Published papers

© 2019, Springer-Verlag GmbH Germany, part of Springer Nature. With the objective to investigate the role of the insula in recognizing emotion, we performed direct electrical stimulation over the anterior insular cortex during awake surgery while simultaneously delivering an emotional sensitivity task. We registered 18 consecutive patients with brain tumors associated with the insular lobe, who were undergoing tumor resection. An emotional sensitivity task was employed to measure the patients’ ability to recognize emotions from facial expressions before, during, and after awake surgery. Furthermore, we performed voxel-based lesion symptom mapping (VLSM) to identify the association between relevant brain lesions and emotion recognition. When we performed direct electrical stimulation over the anterior insular cortex during awake surgery, the results showed that the ability to recognize anger was significantly enhanced with the presence of anterior insular stimulation (p < 0.05). Comparing the performance in the emotional sensitivity task before and after surgery, the performance in the anger condition became worse (p < 0.01), but became better in the sadness condition after surgery (p < 0.01). In the case of anger recognition, lower scores in the correct response index were associated with lesions involving the left insula in the VLSM study. Direct electrical stimulation over the anterior insular cortex enhanced anger recognition in patients with insular tumors. In contrast, accuracy of anger recognition was significantly reduced, and sadness was improved, when the performance of emotional sensitivity was compared pre- and post-surgery. Our findings suggest that the insular cortex is involved in changes in emotion recognition, including anger and sadness recognition by modulating arousal level that is closely connected with interoception.

© 2018 The Authors. Psychiatry and Clinical Neurosciences © 2018 Japanese Society of Psychiatry and Neurology 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.

Copyright © 2019 Koreki, Maeda, Okimura, Terasawa, Kikuchi, Umeda, Nishikata, Yagihashi, Kasahara, Nagai, Moriyama, Den, Watanabe, Kikumoto, Kato and Mimura. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. Background: Self-disturbances in schizophrenia have recently been explained by an abnormality in the sense of agency (SoA). The cerebral structures of SoA in healthy people are considered to mainly include the insula and inferior parietal lobule. In contrast, the functional lesion of aberrant SoA in schizophrenia is not yet fully understood. Considering the recent explanation of establishing SoA from the standpoint of associative learning, the “agency network” may include not only the insula and inferior parietal lobule but also the striatum. We hypothesized that aberrant SoA in schizophrenia is based on a deficit in the “agency network.” Methods: Functional magnetic resonance imaging data were acquired while patients with schizophrenia (n = 15) and matched controls (n = 15) performed our adaptation method of agency attribution task on a trial-by-trial basis to assess participants' explicit experience of the temporal causal relationship between an action and an external event with temporal biases. Analysis of functional connectivity was done using the right supramarginal gyrus and the right middle frontal gyrus as seed regions. Results: In healthy controls, analyses revealed increased activation of the right inferior parietal lobule (mainly the supramarginal gyrus), right insula, and right middle frontal gyrus as an activation of the agency condition. We defined activated Brodmann areas shown in the agency condition of healthy controls as the seed region for connectivity analysis. The connectivity analysis revealed lower connectivity between the head of the left caudate nucleus and right supramarginal gyrus in the patients compared to healthy controls. Conclusions: This dysconnectivity of the agency network in schizophrenia may lead to self-disturbance through deficits in associative learning of SoA. These findings may explain why pathological function of the striatum in schizophrenia leads to self-disturbance.

© 2020 The Author(s). Background: Interoception is the perception of afferent information that arises from any point within the body. Individual differences in interoception have been associated with affective processing and decision-making processing. The somatic marker hypothesis summarizes the potential effects of interoception on decision-making processes. According to this theory, individuals with interoceptive dysfunction exhibit disadvantageous decision making. Recently, enhancement of interoceptive accuracy, an element of interoception assessed by objective decision-making tasks, has been demonstrated using biofeedback. Garfinkle et al. developed an interoceptive training task, modified from the heartbeat perception task, which enhanced interoceptive accuracy and reduced anxiety symptoms. The purpose of this study was to determine the effects of interoceptive training on decision-making processes. Based on improvements in interoceptive accuracy, we hypothesized that decision-making scores would change in a manner indicative of increased rationality. Methods: This longitudinal interventional study was performed with interoceptive training. Before and after the intervention, interoceptive accuracy and rationality of decision-making processes were assessed using a heartbeat perception task and rational decision-making tasks, respectively. Fourteen healthy volunteers (nine women; mean age, 21.9 ± 4.5 years) participated. The analysis included data from 12 participants. To detect individual differences in the effects of interoceptive accuracy on rationality of decision making, correlation analysis was conducted on change ratios of the indices of interoceptive accuracy and rationality of decision making. Results: Interoceptive training resulted in significant enhancement of interoceptive accuracy scores and significant reductions in somatic symptom and state anxiety scores. In contrast, interoceptive training did not cause significant changes in decision-making indices. There was a significant positive correlation between change ratios of indices of interoceptive accuracy and rationality of decision making. Conclusions: The results suggested a causal relation between interoception and rationality of decision making. These findings will enhance the understanding of mechanisms underlying alterations of decision-making related to psychotherapy by focusing on interoception. Trial registration: Trial registration number: UMIN000037548.

© 2018 IPSJ. Recently, inferring the state of people's mental health via passive mobile sensing has attracted significant attention. Previous studies have used the self-assessed stress levels as the ground truth; however, these are subjective measures. In this study, we use a physiologically-assessed stress metric to minimize the effect of participant subjectivity and further estimate it using behavioral features based on the smartphone usage logs. We initially requested the study participants (39 participants) to attach heart rate sensors for 8 hours per day and simultaneously collected continuous heart rate data and smartphone logs for 42 days. Further, we divided the participants into four types via clustering using the behavioral features derived from their smartphone sensor logs and trained each model via supervised learning using the heart rate data as the ground truth. Our results exhibit that the proposed method is more accurate (71%) as compared to the baseline method (54%). This demonstrates that physiologically-assessed stress levels can be estimated based on the implicit features that are gathered from the smartphone logs.

© 2019 Association for Computing Machinery. Recognizing human cognitive performance is important for preserving working efficiency and preventing human error. This paper presents a method for estimating cognitive performance by leveraging multiple information available in a smartphone. The method employs the Go-NoGo task to measure cognitive performance, and fuses contextual and behavioral features to identify the level of performance. It was confirmed that the proposed method could recognize whether cognitive performance was high or low with an average accuracy of 71%, even when only referring to inertial sensor logs. Combining sensing modalities improved the accuracy up to 74%.

Mental health has received increasing attention in recent years, and a correlation between social interaction during eating and mental health noted. The purpose of this research is to determine if wearable devices can be used to recognize whether a person is eating alone or has company. Using a watch-type device and smartphone, the data, while eating in daily life, was collected. Using this data, we were able to recognize whether a person is eating alone or has company with an accuracy of 96.3%.

In this study, we hypothesized that dynamics of sleep time obtained over consecutive days of extended sleep in a laboratory reflect an individual's optimal sleep duration (OSD) and that the difference between OSD and habitual sleep duration (HSD) at home represents potential sleep debt (PSD). We found that OSD varies among individuals and PSD showed stronger correlation with subjective/objective sleepiness than actual sleep time, interacting with individual's vulnerability of sleep loss. Furthermore, only 1 h of PSD takes four days to recover to their optimal level. Recovery from PSD was also associated with the improvement in glycometabolism, thyrotropic activity and hypothalamic-pituitary-adrenocortical axis. Additionally, the increase (rebound) in total sleep time from HSD at the first extended sleep would be a simple indicator of PSD. These findings confirmed self-evaluating the degree of sleep debt at home as a useful clinical marker. To establish appropriate sleep habits, it is necessary to evaluate OSD, vulnerability to sleep loss, and sleep homeostasis characteristics on an individual basis.

Mindfulness, an attentive non-judgmental focus on "here and now" experiences, has been incorporated into various cognitive behavioral therapy approaches and beneficial effects have been demonstrated. Recently, mindfulness has also been identified as a potentially effective emotion regulation strategy. On the other hand, emotion suppression, which refers to trying to avoid or escape from experiencing and being aware of one's own emotions, has been identified as a potentially maladaptive strategy. Previous studies suggest that both strategies can decrease affective responses to emotional stimuli. They would, however, be expected to provide regulation through different top-down modulation systems. The present study was aimed at elucidating the different neural systems underlying emotion regulation via mindfulness and emotion suppression approaches. Twenty-one healthy participants used the two types of strategy in response to emotional visual stimuli while functional magnetic resonance imaging was conducted. Both strategies attenuated amygdala responses to emotional triggers, but the pathways to regulation differed across the two. A mindful approach appears to regulate amygdala functioning via functional connectivity from the medial prefrontal cortex, while suppression uses connectivity with other regions, including the dorsolateral prefrontal cortex. Thus, the two types of emotion regulation recruit different top-down modulation processes localized at prefrontal areas. These different pathways are discussed.

Psychophysiological markers have been focused to investigate the psychopathology of psychiatric disorders and personality subtypes. In order to understand neurobiological mechanisms underlying these conditions, fear-conditioning model has been widely used. However, simple aversive stimuli are too simplistic to understand mechanisms because most patients with psychiatric disorders are affected by social stressors. The objective of this study was to test the feasibility of a newly-designed conditioning experiment using a stimulus to cause interpersonal conflicts and examine associations between personality traits and response to that stimulus. Twenty-nine healthy individuals underwent the fear conditioning and extinction experiments in response to three types of stimuli: a simple aversive sound, disgusting pictures, and pictures of an actors' face with unpleasant verbal messages that were designed to cause interpersonal conflicts. Conditioned response was quantified by the skin conductance response (SCR). Correlations between the SCR changes, and personality traits measured by the Zanarini Rating Scale for Borderline Personality Disorder (ZAN-BPD) and Revised NEO Personality Inventory were explored. The interpersonal conflict stimulus resulted in successful conditioning, which was subsequently extinguished, in a similar manner as the other two stimuli. Moreover, a greater degree of conditioned response to the interpersonal conflict stimulus correlated with a higher ZANBPD total score. Fear conditioning and extinction can be successfully achieved, using interpersonal conflicts as a stimulus. Given that conditioned fear caused by the interpersonal conflicts is likely associated with borderline personality traits, this paradigm could contribute to further understanding of underlying mechanisms of interpersonal fear implicated in borderline personality disorder.

Interoception refers to the process by which the nervous system senses, interprets, and integrates signals originating from within the body, providing a moment-by-moment mapping of the body's internal landscape across conscious and unconscious levels. Interoceptive signaling has been considered a component process of reflexes, urges, feelings, drives, adaptive responses, and cognitive and emotional experiences, highlighting its contributions to the maintenance of homeostatic functioning, body regulation, and survival. Dysfunction of interoception is increasingly recognized as an important component of different mental health conditions, including anxiety disorders, mood disorders, eating disorders, addictive disorders, and somatic symptom disorders. However, a number of conceptual and methodological challenges have made it difficult for interoceptive constructs to be broadly applied in mental health research and treatment settings. In November 2016, the Laureate Institute for Brain Research organized the first Interoception Summit, a gathering of interoception experts from around the world, with the goal of accelerating progress in understanding the role of interoception in mental health. The discussions at the meeting were organized around four themes: interoceptive assessment, interoceptive integration, interoceptive psychopathology, and the generation of a roadmap that could serve as a guide for future endeavors. This review article presents an overview of the emerging consensus generated by the meeting.

Epidemiological studies have shown that sleep debt increases the risk of obesity. Experimental total sleep deprivation (TSD) has been reported to activate the reward system in response to food stimuli, but food-related responses in everyday sleep habits, which could lead to obesity, have not been addressed. Here, we report that habitual sleep time at home among volunteers without any sleep concerns was shorter than their optimal sleep time estimated by the 9-day extended sleep intervention, which indicates that participants had already been in sleep debt in their usual sleep habits. The amygdala and anterior insula, which are responsible for both affective responses and reward prediction, were found to exhibit significantly lowered activity in the optimal sleep condition. Additionally, a subsequent one-night period of TSD reactivated the right anterior insula in response to food images; however, the activity level of amygdala remained lowered. These findings indicate that (1) our brain is at risk of hyperactivation to food triggers in everyday life, which could be a risk factor for obesity and lifestyle diseases, and (2) optimal sleep appears to reduce this hypersensitivity to food stimuli.

Many modern people suffer from sleep debt that has accumulated in everyday life but is not subjectively noticed [potential sleep debt (PSD)]. Our hypothesis for this study was that resolution of PSD through sleep extension optimizes mood regulation by altering the functional connectivity between the amygdala and prefrontal cortex. Fifteen healthy male participants underwent an experiment consisting of a baseline (BL) evaluation followed by two successive interventions, namely, a 9-day sleep extension followed by one night of total sleep deprivation (TSD). Tests performed before and after the interventions included a questionnaire on negative mood and neuroimaging with arterial spin labeling MRI for evaluating regional cerebral blood flow (rCBF) and functional connectivity. Negative mood and amygdala rCBF were significantly reduced after sleep extension compared with BL. The amygdala had a significant negative functional connectivity with the medial prefrontal cortex (FCamg-MPFC), and this negative connectivity was greater after sleep extension than at BL. After TSD, these indices reverted to the same level as at BL. An additional path analysis with structural equation modeling showed that the FCamg-MPFC significantly explained the amygdala rCBF and that the amygdala rCBF significantly explained the negative mood. These findings suggest that the use of our sleep extension protocol normalized amygdala activity via negative amygdala-MPFC functional connectivity. The resolution of unnoticed PSD may improve mood by enhancing frontal suppression of hyperactivity in the amygdala caused by PSD accumulating in everyday life.

Although a number of studies have investigated the incongruity-detection and resolution process in humor comprehension, it is difficult to functionally and anatomically dissociate these processes. We used event-related potentials (ERP) and standardized low resolution brain electromagnetic tomography analysis (sLORETA) to examine the time course and localization of brain activity during incongruity detection and resolution. We used the same materials as in our previous fMRI study. Eighteen participants read funny and unfunny scenarios and judged whether the target sentence was funny or not. Results indicated that ERPs elicited by a funny punch line showed a P2 component followed by a P600 component over the centro-parietal electrode sites. Our sLORETA analysis of the P2 ERPs revealed a stronger activation for the funny vs. unfunny condition in the superior frontal gyrus (SFG) and medial prefrontal cortex (mPFC). For the P600 ERPs, the funny punch line elicited greater activation in the temporal-parietal regions. These results indicate that incongruity-detection processes activate the SFG and mPFC in the P2 time window, while incongruity-resolution processes generate activation at the temporal-parietal regions in the P600 time window. These results provide the evidence that verbal humor comprehension is processed in steps which start with the incongruity detection in the early P2 time window and followed by a P600 component reflecting incongruity resolution.

Previous studies on prospective memory (PM), defined as memory for future intentions, suggest that psychological stress enhances successful PM retrieval. However, the mechanisms underlying this notion remain poorly understood. We hypothesized that PM retrieval is achieved through interaction with autonomic nervous activity, which is mediated by the individual accuracy of interoceptive awareness, as measured by the heartbeat detection task. In this study, the relationship between cardiac reactivity and retrieval of delayed intentions was evaluated using the event-based PM task. Participants were required to detect PM target letters while engaged in an ongoing 2-back working memory task. The results demonstrated that individuals with higher PM task performance had a greater increase in heart rate on PM target presentation. Also, higher interoceptive perceivers showed better PM task performance. This pattern was not observed for working memory task performance. These findings suggest that cardiac afferent signals enhance PM retrieval, which is mediated by individual levels of interoceptive accuracy. This article is part of the themed issue ‘Interoception beyond homeostasis: affect, cognition and mental health’.

Humor comprehension is a complex process that requires the detection and resolution of the incongruity, eliciting a positive feeling of mirth or reward. We conducted a functional magnetic resonance imaging (fMRI) study to identify the key factors involved in this complex process. To reduce the influence of other factors, we utilized a group of sentences that were nearly identical across conditions (i.e., the first two sentences and the punch line were identical, but the third sentence was different). We found that the punch line (target sentence) in the funny condition induced a perception of funniness and elicited greater activation in language and semantic neural networks, which have been implicated in comprehension processing (i.e., incongruity detection and resolution). We also found increased activation in the mesolimbic reward regions, which have been implicated in the experience of positive rewards in the funny condition. Psycho-physiological interaction analyses revealed that language and semantic regions, such as inferior frontal gyrus (IFG), middle temporal gyrus (MTG), superior temporal gyrus (STG), superior frontal gyrus (SFG), and inferior parietal lobule (IPL) are simultaneously activated during humor comprehension processing. These analyses also revealed that the right MTG, the left IPL, and IFG showed enhanced connectivity with the midbrain. Our findings suggest that these networks play a central role in incongruity detection and resolution, as well as in positive emotional response.