Method and apparatus for visual-evoked responses
First Claim
1. In an apparatus for assessing visually-evoked response, wherein stimulus means are provided to present a variable visual pattern to an observer and analyzing means are provided to analyze scalp potentials of the observer responsive to said pattern;
- the improvement wherein the stimulus means comprise means for temporal modulation of said pattern at a determined rate and simultaneously sweeping another visual parameter, in a determined period, in a range which crosses an observer'"'"'s visual threshold for said other parameter, said analyzing means comprising means for synchronously demodulating said scalp potentials employing said determined rate of the temporal modulation as a reference, at a plurality of different phases with respect to said reference, for producing a display of the scalp potentials demodulated with different phase references.
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Abstract
In an apparatus for assessing visually-evoked response, wherein stimulus means are provided to present a variable visual pattern to an observer and analyzing means are provided to analyze scalp potentials of the observer responsive to said pattern; the improvement wherein the stimulus means comprise means for temporal modulation of the pattern at a determined rate and simultaneously sweeping another visual parameter, in a determined period, in a range which crosses an observer'"'"'s visual threshold for said other parameter, said analyzing means comprising means for synchronously demodulating said scalp potentials employing said determined rate of the temporal modulation as a reference, at a plurality of different phases with respect to said reference, for producing a display of the scalp potentials demodulated with different phase reference.
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Citations
13 Claims
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1. In an apparatus for assessing visually-evoked response, wherein stimulus means are provided to present a variable visual pattern to an observer and analyzing means are provided to analyze scalp potentials of the observer responsive to said pattern;
- the improvement wherein the stimulus means comprise means for temporal modulation of said pattern at a determined rate and simultaneously sweeping another visual parameter, in a determined period, in a range which crosses an observer'"'"'s visual threshold for said other parameter, said analyzing means comprising means for synchronously demodulating said scalp potentials employing said determined rate of the temporal modulation as a reference, at a plurality of different phases with respect to said reference, for producing a display of the scalp potentials demodulated with different phase references.
- View Dependent Claims (2, 3, 4, 5)
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6. In a method for assessing visually-evoked response wherein a variable visual pattern is presented to an observer and the scalp potentials of the observer responding to the stimulus of the variable visual patterns are analyzed;
- the improvement comprising sweeping a visual parameter of said variable visual pattern, in a predetermined period, in a range which crosses an observer'"'"'s visual threshold for said parameter, temporally modulating said pattern at a determined rate during said sweeping, synchronously demodulating said scalp potentials employing said determined rate of the temporal modulation as a reference, at a plurality of different phases with respect to said reference, and producing a display from said demodulated potentials.
- View Dependent Claims (7, 8, 9)
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10. In a method for assessing visually-evoked response by varying a stimulus of a visual pattern presented to an observer and analyzing scalp potentials of said observer in response to said pattern;
- the improvement comprising sweeping a visual parameter of said pattern a plurality of times, each in a determined period, in a range which crosses an observer'"'"'s visual threshold for said parameter, at least one of said sweeps starting below said visual threshold and at least another of said sweeps starting above said visual threshold, temporally modulating said pattern at a determined rate during said sweeping, synchronously demodulating said scalp potentials employing said determined rate of the temporal modulation as a reference, and producing a display from said demodulated scalp potentials, whereby the differences of thresholds of upwardly and downwardly swept visual parameter is a measure of adaptation of said observer.
- View Dependent Claims (11, 12)
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13. In a method for assessing visually-evoked response wherein a variable visual pattern is presented to an observer and the scalp potentials of the observer responding to the stimulus of the variable visual patterns are analyzed;
- the process of selecting a low spatial frequency for the pattern of substantially 1 cycle/degree and sweeping a reversal rate thereof over an entire range of 1 to 50 reversal per second;
observing a response peak at substantially 43 reversals per second;
executing further testing with said reversal rate held constant at the value producing the observed response peak, with said spatial frequency remaining fixed at 1 cycle per degree;
contrast threshold determinations made by sweeping contrast of said pattern constituting a non-invasive test which isolates the performance and integrity of the Y-type retinocortical pathways, whereby the oblique effect is abolished.
- the process of selecting a low spatial frequency for the pattern of substantially 1 cycle/degree and sweeping a reversal rate thereof over an entire range of 1 to 50 reversal per second;
Specification