title: The Anterior Insula Tracks Behavioral Entropy during an Interpersonal Competitive Game.
abstract: In competitive situations, individuals need to adjust their behavioral strategy dynamically in response to their opponent's behavior. In the present study, we investigated the neural basis of how individuals adjust their strategy during a simple, competitive game of matching pennies. We used entropy as a behavioral index of randomness in decision-making, because maximizing randomness is thought to be an optimal strategy in the game, according to game theory. While undergoing functional magnetic resonance imaging (fMRI), subjects played matching pennies with either a human or computer opponent in each block, although in reality they played the game with the same computer algorithm under both conditions. The winning rate of each block was also manipulated. Both the opponent (human or computer), and the winning rate, independently affected subjects' block-wise entropy during the game. The fMRI results revealed that activity in the bilateral anterior insula was positively correlated with subjects' (not opponent's) behavioral entropy during the game, which indicates that during an interpersonal competitive game, the anterior insula tracked how uncertain subjects' behavior was, rather than how uncertain subjects felt their opponent's behavior was. Our results suggest that intuitive or automatic processes based on somatic markers may be a key to optimally adjusting behavioral strategies in competitive situations.
authors.affiliation: Brain Science Institute, Tamagawa University, Machida, Tokyo, Japan; Graduate School of Engineering, Osaka university, Suita city, Osaka, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Takahashi
authors.affiliation: Brain Science Institute, Tamagawa University, Machida, Tokyo, Japan; Division of Humanities and Social Sciences, California Institute of Technology, Pasadena, California, United States of America.
authors.forename: Keise
authors.initials: K
authors.lastname: Izuma
authors.affiliation: Department of Neuropsychiatry, The University of Tokyo Hospital, Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Madoka
authors.initials: M
authors.lastname: Matsumoto
authors.affiliation: Brain Science Institute, Tamagawa University, Machida, Tokyo, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Matsumoto
authors.affiliation: Brain Science Institute, Tamagawa University, Machida, Tokyo, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Omori
mesh_terms: D000293:Adolescent; D000328:Adult; D000066949:Biobehavioral Sciences; D001921:Brain / Q000000981:diagnostic imaging / Q000502:physiology; D003163:Competitive Behavior / Q000502:physiology*; D005260:Female; D005717:Games, Experimental; D006801:Humans; D007398:Interpersonal Relations; D008279:Magnetic Resonance Imaging; D008297:Male; D011859:Radiography