In neuroanatomy, the pretectal area, or pretectum, is a midbrain structure composed of seven nuclei and comprises part of the subcortical visual system.

[1][2][3][4][5] In addition to the pretectum's role in the visual system, the anterior pretectal nucleus has been found to mediate somatosensory and nociceptive information.

[12] While these two regions have not been examined to the same extent as the five primary nuclei, research has shown both the PLi and CPA to receive retinal input, which suggests a role in processing visual information.

From the thalamus the NOT receives inhibitory projections from GABA-producing neurons in the ipsilateral lateral geniculate nucleus and bilateral intergeniculate leaflets.

Its bilateral inhibitory projections to the accessory optic system include connections to the lateral and medial terminal nuclei.

[1] As part of the subcortical visual system, neurons within the pretectal nuclei respond to varying intensities of illuminance and are primarily involved in mediating non-conscious behavioral responses to acute changes in light.

[1][17][19] In addition to its role in maintaining smooth pursuit, the pretectum is activated during the optokinetic nystagmus in which the eye returns to a central, forward-facing position after an object it was following passes out of the field of vision.

From that point, the mechanism by which the eye maintains focus through muscular contractions of the retina is similar to that of the pupillary light reflex.

[22] In addition to its direct antionociceptive mechanism, the NPA projects onto brain regions that, through connections to the somatosensory cortex, regulate the perception of painful stimuli.

Research has shown that the pretectum, in conjunction with the superior colliculus, may be responsible for causing non-circadian changes in REM sleep behaviors.

[25] Pretectal nuclei receiving retinal input, in particular the NOT and the NPP, have been shown to be partially responsible for initiating REM sleep in albino rats.