PHGY 209 Lecture 30: CNS- 5
21 Feb 2018
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Document Summary
Retinal ganglion relative differences of the light (contrast) across their receptive fields. Retinal ganglion cells have receptive fields (portion of the visual field that the ganglion cell recognizes). In addition, there is a structure to the receptive is a center-surround receptive field in which the ganglion compares what is in the center of the receptive field and what is around it. There are two types of ganglion cells: field; there: excitatory center: fires many action is potentials when a bright center surrounded by darkness. Inhibitory center: fires many action potentials when a dark center is surrounded by darkness. In both cell types, uniform light in the center and surround result in no change. The relative distributions of the two types are uniform, but the cells in the fovea are smaller than those in the periphery. The inactivity of cones in darkness accounts for the lack of colour in darkness. Perception of colour is context dependent, like brightness.
