Method and apparatus for aiding in the anatomical localization of dysfunction in a brain
First Claim
1. A method for determining the specific anatomical localization of dysfunction in temporal lobe epilepsy comprising the steps of:
- placing a plurality of electrodes with respect to physical areas of the subject'"'"'s brain;
generating a pseudorandom, repeatable, broadband visual stimulus;
summing the broadband visual stimulus on the retina and associated neural networks of the subject;
amplifying the electrical analog response signal measured by each of the placed electrodes;
recording the amplified analog response signal from each electrode;
resynthesizing the broadband visual stimulus;
cross-correlating the resynthesized broadband visual stimulus with the recorded analog response signal for each placed electrode to obtain at least a first, second and third order Wiener kernel representation thereof;
limiting the bandwidth of the visual stimulus by masking out those portions which produce non-significant electrical analog responses;
summing the bandwidth-limited visual stimulus on the retina and associated networks of the subject;
amplifying the bandwidth-limited electrical analog response signal measured by each of the placed electrodes;
recording the amplified bandwidth-limited electrical analog response signals from each electrode;
resynthesizing the bandwidth-limited visual stimulus;
cross-correlating the resynthesized bandwidth-limited visual stimulus with the stored bandwidth-limited analog response signal for each electrode to recompute at least a first, second and third order Wiener kernel representation thereof;
synthesizing an optimal kernel-defined visual stimulus Λ
for each of said electrodes by multiplying the resynthesized bandwidth-limited visual stimulus by the recomputed Wiener kernel representation of the system;
presenting an optimal Λ
-defined visual stimulus to the subject for each placed electrode;
summing the Λ
-defined visual stimulus on the retina and associated neural network of the subject;
determining which of the Λ
-defined visual stimuli produced neurophysiologically significant responses in the subject; and
utilizing the known locations of those placed electrodes whose Λ
-defined visual stimuli produced said significant responses and the nature thereof to specifically isolate the anatomical location of the dysfunction.
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Abstract
A method and apparatus for synthesizing a set of optimal sensory stimuli designed to elicit an optimal response for each particular brain electrode location in a subject whose brain is being examined to anatomically localize brain dysfunction. A pseudorandom input signal having the general characteristics of Gaussian white noise is generated and converted into a color video visual stimulus which can be observed by the subject and summed on his retina and associated neural network. A plurality of electrodes are positioned with respect to various different and distinct areas of the brain of the subject to be examined. The subject is shown the color video visual stimulus and the electrical analog response from the electrodes is amplified and stored. The stored analog response signals are cross-correlated with the resynthesized input signal to compute a Wiener kernel representation of the response for each electrode. Portions of the pseudorandom input signal which resulted in insignificant analog responses are masked out so that the subsequent generation of pseudorandom input signals will be bandwidth-limited. The analog responses to the bandwidth-limited visual stimulus are cross-correlated with the resynthesized masked input signal and new Wiener kernel representations are recomputed for each electrode. The recomputed Wiener kernel representations of the response from each electrode are then multiplied in an array processor with the resynthesized bandwidth-limited input signal to compute an optimum visual stimulus for each of the electrodes. These optimum visual stimuli may be subsequently displayed to the subject alone or in conjunction with psychophysical tests to aid in anatomically localizing dysfunction in a brain under examination.
38 Citations
25 Claims
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1. A method for determining the specific anatomical localization of dysfunction in temporal lobe epilepsy comprising the steps of:
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placing a plurality of electrodes with respect to physical areas of the subject'"'"'s brain; generating a pseudorandom, repeatable, broadband visual stimulus; summing the broadband visual stimulus on the retina and associated neural networks of the subject; amplifying the electrical analog response signal measured by each of the placed electrodes; recording the amplified analog response signal from each electrode; resynthesizing the broadband visual stimulus; cross-correlating the resynthesized broadband visual stimulus with the recorded analog response signal for each placed electrode to obtain at least a first, second and third order Wiener kernel representation thereof; limiting the bandwidth of the visual stimulus by masking out those portions which produce non-significant electrical analog responses; summing the bandwidth-limited visual stimulus on the retina and associated networks of the subject; amplifying the bandwidth-limited electrical analog response signal measured by each of the placed electrodes; recording the amplified bandwidth-limited electrical analog response signals from each electrode; resynthesizing the bandwidth-limited visual stimulus; cross-correlating the resynthesized bandwidth-limited visual stimulus with the stored bandwidth-limited analog response signal for each electrode to recompute at least a first, second and third order Wiener kernel representation thereof; synthesizing an optimal kernel-defined visual stimulus Λ
for each of said electrodes by multiplying the resynthesized bandwidth-limited visual stimulus by the recomputed Wiener kernel representation of the system;presenting an optimal Λ
-defined visual stimulus to the subject for each placed electrode;summing the Λ
-defined visual stimulus on the retina and associated neural network of the subject;determining which of the Λ
-defined visual stimuli produced neurophysiologically significant responses in the subject; andutilizing the known locations of those placed electrodes whose Λ
-defined visual stimuli produced said significant responses and the nature thereof to specifically isolate the anatomical location of the dysfunction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A system for synthesizing a set of "n" discrete optimal visual stimuli, one optimal visual stimulus for each different and distinct brain area being examined, for use in determining the anatomical localization of brain dysfunction, said system comprising:
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means for generating a pseudorandom input signal having the general characteristics of Gaussian white noise; means responsive to said input signal for displaying a color video visual stimulus representation thereof, said visual stimulus being displayed so that it may be summed on the retina and associated neural network of the subject whose brain is being examined; a plurality of "n" individual electrodes, one of said electrodes being disposed adjacent each of said different and distinct brain areas to be examined for monitoring the electrical spikes and slow potential response produced in said areas when said subject observes said displayed visual stimulus; high impedance, low noise amplifier means having "n" channels, each of said channels being coupled to a different and distinct one of said "n" electrodes for amplifying the spikes and slow potential electrical analog response signals therefrom; means for storing the amplified output of each of said "n" channels; computational means responsive to said storage means and to said input signal-generating means for cross-correlating a resynthesized input signal with said stored electrical analog response signal for computing a Wiener kernel representation of the response from each of said electrodes for determining which portions of said input signal gave rise to insignificant responses; means responsive to a determination of which portions of said input signal were responsible for insignificant responses for masking out the subsequent generation thereof so as to limit the bandwidth of any subsequently generated input signals; said computational means being responsive to the resynthesized subsequently regenerated bandwidth-limited input signal and to the subsequently stored electrical analog response signals measured by said electrodes in response to the subject'"'"'s observation of the displayed bandwidth-limited visual stimulus resulting from said bandwidth-limited input signal for cross-correlating to obtain a recomputed Wiener kernel representation of the output of each of said electrodes; and array processor means responsive to said recomputed Wiener kernel representation of the output of each of said electrodes and to the resynthesized bandwidth-limited input signals for multiplying same to produce an optimal input signal for each of "n" electrodes which can be supplied to said display means for displaying an optimal visual stimulus for testing each of said different and distinct brain areas being examined to anatomically localize brain dysfunction. - View Dependent Claims (19, 20, 21, 22, 23, 24)
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25. A method for determining the anatomical localization of dysfunction in the sensory systems of a brain under examination comprising the steps of:
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placing a plurality of electrodes adjacent various distinct areas of the brain to be examined; generating a sensory stimulus having the general characteristics of white noise; exposing the subject whose brain is being examined to the generated sensory stimulus; amplifying the electrical analog response signal measured by each of the placed electrodes; recording the amplified analog response signal from each electrode; resynthesizing the original sensory stimulus; cross-correlating the resynthesized sensory stimulus with the recorded analog response signal for each placed electrode to obtain at least a first and second order Wiener kernel representation thereof; limiting the bandwidth of the sensory stimulus by masking out those portions which tended to produce insignificant electrical analog responses in the brain of the subject under examination; exposing the subject to a bandwidth-limited sensory stimulus; amplifying the electrical analog response signal measured by each of the placed electrodes; recording the amplified electrical analog response signals from each electrode; resynthesizing the bandwidth-limited sensory stimulus; cross-correlating the resynthesized, bandwidth-limited sensory stimulus with the stored bandwidth-limited analog response signal for each electrode to recompute at least a first and second order Wiener kernel representation thereof; synthesizing an optimal kernel-defined visual stimulus for each of said electrodes by multiplying the resynthesized bandwidth-limited sensory stimulus by the recomputed Wiener kernel representation; subsequently exposing the subject to the synthesized optimal kernel-defined sensory stimuli; and utilizing the known locations of the placed electrodes whose optimal kernel-defined sensory stimuli produced significant neurophysiological responses in the subject to aid in determining the anatomical localization of dysfunction in the brain.
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Specification