Summary of Research Project Results Under the JSPS FY2000
"Research for the future Program"

1.Research Institution Juntentdo University
2.Research Area Life Science
3.Research Field Higher Brain Functions
4.Term of Project FY1996〜FY2000
5.Project Number 96L00204
6.Title of Project Neural Mechanisms of Procedural Memory

7.Projetct Leader
Name Institution,Department Title of Position
Okihide Hikosaka Juntendo University, School of Medicine Professor

8.Core Members

Names Institution,Department Title of Position
Satoru Miyauchi Communications Research Laboratory, Kansai Advanced Research Center Senior Researcher
Hideki Fukuda National Institute of Industrial Health, Department of Work Stress Control Senior Researcher

9.Cooperating Researchers

Names Institution,Department Title of Position
Masamichi Sakagami Juntendo University, School of Medicine Associate Professor
Yoriko Takaikawa Juntendo University, School of Medicine Assistant Professor
Reiko Kawagoe Juntendo University, School of Medicine Assistant Professor

10.Summary of Research Results

The basal ganglia exert powerful inhibition on cortical and subcortical motor areas. This is an ideal mechanism for selection of action: a selective removal of the inhibition allows an action to be triggered while others to be suppressed. It is then very important to ask how this mechanism is used. The basal ganglia, especially the ventral striatum, have been implicated in control of action based on motivation. A prevalent view is that nigro-striatal dopaminergic neurons carry reinforcement signals to modulate the cortico-striatal signal transmissions. However, it is still unknown how such reinforcement signals affect the output of the striatum in relation to behavior. To answer this question, we devised a memory-guided saccade task in which only one out of four directions was rewarded, and examined single cell activity in the caudate nucleus. We found that visual or memory-related responses of presumed projection neurons in the caudate were frequently modulated by expectation of reward, either as an enhancement or as a reduction of response. The cell's preferred direction often changed with the change in the rewarded direction, implying a short-term synaptic plasticity. The modulation of caudate cell activity was correlated with changes in saccade parameters. Our results suggest that the caudate contributes to the determination of oculomotor outputs by affiliating motivational values to visual information.

11.Key Words

(1)Basal ganglia、(2)Frontal cortex、(3)Eye movement
(4)Single unit recording、(5)Reward、(6)Motivation


[Reference Articles]
Author Title of Article
Rand MK Characteristics of sequential movements during early learning period in monkeys.
Journal Volume Year Pages Concerned
Exp Brain Res 131 2000 293-304

Author Title of Article
Sakai K What and when: parallel and convergent processing in motor control.
Journal Volume Year Pages Concerned
J Neurosci 20 2000 2691-2700

Author Title of Article
Lauwereyns J Interference from irrelevant features on visual discrimination by macaques (macaca fuscata) : a behavioral analogue of human stroop effect.
Journal Volume Year Pages Concerned
Journal of Experimental Psychology: Animal Behavior Processes 26 2000 352-357

Author Title of Article
Hikosaka O Role of the basal ganglia in the control of purposive saccadic eye movements.
Journal Volume Year Pages Concerned
Physiol. Rev 80 2000 953-978