Abnormal responses of retinal ganglion cells in Siamese cats to moving stimuli.

The responses of X and Y-Type retinal ganglion cells in Siamese cats to moving slits were compared to those in common cats, in order to assess the center/surround interactions in Siamese cat receptive fields. Responses in the latter animal were quantitatively lower than those in common cats, the RF centers were larger, and the encounter rate for Y-type optic tract fibers was significantly lower than in common cats. Whereas response enhancement of common cat units was predictable following masking of the surround, such an effect could only be observed in Siamese cats when the contrast between the stimulus and background was increased considerably. These data suggest anomalous center/surround interactions in Siamese cats, probably due to the presence of weaker surround influences in that animal.