Abstract
Purpose:
The mouse visual system matures during a critical period lasting for approximately two weeks after eye opening. Data show that form vision during this period can influence development of each stage of the visual system. Because the maturation of cortical and subcortical visual areas may be affected by experience-dependent changes to their retinal inputs during development, we asked whether visual experience alters the development of receptive field (RF) diameters of ON and OFF retinal ganglion cells (RGCs).
Methods:
C57Bl6 mice were reared either in control conditions consisting of a 12/12-hr light/dark cycle (normally reared, NR) or in complete darkness (dark-reared, DR) from before birth to postnatal day (P)30-39. Light-evoked spiking responses of RGCs were recorded in vitro using a multi-electrode array (MultiChannel Systems, Inc.; 60 electrodes with 100 µm separation). RFs were mapped with a Gaussian white-noise checkerboard presented at 25 Hz and 60 µm check size followed by spike-triggered averaging (STA). RF diameter was considered to be the average diameter at 1 standard deviation of the 2D Gaussian fit at the peak of the STA.
Results:
In both ON and OFF RGC populations of DR mice, RGC RF diameters were significantly smaller than in NR mice. Values were (mean ± sem) NR, ON = 206.7 ± 1.5 µm and OFF = 220.6 ± 4.8 µm; DR, ON = 190.1 ± 2.4 µm and OFF = 206.0 ± 4.0 µm. These represent decreases of 15% and 13% in RF area for ON and OFF RGCs, respectively.
Conclusions:
Dark rearing from birth to the end of the critical period modifies spatial RF properties of ON and OFF RGCs in the mouse retina. These findings suggest that early visual experience is critical for normal refinement of retinal circuits. Experience-dependent maturation of the earliest stage of the visual system may thus affect development of functional properties of neurons in higher visual centers.
Keywords: 693 retinal connections, networks, circuitry •
756 visual development •
531 ganglion cells