RESPONSES OF COMPLEX CELLS IN AREA-17 OF THE CAT TO BI-VECTORIAL TRANSPARENT MOTION

We examined the responses to transparent motion of complex cells in ca t area 17 which show directional selectivity to moving random pixel ar rays (RPAs). The response to an RPA moving in the cell's preferred dir ection is inhibited when a second RPA is transparently moving in anoth er direction. The inhibition by the second pattern is quantified as a function of its direction. The response to a pattern moving in the pre ferred direction is never completely suppressed, not even when a secon d pattern is moving transparently in the opposite direction. To the ex tent that supra-spontaneous firing rates signal the presence of the op timal velocity vector, these cells therefore still signal the presence of this line-label stimulus despite additional opposing, or otherwise directed, motion components. The results confirm previous suggestions that, for the computation of motion energy in cat area 17 complex cel ls,a full opponent stage is not plausible. Furthermore, we show that t he response to a combination of two motion vectors can be predicted by the average of the responses to the individual components. Copyright (C) 1996 Elsevier Science Ltd.