An Analysis of Light Adaptation and Inhibitory Input to Retinal Amacrine Cells
PublisherThe University of Arizona.
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AbstractThe retina avoids signal saturation through the use of both dim-light sensing rod and bright-light sensing cone photoreceptor circuits. Photoreceptors are responsible for converting an image into an electrical signal, which is transmitted to bipolar cells and ganglion cells. Amacrine cells modulate the interaction between bipolar cells and ganglion cells through inhibitory signaling, and therefore play a large part in inner retinal processing. However, inhibitory connections between amacrine cells are a little understood signaling component of the retina. Within this study, amacrine cells within the mouse retina were separated into two categories: narrow-field glycinergic and wide-field GABAergic. Amacrine cells were subjected to a light stimuli under dark-adapted, light-adapted, and receptor isolated conditions, and the peak amplitude and charge transfer of the L-IPSC was measured. Wide-field amacrine cells received an increase in the percentage of inhibition from glycine after light adaptation. There is an overall decrease in spontaneous activity with light adaptation, but an increase in the percent of glycinergic spontaneous activity. Spatial inhibition to narrow-field amacrine cells becomes narrower with light adaptation. L-IPSC peak amplitude decreases with light adaptation with application of a full-field light stimulus, and also decreases as the distance between the stimulus and the cell body increases.
Degree ProgramHonors College