Factors influencing the temporal phase of response to bar and grating stimuli for simple cells in the cat striate cortex

Abstract

We have characterized the speed of response of simple cells in cat striate cortex by the temporal phase of the response to bar and grating stimuli. Stimulation of the most responsive sub-region (either ON or OFF) in the receptive field with a 1 Hz temporally modulated bar elicited responses whose phase led the excitatory phase of the stimulus by about 25°. The response to stationary gratings whose contrast was sinusoidally modulated at 2 Hz also showed a phase lead. The differences in the phase of response of ON and OFF sub-regions exhibited a marked scatter about the expected value of 180°. The phase of response to both temporally modulated bars and laterally moving gratings advanced by 20–35° as the stimulus contrast was raised by a factor of 5.