A model of visual cortical temporal frequency tuning

There are several response properties that distinguish cortical simple cells of cat Vf. layer 4 from the geniculate cells that provide their input. We have recently demonstrated that a developmentally motivated pattern of intracortical inhibition, in conjunction with the observed pattern of geniculocortical connections, can robustly account for the contrast-invariance of simple cell orientation tuning. We now show that this same model circuit unexpectedly accounts for the low-pass shift in the temporal frequency tuning curves of cortical cells relative to geniculate cells. This arises when NMDA-mediated excitatory conductances are included in the thalamocortical synapses, at levels observed experimentally. (C) 2001 Published by Elsevier Science B.V.