- Eye Movements 411
Smooth Pursuit
■ Each hemisphere is responsible for ipsilateral smooth
pursuit eye movements; for instance, the right
hemisphere detects and tracks images as they move to
the right.
■ M retinal ganglion cells receive rod photoreceptor
detection of the target’s movement.
■ Th e primary visual cortex projects to visual area V5
(the human homologue to the macaque middle
temporal [MT] area).
■ Area V5 projects to visual area V5a (the human
homologue to the macaque medial superior temporal
[MST] area).
■ Area V5a projects to the posterior parietal cortex,
which projects to the frontal eye fi elds.
■ Th e frontal eye fi elds (and other cortical visual
areas, as well) project to the ipsilateral pontine
nuclei.
■ Th e pontine nuclei project across midline to the
opposite side of the cerebellum, most notably to the
vestibulocerebellum.
■ Th e cerebellum projects to the ipsilateral medial
vestibular nucleus in the medulla.
■ Th e medial vestibular nucleus projects to the
contralateral abducens nucleus (on the side of the
brain that detected the movement), which excites the
fi nal common pathway for horizontal eye
m o v e m e n t s.Pupillary Light Refl ex
■ O p t i c fi bers of the pupillary light refl ex synapse in
the pretectal olivary nucleus of the pretectal area
rather than the lateral geniculate nucleus.
■ Th e prectectal olivary nucleus projects directly to the
ipsilateral Edinger–Westphal nucleus and to the
contralateral Edinger–Westphal nucleus via the
posterior commissure.
■ Each Edinger–Westphal nucleus projects to its
ipsilateral ciliary ganglion.
■ Th e ciliary ganglion sends short ciliary nerves to
innervate the sphincter pupillae muscles to produce
pupillary constriction.