The long-term objectives are to work out the neural wiring of the oculomotor system. Data are collected from human and animal experiments and interpreted in the form of control-systems models to try and provide mechanistic explanations for human oculomotor disorders.
One specific aim i s to try and locate the neural integrator that converts eye-velocity to eye-position commands. Lesions of the vestibular nucleus in monkeys may implicate this nucleus and recording from tonic cells in the reticular formation may reveal their involvement. The feasibility of the reverberating-collateral hypothesis for the integrator will be tested by a computer model. Another specific aim is to find whether or not plasticity of the vestibulo-ocular reflex (vor) is in the flocculus by surveying cell types in the cat flocculus, studying the appropriate types during visually-induced changes in the gain of the vor and the response of such cells to an interruption of climbing fiber signals from the inferior olive by injection of a local anesthetic. Another aim is to demonstrate plasticity in the human pursuit system by utilizing the dissociation of neural commands and eye movements that occur in muscle palsy and to incorporate the findings in a model of pursuit. Another aim is to record from burst neurons in the monkey that create vertical saccades and find out if their planes of action lie near those of the canals or eye muscles by rotating them in and around such planes to evoke quick phases. Another aim is to utilize very large eye and head movements to study and model the interaction of the vor and neural saccadic commands.
The final aim i s to demonstrate that subjects can cancel (suppress) their vor in roll. Since there is no torsional pursuit, this implies that there must exist a neurological system distinct from pursuit to cancel the vor. These projects are designed to quantify the behavior of human oculomotor subsystems, identify and describe new subsystems, describe interactions between them, and provide a neural scheme in the form of a model to explain their normal behavior. These measurements form a basis for the diagnosis of eye movement disorders in human beings and our hypotheses of signal processing by the neural substrates of these systems can often provide a hypothesis for the etiology of those disorders. These projects are also directed to studying the extent to which these systems can recover normal function following dysmetria caused by trauma or disease and the neural mechanisms underlying this plasticity.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY000598-20
Application #
3255459
Study Section
Visual Sciences B Study Section (VISB)
Project Start
1979-05-01
Project End
1989-04-30
Budget Start
1988-05-01
Budget End
1989-04-30
Support Year
20
Fiscal Year
1988
Total Cost
Indirect Cost
Name
Johns Hopkins University
Department
Type
Schools of Medicine
DUNS #
045911138
City
Baltimore
State
MD
Country
United States
Zip Code
21218
Arnold, D B; Robinson, D A; Leigh, R J (1999) Nystagmus induced by pharmacological inactivation of the brainstem ocular motor integrator in monkey. Vision Res 39:4286-95
Arnold, D B; Robinson, D A (1997) The oculomotor integrator: testing of a neural network model. Exp Brain Res 113:57-74
Luebke, A E; Robinson, D A (1994) Gain changes of the cat's vestibulo-ocular reflex after flocculus deactivation. Exp Brain Res 98:379-90
Kapoula, Z; Robinson, D A; Optican, L M (1993) Visually induced cross-axis postsaccadic eye drift. J Neurophysiol 69:1031-43
Arnold, D B; Robinson, D A (1992) A neural network model of the vestibulo-ocular reflex using a local synaptic learning rule. Philos Trans R Soc Lond B Biol Sci 337:327-30
Shelhamer, M; Robinson, D A; Tan, H S (1992) Context-specific gain switching in the human vestibuloocular reflex. Ann N Y Acad Sci 656:889-91
Shelhamer, M; Robinson, D A; Tan, H S (1992) Context-specific adaptation of the gain of the vestibulo-ocular reflex in humans. J Vestib Res 2:89-96
Luebke, A E; Robinson, D A (1992) Climbing fiber intervention blocks plasticity of the vestibuloocular reflex. Ann N Y Acad Sci 656:428-30
Anastasio, T J; Robinson, D A (1991) Failure of the oculomotor neural integrator from a discrete midline lesion between the abducens nuclei in the monkey. Neurosci Lett 127:82-6
Arnold, D B; Robinson, D A (1991) A learning network model of the neural integrator of the oculomotor system. Biol Cybern 64:447-54

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