Thalamic relay of spontaneous retinal activity prior to vision.

Before vision, retinal ganglion cells produce spontaneous waves of action potentials. A crucial question is whether this spontaneous activity is transmitted to lateral geniculate nucleus (LGN) neurons. Using a novel in vitro preparation, we report that LGN neurons receive periodic barrages of postsynaptic currents from the retina that drive them to fire bursts of action potentials. Groups of LGN neurons are highly correlated in their firing. Experiments in wild-type and NMDAR1 knockout mice show that NMDA receptor activation is not necessary for firing. The transmission of the highly correlated retinal activity to the LGN supports the hypothesis that retinal waves drive retinogeniculate synaptic remodeling. Because LGN neurons are driven to fire action potentials, this spontaneous activity could also act more centrally to influence synaptic modification within the developing visual cortex.