Response properties of X and Y LGN neurons in Siamese cats

We investigated quantitatively the receptive-field properties of neurons in the lateral geniculate nucleus of Siamese cats. The experimental animals, "Mid-western" Siamese cats, exhibited varied degrees of ocular misalignment. The percentage of Y-cells, which receive projections from the area centralis, was significantly greater in Siamese cats than in normally pigmented cats. The spatial resolution of many, but not all, X-cells within the central 5 degrees of Siamese cats was reduced. A substantial number of Y-cells had significantly longer latencies to stimulation of the optic chiasm. In addition, some Siamese cat units had abnormal contrast threshold and lineweighting functions along with large receptive field center size and weak inhibitory effects from the RF surround. Finally, large variability was found with respect to the abnormalities among cells within a given cat and more importantly among the individual Siamese cats which we studied.