Fig. 3. Graviceptive pathways from the otoliths and vertical semicircular canals mediating the vestibular reactions in the roll plane. The projections from the otoliths and the vertical semicircular canals to the ocular motor nuclei (trochlear nucleus IV, oculomotor nucleus III, abducens nucleus VI) and the supranuclear centers of the interstitial nucleus of Cajal (INC), and the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) are shown. The subserve the vestibulo-ocular reflex (VOR) in three planes. The VOR is part of a more complex vestibular reaction that also involves the vestibulospinal connections via the medial and lateral vestibulospinal tracts for head and body posture control. Furthermore, connections to the assumed vestibular cortex (area 2v and 3a and the parietoinsular vestibular cortex, PIVC) via the vestibular nuclei of the thalamus (Vim, Vce) are depicted. Graviceptive vestibular pathways for the roll plane cross at the pontine level. Ocular tilt reaction (OTR) is depicted schematically on the right in relation to the level of the lesion (i.e., ipsiversive OTR with peripheral and pontomedullary lesions) contraversive OTR with pontomesencephalic lesions. In vestibular thalamus lesions, the tilts of the subjective visual vertical may be contraversive or ipsiversive; in vestibular cortex lesions, they are preferably contraversive. (From Brandt T, Dieterich M: Vestibular syndromes in the roll plane: topographic diagnosis from brainstem to cortex. Ann Neurol 1994;36:337–347.)