Requirement of the nicotinic acetylcholine receptor beta 2 subunit for theanatomical and functional development of the visual system

In the mammalian visual system the formation of eye-specific layers at the thalamic level depends on retinal waves of spontaneous activity, which rely on nicotinic acetylcholine receptor activation. We found that in mutant mi ce lacking the beta2 subunit of the neuronal nicotinic receptor, but not in mice lacking the alpha4 subunit, retinofugal projections do not segregate into eye-specific areas, both in the dorso-lateral geniculate nucleus and i n the superior colliculus. Moreover, beta2-/- mice show an expansion of the binocular subfield of the primary visual cortex and a decrease in visual a cuity at the cortical level but not in the retina. We conclude that the bet a2 subunit of the nicotinic acetylcholine receptor is necessary for the ana tomical and functional development of the visual system.