2012年11月7日水曜日

Inactivating Anterior Insular Cortex Reduces Risk Taking


Hironori Ishii, Shinya Ohara, Philippe N. Tobler, Ken-Ichiro Tsutsui, and Toshio Iijima
J. Neurosci. 2012;32 16031-16039
http://www.jneurosci.org/cgi/content/abstract/32/45/16031?etoc

前島皮質(眼窩前頭皮質)の活動を抑制されたラットはリスク回避(愛好)的になる。なお、リスクに関係ない実験課題における行動は変化しない。前島皮質と眼窩前頭皮質はどちらもリスク下の意思決定に重要な役割を果たすが、その働きは逆の効果を持つ。 http://www.jneurosci.org/content/32/45/16031

We often have to make risky decisions between alternatives with outcomes that can be better or worse than the outcomes of safer alternatives. Although previous studies have implicated various brain regions in risky decision making, it remains unknown which regions are crucial for balancing whether to take a risk or play it safe. Here, we focused on the anterior insular cortex (AIC), the causal involvement of which in risky decision making is still unclear, although human imaging studies have reported AIC activation in various gambling tasks. We investigated the effects of temporarily inactivating the AIC on rats' risk preference in two types of gambling tasks, one in which risk arose in reward amount and one in which it arose in reward delay. As a control within the same subjects, we inactivated the adjacent orbitofrontal cortex (OFC), which is well known to affect risk preference. In both gambling tasks, AIC inactivation decreased risk preference whereas OFC inactivation increased it. In risk-free control situations, AIC and OFC inactivations did not affect decision making. These results suggest that the AIC is causally involved in risky decision making and promotes risk taking. The AIC and OFC may be crucial for the opposing motives of whether to take a risk or avoid it.

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