LARGE inactive regions of the retina of adult cats were produced by th
e novel method of inducing monocular retinal detachment. Within a few
hours, neurones throughout the detachment projection zone in primary v
isual cortex (55-136 mm(2)), including some > 4.5 mm from its boundary
, were found to have large receptive fields displaced onto intact reti
na. The new receptive fields of some neurones represented shifts of up
to 9 mm across the retinotopic representation. For these rapid change
s to occur pre-existing viable circuits must provide a cortical locus
with inputs from a wide extent of the retina. Receptive fields, and th
e retinotopic map, for stimulation of the other eye were unchanged.