title: Neural and sympathetic activity associated with exploration in decision-making: further evidence for involvement of insula.
abstract: We previously reported that sympathetic activity was associated with exploration in decision-making indexed by entropy, which is a concept in information theory and indexes randomness of choices or the degree of deviation from sticking to recent experiences of gains and losses, and that activation of the anterior insula mediated this association. The current study aims to replicate and to expand these findings in a situation where contingency between options and outcomes is manipulated. Sixteen participants performed a stochastic decision-making task in which we manipulated a condition with low uncertainty of gain/loss (contingent-reward condition) and a condition with high uncertainty of gain/loss (random-reward condition). Regional cerebral blood flow was measured by (15)O-water positron emission tomography (PET), and cardiovascular parameters and catecholamine in the peripheral blood were measured, during the task. In the contingent-reward condition, norepinephrine as an index of sympathetic activity was positively correlated with entropy indicating exploration in decision-making. Norepinephrine was negatively correlated with neural activity in the right posterior insula, rostral anterior cingulate cortex, and dorsal pons, suggesting neural bases for detecting changes of bodily states. Furthermore, right anterior insular activity was negatively correlated with entropy, suggesting influences on exploration in decision-making. By contrast, in the random-reward condition, entropy correlated with activity in the dorsolateral prefrontal and parietal cortices but not with sympathetic activity. These findings suggest that influences of sympathetic activity on exploration in decision-making and its underlying neural mechanisms might be dependent on the degree of uncertainty of situations.
authors.affiliation: Department of Psychology, Nagoya University Nagoya, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Ohira
authors.affiliation: Department of Psychiatry and Neurosciences, Hiroshima University Hiroshima, Japan.
authors.forename: Naho
authors.initials: N
authors.lastname: Ichikawa
authors.affiliation: Human Technology Research Institute, National Institute of Advanced Industrial Science and Technology Tsukuba, Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Kimura
authors.affiliation: Chubu Ryogo Center, Kizawa Memorial Hospital Minokamo, Japan.
authors.forename: Seisuke
authors.initials: S
authors.lastname: Fukuyama
authors.affiliation: Chubu Ryogo Center, Kizawa Memorial Hospital Minokamo, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Shinoda
authors.affiliation: Chubu Ryogo Center, Kizawa Memorial Hospital Minokamo, Japan.
authors.forename: Jitsuhiro
authors.initials: J
authors.lastname: Yamada
keywords: decision-making; entropy; exploration; positron emission tomography (PET); sympathetic activity