On and off sublaminae in the lateral geniculate nucleus of the ferret

Like the retinal ganglion cells from which they receive their input, most relay neurons in the lateral geniculate nucleus have ON- or OFF-center receptive fields with antagonistic surrounds. In the cat, neurons with these two types of receptive fields are anatomically intermingled, even though the ON and OFF systems are functionally segregated. In the ferret, there is a sublamination of the retinal input to lateral geniculate nucleus laminae A and A1. We have investigated the function of this sublamination by making microelectrode recordings and have found that each sublamina consists of geniculate neurons of a single center type.