Signal transfer from photoreceptors to bipolar cells in the retina of the tiger salamander.
Under conditions of dark-adaptation, in response to weak stimuli, the distal retina behaves as a linear system. During the process of voltage transfer from the rods to the bipolar cells the information encoded in the rod responses is spatially filtered. The spatial filtering is determined by the spatial properties of the receptive field of the bipolar cell. These, in turn, depend upon the spatial properties of three syncytia, those of the receptors, the horizontal cells and the bipolar cells themselves. The response of the bipolar cell to these weak stimuli is a linear difference of two components; a component generated by the receptive field center and a component generated by the receptive field surround. The receptive field surround is misnamed since it extends throughout the receptive field center and contributes to the response of the bipolar cell to stimuli located anywhere within the receptive field. The receptive field surround has the spatial properties that would be expected if it were generated by an input from the horizontal cells to the receptive field center of the bipolar cell. The cellular pathway mediating this input remains unclear though we have evidence that it involves, at least in part, a feedforward pathway from horizontal cells to bipolar cells. If a feedback pathway also exists it is not mediated by the GABAA synapse on the synaptic terminals of the cones.
Owen
W G
WG
Department of Biophysics & Medical Physics, University of California, Berkeley 94720.
Hare
W A
WA
D000818:Animals; D010786:Photoreceptor Cells / Q000502:physiology*; D012160:Retina / Q000166:cytology / Q000502:physiology*; D015398:Signal Transduction; D014562:Caudata / Q000502:physiology*