Corpus: Lateral geniculate nucleus

The lateral geniculate body, or CGL for short, is a core area in the region of the metathalamus below the pulvinar and as such is part of the visual pathway. It receives afferents from the retina via the optic tract and transmits information via the optic radiatio to the neurones of the striate area and the superior colliculi.

The corpus geniculatum laterale contains visual information of a visual field via the optic tract, which is transmitted to the visual cortex. A distinction is made between six layers. The inner two are magnocellular layers, which are part of the fast M system for recognising movement. The outer four layers are parvocellular and belong to the slow P system for colour and shape recognition. The fibres of the ipsilateral retinal ganglion cells form synapses in layers 2, 3 and 5, while the contralateral nerve fibres terminate in layers 1, 4 and 6.^[1]

Furthermore, there is an additional group of very small neurons that form the so-called coniocellular layers between the above-mentioned layers. They receive their stimuli from cones for short-wave blue perception.

The corpus geniculatum laterale receives its afferents not only from the retina, but also from many other brain regions, including the visual cortex, the superior colliculi, the pretectal area and the reticular nucleus of the thalamus. These afferents can have an excitatory, inhibitory or modulating effect.

The efferents of the CGL travel with the radiatio optica through the capsula interna to the primary visual cortex (V1), possibly also to the secondary (V2) and tertiary visual cortex (V3).

The processing procedures in the corpus geniculatum laterale are the subject of basic research and have so far (2023) only been rudimentarily investigated. Among other things, the CGL is supposed to enable the spatial allocation of objects in the perceptual field and the identification of identical objects in temporally offset individual perceptions.

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