Functional organization of surgically created visual circuits

Lesions of cerebral targets of the retina in newborn hamsters, when combine d with transection of lemniscal pathways to the primary auditory or somatos ensory thalamic nuclei or the secondary thalamic visual nucleus, can induce the formation of permanent retinal pr ejections to the deafferented non-vi sual structures. These projections are retinotopically organized and form f unctional synapses. Consequently, neurons in the auditory or somatosensory cortices, which normally are not driven by visual stimuli, become visually responsive and have receptive field properties that ressemble, in several i mportant ways, those of neurons in the visual cortex of normal animals. The surgically-induced retino-thalamo-cortical pathways can mediate visually g uided behaviors whose normal substrate, the pathway from the retina to the primary visual cortex via the thalamic dorsal lateral geniculate nucleus, i s missing.