1994 Fiscal Year Final Research Report Summary
Functinal Role of Modular Organization in the Basal Ganglia
| Project/Area Number |
05454682
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
神経・脳内生理学
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| Research Institution | Osaka University |
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Principal Investigator |
KIMURA Minoru Osaka University Faculty of Health and Sport Sciences Professor, 健康体育部, 教授 (40118451)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUMOTO Naoyuki Osaka University Faculty of Health and Sport Sciences Research Assistant, 健康体育部, 助手 (00252726)
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| Project Period (FY) |
1993 – 1994
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| Keywords | BASAL GANGLIA / MOTOR LEARNING / MEMORY / NIGROSTRIATAL DOPAMINE SYSTEM / MONKEY / DLASSICAL |
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| Research Abstract |
The purpose of the present investigation was to clarify role of nigrostriatal dopamine system in in an acquisition of new activity through behaviral conditioning. Classical conditioning of an auditory click with reward juice was used using 3 macaque mankeys (Macaca fuscata). In about three weeks, all animals acquied the behavioral conditioning and the orofacial movements to consume reward water delivered upon the spoon in front of mouth became stereotyped. More that 60% of tonically active neurons (TANs) recorded in the striatum became responsive to the conditioning click. Then, we depleted nigrostriatal dopamine through an infusion of dopaminergic neurotoxin MPTP for two weeks into the striatum unilaterally. Animals showed a tandency to turn to the MPTP injected side in their home cages, which was the sign of unilateral dopamine depletion. The acquierd conditioned orofacial movements after conditioning click stimuli became clumsy and not automatic. Quite surprisingly, only very small
… More
number (10-15%) of TANs in the MPTP injected side showed responses to conditioning click, while the responses of TANs in the contralateral intact striatum was preserved. Systemic injection of dopamine receptor agonist, apomorphine, restored stereotyped behavior and TAN responses, and thus demonstrated that the dramatic effect of MPTP on the acquired behavior and neuronal sctivity was induced specifically through dopamine system. These results an hypothesis on the function of nigrostriatal dopamine system in behavioral learning and memory. In an intial stage of behavioral learning, nigrostriatal system send large amount of dopamine with an information of "motivation" or "incentive". This would let striatal neurons to acquire responses to conditioning stimulus occurred in conjunction with dopamine release at striatal terminals of nigrostriatal neurons. After learning is established, the nigrostriatal system send base line amount of dopamine for the striatal neurons to express the learned activity which will lead to stereotyped conditioned behavior. Less
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