Neural discharge coupled to saccade offset in the cat visual cortex.

The increase in neural activity in cat visual cortex associated with eye movements has been thought to reflect a replica of the motor command signal. We examined the timing of the saccade-related increase in neural activity in cat areas 17 and 18 in relation to saccade onset and offset. The increase in activity was temporally coupled to saccade offset rather than onset both for visually guided saccades and for spontaneous saccades in the dark. Overall, it occurred 63 ms after saccade offset, and the peak was higher and sharper for data aligned at saccade offset than for onset. These results are inconsistent with the idea that saccade-related activity in cat visual cortex reflects a copy of the motor command signal.