superior colliculus

either of a pair of rounded prominences (colliculi) in the brain, one of which lies near each cerebral peduncle, rostrally to the inferior colliculus and immediately beneath the pineal gland. The superior colliculus receives fibers from the optic tract and projects fibers to several stations, including the lateral geniculate nucleus and the reticular formation. The superior colliculus gives rise to the tectospinal tract and is involved in orienting movements of the head and eye toward external stimuli. See also blindsight.

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Psychology term of the day

November 17th 2024

REM sleep

rapid-eye-movement sleep: the stage of sleep, formerly called desynchronized sleep, in which most dreaming tends to occur during which electroencephalograms show activity that resembles wakefulness (hence, it is also known as paradoxical sleep) except for inhibition of most skeletal and cranial muscles. This stage has two phases—tonic and phasic—and it is largely during the phasic period that muscle twitches and bursts of rapid eye movements occur. REM sleep accounts for one quarter to one fifth of total sleep time. Compare NREM sleep.