Unique functional properties of on and off pathways in the developing mammalian retina

Document Type

Journal Article

Publication Date

6-15-2001

Journal

Journal of Neuroscience

Volume

21

Issue

12

DOI

10.1523/jneurosci.21-12-04310.2001

Keywords

APB; Dendritic stratification; Development; On and Off pathways; Retina; Retinal ganglion cell; Visual system

Abstract

In the mature retina, the dendrites of On and Off ganglion cells are segregated into separate sublaminas of the inner plexiform layer, but early in development these processes are multistratified, ramifying more widely within this synaptic layer. The dendritic pattern exhibited by immature ganglion cells suggests that there may be a functional convergence of On and Off pathways in the developing retina, but previous studies have provided evidence against this. Here we demonstrate by patch-clamp recordings and dye filling that ganglion cells with multi-stratified dendrites respond to the onset, as well as the offset, of light. We further show that, in the dark-adapted retina, the glutamate analog 2-amino-4-phosphonobutric acid abolishes On and Off discharges in ganglion cells with multistratified dendrites. In contrast, in cells with stratified dendrites, this drug selectively blocks On responses. These findings provide evidence for unique functional attributes of On and Off pathways in the developing retina. The properties of immature ganglion cells documented here have important implications for the roles ascribed to neuronal activity in refining connections during the early development of the visual system.

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