Published papers

Interoception is the perception of the internal bodily state, including the autonomic nervous system. Recently, heartbeat evoked potentials (HEP) have been proposed as a measure of interoception. HEP is considered a brain potential with high temporal resolution reflecting afferent signals from the cardiovascular system without the need for subjective reporting. HEP relates to various cognitive responses such as attention, emotion, self-awareness, and symptoms of psychiatric disorders. In this review, we overview the studies of HEP, which is expected to be a useful index of mind-body interactions, and discuss the relationship between interoception and cognitive functions.

Emotions are accompanied by physical reactions, such as facial expressions and heart rate changes. This paper focuses on facial skin blood flow (SkBF) as an index of the autonomic nervous system. Facial SkBF is a unique indicator compared to heart rate or sweating because it is related to facial temperature and facial color changes. The SkBF does not react uniformly in all areas of the face and has different reactivity in each part of the face, such as the forehead, cheek, or nose. In several previous studies, the time window for the analyses was about 30 seconds or more, however, focusing on short-term rapid responses, e.g. 5 seconds, is critical for clarifying the mechanisms of mental disorders related to facial SkBF and clinical intervention.

Dissociation is a defense mechanism against overwhelming stress and is caused by hyper-inhibition on specific brain activities. This study examined the effects of situational uncontrollability on memory suppression in individuals with dissociative tendencies. To manipulate controllability, participants performed speech tasks designed to induce either a sense of control or a lack of control within the situation. In each condition, participants listened to narratives containing neutral, positive, and negative information, followed by immediate free recall tasks. The results showed that dissociative tendencies selectively influenced the recall of negative information. Higher dissociative tendencies were associated with lower recall performances of negative information under uncontrollable situations and higher recall under controllable situations. These findings suggest that individuals with high dissociative tendencies cope with uncontrollable situations by suppressing access to negative information. The selective suppression of negative information may serve as an objective marker of dissociative tendencies.

Individuals with higher depressive and ruminative tendencies exhibit biases in self-related information processing, leading to maladaptive responses. This study aimed to elucidate differences in referential processing between the self and self-related others in the context of positive and negative self-relevant events. To examine the effects of depressive and ruminative tendencies, we measured the endorsement of positive and negative words, reaction time, and event-related potentials (ERPs) as attention indices. Higher depressive and ruminative tendencies were associated with maladaptive self-endorsement, whereas endorsements of others corresponded with event valence. Higher depressive and ruminative tendencies were linked to reduced attention to negative words when referencing others in negative events, independent of adaptive aspects of rumination, though no significant effects were observed on reaction times. These findings suggest that depressive and maladaptive ruminative tendencies impair contextually appropriate attention to self-related others, potentially leading individuals to attribute event valence to the self rather than to others.

＜文献概要＞本論では,まず主観的感覚である心理的痛みを測定する方法について述べ,その神経メカニズムについて概説する。特に,島皮質および帯状皮質から構成されるセイリエンスネットワークを中心とした神経基盤の関与について,内受容感覚との関連性に着目しながら述べる。次に,心理的痛みを病態として捉える疾患概念に焦点を当て,身体症状症などに関する研究成果を概観し,心理的痛みの緩和および今後の研究の方向性について考察する。

＜文献概要＞主観的感情は,内受容感覚の中枢である島皮質,および自律神経活動が介する身体の活動を同時に検討することにより,科学的に扱うことができるようになった。島皮質前部と帯状回前部から成るセイリエンスネットワークは,身体の状態がホメオスタシスから逸脱しているかをモニターし,それを回復の方向に導く役割を持つ。身体状態の逸脱の認識と,自らが置かれた状況の理解が統合されることにより,主観的感情が生み出される。

＜文献概要＞島皮質に関わる脳腫瘍患者に対して,表情認識課題[顔写真から表情を認識する課題(怒り,喜び,悲しみ,嫌悪,感情なし)]を用いながら実際に覚醒下手術中に島皮質を直接刺激することで,感情認識に関わる脳機能ネットワーク解析を行った。表情が表す感情の種類,強さの識別に対して検討した。島皮質が,身体内部からの情報である内受容感覚に基づく覚醒度の神経基盤として,怒りや悲しみなどの感情認識の変化に関わることを示唆する。

広く知られるホメオスタシスの概念の影響で身体の内部環境は一定であると思われがちであるが,実際には一定の幅で変動する.この変動はさまざまな因子により生じ,そのひとつは情動である.情動は闘争・逃走行動などの情動行動を伴い,その遂行には自律神経活動や内分泌活動による身体の生理学的変化を必要とする.身の危険を察知した際に,闘争・逃走行動を起こす前から身体の生理学的変化は生じており,それは自律神経系の予測的活動といえる.情動と自律神経活動は一体のものであり,そこで重要な働きをするのが辺縁系である.辺縁系は情動行動の遂行のために事前に自律神経反射のセットポイントを変化させる.ストレスに曝露した際に辺縁系が主体となり予測的に内部環境を変化させて情動行動を円滑に行えるようにする機構があると推察される.ストレス負荷により内部環境が変化する現象をアロスタシス(allostasis)とよび,ストレス性疾患の病態を理解するためのモデルとなっている.(著者抄録)