Analysis of the alpha activity envelope in electroencephalography in relation to the ratio of excitatory to inhibitory neural activity.

Alpha waves, one of the major components of resting and awake cortical activity in human electroencephalography (EEG), are known to show waxing and waning, but this phenomenon has rarely been analyzed. In the present study, we analyzed this phenomenon from the viewpoint of excitation and inhibition. The alpha wave envelope was subjected to secondary differentiation. This gave the positive (acceleration positive, Ap) and negative (acceleration negative, An) values of acceleration and their ratio (Ap-An ratio) at each sampling point of the envelope signals for 60 seconds. This analysis was performed on 36 participants with Alzheimer's disease (AD), 23 with frontotemporal dementia (FTD) and 29 age-matched healthy participants (NC) whose data were provided as open datasets. The mean values of the Ap-An ratio for 60 seconds at each EEG electrode were compared between the NC and AD/FTD groups. The AD (1.41 ±0.01 (SD)) and FTD (1.40 ±0.02) groups showed a larger Ap-An ratio than the NC group (1.38 ±0.02, p<0.05). A significant correlation between the envelope amplitude of alpha activity and the Ap-An ratio was observed at most electrodes in the NC group (Pearson's correlation coefficient, r = -0.92 ±0.15, mean for all electrodes), whereas the correlation was disrupted in AD (-0.09 ±0.21, p<0.05) and disrupted in the frontal region in the FTD group. The present method analyzed the envelope of alpha waves from a new perspective, that of excitation and inhibition, and it could detect properties of the EEG, Ap-An ratio, that have not been revealed by existing methods. The present study proposed a new method to analyze the alpha activity envelope in electroencephalography, which could be related to excitatory and inhibitory neural activity.

Pandemic-Induced Occupational Disruption and Association With Health in Japanese Community-Dwelling Older Adults.

The COVID-19 pandemic caused occupational disruption and adverse health outcomes in community-dwelling older adults. This study aimed to investigate the extent of occupational disruption in older adults and its relationship to health-related quality of life (QOL), depression, and frailty. In this cross-sectional study, retention rates in four activity domains and relationships with health outcomes were examined in Japanese older adults aged ≥65 years (n=163) using canonical correlation analysis (CCA) and mixed linear models. More than 25% of activities were restricted compared with the pre-pandemic period. CCA demonstrated correlations between four retention rates and health outcomes (canonical correlation = .42, p = .0003). Retention in instrumental and social activities independently predicted QOL and depression (p < .05). This study highlights that different activities may have different effects on health outcomes and can provide community occupational therapy practitioners with a perspective to assess occupational disruption and identify activities for intervention.

Pandemic-Induced Changes of Daily Routine and Its Association with Health for Japanese Older AdultsWe investigated the changes in daily activity due to the COVID-19 pandemic among community-dwelling older adults in Japan and examined their association with health outcomes. The results showed that more than 25% of activity was reduced due to the pandemic. There was a moderate association between changes in activity and physical, mental, and subjective health. Especially, instrumental and social activities were strongly associated with mental and subjective health. This study highlights the possibility that different types of activities may have different effects on health. Our study can provide occupational therapy practitioners supporting community-dwelling older adults with a perspective to assess changes in daily activities due to the pandemic and identify activities to target for future intervention. As this study was conducted at a single point in time, future studies should be conducted at multiple points in time.

Changes in Community-Dwelling Elderly's Activity and Participation Affecting Depression during COVID-19 Pandemic: A Cross-Sectional Study.

We determined the changes in the activity or participation of the community-dwelling elderly in Japan during the COVID-19 pandemic and identified the activities leading to depression. This will allow us to evaluate rehabilitation interventions that can be used to minimize or eliminate the negative impact of COVID-19 on today's community-dwelling elderly. Herein, demographics, activity or participation (Activity Card Sort-Japan version: ACS-JPN), the number of social networks (Lubben Social Network Scale: LSNS), and depression (Geriatric Depression Scale: GDS) were examined in 74 community-dwelling elderly in Japan from August to October 2020. A statistical analysis was conducted to determine the effect of demographics on GDS, LSNS, and ACS-JPN, to compare the activity retention rates of the four domains using ACS-JPN, and to extract the activities that might affect depression using a generalized linear model. The results show that the retention of leisure activity with a high physical demand (H-leisure) and sociocultural activities was significantly lower than instrumental activities of daily living and leisure activity with a low physical demand (L-leisure). L-leisure and the number of social networks were possible risk factors for depression during the pandemic. This study highlighted the importance of maintaining the number of L-leisure and social networks at home to prevent depression in community-dwelling elderly when they could not perform outdoor activities and direct interpersonal interaction.

Identification of Subgroups of Activity Participation in Group of Community-Dwelling Older Adults.

Occupational therapy in public health is advancing for groups of older adults, but few studies have focused on measuring population-based activity engagement. This study aimed to identify subgroups based on the daily activity pattern of community-dwelling older adults. Japanese older adults aged ≥65 years responded to a 128-activity-item questionnaire. Sparse principal component analysis was applied to summarize the activities, and k-means clustering was used to identify subgroups. Respondents were divided into three subgroups (subgroup 1: n = 39, high instrumental/leisure and social/cognitive activity; subgroup 2: n = 51, high instrumental/leisure and low social/cognitive activity; subgroup 3: n = 44, low instrumental/leisure and social/cognitive activity). The three subgroups were associated with sociodemographics (sex, area, education, and activity level) (p < .05). This study highlighted the activity-based subgroups of older adults and provided a novel viewpoint regarding occupation-based community assessments in addition to previous community occupational therapy practice.

Gender differences in psychosocial factors related to severe stress in a construction company in Japan.

BACKGROUND: In Japan, women's participation in the workforce has been increasing. However, there are few studies about gender differences in stress factors in the workplace. OBJECTIVES: We aimed to clarify gender differences in psychosocial factors in the workplace related to severe stress. METHODS: In total, 930 male and 339 female employees working in a construction company in Japan participated in this study. We used individual responses to the Brief Job Stress Questionnaire (BJSQ) conducted by their company for the most recent year between 2016 and 2019. Data were categorized by gender, and we extracted the factors contributing to severe stress using logistic regression. RESULTS: We identified 142 men and 32 women who had severe stress. Logistic regression analysis showed that six factors ("Qualitative job overload", "Job control", "Interpersonal conflict", "Poor physical environment", "Supervisor's support", and "Job satisfaction and life satisfaction") were significantly associated with the presence of severe stress in men. In women, five factors ("Qualitative job overload", "Job control", "Interpersonal conflict", "Suitable work", and "Job satisfaction and life satisfaction") showed a significant association with severe stress. CONCLUSION: Factors associated with severe stress were "Poor physical environment" and "Supervisor's support" in men, and "Suitable work" in women.

Pre-stimulus alpha oscillation and post-stimulus cortical activity differ in localization between consciously perceived and missed near-threshold somatosensory stimuli.

Conscious perception of a near-threshold (NT) stimulus is characterized by the pre- and post-stimulus brain state. However, the power of pre-stimulus neural oscillations and strength of post-stimulus cortical activity that lead to conscious perception have rarely been examined in individual cortical areas. This is because most previous electro- and magnetoencephalography (EEG and MEG, respectively) studies involved scalp- and sensor-level analyses. Therefore, we recorded MEG during a continuous NT somatosensory stimulus detection task and applied the reconstructed source data in order to identify cortical areas where the post-stimulus cortical activity and pre-stimulus alpha oscillation predict the conscious perception of NT somatosensory stimuli. We found that the somatosensory hierarchical processing areas, prefrontal areas and cortical areas belonging to the default mode network showed stronger cortical activity for consciously perceived trials in the post-stimulus period, but the cortical activity in primary somatosensory area (SI) is independent of conscious perception during the early stage of NT stimulus processing. In addition, we revealed that the pre-stimulus alpha oscillation only in SI is predictive of conscious perception. These findings suggest that the bottom-up stream of somatosensory information flow following SI and pre-stimulus alpha activity fluctuation in SI as a top-down modulation are crucial constituents of conscious perception.

Chronic pain-related cortical neural activity in patients with complex regional pain syndrome.

Quantitative objective measurement of chronic pain is important. We elucidated chronic pain-related cortical neural activity and neural connectivity among pain-related brain regions in complex regional pain syndrome (CRPS). Resting-state magnetoencephalography recordings were performed. Cortical current density and neural connectivity, revealed by amplitude envelope correlation (AEC), were estimated on standardized brain magnetic resonance imaging. Intra-experiment pain was assessed subjectively using a visual analogue scale (VAS). The correlation between current density and VAS scores was calculated for the occipital areas and pain-related cortices. Current density in the primary (SI) and secondary (SII) somatosensory cortex and precuneus in both hemispheres was negatively correlated with the pain VAS score. The AEC and VAS values were significantly correlated for the SII and the precuneus and for the SII and insular cortex in the alpha frequency band in the right hemisphere. In the theta frequency band, the AEC and VAS values correlated for the SII and posterior cingulate cortex in the right hemisphere. Our results suggested that disruption of pain processes and functions in the default mode network occurs in CRPS. Our method targeting the neural mechanism of pain has the potential to offer a clinically objective means of evaluating it.

Items Selection for the Japanese Version of the Preschool Activity Card Sort.

Preschool Activity Card Sort (PACS) is a valid measure of preschoolers' participation and is a useful and unique tool for focusing on the extent and frequency of their participation. However, given the cultural differences between Japan and other countries, researchers should consider these differences when adapting the PACS for use with children in Japan. The purpose of this study was to select culturally suitable activity items to develop the Japanese version of PACS (PACS-JPN). A two-round survey of parents (who had typically developing children aged between 3 and 6 years) was conducted. The final version of the PACS-JPN included 98 activity items. The PACS-JPN reflects Japanese sociocultural background and allows occupational therapists to assess preschoolers' actual participation by assessing multiple aspects of children's community life. The psychometric properties, including the validity and reliability of the PACS-JPN should be examined in future research.

Selection of Activity Items for Development of the Activity Card Sort-Japan Version.

The Activity Card Sort (ACS) can both record the clients' participation and any changes, which is a useful tool for practitioners to establish tailored occupation-focused goals. However, there is a limitation to apply the ACS to Japanese older adults as it consists of culturally relevant activities in the United States. The aim of this study was to select activity items reflecting Japanese older adults' lifestyles and opinions to develop the Activity Card Sort-Japan Version (ACS-JPN). In the item selection process, a two-round questionnaire survey was conducted for community-dwelling Japanese older adults (Round 1: n = 177, M age = 69.9 years; Round 2: n = 178, M age = 74.9 years). Seventy-two activity items were finally included in the ACS-JPN and were classified into four domains. The ACS-JPN has some unique features compared with other ACS versions. This study only selected activity items. Further work on psychometric properties is needed.

Association between changes in visual evoked magnetic fields and non-motor features in Parkinson's disease.

Visual dysfunction can be caused by several abnormalities, including dysfunctions in the visual cortex and retina. Our aim was to investigate changes in visual evoked brain responses in the primary visual cortex associated with Parkinson's disease (PD). Sixteen healthy control subjects and ten patients with PD participated in this study. We assessed the visual evoked magnetic field (VEF) using magnetoencephalography (MEG). Checkerboard pattern reversal (CPR) and monotonous grating pattern (MGP) stimulations were used. Magnetic resonance imaging (MRI) was performed to analyze brain volume and generate a tractogram. Cognitive and olfactory function, and Unified Parkinson's Disease Rating Scale (UPDRS) scores were evaluated in patients with PD. Four components of the VEF (1M, 2M, 3M, 4M) were observed following stimulation. For both stimuli, results from the 1M and 2M components were significantly greater and the latency of the 1M component was increased markedly in the PD group compared with the healthy control group. In the PD group, 1M latency correlated with the UPDRS score of 1 for both stimuli, and a correlation was observed between olfactory function and the UPDRS score of 3 for the CPR stimulation alone. We suggest that the conduction delay observed following visual stimulation occurs peripherally rather than in the primary visual cortex. Degeneration of selective elements of the visual system in the retina, possibly midget cells, may be involved.

The temporal stability and variability across frequency bands in neural synchrony between primary and secondary somatosensory areas following somatosensory stimulation.

OBJECTIVES: To examine the temporal stability and variability of neuronal synchronization among the contralateral primary somatosensory cortex (cSI) and contralateral (cSII) and ipsilateral secondary somatosensory cortex (iSII) in response to median nerve stimulation. METHODS: Both the spontaneous magnetoencephalography (MEG) signals as the pre-stimulus condition and somatosensory evoked magnetic-fields (SEF) were recorded in eleven healthy subjects. We calculated a phase-locking value (PLV) between two areas among cSI, cSII, and iSII in five frequency bands (theta: 5-7 Hz, alpha: 8-12 Hz, beta: 15-29 Hz, gamma-1: 30-59 Hz, and gamma-2: 60-90 Hz), and compared the PLV among in pre-stimulus and stimulus conditions. RESULTS: The PLV between cSI and cSII for the theta band activity varied within 2 s from the stimulus onset. On the other hand, the PLV between cSI and iSII for the alpha band did not vary within 2 s. CONCLUSION: The fluctuation of neuronal synchrony among sensory-related cortices in response to median nerve stimulation depends on the induced frequency band and inter-region. SIGNIFICANCE: This study is the first to report the temporal characteristic of stimulus-driven neural synchrony following somatosensory stimulation.

Functional inter-cortical connectivity among motor-related cortices during motor imagery: A magnetoencephalographic study.

Neural connectivity was measured during motor imagery (MI) and motor execution (ME) using magnetoencephalography in nine healthy subjects, MI, and at rest. Lower coherence values during ME and MI between sensorimotor areas than at rest, and lower values during MI between the left supplementary motor area and inferior frontal gyrus than ME suggested the sensorimotor network of MI functioned with similar connectivity to ME and that the inhibitory activity functioned continuously during MI, respectively.

Recovery function of somatosensory evoked brain response in patients with carpal tunnel syndrome: A magnetoencephalographic study.

OBJECTIVE: The recovery function of somatosensory evoked magnetic fields (SEFs) was recorded to investigate excitatory and inhibitory balance in the somatosensory cortex of patients with carpal tunnel syndrome. METHODS: SEFs were recorded in patients and controls. Recordings were taken following median nerve stimulation with single and double pulses with interstimulus intervals of 10-200ms. The root mean square for the N20m component following the second stimulation was analyzed. SEFs following stimulation of the first and middle digits were also recorded and the location for the equivalent current dipoles was estimated in three-dimensional planes. RESULTS: Distances on the vertical axis between the equivalent current dipoles for the first and third digits were shorter in patients than in control participants. The root mean square for the N20m recovered earlier in patients compared to controls; this was statistically significant at an interstimulus interval of 10ms. There was no relationship between N20m recovery and the equivalent current dipole location in the primary somatosensory cortex. CONCLUSIONS: Carpal tunnel syndrome was associated with functional disinhibition and destruction of the somatotopic organization in the primary somatosensory cortex. SIGNIFICANCE: Disinhibitory changes might induce a maladaptation of the central nervous system relating to pain.

Disinhibitory shift of recovery curve of somatosensory-evoked response in elderly: A magnetoencephalographic study.

OBJECTIVE: The aim of the study was to investigate the functional differences between N20m and P30m components of somatosensory-evoked magnetic cortical field (SEF) in young and senior subjects. METHODS: Twenty-nine healthy subjects, 13 younger (mean age: 21.8years) and 16 senior (63.8 years), participated. Magnetic fields were measured using a 160-channel, whole head MEG. Single- and paired-pulse stimulations of 200 artifact-free MEG signal epochs were averaged separately. We calculated how aging affects recovery function of SEFs. RESULTS: The senior showed a prolonged N20m peak latency compared to the younger, although the P30m peak latency was not significantly different between groups. The N20m ratios at 60 and 80 ms in the senior were significantly increased compared to the ratios in the younger (60 ms: P<0.05, 80 ms: P<0.001). The P30m ratios at inter-stimulus interval (ISI) of 80 and 100 ms showed even disinhibition in the senior than in the younger (P<0.05). The younger also showed a significantly negative correlation between P30m and N20m components' recovery curves (R=0.72, P<0.05). CONCLUSION: Aging-related changes that occurred in recovery functioning were the decrease in N20m component suppression and the increase in P30m component recovery, indicating that the N20m and P30m components have different functions in aging-related recovery changes. SIGNIFICANCE: Our results show that the N20m ratio at an ISI of 80 ms was significantly increased in the senior group, indicating that the second stimulus-evoked SEF was less inhibited by the initial stimulus at this ISI, suggesting less refractory effect or increased disinhibition.

Effects of emotional music on visual processes in inferior temporal area.

To investigate the effects of emotional music on visual processes, we analyzed visual evoked magnetic fields (VEF) on listening to emotional music in 14 healthy subjects. Positive and negative pieces of music were delivered during VEF recording following stimulation by emotionally neutral pictures of faces and landscapes. VEF components at 100 (M100) and 150 (M170)ms after stimulus onset were analyzed, and the estimated current strength for M170 following face stimulation was enhanced with negative compared to positive music in the right hemisphere. The equivalent current dipole for M100 and M170 was estimated in the primary visual cortex (V1) and inferior temporal area (IT), respectively. The present results indicate that background music showed a top-down control of the visual processes in IT, which is a core site responsible for the interpretation of facial expression. The emotional contents of music could alter visual processes, especially those involving the face.

Event-related potential study of frontal activity during imagination of rhythm.

In 11 healthy volunteers, we used event-related potentials (ERP) to investigate the frontal activity associated with imagining a beat. In imagery sessions, subjects were asked to imagine a rhythm during a silent recording period following a series of guide sounds played at 1 Hz. In control sessions, subjects were asked to imagine a vowel sound ("a") continuously during the silent recording period. In eight subjects, relative negative potentials were recorded during imagery sessions (compared with potentials in control sessions), with timing that was similar to that of the guide sounds. Activity in the left frontal region was more significant than that in other areas during beat imagination. These data indicate that a semantic strategy for simple rhythm imagery might involve temporary phasic activation in the left frontal area, although rhythm production and perception might be generated in the right side, as reported in previous studies.

Effect of task-irrelevant high-speed verbal stimulation on a visual/verbal word-discrimination task: an event-related potential study.

OBJECTIVES: We investigated whether incomprehensible high-speed auditory speech stimulation was processed and interacted with visual-word discrimination processing. We hypothesised that an interaction might indicate the capacity of working memory (WM) to perform the temporal processing of auditory verbal information. METHODS: We recorded P300 for a visual-word discrimination Oddball paradigm in 14 healthy subjects. Auditory speech and reversed speech stimulation were presented at various speeds as task-irrelevant stimuli during the P300 tasks. RESULTS: The P300 latency was prolonged under forward high-speed speech stimuli (× 2.5 and × 3.5) compared with the standard speed and white noise, but there was no effect of reversed speech stimuli on the P300 latency during the word-discrimination paradigm. CONCLUSIONS: We considered that high-speed speech stimulation was processed without conscious comprehension and competed with verbal processing during the visual-word-discrimination task, possibly by interfering with the use of WM. SIGNIFICANCE: The present study shows the capacity of the brain to process high-speed verbal stimulation and the interaction with a visual-verbal task.

Variability of P300 in elderly patients with dementia during a single day.

We recorded P300 sequentially during a single day in nine patients with dementia in a health care facility. The variability of the P300 response and the relationship between P300 and the Revised Hasegawa Dementia Scale were investigated. The sequential P300 latency and amplitude measurements varied significantly during the day, but the value changes were not related to the scheduled programs in the facility. Although there was no correlation between the values of latency or amplitude and Revised Hasegawa Dementia Scale (HDS-R), the variability index of the P300 latency correlated with the HDS-R score. Variability in the P300 response was considerable and the reproducibility was poor in elderly patients with dementia during the day, although the P300 latency was consistently prolonged. These results suggested that the variability of P300 was not due to transient changes in the level of consciousness, but was related to the latent pathology of fluctuating cognitive functions in patients with dementia.