Neither discrete peripheral retinal lesions nor the normal
optic disk produces obvious holes in one's percept of the
world because the visual brain appears to perceptually “fill
in” these blind spots. Where in the visual brain or how
this filling in occurs is not well understood. A prevailing
hypothesis states that topographic map of visual cortex reorganizes
after retinal lesions, which “sews up” the hole
in the topographic map representing the deprived area of cortex
(cortical scotoma) and may lead to perceptual filling in. Since
the map reorganization does not typically occur unless
retinotopically matched lesions are made in both eyes, we
investigated the conditions in which monocular retinal lesions
can induce comparable map reorganization. We found that following
monocular retinal lesions, deprived neurons in cat area 17 can
acquire new receptive fields if the lesion occurred relatively
early in life (8 weeks of age) and the lesioned cats experienced
a substantial period of recovery (>3 years). Quantitative
determination of the monocular and binocular response properties
of reactivated units indicated that responses to the lesioned
eye for such neurons were remarkably robust, and that the
receptive-field properties for the two eyes were generally similar.
Moreover, excitatory or inhibitory binocular interactions were
found in the majority of experimental units when the two eyes
were activated together. These results are consistent with the
hypothesis that map reorganization after monocular retinal lesions
require experience-dependent plasticity and may be involved
in the perceptual filling in of blind spots due to retinal lesions
early in life.