Consequences of visual deprivation in the absence of binocular competitive mechanisms in Siamese cat area 17.
The Siamese cat is a mutant with abnormally crossed visual pathways, which provides a model for studying the effects of visual deprivation in the absence of binocular competitive interactions. Siamese cats are known to be resistant to the effects of monocular eyelid suture. To further explore the nature of this resistance, the receptive field properties of neurons in area 17 of monocularly (MD) and binocularly (BD) deprived Siamese cats were studied. Neither condition produced a loss of cortical responsiveness, which is a characteristic result of binocular deprivation in normally pigmented cats. Somewhat more units in the deprived hemisphere of MD Siamese cats were orientation-selective, and many more units were direction-selective than in BD Siamese cats. This difference may be due to an effect of visual attentional mechanisms, which can function in MD but not BD Siamese cats. To test whether the resistance to the effects of visual deprivation in Siamese cats might be a more general phenomenon. Siamese and normally pigmented cats were raised in an 8-Hz stroboscopically illuminated environment. Both groups showed a severe loss of direction selectivity. Some of the normally pigmented cats also showed a loss of binocularity, which appeared to be secondary to strabismus.
Berman
N E
NE
Department of Anatomy University of Kansas Medical Center, Kansas City 66103.
Pearson
H E
HE
Payne
B R
BR
D000818:Animals; D002415:Cats; D005074:Evoked Potentials, Visual; D007839:Functional Laterality / Q000502:physiology*; D009039:Motion Perception / Q000502:physiology; D009799:Ocular Physiological Phenomena; D010775:Photic Stimulation; D014793:Visual Cortex / Q000254:growth & development* / Q000502:physiology; D014794:Visual Fields / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology*