The purpose of the proposed research is to investigate the relationships between morphological and physiological characteristics of vestibular nuclei and primary afferent neurons. Electrophysiological studies will be conducted on decerebrated gerbils to examine the responses of neurons in the major vestibular nuclei and selected accessory nuclei to time-varying linear head acceleration and to angular acceleration about the vertical head axis. Linear force will be applied in the form of sinusoidal translational head acceleration at single fundamental frequencies ranging, from 0.2 to 5.0 Hz, along the cardinal horizontal and vertical head axes. This study will provide data related to mechanisms for convergence of input from semicircular canals and otolith organ receptors onto single neurons of the vestibular nuclei. In addition, measures of the relationship between the stimulus vector and the nature of the neuronal response will be used to test hypotheses concerning the functional organization of the central otolith related system. Two sets of anatomical experiments will be conducted. Vestibular nuclei neurons that exhibit responses to linear head acceleration will be injected intracellularly with horseradish peroxidase (HRP) to label the cell bodies and their processes. Physiological characteristics and morphological features will be compared. In double labeling experiments, physiologically identified otolith-related afferents will be intra-axonally injected with HRP; concurrently, ipsilateral vestibular nuclei neurons that respond both monosynaptically to electrical stimulation of the labyrinth and to linear forces will be labeled intracellularly with a fluorescent dye, e.g. Lucifer Yellow or Texas Red. This will provide direct anatomical identification of second order neurons and both physiological and anatomical description of their primary vestibular input from otolith related afferents.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS024391-02
Application #
3408940
Study Section
Hearing Research Study Section (HAR)
Project Start
1986-12-01
Project End
1989-11-30
Budget Start
1987-12-01
Budget End
1988-11-30
Support Year
2
Fiscal Year
1988
Total Cost
Indirect Cost
Name
University of Texas Medical Br Galveston
Department
Type
Schools of Medicine
DUNS #
041367053
City
Galveston
State
TX
Country
United States
Zip Code
77555
Kevetter, G A; Perachio, A A (1989) Projections from the sacculus to the cochlear nuclei in the Mongolian gerbil. Brain Behav Evol 34:193-200
Perachio, A A; Kevetter, G A (1989) Identification of vestibular efferent neurons in the gerbil: histochemical and retrograde labelling. Exp Brain Res 78:315-26
Newlands, S D; Kevetter, G A; Perachio, A A (1989) A quantitative study of the vestibular commissures in the gerbil. Brain Res 487:152-7