Intracellular recordings from binocularly activated cells in the cat's dorsal lateral geniculate nucleus

Five binocularly activated cells near the interlaminar layers of the dorsal lateral geniculate nucleus have been studied with intracellular recording techniques. Four neurons were relay cells and antidromically activated from the visual cortex. They received monosynaptic excitation and disynaptic inhibition from Y type retinal ganglion cells in both eyes and disynaptic recurrent inhibition. The fifth cell was similar to perigeniculate neurons. It received disynaptic excitation from retinal ganglion cells in both eyes and monosynaptic excitation from antidromically activated relay cell axons. It was also inhibited from all these sources after an additional synaptic delay. The cell had a large receptive field, about twice the center size of neighboring relay cells, and gave on-off responses from the entire response area. Such displaced perigeniculate like cells may explain why relay cells issue occasional axon collaterals within the dorsal lateral geniculate nucleus.