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This Article Full Text Full Text (PDF) All Versions of this Article: 94/6/4481    most recent 00101.2005v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Fuchs, A. F. Articles by Phillips, J. O. Search for Related Content PubMed PubMed Citation Articles by Fuchs, A. F. Articles by Phillips, J. O.

Behavior of the Position Vestibular Pause (PVP) Interneurons of the Vestibuloocular Reflex During Head-Free Gaze Shifts in the Monkey

¹Departments of Physiology and Biophysics and ²Otolaryngology, Head, and Neck Surgery and ³Washington Regional Primate Research Center, University of Washington, Seattle, Washington

Submitted 28 January 2005; accepted in final form 18 August 2005

Most behavioral studies indicate that the efficacy (gain) of the vestibuloocular reflex (VOR) in primates is modulated during the voluntary head movements that accompany large shifts in the direction of gaze. However, the timing and degree of this modulation is the subject of some debate. The neurophysiological substrate for this apparent gain reduction has been sought in the behavior of the type I position vestibular pause (PVP) neuron, a well-known type of interneuron in the direct VOR pathway. With the head fixed, PVPs increase their firing rates with contraversive eye position and with ipsiversive passive head rotation and also cease firing (pause) for the duration of ipsiversive saccades. During head-free ipsiversive gaze shifts, the eyes and head move in the same direction. If the vestibular signal carried by PVPs provides the primary drive for the VOR, the vestibular signal should be present during ipsiversive gaze shifts to the degree that the VOR is present. Of 25 type I PVPs recorded, 21 ceased their discharge for the entire duration of the rapid, eye-saccade component of an ipsiversive gaze shift. The resumption of activity occurred, on average, 13 ms after the end of the saccade. These results suggest that the activity of the vast majority of PVP neurons do not reflect the state of the VOR, but rather PVPs are completely eliminated from participation in the reflex during head-free gaze movements. We conclude that if any modulation of the VOR does exist, it must occur through other, probably longer-latency, pathways.

This article has been cited by other articles:

				T. A. Knight and A. F. Fuchs Contribution of the Frontal Eye Field to Gaze Shifts in the Head-Unrestrained Monkey: Effects of Microstimulation J Neurophysiol, January 1, 2007; 97(1): 618 - 634. [Abstract] [Full Text] [PDF]