Suppression of visual cortical activity following tactile periorbital stimulation; its role during eye blinks

Summary

Single units were recorded in area 17 of anesthetized and paralyzed cats. The discharges of cortical units, either spontaneous or driven by two dimensional visual drifting noise, were analyzed during unilateral tactile stimulation (air puffs or taps) of the skin around the eye. This stimulation evokes a blink response in the normal non-curarized animal. The activity in the branch of the facial nerve innervating the orbicularis oculi muscles responsible for the blink was also recorded on the stimulated side. Following the mechanical stimulation, the discharges of both simple and complex visual cells were strongly inhibited with a latency of 70–80 ms. Inhibition was sometimes preceded by a brief increase in firing rate. This typical response was present only when the cutaneous stimulus was effective in triggering a discharge in the motor nerve which drives the orbicularis oculi muscles. Moreover, when a visual response was evoked by a temporary masking of the visual stimulus, this response was suppressed by the association with a tap stimulation.