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This Article Full Text Full Text (PDF) All Versions of this Article: 98/6/3269    most recent 00741.2007v1 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 PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Quinet, J. Articles by Goffart, L. Search for Related Content PubMed PubMed Citation Articles by Quinet, J. Articles by Goffart, L.

Head-Unrestrained Gaze Shifts After Muscimol Injection in the Caudal Fastigial Nucleus of the Monkey

¹Unité 534, Institut National de la Santé et de la Recherche Médicale/Université Claude Bernard Lyon, IFR 19 Institut des Neurosciences de Lyon, Bron; and ²Equipe Dynamique de la Vision et de l'Action, I.N.C.M., UMR 6193 Centre National de la Recherche Scientifique–Aix-Marseille Universités, Marseille, France

Submitted 4 July 2007; accepted in final form 9 October 2007

The effects of unilateral cFN inactivation on horizontal and vertical gaze shifts generated from a central target toward peripheral ones were tested in two head unrestrained monkeys. After muscimol injection, the eye component was hypermetric during ipsilesional gaze shifts, hypometric during contralesional ones and deviated toward the injected side during vertical gaze shifts. The ipsilesional gaze hypermetria increased with target eccentricity until 24° after which it diminished and became smaller than the hypermetria of the eye component. Contrary to eye saccades, the amplitude and peak velocity of which were enhanced, the amplitude and peak velocity of head movements were reduced during ipsilesional gaze shifts. These changes in head movement were not correlated with those affecting the eye saccades. Head movements were also delayed relative to the onset of eye saccades. The alterations in head movement and the faster eye saccades likely explained the reduced head contribution to the amplitude of ipsilesional gaze shifts. The contralesional gaze hypometria increased with target eccentricity and was associated with uncorrelated reductions in eye and head peak velocities. When compared with control movements of similar amplitude, contralesional eye saccades had lower peak velocity and longer duration. This slowing likely accounted for the increase in head contribution to the amplitude of contralesional gaze shifts. These data suggest different pathways for the fastigial control of eye and head components during gaze shifts. Saccade dysmetria was not compensated by appropriate changes in head contribution, raising the issue of the feedback control of movement accuracy during combined eye-head gaze shifts.

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