The information content of spontaneous retinal waves

Spontaneous neural activity that is present in the mammalian retina before the onset of vision is required for the refinement of retinotopy in the lat eral geniculate nucleus and superior colliculus. This paper explores the in formation content of this retinal activity, with the goal of determining co nstraints on the nature of the developmental mechanisms that use it. Throug h information-theoretic analysis of multielectrode and calcium-imaging expe riments, we show that the spontaneous retinal activity present early in dev elopment provides information about the relative positions of retinal gangl ion cells and can, in principle, be used at retinogeniculate and retinocoll icular synapses to refine retinotopy. Remarkably, we find that most retinot opic information provided by retinal waves exists on relatively coarse time scales, suggesting that developmental mechanisms must be sensitive to timi ng differences from 100 msec up to 2 sec to make optimal use of it. In fact , a simple Hebbian-type learning rule with a correlation window on the orde r of seconds is able to extract the bulk of the available information. Thes e findings are consistent with bursts of action potentials (rather than sin gle spikes) being the unit of information used during development and sugge st new experimental approaches for studying developmental plasticity of the retinogeniculate and retinocollicular synapses. More generally, these resu lts demonstrate how the properties of neuronal systems can be inferred from the statistics of their input.