Unilateral visual cortex deafferentation induces changes in receptive field properties of cortical cells in the intact hemisphere of normal and of monocularly deprived cats

Receptive field properties and the selectivity of cortical cells to visual stimulation were studied in the visual cortices (the boundary between areas 17 and 18) of both hemispheres following unilateral deafferentation in normal and in early monocularly deprived cats. Almost no visual activity was encountered in the deafferented hemisphere and a considerable diminution in visual responsiveness was found in the intact hemisphere of all experimental cats. Responsiveness had increased with recovery time; unresponsive cells had consisted 44.6% of the cells in the intact hemisphere of the acute, 34.7% in the 3-month chronic and 14.5% in the normal cats. Disregarding the bias due to an early monocular deprivation, the ocular dominance distribution of the cells in the intact hemispheres of these cats was unaffected. Selectivity was markedly reduced in the intact hemisphere of the deafferented cats as expressed mainly in the increased orientation tuning range and in the proportion of orientation-selective cells. The proportion of these cells was 45.5% in the deafferented cats, 38.6% in the deafferented monocularly deprived cats, 65.3% in the monocularly deprived and 81.9% in the normal control cats. A similar trend, although less prominent, was found in respect to the proportion of direction-selective cells. The size of receptive fields was only slightly affected in the deafferented deprived cats. Receptive fields were considerably larger in size (length) in the deafferented cats in comparison to their respective normal and monocularly deprived controls. It is concluded that the absence of visual input from the deafferented hemisphere is bidirectionally affecting the corpus callosum. This is mainly reflected in the reduction in the excitability level of the cells in the intact hemisphere, which results in modification of the selectivity of the cells to orientation and direction of movement of the visual stimuli.