Vestibular influences on ocular accommodation in cats.

Electrical stimulation of the utricle in C-1 transected cats (whose labyrinths remained sensitive to natural stimulation) induced bilateral pupillary dilatation and bilateral 0.4 to 3.0 diopter lens change in an anti-accommodative direction. Both effects could still be induced two weeks after cutting the ipsilateral cervical sympathetic trunk. It is concluded that these effects take place by inhibiting the parasympathetic pathway originating in the Edinger-Westphal nucleus. The mediating pathways from the vestibular complex to the Edinger-Westphal nucleus pass through the brain stem in the region outside the medial longitudinal fasciculi.