Nucleus prepositus
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ToursExplore Lably’s 3D toursInjury to the nucleus prepositus results in inability to hold gaze upon a visual target; conjugate eye movement is unaffected.
It may be conceptually regarded as a vestibular nucleus.
Anatomy
The nucleus prepositus is situated near the hypoglossal nucleus. It is continuous rostrally with the paramedian pontine reticular formation, and caudally with the intercalated nucleus. It is situated medial to the medial vestibular nucleus.
Connections
It is connected to the superior colliculus, and has reciprocal connections with the serotonergic raphe nuclei (thereby possibly participating in blood pressure regulation).
Afferents
It receives afferents from the frontal eye fields, medial and dorsal vestibular nuclei, paramedian pontine reticular formation, and interstitial nucleus of Cajal.
Efferents
The nuclei project principally to all three cranial nerve nuclei controlling extrinsic eye muscles (the oculomotor (CN III), trochlear (CN IV), and abducens (CN VI) nuclei) via the medial longitudinal fasciculus, with additional efferents to the vestibular nuclei, and vestibulocerebellum.
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Function
The nucleus prepositus integrates velocity-position information for horizontal eye movements to enable eccentric gaze. Tonic neurons of the nucleus (along with those of with the medial vestibular nucleus) are believed to maintain eccentric (i.e. off resting position) direction of gaze, counteracting forces pulling the eye back to its default, resting, straight-forward gazing position after saccades. The nucleus prepositus is thought to provide information about eye position.