title: Saccadic dysmetria following inactivation of the primate fastigial oculomotor region.
abstract: The caudal part of the fastigial nucleus, or the fastigial oculomotor region (FOR), plays an important role in executing accurate saccades. Inactivation of a monkey FOR leads to dysmetric saccades. Currently available data suggest that the dysmetria could be described as a parametric, uniform change in saccadic gain or, alternatively, as a constant error in the specification of the saccadic goal. To discriminate between these two possibilities, we examined the effect of FOR inactivation in the monkey. After a unilateral injection of muscimol into the FOR, ipsiversive saccades overshot a target. Gains were similar for movements of different sizes. The overshoot increased proportionately with the target distance and had a very small constant component. The present study indicates that the hypermetria of ipsiversive saccades after inactivation of the monkey FOR is primarily due to a uniform gain increase for all sizes of saccades.
authors.affiliation: Department of Physiology, Institute of Basic Medical Sciences, University of Tsukuba, 1-1-1 Tenno-dai, Tsukuba, Ibaraki 305-8575, Japan. iwamoto@md.tsukuba.ac.jp
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Iwamoto
authors.forename: Kaoru
authors.initials: K
authors.lastname: Yoshida
mesh_terms: D000818:Animals; D002524:Cerebellar Ataxia / Q000503:physiopathology; D002529:Cerebellar Nuclei / Q000502:physiology / Q000503:physiopathology; D018755:GABA Agonists / Q000008:administration & dosage; D008253:Macaca mulatta; D008297:Male; D009118:Muscimol / Q000008:administration & dosage; D012438:Saccades / Q000502:physiology*
chemical_list: D018755:GABA Agonists; D009118:Muscimol