Abstract

Experiments are planned to study the neural substrate of tonic neck and vestibular reflexes to try and determine how an output with known reflex dynamics and appropriate spatial properties is produced in decerebrate cats. Emphasis will be on the spinal part of the reflex pathway, and a combination of electrophysiology and natural stimulation will be used. Tonic neck reflexes will be evoked by head rotation in labyrinthectomized cats or by body rotation with the head fixed in labyrinth-intact cats. Vestibular reflexes will be evoked by whole-body tilt. Combinations of sinusoidal pitch and roll tilt will be used to determine the most effective stimulus plane, i.e. the response vector of the muscle or neuron under investigation. At first, response vectors for neck and vestibular reflexes will be determined for a variety of limb muscles (EMG recording), and for different types of motoneurons (intracellular recording). Motoneuron recording will also enable us to study the dynamics of the depolarization evoked by neck rotation. Next will be a study of the connections of cervical and lumbar propriospinal neurons with identified neck response vectors. Intra-axonal HRP injection will be used to trace axonal branching, and spike triggered averaging to look for connections with motoneurons. In the latter case, recording will be from ventral roots or motoneurons. Neck and limb afferent input to propriospinal neurons will also be investigated. The role of Ia inhibitory neurons in the tonic neck reflex will be explored by looking for modulation of neurons with identified afferent input. For vestibulospinal reflexes the goal will be to find relay neurons between vestibular nuclei and motoneurons. Signals relayed to the cervical enlargement by C3-C4 propriospinal neurons and by reticulospinal neurons will be studied. In addition, we will study the responses of interneurons in C1-C4 that could be involved in pathways to neck motoneurons. Some work on vestibulospinal reflexes will be done on cats with inactivated semicircular canals, to study pure otolith effects.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS002619-28
Application #
3393245
Study Section
Neurology B Subcommittee 1 (NEUB)
Project Start
1976-04-01
Project End
1993-03-31
Budget Start
1987-04-01
Budget End
1988-03-31
Support Year
28
Fiscal Year
1987
Total Cost
Indirect Cost

  Institution

Name
Rockefeller University
Department
Type
Graduate Schools
DUNS #
071037113
City
New York
State
NY
Country
United States
Zip Code
10065

  Publications

Moroney, J T; Bagiella, E; Tatemichi, T K et al. (1997) Dementia after stroke increases the risk of long-term stroke recurrence. Neurology 48:1317-25
Endo, K; Kasper, J; Wilson, V J et al. (1994) Response of commissural and other upper cervical ventral horn neurons to vestibular stimuli in vertical planes. J Neurophysiol 71:11-6
Wilson, V J (1993) Vestibulospinal reflexes and the reticular formation. Prog Brain Res 97:211-7
Bolton, P S; Goto, T; Wilson, V J (1993) Horizontal canal input to upper cervical commissural neurons. Exp Brain Res 92:549-52
Yates, B J; Goto, T; Bolton, P S (1993) Responses of neurons in the rostral ventrolateral medulla of the cat to natural vestibular stimulation. Brain Res 601:255-64
Yates, B J; Goto, T; Kerman, I et al. (1993) Responses of caudal medullary raphe neurons to natural vestibular stimulation. J Neurophysiol 70:938-46
Bolton, P S; Endo, K; Goto, T et al. (1992) Connections between utricular nerve and dorsal neck motoneurons of the decerebrate cat. J Neurophysiol 67:1695-7
Yates, B J; Goto, T; Bolton, P S (1992) Responses of neurons in the caudal medullary raphe nuclei of the cat to stimulation of the vestibular nerve. Exp Brain Res 89:323-32
Bolton, P S; Goto, T; Schor, R H et al. (1992) Response of pontomedullary reticulospinal neurons to vestibular stimuli in vertical planes. Role in vertical vestibulospinal reflexes of the decerebrate cat. J Neurophysiol 67:639-47
Wilson, V J; Bolton, P S; Goto, T et al. (1992) Spatial transformation in the vertical vestibulocollic reflex. Ann N Y Acad Sci 656:500-6

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