lateral geniculate nucleus

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A peanut-sized structure at the side of each lobe of the thalamus, receiving most of its input via the optic tract from the opposite half of the visual field as represented on the retinas of both eyes, these inputs preserving the centre-surround receptive fields of the retinal ganglion cells and being arranged in a topographic map so that points close together on the retina are close together in the lateral geniculate nucleus, and relaying most of them to the primary visual cortex (Area V1), where the topographic order is preserved. It contains six layers of cells, three receiving inputs from the left (L) eye alternating with three from the right (R) eye, in the order from top to bottom LRLRRL in the left geniculate or RLRLLR in the right geniculate, with the six maps of the visual field superimposed exactly. It also receives inputs from the primary visual cortex to which it projects and from the brainstem reticular formation, affecting visual attention. Also called the lateral geniculate body. See also magnocellular system, parvocellular system, pretectal pathway, retinotopic map. lateral geniculate nuclei pl. LGN abbrev. [From Latin lateralis situated on the side, from latus the side + geniculatus knee-shaped, from geniculum a little knee, diminutive of genus a knee]

Subjects: Psychology.

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