Permanent perceptual and neurophysiological effects of visual deprivation in the cat

Summary The purpose of the present study was to analyze recovery of visual perception in kittens whose deprived eye had permanently lost access to most selective cortical neurons. Twelve kittens were reared monocularly for 3 months or more; then the deprived eye was opened and the experienced eye was shut (cross-suture treatment) in an attempt to push recovery. Monocular training through the deprived eye was administered on a series of discrimination problems and transposition tests. Some recovery from the monocular deprivation was evident. These kittens learned an orientation problem (horizontal vs. vertical stripes) in an abstract manner. However, on the form problem (upright vs. inverted triangle) they were still noteably deficient when compared to normal controls: 1. Acquisition of the form problem was shown to be strongly dependent on flux cues and 2. Interocular transfer was deficient. Microelectrode and visual evoked potential recording with the cross-suture group revealed no discernible recovery from the deprivation treatment at the visual cortex. Of 34 neurons recorded from 4 animals, only one could be driven by the initially deprived eye. No binocularly driven cells were found. Late components of the VEP were reduced in amplitude when elicited through the deprived eye. We conclude that when forced to use an eye which influences only a small number of neurons, all of which have abnormal receptive fields, animals can learn a wide variety of form problems, but only by using local flux cues. Form perception with a normal degree of stability in the presence of environmental changes appears to depend on cortical neurons with form-selective receptive fields.