Horizontal eye movement networks in primates as revealed by retrograde transneuronal transfer of rabies virus: differences in monosynaptic input to "slow" and "fast" abducens motoneurons.

Full Abstract

The sources of monosynaptic input to "fast" and "slow" abducens motoneurons (MNs) were revealed in primates by retrograde transneuronal tracing with rabies virus after injection either into the distal or central portions of the lateral rectus (LR) muscle, containing, respectively, "en grappe" endplates innervating slow muscle fibers or "en plaque" motor endplates innervating fast fibers. Rabies uptake involved exclusively motor endplates within the injected portion of the muscle. At 2.5 days after injections, remarkable differences of innervation of slow and fast MNs were demonstrated. Premotor connectivity of slow MNs, revealed here for the first time, involves mainly the supraoculomotor area, central mesencephalic reticular formation, and portions of medial vestibular and prepositus hypoglossi nuclei carrying eye position and smooth pursuit signals. Results suggest that slow MNs are involved exclusively in slow eye movements (vergence and possibly smooth pursuit), muscle length stabilization and gaze holding (fixation), and rule out their participation in fast eye movements (saccades, vestibulo-ocular reflex). By contrast, all known monosynaptic pathways to LR MNs innervate fast MNs, showing their participation in the entire horizontal eye movements repertoire. Hitherto unknown monosynaptic connections were also revealed, such as those derived from the central mesencephalic reticular formation and vertical eye movements pathways (Y group, interstitial nucleus of Cajal, rostral interstitial nucleus of the medial longitudinal fasciculus). The different connectivity of fast and slow MNs parallel differences in properties of muscle fibers that they innervate, suggesting that muscle fibers properties, rather than being self-determined, are the result of differences of their premotor innervation.

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Author information

Author/s: Ugolini, Gabriella (G); Klam, François (F); Doldan Dans, Maria (M); Dubayle, David (D); Brandi, Anne-Marie (AM); Büttner-Ennever, Jean (J); Graf, Werner (W);

Affiliation: Laboratoire de Neurobiologie Cellulaire et Moléculaire, CNRS, F-91198 Gif-Sur-Yvette, France. gabriella.ugolini(-atsign-)nbcm.cnrs-gif.fr

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't

Journal: The Journal of comparative neurology (J Comp Neurol), published in United States. (Language: eng)

Reference: 2006-Oct; vol 498 (issue 6) : pp 762-85

Dates: Created 2006/08/28; Completed 2006/10/25; Revised 2006/11/15;

PMID: 16927266, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Abducens Nerve - cytology; virology
Animals
Brain Stem - cytology; virology
Eye Movements
Female
Image Processing, Computer-Assisted

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