Abstract
Purpose: :
Visual experience shapes several aspects of postnatal retinal development. While many features of mammalian retinal ganglion cells (RGCs) appear mature before the eyes open, morphological and physiological data from mice and cats indicates that an additional maturational process occurs after eye-opening. In the cat, many RGCs have larger centers and surrounds in young retina compared to the adult. We examined these properties in mice at different ages to determine whether a similar process occurs.
Methods: :
A multi-electrode array was used to record extracellular spiking responses to visual stimuli from ganglion cells of retinas isolated from C57Bl6 mice at postnatal day (P)13-P16 (i.e., around the time of eye-opening) and at P28-P40. Spots of light of increasing diameter (60-660, 900, 1200, and 2400 microns on the retina) at low photopic intensity were presented, centered on individual electrodes, to measure response properties and estimate the center size (as spot size causing the maximum peak response) and surround strength (as difference of peak responses to the optimal spot and the largest spots) of individual RGCs’ receptive fields.
Results: :
Spontaneous activity in the young retinas was more prevalent and appeared more prone to bursting than in the older retinas. Responses of young and older RGCs to light onset and offset were robust. Response durations to light onset but not to light offset were longer in the young retina. Median center size for responses to light onset and to offset were smaller in the population of young RGCs while effective surround strength was greater compared to the older RGC population.
Conclusions: :
Firing properties and center-surround properties were different in young versus older RGCs in mice. These changes indicate that maturation of RGC response properties occurs in the mouse retina after eye-opening. The functional changes that occur in mouse RGCs are different in some respects than changes that occur in the cat retina over a similar maturational period.
Keywords: ganglion cells • receptive fields • electrophysiology: non-clinical