Monocular focal retinal lesions induce short–term topographic plasticity in adult cat visual cortex

Electrophysiological recording in primary visual cortex (V1) was performed both prior to and in the hours immediately following the creation of a discrete retinal lesion in one eye with an argon laser. Lesion projection zones (LPZs; 21 to 64 mm2) were defined in visual cortex by mapping the extent of the lesion onto the topographic representation in cortex. There was no effect on neuronal responses to the unlesioned eye or on its topographic representation. However, within hours of producing the retinal lesion, receptive fields obtained from stimulation of the lesioned eye were displaced onto areas surrounding the scotoma and were enlarged compared with the corresponding field obtained through the normal eye. The proportion of such responsive recording sites increased during the experiment such that 8 to 11 hours post lesion 56% of recording sites displayed neurons responsive to the lesioned eye. This is an equivalent proportion to that previously reported with long–term recovery (three weeks to three months). Responsive neurons were evident as far as 2.5 mm inside the border of the LPZ. The reorganization of the lesioned eye representation produced binocular disparities as great as 15° suggesting interactions between sites in V1 up to 5.5 mm apart.