The formation of the retinotopic map depends on the action of axon guidance molecules,activity-dependent mechanisms and axonal competition. However, little is known about theplasticity potential of the system and the effects on the remodelling of retinocollicularconnections upon retinal insults. Here we create a mouse model in which retinal ganglioncells that project to anterior and posterior superior colliculus undergo cell death duringtopographic map formation. We show that the remaining retinal ganglion cells expand thetargeted area in the superior colliculus and at the same time increase their spatial coverage inthe retina in a correlated fashion. The resulting contralateral topographic map is overallmaintained but less precise, while ipsilateral retinal ganglion cell axons are abnormallydistributed in anterior and posterior superficial superior colliculus. These results suggest thepresence of plastic mechanisms in the developing mammalian visual system to adjust retinalspace and its target coverage and ensure a uniform map.
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