Effects of trunk-to-head rotation on the labyrinthine responses of rat reticular neurons

M. Barresi, C. Grasso, L. Bruschini, S. Berrettini, D. Manzoni
Neuroscience. 2012-11-01; 224: 48-62
DOI: 10.1016/j.neuroscience.2012.08.011

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1. Neuroscience. 2012 Nov 8;224:48-62. doi: 10.1016/j.neuroscience.2012.08.011. Epub
2012 Aug 14.

Effects of trunk-to-head rotation on the labyrinthine responses of rat reticular

Barresi M(1), Grasso C, Bruschini L, Berrettini S, Manzoni D.

Author information:
(1)Department of Physiological Sciences, Pisa University, I-56127 Pisa, Italy.

Vestibulospinal reflexes elicited by head displacement become appropriate for
body stabilization owing to the integration of neck input by the cerebellar
anterior vermis. Due to this integration, the preferred direction of spinal
motoneurons’ responses to animal tilt rotates by the same angle and by the same
direction as the head over the body, which makes it dependent on the direction of
body displacement rather than on head displacement. It is known that the
cerebellar control of spinal motoneurons involves the reticular formation. Since
the preferred directions of corticocerebellar units’ responses to animal tilt are
tuned by neck rotation, as occuring in spinal motoneurons, we investigated
whether a similar tuning can be observed also in the intermediate station of
reticular formation. In anaesthetized rats, the activity of neurons in the
medullary reticular formation was recorded during wobble of the whole animal at
0.156 Hz, a stimulus that tilted the animal’s head by a constant amplitude (5°),
in a direction rotating clockwise or counter clockwise over the horizontal plane.
The response gain and the direction of tilt eliciting the maximal activity were
evaluated with the head and body axes aligned and during a maintained
body-to-head displacement of 5-20° over the horizontal plane, in either
direction. We found that the neck displacement modified the response gain and/or
the average activity of most of the responsive neurons. Rotation of the response
direction was observed only in a minor percentage of the recorded neurons. The
modifications of reticular neurons’ responses were different from those observed
in the P-cells of the cerebellar anterior vermis, which rarely showed gain and
activity changes and often exhibited a rotation of their response directions. In
conclusion, reticular neurons take part in the neck tuning of vestibulospinal
reflexes by transforming a head-driven sensory input into a body-centred postural
response. The present findings prompt re-evaluation of the role played by the
reticular neurons and the cerebellum in vestibulospinal reflexes.

Copyright © 2012 IBRO. Published by Elsevier Ltd. All rights reserved.

DOI: 10.1016/j.neuroscience.2012.08.011
PMID: 22903024 [Indexed for MEDLINE]

Auteurs Bordeaux Neurocampus