Premium
Hindlimb Inputs Alter the Processing of Vestibular Signals
Author(s) -
McCall Andrew A,
Miller Derek M,
DeMayo William M,
Yates Bill J,
Bourdages George H
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.1283.1
Subject(s) - vestibular system , proprioception , vestibular nuclei , somatosensory system , neuroscience , anatomy , sensory system , hindlimb , decerebrate state , balance (ability) , afferent , semicircular canal , biology , stimulation , electric stimulation
Although the vestibular system has exquisite sensitivity in signaling head movement in space, additional information about the orientation of the body is needed for the control of balance. Vestibular afferent information is interpreted and shaped in the context of proprioceptive and visual information. To achieve stable balance, it is likely that integration of vestibular and leg proprioceptive afferent signals is critical, since the legs typically serve as the sole interface with the ground and limb position shapes vestibulospinal responses. However, virtually nothing is known about how limb afferent signals are integrated with vestibular afferent signals in central vestibular pathways. The primary goal of this study was to determine the influence of somatosensory limb inputs on the activity of vestibular nucleus neurons. Experiments were conduced in decerebrate and conscious felines, and entailed extracellular recordings from neurons in the caudal aspect of the vestibular nuclei during ramp‐and‐hold movements of the hindlimb and vertical plane whole body rotations. In both preparations, vestibular nucleus neurons responded to the two stimuli, but the responses differed in decerebrate and conscious animals. In decerebrate animals (panel A of figure), the activity of vestibular nucleus neurons was aligned with hindlimb position, with some units affected by limb flexion and others by limb extension. In conscious animals (panel B of figure), the activity of vestibular nucleus neurons was altered by limb movement, regardless of the direction. These data suggest that the processing of labyrinthine inputs by the vestibular system differs when limbs are stationary or moving, as during locomotion. Since responses to hindlimb movement were distinct in conscious and decerebrate animals, these findings also show that supratentorial structures modify the integration of limb and vestibular signals by brainstem neurons. Support or Funding Information Supported by NIH Grant K08‐DC013571‐01.Responses of vestibular nucleus neurons to hindlimb movement in decerebrate (A) and conscious (B) felines. In decerebrate animals, activity of vestibular nucleus neurons was related to hindlimb position (A) , whereas in conscious animals neurons responded to hindlimb movement (B).