Bandpass characteristics of high-frequency sensitivity and visual experience in blindsight

Abstract

Patient RP suffers a unilateral right homonymous quadrant anopia but demonstrates better than chance discrimination for stimuli presented in the blind field at temporal frequencies between 33 and 47 Hz (all significant at p < .05, binomial). Examination of her reports of visual experience during blind-field discrimination suggests a more complex picture in which experiences particular to correct discrimination are not found at low-mid-gamma frequencies, but are significantly more likely than average (76%, p < .001) at a lower frequency (22 Hz) at which blindsight is not observed. We believe that visual experience may serve to support blindsight if discrimination tasks are generally impaired at frequencies outside of the low-mid-gamma band. If this is so, although generally experienced as non-specific and unstructured light, the visual experience that accompanies discrimination performance must be based upon a neural representation which includes information on the visual features present in the stimulus.