1998 Fiscal Year Final Research Report Summary
Disturbance of eye movement in schizophrenia and the involvement of the neurotransmitters in the frontal eye field and prefrontal cortex
| Project/Area Number |
09670971
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Psychiatric science
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
FUKUSHIMA Junko College of Medical Technology, Hokkaido Univ., Professor, 医療技術短期大学部, 教授 (40208939)
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| Project Period (FY) |
1997 – 1998
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| Keywords | schizophrenia / smooth pursuit eye movement / gaze velocity / frontal eye field / pursuit vestibular interaction |
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| Research Abstract |
Visual information from a moving object can be obtained accurately by smooth pursuit eye movement. During movement of the head, the smooth pursuit system interacts with the vestibular system to maintain the accuracy of eye movement in space (i.e. gaze). To function correctly, this interaction requires calculation of gaze in order to match eye velocity in space to actual target velocity.
It has been reported that schizophrenia patients showed disturbances in smooth pursuit eye movement (Holzman), as well as impairment of eye head coordination (Fukushima). The frontal eye field (FEF) has been reported to control smooth pursuit eye movement and that the patients with localized lesion of this area showed similar abnormalities with those of schizophrenics. To understand the role of the EF in pursuit-vestibular interactions and to clarify the neural mechanism of these abnormalities in schizophrenics, we conducted the following experiment. By assigning the monkeys the behavioral tasks that dissociate eye movement in the orbit from eye movement in space, we were able to show that the activity of the majority of frontal pursuit neurons in alert monkeys carry gaze velocity signals. They also responded to whole body rotation in complete darkness revealing a vestibular senseitivity. When the monkeys fixated the stationary target, similar modulation we observed responding to retinal image velocity of a second target. Muscimol infusion into the pursuit area severely impaired smooth gaze tracking. These results suggest that FEF pursuit neurons can provide actual target velocity signals and command signals for voluntary smooth gaze tracking during pursuit vestibular interaction. The chemical deactivation by Muscimol injection revealed similar abnormalities to those of schizophrenia patients, suggesting that these areas are responsible for the disturbance of eye movements in schizophrenics.
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