Development of asymmetric inhibition underlying direction selectivity in the retina

How the retina gains a sense of direction The ability to detect motion in the visual scene is a fundamental computation in the visual system that is first performed in the retina. The cells responsible for encoding motion direction are the direction-sensitive ganglion cells (DSGCs), which fire a maximum number of action potentials during movement in one direction and fire minimally during movement in the opposite direction. Highly selective wiring from inhibitory cells contributes to determining the direction-selection characteristics of these ganglion cells, yet how the asymmetric wiring inherent to these connections is established was unknown. Two groups using complementary techniques, including pharmacology, electrophysiology and optogenetics, report that although inhibitory inputs to both sides of the direction-selective cell are uniform early in development, by the second postnatal week, inhibitory synapses on the null side strengthen while those on the preferred side remain constant. These plasticity changes occur independent of neural activity, suggesting a specific developmental program is executed to produce the direction-selective circuitry in the retina.