September 29, 2017
Keio University School of Medicine
Tokyo Metropolitan Institute of Medical Science
National Institute for Physiological Sciences, National Institutes of Natural Sciences
A joint research group including Associate Professor Kenji Tanaka and Professor Masaru Mimura of the Department of Neuropsychiatry, Keio University School of Medicine; Principal Investigator Akiyoshi Natsubori of the Tokyo Metropolitan Institute of Medical Science; and Associate Professor Kenta Kobayashi of the National Institute for Physiological Sciences, National Institutes of Natural Sciences, has discovered through experiments with mice that initiating goal-directed behavior requires not only an increase in the activity of "motivation neurons" in the lateral part of a brain region called the ventral striatum, but also a decrease in the activity of "caprice neurons" in its medial part.
In previous research, the group used experiments with mice to identify the brain region responsible for motivational deficits and discovered the existence of a "motivation switch." It was also known that acting toward a goal requires the activation of nerve cells ("motivation neurons") in the lateral part of the brain region called the ventral striatum, and that dysfunction of these "motivation neurons" impairs the initiation of behavior, leading to a loss of motivation.
To elucidate the brain mechanism that, in contrast to "motivation," "suppresses" behaviors unrelated to a goal, the research group has now conducted further studies and found the following results regarding the function of nerve cells in the medial part of the ventral striatum.
(1) Activation of nerve cells in the medial part of this brain region ("caprice neurons") increases futile actions. (2) Suppressing the activity of these nerve cells inhibits actions unrelated to the goal, promoting goal-congruent behavior. (3) These nerve cells do not control motivation itself ("motivation neurons"); rather, when the goal changes, their activity suppression is released, enabling flexible behavioral selection.
The results of this research were published in the general science journal "Current Biology" on September 28, 2017.
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