Retinal waves are spontaneous bursts of action potentials that propagate in a wave-like fashion across the developing retina.
The signals from retinal waves drive the activity in the dorsal lateral geniculate nucleus (dLGN) and the primary visual cortex.
The waves are thought to propagate across neighboring cells in random directions determined by periods of refractoriness that follow the initial depolarization.
Retinal waves are thought to have properties that define early connectivity of circuits and synapses between cells in the retina.
One of the first scientists to theorize the existence of spontaneous cascades of electrical activity during retinal development was computational neurobiologist David J. Willshaw.
Willshaw thought this difference in the firing strength and the location of cells was responsible for determining the activities' boundaries.
"[1] From this purely theoretical concept, Italian scientists Lucia Galli and Lamberto Maffei used animal models to observe electrical activity in ganglion cells of the retina.
[2] As the idea of retinal waves became established, neurobiologist Carla Shatz used calcium imaging and microelectrode recording to visualize the movement of action potentials in a wave-like formation.
Microelectrode recordings were also thought to show LGN neurons being driven by the wave-like formation of electrical activity across neighboring retinal ganglion cells.
Wong speculated that electrical activity, within the retina, is involved in the organization of retinal projections during prenatal development.
Wong also speculated that specific parts of the visual system, such as the ocular dominance columns, require some form of electrical activity in order to develop completely.
Similar synchronized spontaneous activity early in development has been seen in neurons of the hippocampus, spinal cord, and auditory nuclei.
Activity propagated via gap junctions has not been observed in all test subjects; for example, research has shown that ferret retina ganglion cells are not coupled.
Broadly put, waves are produced and continue over a relatively long developmental period, during which new cellular components of the retina and synapses are added.
Variation in the mechanisms of retinal waves account for diversity in the connections between cells and the maturation of processes in the retina.
[4] Waves are generated at random but limited spatially due to a refractory period in cells after bursts of action potentials have been produced.
Calcium imaging allows analysis of wave pattern over a large area of the retina (more than with multielectrode recording).
[9] Effects of the pharmacological agents on retinal ganglion cell activity are observed using either MEA or calcium imaging.
[9] There is currently still much controversy about whether retinal waves play an 'instructive' or a 'permissive' role in the formation of eye-specific projections in the retinogeniculate pathway.
First, the long-term effects of treatment with TTX are unknown, as it is not yet possible to monitor the retinal activity for a long duration in an intact animal.