Association of brain-autonomic activities and task accuracy under cognitive load: a pilot study using electroencephalogram, autonomic activity measurements, and arousal level estimated by machine learning.

The total amount of mental activity applied to working memory at a given point in time is called cognitive load, which is an important factor in various activities in daily life. We have proposed new feature quantities that reflect the time-series changes in the power of typical frequency bands in electroencephalogram (EEG) for use in examining the relationship between brain activity and behavior under cognitive load. We also measured heart rate variability (HRV) and spontaneous skin conductance responses (SCR) to examine functional associations among brain activity, autonomic activity, and behavior under cognitive load. Additionally, we applied our machine learning model previously developed using EEG to the estimation of arousal level to interpret the brain-autonomic-behavior functional association under cognitive load. Experimental data from 12 healthy undergraduate students showed that participants with higher levels of infra-slow fluctuations of alpha power have more cognitive resources and thus can process information under cognitive load more efficiently. In addition, HRV reflecting parasympathetic activity correlated with task accuracy. The arousal level estimated using our machine learning model showed its robust relationship with EEG. Despite the limitation of the sample size, the results of this pilot study suggest that the information processing efficiency of the brain under cognitive load is reflected by time-series fluctuations in EEG, which are associated with an individual's task performance. These findings can contribute to the evaluation of the internal state of humans associated with cognitive load and the prediction of human behaviors in various situations under cognitive load.

Dual decline in subjective gait speed and domain-specific cognition is associated with higher risk of incident dementia in older Japanese adults: A 15-year age-specific cohort study.

OBJECTIVES: Dual decline in gait speed and cognition has been found to have higher dementia risk than no decline or pure decline. However, evidence from the Asian population is lacking. Therefore, we aimed to investigate the association of dual decline from age 65 to 70 years with late-life dementia in older Japanese adults with different personal characteristics. METHODS: Data were collected from an age-specific cohort study conducted in 482 Japanese 65-year-old adults. We investigated participant demographics, medical histories, lifestyles, subjective gait speed, and cognition at both 64/65 and 70/71 years old, and confirmed dementia until age of 85 years. Cox proportion hazard models were used to estimate the risk of dementia, with adjustments for covariates, and death was treated as a competing risk. RESULTS: After a mean follow-up period of 12.5-years, 111 participants developed dementia. Older adults with dual decline are more likely to have hyperlipidemia, diabetes, and smoking habits. And we found that dual decline in gait speed and domain-specific cognition was associated with a higher risk of dementia compared with no decline in most cognitive tests, with the highest risk observed for gait speed combined with memory (sub-distribution hazard ratio:3.89, 95 %, confidence intervals: [1.68-9.01]). However, significant differences only existed in men after stratification by sex. CONCLUSIONS: A dual decline in subjective gait speed and cognition may serve as a robust predictor of dementia over a decade prior to its onset, particularly in men. These findings highlighted the importance of screening for dual decline at an early age.

The physiological basis of leader-follower roles in the dyadic alternating tapping task.

Introduction: Cooperative and collaborative behaviors are important concepts for co-creative communication. One of the key elements for these behaviors is the leader-follower roles in human communication. Leaders are those who maintain their own pace and rhythm, on the contrary, followers are those who follow the pace and rhythm of the other. Well-coordinated leader-follower roles would produce better cooperative and collaborative behaviors, which could promote co-creative communication. Methods: Here, to explore the physiological basis for the leader-follower roles, we conducted the dyadic alternating tapping task with electrocardiographic and electroencephalographic recordings. The task would be stable for modeling human communication in the laboratory because it includes timing control in tens of milliseconds and turn-taking. Given that human communications are complex and constantly fluctuating, this study estimated the degree of leader-follower with the state-space model. This model allowed us to calculate two parameters independently for estimating the degree of leader-follower of each participant: αSelf (degree of one's tap(n) was explained by one's tap(n-1)) and αPair (degree of one's tap(n) was explained by one's tap (n-1) and pair's tap (n-1)). Results: The result showed heart rate synchronization in the group in which both participants had high αPair. Also, the high-frequency component of heart rate variability was positively correlated with αPair. EEG analyses suggested the deactivation of the mirror neuron system (increasing φ1) in the participants with higher αSelf than lower ones. The activation of the mirror neuron system (increasing φ2) was shown in the participants with lower αPair than higher ones. Discussion: These data of physiological basis for leader-follower roles could be useful for the constructivist approach to co-creative communication.

[Integration of Interoception, Decision-Making, and Affect: Allostasis as Predictive Processing].

Allostasis refers to the mechanism by which the brain changes bodily states to adapt to the environment in order to achieve stability or homeostasis. This concept was originally proposed by Sterling and Eyer in 1988. Recently, allostasis has been reconceptualized from the viewpoint of predictive processing, a theory arguing that the brain regulates perception and motor movement by generating predictions through inner models of the external world and self and minimizing the prediction error between the predictions and sensory signals. This idea provides integrated explanations of a wide range of phenomena, including homeostasis, decision-making, and the accompanying emotions and consciousness. Although this theory is a hypothesis, empirical evidence has been proposed in recent years. This article introduces the theory of predictive processing of allostasis, recent related research findings, and issues to be examined in the future.

Temporal change in the association between life satisfaction and functional decline with gender differences: an age-specific prospective cohort study.

BACKGROUND: Although life satisfaction (LS) has been shown to predict mortality, research studying the relationship between LS and functional decline is scarce. This study examined the association between LS and functional decline across four time points in young-old Japanese adults. METHODS: We analysed 1,899 community-dwelling 65-year-olds in this age-specific cohort study conducted between 2000 and 2005. The Life Satisfaction Index K was used to evaluate LS and was classified into quartiles. Functional decline was determined using the Japanese Long-Term Care Insurance (LTCI) system: 1) mild disability; 2) severe disability; 3) all-cause mortality; 4) mild or severe disability; 5) severe disability or death; 6) mild or severe disability, or death. Adjusted hazard ratios (HR) with 95% confidence intervals (CI) were calculated using the Cox proportional hazard model. The analyses were conducted in the 8th, 10th, 12th, and 14th years to assess the effect of LS on functional decline across time points. RESULTS: The impact of LS gradually weakened over time. In the 8th year (aged 72-73), a higher LS was associated with a lower risk of mild or severe disability among the women participants (adjusted HR [95% CI] = 0.30 [0.11-0.81]). However, the effect disappeared gradually (adjusted HR [95% CI] = 0.55 [0.27-1.14]) in the 10th year (aged 74-75), 0.72 (0.41-1.26) in the 12th year (aged 76-77), and 0.68 (0.41-1.14) in the 14th year (aged 78-79). This trend continued in severe disability or death (adjusted HR [95% CI] = 0.24 [0.06-0.70], 0.31 [0.11-0.76], 0.57 [0.28-1.14], and 0.60 [0.32-1.12]) and mild or severe disability, or death (adjusted HR [95% CI] = 0.30 [0.14-0.68], 0.46 [0.24-0.87], 0.67 [0.41-1.10], and 0.65 [0.42-1.02]) in the 8th, 10th, 12th, and 14th years, respectively. No statistically significant association was found among men at any time points or in any classification of outcomes. CONCLUSIONS: Higher LS scores in 65-year-old women were associated with a lower risk for functional decline in any combination of mild disability, severe disability, or death. Additionally, the effect of LS was observed to weaken over time. TRIAL REGISTRATION: This is not an intervention survey and does not require registration.

Effects of mild psychological stress on facial impressions.

Introduction: Appearance plays an important role in maintaining a positive impression in social interactions. Psychological stress is known to have an adverse effect on facial skin, as indicated in previous studies. However, no study has investigated the negative effect of stress on facial impressions. Therefore, we aimed to investigate changes in impressions from facial images before and after mental stress tasks using an online survey. Method: Thirteen Japanese men were recruited to have their facial photographs taken before and after undergoing a psychological stress task. We observed the physiological effects of an increased heart rate and decreased blood flow on the cheek skin. Four average facial images were created for each time point (control: "baseline;" stress: "0H," "1H," and "3H") from their facial photographs. An online survey was conducted with 700 Japanese participants, who compared the "baseline" to other images and selected one of two options in each of the six questionnaire items of impressions. Results: The results showed that the rate of participants who chose "baseline" was significantly lower in the items "looks tired," "looks old," and "looks irritated" and higher in "looks clean-cut" and "looks healthy" compared to other images created from photographs after the stress task ("0H," "1H," and "3H"). Conclusion: These results suggest that psychological stress loading not only causes physiological changes in autonomic nervous activity and skin blood flow but also negatively impacts facial impressions for a few hours following a mild stress load.

Changes in social activities and the occurrence and persistence of depressive symptoms: Do type and combination of social activities make a difference?

OBJECTIVE: We aimed to explore the association between changes in social activities and the occurrence/persistence of depressive symptoms and investigate the difference in effect sizes among the types and combinations of social activities. METHODS: The study adopted a valid 15-item Geriatric Depression Scale to assess depressive symptoms in 2480 community-dwelling adults aged 64/65 years. Changes in social-related, learning, and personal activities were classified into four categories: continued low frequency (CLF), increased frequency (IF), decreased frequency (DF), and continued regular frequency (CRF)1. Relative ratios (RRs) and 95% confidence intervals (95% CI) were calculated using a modified Poisson regression model. RESULTS: Those without depressive symptoms at baseline and who engaged in social-related (RRIF = 0.56 (0.39, 0.81), RRCRF = 0.55 (0.41, 0.74)), learning (RRIF = 0.63 (0.44, 0.89), RRCRF = 0.62 (0.46, 0.85)), and personal activities (RRIF = 0.37 (0.24, 0.57), RRCRF = 0.41 (0.30, 0.56)) at IF or CRF were less likely to develop depressive symptoms. Those with depressive symptoms at baseline, engaging in personal activities at IF (RR=0.67 (0.51, 0.87)) and CRF (RR= 0.80 (0.65-1.00)) were less likely to have persistent depressive symptoms. Participation in all three activities consistently at a regular frequency was inversely associated with the occurrence/persistence of depressive symptoms. CONCLUSIONS: The effect of personal activities was more manifest in preventing depressive symptoms than the other two kinds, regardless of depressive symptoms at baseline. Regularly engaging in a combination of all three activities at baseline and follow-up was associated with the occurrence and persistence of depressive symptoms.

Interoceptive accuracy correlates with precision of time perception in the millisecond range.

It has been proposed that accuracy in time perception is related to interoceptive accuracy and vagal activity. However, studies investigating time perception in the supra-second range have provided mixed results, and few studies have investigated the sub-second range. Moreover, there is a lack of studies investigating the relationship between precision in time perception and interoceptive accuracy. A recent meta-analytic review of neuroimaging studies proposed a dynamic interaction between two types of timing processing-an endogenous time keeping mechanism and the use of exogenous temporal cues. Interoceptive accuracy may affect both accuracy and precision of primary temporal representations, as they are generated based on the endogenous time keeping mechanism. Temporal accuracy may vary when adapted to the environmental context. In contrast, temporal precision contains some constant noise, which may maintain the relationship with interoceptive accuracy. Based on these assumptions, we hypothesized that interoceptive accuracy would be associated with temporal precision in the sub-second range, while vagal activity would be associated with temporal accuracy. We used the temporal generalization task, which allowed us to calculate the indices of temporal accuracy and temporal precision in line with the existing research, and also compute the index of participants' sensitivity according to the signal detection theory. Specifically, we investigated whether (1) interoceptive accuracy would correlate with temporal accuracy, temporal precision, or sensitivity and (2) resting-state vagal activity would correlate with temporal accuracy, temporal precision, or sensitivity. The results indicated that interoceptive accuracy was positively correlated with temporal precision as well as sensitivity, but not with temporal accuracy, in the sub-second range time perception. Vagal activity was negatively correlated only with sensitivity. Furthermore, we found a moderation effect of sensitivity on the relationship between vagal activity and perceived duration, which affected the association between vagal activity and temporal accuracy. These findings suggest the importance of precision as an aspect of time perception, which future studies should further explore in relation to interoception and vagal activity, and of the moderation effects of factors such as participants' sensitivity in this context.

Changes in behavioral activities and transition of depressive symptoms among younger-old community-dwelling adults during 6 years: An age-specific prospective cohort study.

OBJECTIVE: Regular engagement in behavioral activities plays a crucial role against depressive symptoms in older adults. This study aims to explore the relationship between behavioral activities and the temporal evolution of depressive symptoms. METHODS: We included community-dwelling Japanese adults aged 64 or 65 years with and without depressive symptoms enrolled in the New Integrated Suburban Seniority Investigation (NISSIN) project. Depressive symptoms at baseline and follow-up were assessed using the 15-item Geriatric Depression Scale. Behavioral activities were measured by self-reported questions. Risk ratios and 95% confidence intervals were calculated using modified Poisson regression, adjusting for relevant sociodemographic variables and health-related confounders. RESULTS: During the 6 year follow-up period, 139 (10.1%) without depressive symptoms at baseline developed such symptoms over time, while 174 (51.6%) with depressive symptoms improved to the point of these symptoms being absent. The participants without depressive symptoms at baseline and those who engaged in social activity or daily walking at a continued regular frequency (CRF) or an increased frequency (IF) and exercise habits at CRF were the least likely to have depressive symptoms onset at follow-up. There was no significant difference between the changes in behavioral activities and the improvement of depressive symptoms after controlling for confounders. Participants engaging in a greater variety of behavioral activities at CRF were less likely to experience a new onset of depressive symptoms. CONCLUSIONS: Consistent and regular participation in one or more behavioral activities was significantly associated with the onset of depressive symptoms in Japanese community-dwelling older adults.

Effect of Indoor Forest Bathing on Reducing Feelings of Fatigue Using Cerebral Activity as an Indicator.

We created an indoor forest bathing environment in a sunlight-type environmentally controlled chamber and both physiological and psychological measurements were conducted for the evaluation of mental fatigue reduction. At first, a working memory load experiment was performed among 10 participants in a space without plants to identify an indicator correlating with feelings of fatigue, using the cerebral activity of the prefrontal cortex. Then, the indicator was used to evaluate whether a 20-min exposure to an indoor forest bathing environment reduced the level of the feeling of fatigue. The working memory load experiment demonstrated that, when mental fatigue increased, the amount of oxygenated hemoglobin (oxy-Hb) in the right prefrontal cortex and the right-left difference in oxy-Hb (ΔRL oxy-Hb) in the prefrontal cortex increased. These were proposed as indicators of mental fatigue. In the indoor forest bathing experiment, staying in an indoor green space showed that the subjective values of feeling of fatigue decreased and ΔRL oxy-Hb decreased. Since these results demonstrated an opposite effect to the increase in ΔRL oxy-Hb related to the feeling of fatigue, it was inferred that the decrease in ΔRL oxy-Hb reflected the fatigue reduction in the indoor forest bathing environment.

Somatic Symptoms: Association Among Affective State, Subjective Body Perception, and Spiritual Belief in Japan and Indonesia.

This study aimed to examine differences in the following somatic symptoms: affective state (i.e., health concerns, anxiety, and positive and negative affect), somatosensory amplification, spirituality in Japan and Indonesia, and associations among all variables from each culture. Previous studies and a potential bio-psycho-spiritual model has identified the association of each variable in the development of somatic symptoms. Moreover, they demonstrated that individuals who describe themselves as more religious and spiritual report better physical and mental health. A total of 469 and 437 university students from Japan and Indonesia, respectively, completed the questionnaires for assessing somatic symptoms, health concerns, trait anxiety, positive and negative affect, somatosensory amplification, and spiritual belief. This study found significant differences in health concerns, positive and negative affect, state anxiety, and spiritual belief. Moreover, the difference in somatosensory amplification was negligible. There is a shared association in both cultures among somatic symptoms, affective state, subjective body perception, and spirituality. Health concerns and trait anxiety moderated somatosensory amplification in the development of somatic symptoms. However, the role of spirituality belief in somatic symptoms was observed in the Japanese and Indonesian cultures in relation to positive affect.

Mothers' interoceptive sensibility mediates affective interaction between mother and infant.

Interoceptive sensibility, which denotes the self-perceived sensitivity to inner-body sensations, has been associated with the emotional experiences and inferences of others' emotional states. Focusing on the role of interoceptive sensibility in the emotional states and psychological well-being of mothers during caregiving, this study explores how physiological arousal and interoceptive sensibility mediate the association between mother-infant interaction and maternal well-being using an experience sampling method. Infant-directed-singing (IDS) with social touch was used to facilitate mother-infant interaction. Pairs of 2-8-month-old infants and their mothers participated. Mothers in an IDS group (N = 25) and a no-IDS group (N = 26) recorded their and the infant's daily feelings and physiological states using a smartphone application for one month. All participants, including the control group (N = 78) who neither performed IDS nor used the application, answered the Multidimensional Assessment of Interoceptive Awareness questionnaire before and after the recording period. Results indicated that IDS improved mother-infant interactions and positive feelings, enhancing maternal physiological arousal. Increased interoceptive sensibility enhanced infants' positive feelings in the IDS group, whereas in the no-IDS group, it weakened mother's positive feelings, suggesting that maternal interoceptive sensibility mediated the effects of IDS on mother and infant well-being.

Effects of interoceptive accuracy on timing control in the synchronization tapping task.

Humans often perform rhythmic synchronized movements. Professional musicians and dancers particularly perform such movement tasks well and have a higher interoceptive accuracy (IAcc) than non-musicians and non-dancers. We thus hypothesized that rhythmic synchronized movements might be enhanced by a higher IAcc. To investigate this hypothesis, this study conducted a heartbeat counting task and a rhythmic synchronization tapping task with normal (easier) and slow (harder) tempi metronomes. Inconsistent with our hypothesis, however, a higher IAcc was negatively correlated with timing control, but only in the slow tempo condition [r (30) = 0.46, p < 0.05]. This suggests that a higher IAcc did not enhance timing control in rhythmic synchronized movements but rather weakened it, resting heart rate variability was not correlated with timing control.

A learning mechanism shaping risk preferences and a preliminary test of its relationship with psychopathic traits.

People tend to avoid risk in the domain of gains but take risks in the domain of losses; this is called the reflection effect. Formal theories of decision-making have provided important perspectives on risk preferences, but how individuals acquire risk preferences through experiences remains unknown. In the present study, we used reinforcement learning (RL) models to examine the learning processes that can shape attitudes toward risk in both domains. In addition, relationships between learning parameters and personality traits were investigated. Fifty-one participants performed a learning task, and we examined learning parameters and risk preference in each domain. Our results revealed that an RL model that included a nonlinear subjective utility parameter and differential learning rates for positive and negative prediction errors exhibited better fit than other models and that these parameters independently predicted risk preferences and the reflection effect. Regarding personality traits, although the sample sizes may be too small to test personality traits, increased primary psychopathy scores could be linked with decreased learning rates for positive prediction error in loss conditions among participants who had low anxiety traits. The present findings not only contribute to understanding how decision-making in risky conditions is influenced by past experiences but also provide insights into certain psychiatric problems.

Reliability of Online Surveys in Investigating Perceptions and Impressions of Faces.

Online experimental methods are used in psychological studies investigating the perceptions and impressions of facial photographs, even without substantial evidence supporting their reliability and validity. Although, the quality of visual stimuli is more difficult to control remotely, the methods might allow us to obtain a large amount of data. Then the statistical analysis of a larger volume of data may reduce errors and suggest significant difference in the stimuli. Therefore, we analyzed the reliability and validity of online surveys in investigating the perceptions (shine, red, and dark) and impressions (attractiveness, trustworthy, and so on) of facial photographs created from averaged faces with skin tones modified using computer graphics (CG). In this study, we conducted online (Online1) and laboratory experiments with well-controlled conditions (Control). For each experiment, 50 participants (men and women in Japan, age: 20-59years) completed the same questionnaire regarding their impressions of the same 28 CG facial photographs. The results showed significant correlations between the two experiments for all 19 items in the questionnaire. SD in the Online1 compared to the Control from the stimuli and individual differences were 56-84 and 88-104% in each questionnaire items, respectively. Moreover, the rates of mismatching perceptual evaluations to the corresponding physical features demonstrated in the photographs were 4.9-9.7% on average in an additional online survey of another 2,000 participants (Online2). These results suggest that online surveys can be applied to experiments to investigate impressions from CG facial photographs instead of general laboratory experiment by obtaining an appropriate number of participants to offset larger statistical errors that may result from the increased noise in the data from conducting the experiment online.

Prediction of 11-year incidence of psychophysically dependent status or death among community-dwelling younger elderlies: from an age-specified community-based cohort study (the NISSIN project).

BACKGROUND: Predicting adverse health events and implementing preventative measures are a necessary challenge. It is important for healthcare planners and policymakers to allocate the limited resource to high-risk persons. Prediction is also important for older individuals, their family members, and clinicians to prepare mentally and financially. The aim of this study is to develop a prediction model for within 11-year dependent status requiring long-term nursing care or death in older adults for each sex. METHODS: We carried out age-specified cohort study of community dwellers in Nisshin City, Japan. The older adults aged 64 years who underwent medical check-up between 1996 and 2000 were included in the study. The primary outcome was the incidence of the psychophysically dependent status or death or by the end of the year of age 75 years. Univariable logistic regression analyses were performed to assess the associations between candidate predictors and the outcome. Using the variables with p-values less than 0.1, multivariable logistic regression analyses were then performed with backward stepwise elimination to determine the final predictors for the model. RESULTS: Of the 1525 female participants at baseline, 105 had an incidence of the study outcome. The final prediction model consisted of 15 variables, and the c-statistics for predicting the outcome was 0.763 (95% confidence interval [CI] 0.714-0.813). Of the 1548 male participants at baseline, 211 had incidence of the study outcome. The final prediction model consisted of 16 variables, and the c-statistics for predicting the outcome was 0.735 (95% CI 0.699-0.771). CONCLUSIONS: We developed a prediction model for older adults to forecast 11-year incidence of dependent status requiring nursing care or death in each sex. The predictability was fair, but we could not evaluate the external validity of this model. It could be of some help for healthcare planners, policy makers, clinicians, older individuals, and their family members to weigh the priority of support.

Food group intakes and all-cause mortality among a young older Japanese population of the same age: the New Integrated Suburban Seniority Investigation Project.

Evaluating the effects of dietary intake on mortality in older populations has become increasingly important in modern aging societies. The objective of the present study was to investigate the associations between food group intakes and all-cause mortality among a young older population. We conducted a prospective study on 1,324 men and 1,338 women aged 64-65 years at baseline who were living in a suburban city from 1996 to 2005. The participants were followed for all-cause mortality from 1996 through 2015 to assess the effects of 17 food group intakes (g) per 1,000 kcal after multivariable adjustments in proportional hazard models. During follow-up (mean: 13.2 years), 339 deaths were registered. In women, total mortality was significantly and inversely associated with the consumption of milk and dairy products and vegetables. The hazard ratios across intake quartiles after multivariable adjustment were 1, 0.70 (95% confidence interval: 0.42-1.17), 0.66 (0.40-1.10), and 0.40 (0.22-0.75) (P for trend = 0.003) for milk and dairy products, and 1, 0.77 (0.46-1.28), 0.83 (0.50-1.38), and 0.42 (0.23-0.78) (P for trend = 0.008) for vegetables. In men, a positive association was found between total mortality and sugar and sweetener consumption (P for trend = 0.038). Higher consumption of milk and dairy products and vegetables was suggested to reduce all-cause mortality in young older women.

Interoceptive Accuracy Did Not Affect Moral Decision-Making, but Affect Regret Rating for One's Moral Choices.

Previous studies have revealed the effect of interoceptive accuracy (IAcc), a behavioral measure of the ability to feel physiological states and regulation for that, which origin emotion on decision-making such as gambling. Given that decision-making in moral dilemma situations is affected by emotion, it seems that IAcc also affects moral decision-making. The present study preliminarily investigates whether IAcc affects decision-making and emotional ratings such as regret for one's own choices in moral dilemma situations. IAcc did not affect moral choice (deontological or utilitarian option), but affected regret ratings for one's moral choice in portions of dilemma scenarios. Moreover, people with higher IAcc make deontological choices more rapidly than those with lower IAcc in self-related dilemma scenarios. These results suggest that people with higher IAcc feel stronger emotional conflicts about utilitarian choices but weaker conflicts about deontological choices than people with lower IAcc depending on the moral dilemma scenario.