Facilitation as well as inhibition of the blink reflex by a visual prepulse requires intact striate cortex

Objective The role of visual cortex in modulation of the human eye blink reflex was assessed. Methods Participants were 13 patients with unilateral striate cortex damage. Nonreflexogenic gratings were presented in their intact or blind hemifield prior to white noise or air puff blink-eliciting stimuli. Results Inhibition of reflex amplitude was observed at asynchronies ranging from about 120 to 600 ms for visible but not invisible prepulses. Facilitation by intact-hemifield gratings was observed for (1) the latency of the acoustic blink reflex, (2) the amplitude of the disynaptic cutaneous blink reflex, R1, and (3) the latency of voluntary hand-grip reactions to the reflexogenic stimuli. These facilitatory effects were absent on trials with blind-hemifield prepulses. Conclusions An intact V1 is required for prepulse facilitation as well as inhibition. Significance These results extend a popular model of sensorimotor gating deficits in schizophrenia.