Abstract
Purpose: :
To determine how the receptive field properties of identified ganglion cells in the mouse change under different light intensities. In particular we have measured the spatial surround properties in scotopic, mesopic and photopic light conditions.
Methods: :
A mouse with GFP expressed in a subset of retinal ganglion cells was used to perform target patch clamp recordings in the isolated retina. Two-photon laser imaging was used to detect GFP-positive cells. The spiking activity of individual cells was recorded in loose patch configuration. Flashing and moving squares of different sizes were used to explore the spatial receptive field properties of each cell. These stimuli were presented at different background light intensities ranging across 7 log units from 10 - 10^7 (photon/um2/s). The morphology of each cell was determined by reconstruction from the two-photon scans.
Results: :
Our results illustrate that for all cell types tested the receptive fields shrink as one move from scotopic to mesopic light levels. For large ON and OFF cells the inhibitory surround disappears at very low light levels and slowly emerges as the light level increases. ON-OFF cells with more complex receptive fields such as the ON-OFF DS cell and the Local Edge Detector demonstrated similar properties.
Conclusions: :
Our stimulation with squares of increasing size demonstrate that the surround of all cell types recorded gets stronger as one moves from scotopic to mesopic or photopic light conditions. Future experiments will focus on the complex receptive field properties of these cells such as their directional selectivity.
Keywords: ganglion cells • retinal connections, networks, circuitry • electrophysiology: non-clinical