Editing Visual system (section)

===Lateral geniculate nucleus===
: {{Main|Lateral geniculate nucleus}}

The '''lateral geniculate nucleus''' (LGN) is a sensory relay nucleus in the thalamus of the brain. The LGN consists of six layers in [[human]]s and other [[primate]]s starting from [[Catarrhini|catarrhines]], including [[cercopithecidae]] and [[Ape|apes]]. Layers 1, 4, and 6 correspond to information from the contralateral (crossed) fibers of the nasal retina (temporal visual field); layers 2, 3, and 5 correspond to [[information]] from the ipsilateral (uncrossed) fibers of the temporal retina (nasal visual field).

Layer one contains M cells, which correspond to the M ([[Magnocellular cell|magnocellular]]) cells of the optic nerve of the opposite eye and are concerned with depth or motion. Layers four and six of the LGN also connect to the opposite eye, but to the P cells (color and edges) of the optic nerve. By contrast, layers two, three and five of the LGN connect to the M cells and P ([[Parvocellular cell|parvocellular]]) cells of the optic nerve for the same side of the brain as its respective LGN.

Spread out, the six layers of the LGN are the area of a [[credit card]] and about three times its thickness.  The LGN is rolled up into two [[Ellipsoid|ellipsoids]] about the size and shape of two small birds' eggs. In between the six layers are smaller cells that receive information from the K cells (color) in the retina.  The neurons of the LGN then relay the visual image to the [[primary visual cortex]] (V1) which is located at the back of the brain ([[Posterior (anatomy)|posterior end]]) in the [[occipital lobe]] in and close to the [[calcarine sulcus]]. The LGN is not just a simple relay station, but it is also a center for processing; it receives reciprocal input from the [[Cortical layer|cortical]] and subcortical layers and [[reciprocal innervation]] from the visual cortex.<ref name=Tov2008 />

[[File:Lisa analysis.png|left|thumb|200px| Scheme of the [[optic tract]] with image being decomposed on the way, up to simple cortical cells (simplified)]]