Purchase this article with an account.
J.J. Pang, F. Gao, S.M. Wu; Voltage Clamp Analysis of Synaptic Inputs Mediating Light Responses of ON and OFF Alpha Ganglion Cells in Dark-adapted Mouse Retina . Invest. Ophthalmol. Vis. Sci. 2003;44(13):3234.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: The objective is to determine bipolar cell and amacrine cell synaptic inputs mediating light responses of ON and OFF alpha ganglion cells in the mouse retina and add physiological information to our understanding of mammalian retinal circuitry set forth by anatomical studies. Methods: Light-evoked responses were recorded by whole-cell voltage clamp and "loose patch" electrodes under infrared guidance from dark-adapted flat-mounted mouse retina. Three-dimensional morphology of each recorded cell was observed by Lucifer yellow fluorescence under the confocal microscope. Results: 53 ganglion cells with alpha-cell-like morphology exhibited three main types of light responses: (1) ON alpha ganglion cells (ONαGCs) exhibited no spike activity in darkness, increased spikes in light, sustained light-evoked inward cation current (ΔIC) at ECl, sustained light-evoked chloride current (ΔICl) of varying amplitude at EC, and large somas (20-25 µm in diameter) with alpha-cell-like dendritic fields about 180-350 µm in diameter stratifying at approximately 70% IPL depth. (2) The transient OFF alpha cells (tOFFαGCs) exhibited no spike activity in darkness, transient increased spikes at light offset, small sustained light-evoked outward ΔIC in light and large transient inward ΔIC at light offset, sustained outward ΔICl in light, and a morphology similar to the ONαGCs except that their dendrites stratified at approximately 30% IPL depth. (3) The sustained OFF alpha cell (sOFFαGCs) exhibited maintained spike activity of 5-20 Hz in darkness, sustained decreased spikes in light, sustained outward ΔIC and sustained outward ΔICl in light, and a morphology similar to the tOFFαGCs. The rod/cone inputs to ΔIC and ΔICl in each type of alpha ganglion cell were determined by the response thresholds for 500nm light and the response dynamic ranges. Conclusions: Our physiological data support the general inner retinal circuitry set forth by anatomical studies and provide more detailed information on how signals are processed at individual synapses. Our results do not support, however, the assertion that most alpha ganglion cells give rise to transient responses.
This PDF is available to Subscribers Only