Much of our present understanding of the neuronal and synaptic organization of the oculomotor system has evolved from morphological, physiological, and clinicopathological studies of the neurones, nuclei, and pathways that are related to various types of eye movement. The correlation of the neuronal activity of premotor neurones with the activity of both the oculomotor motoneurones and the extracular muscles suggests synaptic relationships that underly neuronal interactions in the oculomotor system, particularly in the vestibulo-ocular reflex.
The specific aims of the proposed studies are directed toward delineating similarities and/or differences in the patterns of synaptic connectivity of second-order vestibular neurones with motoneurones in the oculomotor, trochlear, and abducens nuclei. Physiologically-identified second-order vestibular neurones or axons will be identified electrophysiologically and stained by intracellular injection of horseradish peroxidase, and their axonal arborizations will be reconstructed by light and electron microscopy to determine the modes and patterns of synaptic connections with different populations of motoneurons. In addition, the postnatal development of abducens motoneurones and internuclear neurones and of the lateral rectus muscle will be examined by electron microscopy in relation to the synaptic inputs to the neurones and the sequential differentiation of different muscle fiber types. The proposed studies are consistent with the long-term goal of elucidating neuronal and synaptic relationships in the oculomotor system underlying gaze and their relationship to disorders of ocular motility.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY002191-08
Application #
3256552
Study Section
Visual Sciences B Study Section (VISB)
Project Start
1978-01-01
Project End
1988-12-31
Budget Start
1985-01-01
Budget End
1985-12-31
Support Year
8
Fiscal Year
1985
Total Cost
Indirect Cost
Name
Virginia Commonwealth University
Department
Type
Overall Medical
DUNS #
City
Richmond
State
VA
Country
United States
Zip Code
23298
Spencer, Robert F; Porter, John D (2006) Biological organization of the extraocular muscles. Prog Brain Res 151:43-80
McClung, J R; Cullen, K E; Shall, M S et al. (2004) Effects of electrode penetrations into the abducens nucleus of the monkey: eye movement recordings and histopathological evaluation of the nuclei and lateral rectus muscles. Exp Brain Res 158:180-8
Dimitrova, Diana M; Shall, Mary S; Goldberg, Stephen J (2003) Stimulation-evoked eye movements with and without the lateral rectus muscle pulley. J Neurophysiol 90:3809-15
Shall, Mary S; Dimitrova, Diana M; Goldberg, Stephen J (2003) Extraocular motor unit and whole-muscle contractile properties in the squirrel monkey. Summation of forces and fiber morphology. Exp Brain Res 151:338-45
Nguyen, L T; Baker, R; Spencer, R F (1999) Abducens internuclear and ascending tract of deiters inputs to medial rectus motoneurons in the cat oculomotor nucleus: synaptic organization. J Comp Neurol 405:141-59
Nguyen, L T; Spencer, R F (1999) Abducens internuclear and ascending tract of Deiters inputs to medial rectus motoneurons in the cat oculomotor nucleus: neurotransmitters. J Comp Neurol 411:73-86
Spencer, R F; Tucker, M G; Choi, R Y et al. (1997) Botulinum toxin management of childhood intermittent exotropia. Ophthalmology 104:1762-7
McNeer, K W; Tucker, M G; Spencer, R F (1997) Botulinum toxin management of essential infantile esotropia in children. Arch Ophthalmol 115:1411-8
Spencer, R F; Wang, S F (1996) Immunohistochemical localization of neurotransmitters utilized by neurons in the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) that project to the oculomotor and trochlear nuclei in the cat. J Comp Neurol 366:134-48
Wang, S F; Spencer, R F (1996) Morphology and soma-dendritic distribution of synaptic endings from the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) on motoneurons in the oculomotor and trochlear nuclei in the cat. J Comp Neurol 366:149-62

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