Functional basis for the preference for slow movement in area 17 of the cat.

Cells which respond only to slowly moving bars (velocity low-pass, or VLP cells) are numerous in area 17 whereas they are lacking in the LGN. The suggestion that this preference for low stimulus velocity is linked to the presence of S cells (equivalent of simple cells) in area 17 was critically evaluated by correlating S cell characteristics (subregion overlap, receptive field width and presence of inhibitory zones) with velocity preference. It was found that VLP cells generally respond only to relatively long durations of stationary stimulation and that this need of temporal summation best explains the preference for slow movement in area 17.