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Fig. 6.1. Reorganization of receptive fields after a retinal lesion. The receptive field distributions in the intact and the lesioned eye of a single adult cat are plotted in visual space 4-8 hours after a retinal lesion in one eye. (a) The electrode penetration site (vertical line) is shown along with the locations (open circles) of neurons whose receptive fields are plotted in (b) and (c). The arrows on the left mark the boundary of the cortical region that represennts the retinal lesion. The neurons are labeled "e" to "r" from top to bottom and span a distance of about 5 mm. (b) The receptive fields in the visual space of the intact eye are shown as rectangles labeled "e" to "r" according to the neuron's position along the penetration site. The grid lines are spaced 10^o apart and the black diamond marks the area centralis. The dashed contour in the middle marks the area that corresponds to the scotoma in the lesioned eye; the receptive fields within this region are colored gray. The receptive fields show an orderly progression from left to right. In another penetration before the lesion (not shown), a distribution similar to that in (b) was observed in both eyes; therefore, the distribution in the intact eye suggests how the receptive fields in the lesioned eye were located before the lesion. (c) In the lesioned eye, the scotoma is shown as a dark gray area. The receptive fields that used to respond to the area inside the scotoma (the gray rectangles labeled "e" to "o") have moved outward, and now represent the perilesion area. Several of them (e.g. "g", "h", and "m") have also aligned with the scotoma boundary. As a result, the unresponsive area in the cortex (a perceptual blind spot) has disappeared, even though damage persists in the retina. Reprinted with permission from Calford et al. (1999), copyright 1999 by the Royal Society of London.