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Sources of calretinin inputs to motoneurons of extraocular muscles involved in upgaze
Author(s) -
Ahlfeld Julia,
Mustari Michael,
Horn Anja K.E.
Publication year - 2011
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.2011.06168.x
Subject(s) - oculomotor nucleus , neuroscience , medial longitudinal fasciculus , vestibular nuclei , calretinin , nucleus , brainstem , excitatory postsynaptic potential , extraocular muscles , anatomy , axoplasmic transport , eye movement , vestibular system , abducens nucleus , reflex , chemistry , biology , central nervous system , medicine , pathology , inhibitory postsynaptic potential , immunohistochemistry , midbrain
Recent monkey studies showed that motoneurons of the oculomotor nucleus involved in upward eye movements receive a selective input from afferents containing calretinin (CR). Here, we investigated the sources of these CR‐positive afferents. After injections of tract‐tracers into the oculomotor nucleus (nIII) of two monkeys, the retrograde labeling was combined with CR‐immunofluorescence in frozen brainstem sections. Three sources of CR inputs to nIII were found: the rostral interstitial nucleus of the medial longitudinal fascicle (RIMLF), the interstitial nucleus of Cajal, and the y‐group. CR is not present in all premotor upward‐moving pathways. The excitatory secondary vestibulo‐ocular neurons in the magnocellular part of the medial vestibular nuclei contained nonphosphorylated neurofilaments, but no CR, and they received a strong supply of large CR‐positive boutons. In conclusion, the present study presents evidence that only specific premotor pathways for upward eye movements—excitatory upgaze pathways—contain CR, but not the up vestibulo‐ocular reflex pathways. This property may help to differentiate between premotor up‐ and downgaze pathways in correlative clinico‐anatomical studies in humans.