Cerebellar influences on accessory oculomotor nuclei of the rat: a neuroanatomical, immunohistochemical and electrophysiological study
| Autor: | Giuseppe Smecca, G. Bosco, Sabina Berretta, Vincenzo Perciavalle, Genoveffa Giaquinta |
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| Jazyk: | angličtina |
| Rok vydání: | 1993 |
| Předmět: |
Male
Cerebellum Eye Movements Stilbamidines Wheat Germ Agglutinins Electrophysiology horseradish peroxidase male wheat germ agglutinins axonal transport rats wistar immunohistochemistry rats stilbamidines animals electric stimulation reaction time fluorescent dyes cerebellum periaqueductal gray brain mapping eye movements wistar Biology Settore BIO/09 Axonal Transport Periaqueductal gray Oculomotor nucleus Posterior commissure Reaction Time medicine Animals Periaqueductal Gray Rats Wistar Extracellular field potential Horseradish Peroxidase Fluorescent Dyes Brain Mapping General Neuroscience Anatomy Immunohistochemistry Electric Stimulation Wheat germ agglutinin Rats medicine.anatomical_structure Axoplasmic transport Neuroscience Nucleus |
| Popis: | With the aim to evaluate a possible neocerebellar control on eye movements, the projections from the cerebellar lateral nucleus (LN) to the accessory oculomotor nuclei (i.e., the nucleus of posterior commissure, the nucleus of Darkschewitsch, and the interstitial nucleus of Cajal), the putative neurotransmitters subserving this pathway, and the nature of the synaptic influences exerted by these projections were studied in adult rats. We used the orthograde transport of horseradish peroxidase conjugated with wheat germ agglutinin (WGA-HRP) to identify the mesencephalic areas where cerebellofugal fibers terminate, and retrograde labeling with the fluorescent dye fluoro-gold to estimate the incidence of cerebellar neurons projecting to the accessory oculomotor nuclei. Orthograde labeling showed that only a small contingent of cerebellofugal fibers reaches the contralateral accessory oculomotor nuclei. The retrogradely labeled cells were located primarily in the small-celled part of LN. By immunohistochemistry, we observed that all the cells retrogradely labeled from the accessory oculomotor area were also stained by using glutamate or aspartate antisera, but none of them were double-stained with a GABA antiserum. Electrical stimulation of the contralateral LN elicited changes in firing rate of a significant fraction of cells belonging to the accessory oculomotor nuclei (36.4% in the nucleus of posterior commissure, 47.1% in the nucleus of Darkschewitsch, and 44.6% in the interstitial nucleus of Cajal). In 57.8% of the cases, the responses were excitations, most of which had latencies and response characteristics compatible with a monosynaptic linkage. The remaining 42.2% of the cases were inhibitions with latencies ranging between 5 and 22 ms. Extracellular field potential recordings within the contralateral accessory oculomotor nuclei were interpreted as arising from impulses propagating along excitatory axons projecting in a bundle from the cerebellum. Stimulation of LN area in rats following intranuclear injection of kainic acid was not capable of evoking short latency excitations, so these responses can be considered to depend on the activation of LN efferents. The LN projection on accessory oculomotor nuclei could be part of the final precise control exerted by the neocerebellum on those brain structures concerned with movements of the eyes. |
| Databáze: | OpenAIRE |
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