PSYC 2220 Lecture Notes - Lecture 3: Contrast Effect, Mach Bands, Limulus
11 Dec 2016
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Document Summary
Experiments done on limulus crab or horseshoe crab to demonstrate how lateral inhabition effects the responses of neurons in a whole circuit. Their eyes consist of hundreds of tiny structures called ommatidia, and these allow for recording/stimulation of individual receptors. Basic finding was: when they stimulated a single receptor, it led to a rapid firing rate of the nerve fibre. But when they added light into neighboring receptors, the firing rate of the nerve fibre was reduced. Lighter when surrounded by a dark area. Darker when surrounded by a light: receptors that are stimulated by the bright surrounding area send a large amount of inhibition to cells in the centre. Resulting perception is of a darker area than when this stimulus is viewed alone: receptors that are stimulated by the dark surrounding area send a small amount of inhibition to cells in the centre. Lateral inhibition can not explain all of the light phenomena we see/encounter.
