A pathway in the brainstem for roll-tilt of the subjective visual vertical: Evidence from a lesion-behavior mapping study

Abstract

The perceived subjective visual vertical (SVV)isanimportant signofavestibular otolith tone imbalanceinthe roll plane. Previous studies suggested that unilater alpontomedullary brain stemlesions cause ipsiversive roll-tilt of SVV, where a spontomesence phaliclesions cause contraversive roll-tilts of SVV. However, previous data were of limited quality and lacked a statistical approach. We therefore tested roll-tilt of the SVV in 79 human patients with acute unilateral brainstem lesions due to stroke by applying modern statistical lesion- behavior mapping analysis. Roll-tilt of the SVV was verified to be abrainstem sign, and for the first timeit was confirmed statistically that lesions of the medial longitudinal fasciculus (MLF) and the medial vestibular nucleus are associated with ipsiversive tilt of the SVV, whereas contraversive tilts are associated with lesions affecting the rostral interstitial nucleus of the MLF, the superior cerebellar peduncle, the oculomotor nucleus, and the interstitial nucleus of Cajal. Thus, these structures constitute the anatomical pathway in the brainstem for verticality perception. Present data indicate that graviceptive otolith signals present a predominant role in the multisen-sory system of verticality perception. © 2012 the authors.