The objective of this research is to contributed to a better understanding of the neural mechanisms subserving the cerebellar control of eye movements. The significance of the cerebellum as a part of oculomotor control system has long been suggested from the clinical observations and the results of animal experiments. However, the precise location of the oculomotor area in the vermis was inconclusive in the literature until recently a small area in the posterior vermis was found to evoke saccades with very weak currents in the monkey. We now know that the Purkinje cells in this cerebellar cortex project almost exclusively to an ellipsoidal region in the caudodorsal portion of the fastigial nucleus and that oculomotor signals from the cortical area are transmitted to the brainstem through this region. The specific objectives of this research focus on the determination of the pathways for the oculomotor signals beyond the ellipsoidal fastigial region in the monkey. Anterogradely HRP-labeled axons of the fastigial neurons will be traced into the brainstem nuclei after injecting wheat germ-agglutinin conjugated horseradish peroxidase (WGA/HRP) into the ellipsoidal region which is identified by recording saccade-related units and confirming that these units are inhibited by vermal stimulation. The single-unit studies focus on the analyses of the variety and distribution of signals concerning saccadic directions within the ellipsoidal region and within the projection areas of the fastigial region that will be identified by tracing HRP-labeled axons of fastigial neurons. The saccade-related discharges of the fastigial neurons will be analyzed in relation to each of the horizontal and vertical components of the saccade. When projection areas of the ellipsoidal region are determined, their roles in transmitting oculomotor signals will be studied by analyzing discharges of neurons during saccades. In order to confirm that the neurons are anatomically connected to the ellipsoidal region, such neurons will be searched for that are inhibited during stimulations of the oculomotor vermis. The determination of the cerebello-oculomotor projections from the ellipsoidal region in the fastigial nucleus and the analyses of neuronal correlates of oblique eye movements, both in the cerebellum and in the brainstem, will provide important new information concerning the functional significance of the cerebellum in the oculomotor system.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY004063-10
Application #
3258538
Study Section
Visual Sciences B Study Section (VISB)
Project Start
1981-07-01
Project End
1993-06-30
Budget Start
1991-07-01
Budget End
1993-06-30
Support Year
10
Fiscal Year
1991
Total Cost
Indirect Cost
Name
Indiana University Bloomington
Department
Type
Schools of Optometry/Ophthalmol
DUNS #
006046700
City
Bloomington
State
IN
Country
United States
Zip Code
47401
Ohtsuka, K; Noda, H (1995) Discharge properties of Purkinje cells in the oculomotor vermis during visually guided saccades in the macaque monkey. J Neurophysiol 74:1828-40
Pietsch, P; Sato, H; Noda, R et al. (1993) Phototaxic behavior and the retinotectal transport of horseradish peroxidase (HRP) in surgically created cyclopean salamander larvae (Ambystoma). Neurosci Res 18:35-43
Ohtsuka, K; Noda, H (1992) Burst discharges of fastigial neurons in macaque monkeys are driven by vision- and memory-guided saccades but not by spontaneous saccades. Neurosci Res 15:224-8
Noda, H; Sato, H; Ikeda, Y et al. (1992) Fastigiofugal fibers encoding horizontal and vertical components of saccades as determined by microstimulation in monkeys. Neurosci Res 13:163-73
Sato, H; Noda, H (1992) Posterior vermal Purkinje cells in macaques responding during saccades, smooth pursuit, chair rotation and/or optokinetic stimulation. Neurosci Res 12:583-95
Sato, H; Noda, H (1992) Saccadic dysmetria induced by transient functional decortication of the cerebellar vermis [corrected] Exp Brain Res 88:455-8
Ohtsuka, K; Noda, H (1992) Burst discharges of mossy fibers in the oculomotor vermis of macaque monkeys during saccadic eye movements. Neurosci Res 15:102-14
Murakami, S; Noda, H; Warabi, T (1991) Converging eye movements evoked by microstimulation of the fastigial nucleus of macaque monkeys. Neurosci Res 10:106-17
Ohtsuka, K; Noda, H (1991) The effect of microstimulation of the oculomotor vermis on discharges of fastigial neurons and visually-directed saccades in macaques. Neurosci Res 10:290-5
Noda, H (1991) Cerebellar control of saccadic eye movements: its neural mechanisms and pathways. Jpn J Physiol 41:351-68

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