Receptive fields of cat's non-relay lateral geniculate and perigeniculate neurons.

Two groups of neurons are postulated to serve as inhibitory interneurons for principal lateral geniculate cells: intrageniculate interneurons and the perigeniculate neurons. We analysed the spatiotemporal characteristics of receptive fields (RFs) of cells from both groups identified by their anatomical position and responses to electrical stimulation of the optic chiasm and visual cortex. Intrageniculate interneuronal RFs resembled in all respects those of relay cells. One third of perigeniculate neurons had erratic responses to visual stimuli. Those which responded well to flashing stimuli possess large (up to 20 degrees) spatially heterogeneous ON/OFF type RFs. Spatiotemporal extents of excitatory domains of both intrageniculate interneurons and perigeniculate neurons RFs correspond to the extents of inhibitory domains in the principal cell RFs which were described previously.