RT Journal Article SR Electronic T1 Vestibular-nerve inputs to the vestibulo-ocular reflex: a functional- ablation study in the squirrel monkey JF The Journal of Neuroscience JO J. Neurosci. FD Society for Neuroscience SP 1636 OP 1648 DO 10.1523/JNEUROSCI.11-06-01636.1991 VO 11 IS 6 A1 Minor, LB A1 Goldberg, JM YR 1991 UL http://www.jneurosci.org/content/11/6/1636.abstract AB Advantage was taken of differences in the electrical excitability of vestibular-nerve fibers to characterize the afferent input to the canal- related vestibulo-ocular reflex. Large anodal (inhibitory) currents, when delivered to both ears, result in a selective, reversible ablation of irregular afferents. Their background discharge and responses to head rotations are temporarily abolished. The same currents have less effect on the background discharge and no effect on the rotational sensitivity of regular afferents. Eye movements were evoked by head rotations in alert monkeys. The ablating currents did not alter the ocular responses to sinusoidal head rotations in yaw or pitch planes. Responses to rapid changes in head velocity were similarly unaffected. It is concluded that irregular afferents do not make a net contribution to the reflex. Slow-phase eye movements evoked by unilateral galvanic currents are consistent with this conclusion. The results are incorporated into a systems model of the reflex. There are three conclusions from the model: (1) the signal to motoneurons consists of the sum of three components related, respectively, to head velocity, eye position, and filtered eye velocity; (2) regular afferents provide the best match to the dynamic requirements of the reflex; and (3) the central pathways responsible for all three signal components receive regular inputs.