| Project/Area Number |
14510114
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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 |
実験系心理学
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| Research Institution | Tokyo Metropolitan Institute for Neuroscience |
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Principal Investigator |
HIKOSAKA Kazuo Tokyo Metropolitan Institute for Neuroscience, Psychology, Researcher, 東京都神経科学総合研究所, 研究員 (60129004)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2004: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2003: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2002: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | Orbitofrontal cortex / Reward expectancy / Primate / Neuronal activity / 刺激-報酬連合 / 並列情報処理 / 手がかり刺激 / 報酬予測 / 刺激-報酬連合学習 / 注意過程 / 神経細胞活動 / 手がかり刺激提示前活動 |
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| Research Abstract |
The impulsive behavior is one of severe impairments in goal-directed behavior. To understand the mechanism underlying the impulsive behavior, it is important to investigate differences in reward expectancy or behavior between "getting a preferred reward" and "getting a non-preferred reward". Therefore, I examined pre-instruction, baseline activities of neurons in orbitofrontal cortex (OFC) in relation to reward expectancy during the delayed reaction time task. In this task, an instruction cue indicated whether reward would be present or absent in the trial. Each set of four consecutive trials constituted one block within which three different kinds of rewards and one trial with no reward were given in a fixed order that differed from the monkey's reward preference. I identified two types of OFC neurons with reward expectancy-related pre-instruction activities : Step-type neurons showed stepwise changes (increase or decrease) in pre-instruction activity toward the trial with a particular outcome, which usually was the most or least attractive within a block ; Pref-type neurons showed pre-instruction activity changes according to the monkey's preference for each trial's outcome. I propose that Step- and Pref-type neurons are related to long- and short-range reward expectancies of a particular outcome, respectively. The OFC is considered to play important roles in goal-directed behavior by adjusting the motivational level toward a certain (current or future) outcome of a particular motivational significance based on the two kinds of reward expectancy processes. Impairments in goal-directed behavior, including impulsive behavior, by OFC patients may be caused by a lack of long-range expectancy or by a deficit in compromising between short- and long-range expectancies.
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