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Role of the Dorsolateral Pontine Nucleus in Visual-Vestibular Behavior
aDivision of Visual Science, Yerkes National Primate Research Center and bDepartment of Neurology, Emory University, Atlanta, Georgia 30022, USA
Address for correspondence: Michael J. Mustari, Ph.D., Division of Visual Science, Yerkes National Primate Research Center and Department of Neurology, Emory University, 954 Gatewood Road N.E., Atlanta, GA 30022. Voice: 404-727-9194; fax: 404-727-7729. mjmustar{at}rmy.emory.edu Ann. N.Y. Acad. Sci. 1004: 196-205 (2003).
Visual-vestibular behavior depends on signals traveling in climbing and mossy fiber pathways. Our study examined the role of the dorsolateral pontine nucleus (DLPN), a major component of the cortico-ponto-cerebellar mossy fiber pathway. DLPN neurons discharge in relation to smooth pursuit and during visual stimulation, indicating a potential role in visually guided motor learning in the vestibulo-ocular reflex (VOR). We used unilateral muscimol injections to determine the potential role of the DLPN in short-term VOR gain adaptation. Preinjection adaptation of VOR gain was achieved by sinusoidal rotation (0.2 Hz, 30°/s) for 2 h while the monkey viewed a stationary visual surround through either magnifying (x2) or minifying (x0.5) lenses. VOR gain increases (23-32%) or decreases (22-48%) as measured in complete darkness (VORd) were achieved. Following DLPN inactivation, initial acceleration of ipsilateral smooth-pursuit was reduced by 35-68%, and steady state gain was reduced by 32-61%. Furthermore, the monkey's ability to cancel the VOR was impaired. In contrast to these significant deficits in ipsilesional smooth pursuit, the VOR during lens viewing was similar to that measured in preinjection control experiments. Similarly, following 2 h of adaptation, VORd gain adaptation was indistinguishable from control adaptation values for either ipsilesional or contralesional directions of head rotation. Our results suggest that visual error signals for short-term adaptation of the VOR are derived from sources other than the DLPN, such as those from the accessory optic system.
Key Words: vestibular ocular • smooth pursuit • eye movement • pontine This article has been cited by other articles:
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