Saccadic dysmetria following inactivation of the primate fastigial oculomotor region

Neurosci Lett. 2002 Jun 14;325(3):211-5. doi: 10.1016/s0304-3940(02)00268-9.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cerebellar Ataxia* / physiopathology
  • Cerebellar Nuclei* / physiology
  • Cerebellar Nuclei* / physiopathology
  • GABA Agonists / administration & dosage
  • Macaca mulatta
  • Male
  • Muscimol / administration & dosage
  • Saccades / physiology*


  • GABA Agonists
  • Muscimol