Comparative study on the offset responses of simple cells and complex cells in the primary visual cortex of the cat

Simple and complex cells are two basic and distinct functional types of neurons in the mammalian primary visual cortex. Here, we studied the onset response and the offset response of simple and complex cells to a flashing visual stimulus in the cat's area 17. Compared with simple cells, complex cells exhibited greater similarity between the onset and offset responses in peak latency. For simple cells, onset response had greater peak amplitude and signal-to-noise ratio than offset response, and for complex cells, vice versa. For both types of cortical cells, the amplitude of offset responses increased with stimulus duration within 100 ms significantly, while the onset response did not. However, to elicit a detectable offset response, complex cells tended to require shorter stimulus duration than simple cells did. In regard to the similarity of psychophysical data, these results suggest that the rebound offset response of cortical cells to disappearance of a visual pattern might be correlated to visual persistence in humans.