Published papers

Aim: While emotional processing is implicated in various psychiatric illnesses, its differences among diagnoses are unclear. We compared associative learning of social values in patients with depression and schizophrenia by measuring skin conductance response to interpersonal stimuli. Methods: We included 20 female outpatients each with depression and schizophrenia. They underwent Pavlovian conditioning experiments in response to a classical aversive sound, and an interpersonal stimulus that was designed to cause aversive social conditioning with actors’ faces coupled with negative verbal messages. Multiple regression analysis was performed to examine the associations between the degree of conditioned response and the clinical characteristics of the participants. Results: Conditioned responses during the acquisition phase in both conditions were higher in depression compared to schizophrenia. Patients with depression successfully showed fear conditioning in both conditions, and they exhibited slower extinction in the interpersonal condition. The conditioned response during the extinction phase showed a positive association with Emotion Regulation Questionnaire Expressive Suppression score, and a negative association with the Emotion Regulation Questionnaire Cognitive Reappraisal score and the use of antidepressants. Patients with schizophrenia did not become conditioned in either of the conditions. The Positive and Negative Syndrome Scale Negative Syndrome score was negatively associated with the degree of conditioned response during the acquisition phase in the interpersonal condition. Conclusion: Female patients with schizophrenia, especially those who prominently demonstrated negative symptoms, suggested their intrinsic impairments in the associative learning of social context. Antidepressants and adaptive emotional regulation strategy may enhance the extinction learning of aversive social conditioning in depression.

Postural tachycardia syndrome (PoTS), a form of dysautonomia, is characterized by orthostatic intolerance, and is frequently accompanied by a range of symptoms including palpitations, lightheadedness, clouding of thought, blurred vision, fatigue, anxiety and depression. Although the estimated prevalence of PoTS is approximately 5-10 times as common as the better-known condition orthostatic hypotension, the neural substrates of the syndrome are poorly characterized. In the present study, we used magnetic resonance imaging (MRI) with voxel-based morphometry (VBM) applying the diffeomorphic anatomical registration through exponentiated lie algebra (DARTEL) procedure to examine variation in regional brain structure associated with PoTS. We recruited eleven patients with established PoTS and twenty-three age-matched normal controls. Group comparison of grey matter volume revealed diminished grey matter volume within the left anterior insula, right middle frontal gyrus and right cingulate gyrus in the PoTS group. We also observed lower white matter volume beneath the precentral gyrus and paracentral lobule, right pre- and post-central gyrus, paracentral lobule and superior frontal gyrus in PoTS patients. Subsequent ROI analyses revealed significant negative correlations between left insula volume and trait anxiety and depression scores. Together, these findings of structural differences, particularly within insular and cingulate components of the salience network, suggest a link between dysregulated physiological reactions arising from compromised central autonomic control (and interoceptive representation) and increased vulnerability to psychiatric symptoms in PoTS patients.

BackgroundAlzheimer's disease (AD) accounts for the majority of dementia-related disorders among aging populations. Given the irreversible nature of AD, early detection of cognitive impairment is critical for improving prognosis and facilitating timely interventions before individuals meet the clinical criteria for AD.ObjectiveThe objective of this review is to provide a comprehensive summary of recent advances in task-based electroencephalography (EEG), such as using attention and inhibitory control tasks, which has recently emerged as a promising non-invasive biomarker for assessing neurophysiological alterations associated with AD and mild cognitive impairment (MCI).MethodsThis systematic review evaluates the efficacy of task-based EEG biomarkers in distinguishing cognitively impaired individuals from those without impairment. A comprehensive literature search was conducted across PubMed, Semantic Scholar, and SpringerLink databases for studies published between 2017 and 2024.ResultsFindings indicate consistent neurophysiological alterations in MCI and AD, particularly reductions in event-related potential amplitudes and prolonged latencies, with P3 abnormalities observed in about half of the studies assessing selective attention and inhibitory control. Similarly, a comparable number of studies using working memory tasks report disrupted functional connectivity patterns, increased low-frequency oscillations (delta and theta activity), and reduced fast oscillations (alpha and beta activity).ConclusionsThese EEG-based indices demonstrate potential as objective biomarkers for detecting neural alterations associated with cognitive decline in both AD and preclinical dementia stages. Further research is needed to standardize EEG protocols and validate their clinical utility for early diagnosis and disease progression monitoring.

BACKGROUND: Major depressive disorder (MDD) is a highly prevalent psychiatric disorder marked by disrupted brain dynamics. However, the neural mechanisms underlying remission remain poorly understood, particularly regarding common neural markers across diverse therapeutic interventions. Emerging evidence suggests that temporal brain dynamics and their hierarchical organization, referred to as Metastates, serve as sensitive markers of individual variability across cognitive functions. This study evaluated whether Metastate dynamics derived from resting-state functional magnetic resonance imaging (fMRI) differ according to remission status across pharmacotherapy, psychotherapy, and neuromodulation. METHODS: This multicenter observational study included 370 participants: 229 individuals with depression and 141 healthy controls. The depression cohort comprised individuals undergoing cognitive behavioral therapy (n=92), pharmacotherapy (n=59), electroconvulsive therapy (n=50), and repetitive transcranial magnetic stimulation (n=28). Resting-state functional MRI data were analyzed to derive Metastate dynamics, and comparisons were made according to remission status across treatment modalities. RESULTS: Two distinct Metastates were identified: one associated with higher-order cognitive brain regions, and another linked to sensory and motor systems. Participants who achieved remission exhibited greater predictability in transitions between brain states within Metastates, supporting higher-order cognitive functions. This altered transition pattern was accompanied by alterations in the anti-correlation between the default mode and executive function networks, which may underlie the increased predictability. CONCLUSIONS: Remission from MDD may involve a reorganization of hierarchical brain dynamics-particularly in systems supporting cognitive control-and offer a potential treatment-modality-independent biomarker of remission.

In humans, the sense of self is maintained with a certain degree of continuity over time, and this continuity supports a relatively stable life that is not easily disrupted by changes in the surrounding environment. At the same time, the self can be flexibly reshaped by major life events, such as starting employment or getting married, allowing individuals to adapt to new environments. In this article, four researchers introduce and discuss functional neuroimaging findings on the neural mechanisms that support both the stability and flexibility of the self across the domains of social cognition, perceptual–motor, memory, and emotion.

マインドワンダリング（MW）研究では，課題中に提示されるプローブによってMWが捉えられる。そのため，実験中に提示されるプローブは，思考状態の正確な測定において重要である。これまでの手法では，課題集中あるいは課題無関連思考集中に二分するものが主流であった。しかし，思考状態は常にどちらかの思考に分類されるものではなく，複数の状態が共存することが考えられる。本研究では，Go/No-go課題を行っている最中に，思考状態の共存を認める思考プローブを提示し，検討を行った（N＝30）。結果として，複数の思考が共存しているという主観報告が得られた。一方で，主観報告が得られた背景にある状態を，隠れマルコフモデルを用いて推定すると，従来の手法同様，課題集中，MW，両者の中間という思考状態が推定された。さらに，MW状態である区間では他の状態と比較して，反応時間の分散の増加がみられた（F（2, 58）＝6.504, p＝.003）。従来のプローブ法と同様の状態が推定されたことから，従来の手法でもMWを十分捉えていると考えられるが，より正確にMWを捉えるためには，共存状態を考慮する必要があることが示唆された。

ある行動について，それを自分が起こしたと感じる感覚を自己主体感という。本研究では，集団での行動のような，誰が実際の行動の主体か不明である状況における主体判断に焦点を当て，自己主体感が行動の結果や共に作業する相手によってどのような違いが見られるか検討した。面識のない他人あるいは知人と参加者2人で，提示される視覚刺激に対し早押しをさせ，ポジティブあるいはネガティブな結果を提示した後，実際の早押しをしたのが誰であったか判断をさせた。その結果，相手が他人の場合は，感情価にかかわらずフィードバックによる変化が大きいときに，自分が主体であったときの正答率が高くなった。一方，相手が知人の場合は，ネガティブな結果のときの主体判断の正答率が高い傾向にあった。これらの結果から，集団における主体判断には他者への親近性が関与することが示された。また，主体判断の誤答が精神疾患傾向と関係があることも示唆された。