| Description |
The retina is the second most complex organ.A remarkable processing of visual information is carried out at the retinal level before the activity is passed on to higher centers. As in other sensory systems, the retina encodes information in parallel channels, which constitute the spiking output from multiple types of retinal ganglion cells (RGCs). RGCs convey information by increasing their firing in response to an optimal visual stimulus or “trigger feature”.In this talk, I will focus on two types of RGCs, namely the Orientation Selective Ganglion Cell (OS-GC) and the Directional Selective Ganglion Cell (DSGC).
Cells sensitive to the orientation of edges are ubiquitous in visual systems, and have been described in the vertebrate retina, yet thesynaptic mechanisms that generate orientation selectivity (OS) in the retina are largely unknown. Here I will describe the synaptic mechanisms that generate selective responses to vertically and horizontally oriented stimuli in rabbit retinal ganglion cells. The data indicate that the excitatory and inhibitory inputs to orientation-selective ganglion cells are rendered orientation selective within the presynaptic circuitry.
Direction-selective responses arise from directional inhibitory input to DSGCs, and directional excitatory inputs. While the mechanisms generating directional inhibition are well established, the mechanisms for directional excitation are unknown. Here we demonstrate, in accordance with a priori considerations of retinal organization, that excitatory inputs to DSGCs are not directional.
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