Structure and Function of the Lateral Geniculate Nucleus
- The lateral geniculate nucleus (LGN) is a structure in the thalamus and a key component of the mammalian visual pathway.
- It is a small, ovoid, ventral projection of the thalamus where the thalamus connects with the optic nerve.
- There are two LGNs, one on the left and another on the right side of the thalamus.
- In humans, both LGNs have six layers of neurons (grey matter) alternating with optic fibers (white matter).
- The LGN has layers of magnocellular cells, parvocellular cells, and koniocellular cells.
- The magnocellular, parvocellular, and koniocellular layers of the LGN correspond with the similarly named types of retinal ganglion cells.
- Koniocellular cells provide a third channel to the visual cortex and may be involved in color perception.
- The parvo- and magnocellular fibers were previously thought to dominate the ventral and dorsal streams, respectively.
- The koniocellular system has been linked with the integration of somatosensory system-proprioceptive information with visual perception.
- The tectopulvinar pathway is another major retino-cortical visual pathway.
- The LGN receives input from the retina, visual cortex, superior colliculus, pretectum, and other brain structures.
- Only a small percentage of LGN input comes from the retina.
- Non-retinal inputs can be excitatory, inhibitory, or modulatory.
- The LGN also receives some inputs from the optic tectum.
- Regions in the brainstem not involved in visual perception also project to the LGN.
- Information leaving the LGN travels out on the optic radiations.
- Axons from the LGN go to the V1 visual cortex.
- Magnocellular and parvocellular layers send their axons to layer 4 in V1.
- Koniocellular layers send their axons primarily to layers 2 and 3 in V1.
- Axons from layer 6 of visual cortex send information back to the LGN.
- The output of the LGN serves several functions in visual perception.
- Computations are achieved to determine the position of every major element in object space relative to the principal plane.
- The LGN accomplishes temporal decorrelation, making for more efficient coding.
- The LGN likely helps the visual system focus its attention on the most important information.
- Neurons from the LGN may travel to higher cortical areas V2 and V3, contributing to blindsight phenomena.

Ipsilateral and Contralateral Layers
- Each LGN receives input from both eyes but only from one half of the visual field.
- RGCs from the nasal sides of each retina cross to the other side of the brain through the optic chiasma.
- RGCs from the temporal sides of each retina remain on the same side of the brain.
- The right LGN receives visual information from the left visual field, and the left LGN receives visual information from the right visual field.
- The sequence of layers receiving information from the ipsilateral and contralateral eyes is different in the tarsier.

Auditory System Interaction
- The LGN likely communicates with the visual system through the peri-reticular nucleus.
- The auditory system influences visual attention through the LGN.
- Lindeberg determined functional models of LGN cells using Laplacian of Gaussian kernels.
- The theory predicts receptive fields that align with biological measurements.
- Non-lagged LGN cells correspond to first-order temporal derivatives, while lagged LGN cells correspond to second-order temporal derivatives.

Color Processing
- The LGN plays a crucial role in early color processing.
- Opponent channels are created in the LGN to compare signals between different photoreceptor cell types.
- P-cells produce red-green opponent signals.
- M-cells contribute to luminance perception without much color opponency.
- K-cells generate blue-yellow opponent signals.

Rodents
- The lateral geniculate nucleus in rodents consists of the dorsal lateral geniculate nucleus (dLGN), ventral lateral geniculate nucleus (vLGN), and the intergeniculate leaflet (IGL).
- These subcortical nuclei have distinct functions.
- The dLGN receives the majority of input from the retina and exhibits retinotopic organization.
- The vLGN is relatively large in various species and has multiple subdivisions.
- The IGL is a small area dorsal to the vLGN and shares similarities with it in terms of neurochemicals and connections.
- The dorsolateral geniculate nucleus is the primary division of the lateral geniculate body.
- It receives most of its input from the retina.
- The dLGN is laminated and exhibits retinotopic organization.
- It plays a crucial role in visual processing.
- The dLGN has distinct functional properties compared to other divisions of the LGN.
- The ventrolateral geniculate nucleus is relatively large in several species.
- It is divided into external and internal divisions.
- The cytoarchitecture of the vLGN differs between species.
- In cats, the vLGN is divided into three regions: medial, intermediate, and lateral.
- The vLGN has reciprocal connections with other thalamic nuclei and receives input from various sources.

Lateral geniculate nucleus (Wikipedia)

"LGN" redirects here. For other uses, see LGN (disambiguation).

In neuroanatomy, the lateral geniculate nucleus (LGN; also called the lateral geniculate body or lateral geniculate complex) is a structure in the thalamus and a key component of the mammalian visual pathway. It is a small, ovoid, ventral projection of the thalamus where the thalamus connects with the optic nerve. There are two LGNs, one on the left and another on the right side of the thalamus. In humans, both LGNs have six layers of neurons (grey matter) alternating with optic fibers (white matter).

Lateral geniculate nucleus
Hind- and mid-brains; postero-lateral view. (Lateral geniculate body visible near top.)
Details
Part of	Thalamus
System	Visual
Artery	Anterior choroidal and Posterior cerebral
Vein	Terminal vein
Identifiers
Latin	Corpus geniculatum laterale
Acronym(s)	LGN
NeuroNames	352
NeuroLex ID	birnlex_1662
TA98	A14.1.08.302
TA2	5666
FMA	62209
Anatomical terms of neuroanatomy [edit on Wikidata]

The LGN receives information directly from the ascending retinal ganglion cells via the optic tract and from the reticular activating system. Neurons of the LGN send their axons through the optic radiation, a direct pathway to the primary visual cortex. In addition, the LGN receives many strong feedback connections from the primary visual cortex. In humans as well as other mammals, the two strongest pathways linking the eye to the brain are those projecting to the dorsal part of the LGN in the thalamus, and to the superior colliculus.