activity signals;

means for displaying said topographical maps of brain electrical activity responsive to said video output; and

recycle means for returning to said iterative analysis to generate a new set of said difference input activity signals corresponding to selection of a new one of said active and said reference electrode sensors and continuing said iterative analysis and displaying said topographical maps until completion of said identification of said feature of interest.

11. An apparatus for displaying a topographical map of brain electrical activity having a feature of interest therein and sensed by a plurality of electrode sensors disposed on a patient'"'"'s head, each of said plurality of electrode sensors adapted to provide a plurality of input activity signals and each said electrode sensor selectable as an active and a reference electrode sensor, said apparatus comprising:

processing means responsive to said input activity signals for providing an amplified and digitized form of said plurality of input activity signals;

memory means for storing said amplified and digitized form of said input activity signals;

montage means responsive to said stored input activity signals for carrying out an iterative analysis of said amplified and digitized input activity signals for identification of said feature of interest, said iterative analysis comprising selection of at least one said active electrode sensor and at least one said reference electrode sensor from said plurality of electrode sensors, forming a difference input activity signal by subtraction of said stored input activity signal for said active electrode sensor from said stored input activity signal associated with said reference electrode sensor, storing said difference input activity signals and outputting said stored difference input activity signals;

computer means for providing a video output responsive to said stored difference input activity signals;

means for displaying said topographical map of brain electrical activity responsive to said video output; and

recycle means for returning to said iterative analysis to generate a new set of said difference input activity signals corresponding to selection of a new one of said active and said reference electrode sensors and continuing said iterative analysis and displaying said topographical maps until completion of said identification of said feature of interest.

12. An apparatus for displaying a topogrphical map of EEG brain electrical activity having a feature of interest in at least one of a pluraltiy of frequency bands characteristic of a patient, comprising:

a plurality of electrode sensors disposed on the head of the patient for measuring EEG input activity signals at each of said plurality of electrode sensors;

processing means responsive to said EEG input activity signals for providing an amplified and digitized form of said EEG input activity signals;

memory means for storing said amplified and digitized form of said EEG input activity signals;

montage means responsive to said stored EEG input activity signals for carrying out an iterative analysis of said EEG amplified and digitized input activity signals for identification of said feature of interest, said iterative analysis comprising selection of at least one active and at least one reference electrode sensor from among said plurality of electrode sensors, forming an EEG difference input activity signal by subtraction of said EEG input activity signal for said active electrode sensor from said EEG input activity signal for said reference electrode sensor, storing said for EEG difference input activity signals in said memory means and outputting said stored EEG difference input activity signals;

means for sampling said stored EEG difference input activity signals at predetermined intervals to provide a sampled form of said EEG difference input activity signals;

means responsive to said stored difference input activity signals for performing a Fourier transformation of said sampled form of said EEG difference input activity signals to provide a frequency band energy output characteristic of the energy for each of said plurality of frequency bands;

means for displaying said topographical map responsive to said frequency band energy output; and

recycle means for returning to said montage means to carry out said iterative analysis by generating a new set of said EEG difference input activity signals corresponding to selection of a new one of said active and said reference electrode sensors and continuing said iterative analysis and displaying said topographic maps until completion of said identification of said feature of interest.

13. An apparatus for displaying a topographical map of brain electrical activity of a patient and performing on-line analysis by user defined digital filtering of input activity signals arising from said brain electrical activity, comprising:

sensor means responsive to said brain electrical activity and disposed on a patient'"'"'s head for providing changeable amplitude sign input activity signals;

processing means responsive to said changeable amplitude sign intput acitivity signals for providing an amplified and digitized form of said input activity signals;

digitial filter means for filtering said digitized form of said input acitivity signals, said digital filter means being modifiable by the user to allow on-line analysis of the effect of said filter means;

means for providing a video output responsive to said filtered form of said amplified and digitized input activity signals; and

means responsive to said video output for displaying the digitally filtered form of said input activity signals during the collection of said input activity signals.

14. The apparatus as defined in claim 13 wherein the functional form of said filter means is displayed simultaneously with said input activity signals.

15. The apparatus as defined in claim 13 wherein said video output includes the simultaneous display of the unfiltered form and said filtered form of said input activity signals.

16. An apparatus for displaying a topographical map of brain electrical activity of a patient and performing analysis by user defined digital filtering of input activity signals arising from said brain electrical activity, comprising:

sensor means responsive to said brain electrical activity and disposed on a patient'"'"'s head for providing changeable amplitude sign input activity signals;

processing means responsive to said changeable amplitude sign input activity signals for providing an amplified and digitized form of said input activity signals;

digital filter means for filtering said digitized form of said input activity signals, said digital filter means being modifiable by the user to allow analysis of the effect of said filter means;

means for providing a video output responsive to said filtered form of said amplified and digitized input activity signals; and

means responsive to said video output for displaying the digitally filtered form of said input activity signals.

17. A method for analyzing input activity signals from a patient and displaying a topographical map of brain electrical activity, comprising:

sensing changeable amplitdue sign input activity signals of the patient;

processing said changeable amplitude sign input activity signals to provide an amplified and digitized form of said input activity signals;

digitally filtering said digitized form of said input activity signals, the user modifying on-line said input activity signals by applying user changeable filter means to test the effect on said input activity signals;

displaying repeatedly said filtered form of said input activity signals, enabling the user to iteratively determine the effect of said filter means upon said input activity signals; and

generating a video output responsive to said filtered form of said amplified and digitized input activity signals, said video output including a set of interpolated input activity signals for positions between the locations of said sensor means.

18. A system for sensing brain electrical activity and displaying one or more topographical maps of said brain electrical activity, comprising:

apparatus for communicating changeable amplitude sign brain electrical activity data, said apparatus being responsive to sensed and processed data from a plurality of electrode sensors disposed on the head of said patient, wherein said plurality of electrode sensors provide an associated plurality of said changeable amplitude sign brain electrical activity data;

computer means for providing a video output responsive to said communicated brain electrical activity data;

means for displaying said topographical map of said brain electrical activity, responsive to said video output; and

color code means for simultaneously displaying with said topopgraphical map a set of colors associated with said topographical map and each color of said set of colors being displayed only if said color is present in said associated topographical map.

19. An apparatus for displaying a plurality of topographical maps representative of a patient'"'"'s brain electrical activity over a given evoked potential response spectrum time period, comprising:

sensor means disposed on the head of the patient for providing evoked potential signals responsive to said brain electrical activity sensed during said given time period;

means responsive to said evoked potential signals for providing an amplified and digitized form of said evoked potential signals;

means for providing a video output responsive to said evoked potential signals, said video output including interpolated evoked potential signals for positions between the locations of said sensor means;

processing means for mathematically operating on said evoked potential signals obtained during selected portions of said given time period such that each one of said topographical maps represents a visual summary of said evoked potential signals for a different selected portion of said given time period, and such that said plurality of maps together represents a visual summary of said evoked potential for the entirety of said given time period, said plurality of maps also including substantially all of said brain electrical activity sensed during said given time period; and

means responsive to said video output for simultaneously displaying a plurality of said topographical maps.

20. The apparatus as defined in claim 19 wherein said processing means executes said mathematical operation by performing an integration over said selected portions of said given time period.

21. The apparatus as defined in claim 19 wherein said processing means executes said mathematical operation by performing differentiation over said selected portions of said given time period.

22. The apparatus as defined in claim 19 wherein said processing means executes said mathematical operation by performing averages of said evoked potential signals over said selected portions of said given time period.

23. The apparatus as defined in claim 19 wherein said processing means executes said mathematical operation by calculating arithmetic differences of said evoked potential signals over said selected portions of said given time period.

24. The apparatus as defined in claim 19 wherein said processing means executes said mathematical operation by performing statistical analysis of said evoked potential signals over said selected portions of said given time period.

25. An apparatus for displaying a plurality of topographical maps representative of a patient'"'"'s brain electrical activity over a given time period, comprising:

sensor means disposed on the head of the patient for providing EEG signals responsive to said brain electrical activity sensed during said given time period;

means responsive to said EEG signals for providing an amplified and digitized form of said EEG signals;

means for providing a video output responsive to said EEG signals, said video output including interpolated EEG signals for positions between the locations of said sensor means;

processing means for mathematically operating on said EEG signals obtained during selected portions of said given time period such that each one of said topographical maps represents a visual summary of said EEG signals for a different selected portion of said given time period, and such that said plurality of maps together represents a visual summary of said EEG signals for the entirety of said given time period, said plurality of maps also including substantially all of said brain electrical activity sensed during said given time period; and

means responsive to said video output for simultaneously displaying a plurality of said topographical maps.

27. The apparatus as defined in claim 25 wherein said processing means executes said mathematical operation by performing statistical analysis of said EEG signals over said selected portions, of said given time period.

28. An apparatus for displacing a plurality of topographical maps representative of a patient'"'"'s brain electrical activity over a given evoked potential response spectrum time period, comprising:

sensor means disposed on the head of the patient for providing evoked potential signals responsive to said brain electrical activity sensed during said given time period;

means responsive to said evoked potential signals for providing an amplified and digitized form of said evoked potential signals;

means for providing a video output responsive to said evoked potential signals, said video output including interpolated evoked potential signals for positions between the locations of said sensor means;

processing means responsive to said video output for performing a mathematical operation on said video output over selected portions of said given time period with each of said plurality of topographical maps representing a visual summary of said evoked potential signals mathematically processed over one of said selected portions of said given time period; and

menas responsive to said mathematically processed video output for simultaneously displaying said plurality of topographical maps, said plurality of maps together representing a visual summary over said given time period of said evoked potential signals and including substantially all of said brain electrical activity sensed over said given time period.

29. An apparatus for displaying a plurality of topographical maps representative of a patient'"'"'s brain electrical activity sensed during a given evoked potential response spectrum time period, comprising:

sensor means disposed on the head of the patient for providing evoked potential signals responsive to said brain electrical acitivity sensed during said given time period;

means responsive to said evoked potential signals for providing an amplified and digitized form of said evoked potential signals;

means responsive to said amplified and digitized evoked potential signals for providing interpolated evoked potential signals for positions between the locations of said sensor means;

processing means responsive to said amplified, digitized and interpolated evoked potential signals for performing a mathematical operation on said evoked potential signals over selected portions of said time period with each of said plurality of topographical maps representing a visual summary of said evoked potential signals mathematically processed over one of said selected portions of said given time period;

means for providing a video output responsive to said mathematically processed evoked potential signals; and

means responsive to said video output for simultaneously displaying said plurality of topographical maps, said plurality of maps together representing a visual summary over said given time period of said evoked potential signals and including substantially all of said brain electrical activity sensed over said given time period.