Research press release


Nature Neuroscience

Anxiety hinders adjustments to unpredictable outcomes


否定的な結果がいずれ起こる可能性に過剰に注目している不安な人は、何らかの決定をすることが大きなストレスになりかねない不確かな状況から尻込みすることが知られている。Sonia Bishopおよび共同研究者は、全般的な不安のレベルが高い(高特性不安)人は、そうでない人と比べ、予期せぬ否定的な結果にどのように順応するかの学習において違いがあるかを調べた。研究では、被験者は2つの形状から1つを選ばなければならない。形状には一定の強さの電気ショックを受ける確率が関連付けられており、時によってその関連が変化した。Bishopらは、高特性不安の被験者は低特性不安の人に比べ、形状と電気ショックの可能性や強さとの相関が予想しにくいときにショックを避けようと試みる行動を順応させる際の柔軟性が乏しいことを発見した。


Anxious individuals may have more difficulty learning to adjust their behaviour in response to unpredictable outcomes of a particular action, reports a study published online this week in Nature Neuroscience. This difficulty could hinder decision-making particularly in situations that may lead to a negative outcome, which in turn may lead to increased anxiety.

Anxious individuals, who focus disproportionately on the potential occurrence of future negative outcomes, have been known to shy away from situations of uncertainty that can make any decision quite stressful. Sonia Bishop and colleagues examined whether people with higher levels of general anxiety (high trait anxiety) would show differences in learning how to adjust for unpredictable negative outcomes compared to those with lower levels of general anxiety. In this study, participants had to choose one of two shapes, each associated with a specific probability of receiving an electric shock of a particular strength, and at times these associations would change. The authors found that participants with high trait anxiety were less flexible than low trait individuals in adjusting their behaviour to try to avoid shocks when the associations between shapes and shock probability and magnitude were less predictable.

The study also measured the pupil dilatory responses of the subjects. Past research has indicated that pupil diameter may reflect activity in the locus coeruleus-norepinephrine system, which is found in the brainstem and is responsible for our responses to stress; this system’s function may be altered by anxiety. Bishop and colleagues found that high trait anxiety participants displayed reduced pupil dilation when the shape-shock relationship was more unpredictable, which could indicate altered activation of this system and support previous research.

doi: 10.1038/nn.3961

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