Synchronous Bursts of Action Potentials in Ganglion Cells of the Developing Mammalian Retina

TLDR

The mammalian visual system develops orderly connections through action potentials in optic nerve fibers before visual input, with correlated firing of retinal ganglion cells in the same eye thought to direct segregation of their synaptic terminals into eye‑specific layers of the lateral geniculate nucleus. The authors recorded extracellular action potentials from up to 100 ganglion cells simultaneously in isolated newborn ferret and fetal cat retinas to detect such correlations. They found that ganglion cells fired nearly synchronous bursts lasting a few seconds, separated by 1–2 minutes of silence, with each burst propagating as a wave across the retina at ~100 µm/s, providing spatial and temporal cues likely to refine retinal‑lateral geniculate connections.

Abstract

The development of orderly connections in the mammalian visual system depends on action potentials in the optic nerve fibers, even before the retina receives visual input. In particular, it has been suggested that correlated firing of retinal ganglion cells in the same eye directs the segregation of their synaptic terminals into eye-specific layers within the lateral geniculate nucleus. Such correlations in electrical activity were found by simultaneous recording of the extracellular action potentials of up to 100 ganglion cells in the isolated retina of the newborn ferret and the fetal cat. These neurons fired spikes in nearly synchronous bursts lasting a few seconds and separated by 1 to 2 minutes of silence. Individual bursts consisted of a wave of excitation, several hundred micrometers wide, sweeping across the retina at about 100 micrometers per second. These concerted firing patterns have the appropriate spatial and temporal properties to guide the refinement of connections between the retina and the lateral geniculate nucleus.