Pretectum

The pretectum, also known as the pretectal zone, is a region of the mesencephalon composed of seven nuclei and is responsible for much of the subcortical visual system.

Receives sensory information from the ganglion cells of the retina of the eyes, and is the region responsible for maintaining the pupillary reflex to light. As part of the subcortical visual system, neurons in the pretectal nuclei respond to different lighting intensities and are primarily involved in mediating non-conscious behavioral responses to acute changes in light. These responses generally involve the onset of optokinetic reflexes, although pretectum may also regulate nociception and REM sleep.

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