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Mitsuru Kikuchi

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8 papers

1 author row

YNICL Journal 2021 Journal Article

Aberrant brain oscillatory coupling from the primary motor cortex in children with autism spectrum disorders

Kyung-min An
Takashi Ikeda
Chiaki Hasegawa
Yuko Yoshimura
Sanae Tanaka
Daisuke N. Saito
Ken Yaoi
Sumie Iwasaki

Autism spectrum disorder (ASD) often involves dysfunction in general motor control and motor coordination, in addition to core symptoms. However, the neural mechanisms underlying motor dysfunction in ASD are poorly understood. To elucidate this issue, we focused on brain oscillations and their coupling in the primary motor cortex (M1). We recorded magnetoencephalography in 18 children with ASD, aged 5 to 7 years, and 19 age- and IQ-matched typically-developing children while they pressed a button during a video-game-like motor task. The motor-related gamma (70 to 90 Hz) and pre-movement beta oscillations (15 to 25 Hz) were analyzed in the primary motor cortex using an inverse method. To determine the coupling between beta and gamma oscillations, we applied phase-amplitude coupling to calculate the statistical dependence between the amplitude of fast oscillations and the phase of slow oscillations. We observed a motor-related gamma increase and a pre-movement beta decrease in both groups. The ASD group exhibited a reduced motor-related gamma increase and enhanced pre-movement beta decrease in the ipsilateral primary motor cortex. We found phase-amplitude coupling, in which high-gamma activity was modulated by the beta rhythm in the primary motor cortex. Phase-amplitude coupling in the ipsilateral primary motor cortex was reduced in the ASD group compared with the control group. Using oscillatory changes and their couplings, linear discriminant analysis classified the ASD and control groups with high accuracy (area under the receiver operating characteristic curve: 97.1%). The current findings revealed alterations in oscillations and oscillatory coupling, reflecting the dysregulation of motor gating mechanisms in ASD. These results may be helpful for elucidating the neural mechanisms underlying motor dysfunction in ASD, suggesting the possibility of developing a biomarker for ASD diagnosis.

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YNIMG Journal 2021 Journal Article

Effects of familiarity on child brain networks when listening to a storybook reading: A magneto-encephalographic study

Chiaki Hasegawa
Tetsuya Takahashi
Takashi Ikeda
Yuko Yoshimura
Hirotoshi Hiraishi
Sou Nobukawa
Daisuke N. Saito
Hirokazu Kumazaki

Parent-child book reading is important for fostering the development of various lifelong cognitive and social abilities in young children. Despite numerous reports describing the effects of familiarity on shared reading for children, the exact neural basis of the functional network architecture remains unclear. We conducted Magnet-Encephalographic (MEG) experiments using graph theory to elucidate the role of familiarity in shared reading in a child's brain network and to measure the connectivity dynamics of a child while Listening to Storybook Reading (LSBR), which represents the daily activity of shared book reading between the child and caregiver. The LSBR task was performed with normally developing preschool- and school-age children (N = 15) under two conditions: reading by their own mother (familiar condition) vs. an experimenter (unfamiliar condition). We used the phase lag index (PLI), which captures synchronization of MEG signals, to estimate functional connectivity. For the whole brain network topology, an undirected weighted graph was produced using 68 brain regions as nodes and interregional PLI values as edges for five frequency bands. Behavioral data (i.e., the degree of attention and facial expressions) were evaluated from video images of the child's face during the two conditions. Our results showed enhanced widespread functional connectivity in the alpha band during the mother condition. In the mother condition, the whole brain network in the alpha band exhibited topographically high local segregation with high global integration, indicating an increased small-world property. Results of the behavioral analysis revealed that children were more attentive and showed more positive facial expressions in the mother condition than in the experimenter condition. Behavioral data were significantly correlated with graph metrics in the mother condition but not in the experimenter condition. In this study, we identified the neural correlates of a familiarity effect in children's brain connectivity dynamics during LSBR. Furthermore, these familiarity-related brain dynamics were closely linked to the child's behavior. Graph theory applied to MEG data may provide useful insight into the familiarity-related child brain response in a naturalistic setting and its relevance to child attitudes.

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YNIMG Journal 2019 Journal Article

Changes in functional connectivity dynamics with aging: A dynamical phase synchronization approach

Sou Nobukawa
Mitsuru Kikuchi
Tetsuya Takahashi

The dynamics of the human brain network has attracted broad attention, in recognition of the concept that functional connectivity is not static, but changes its pattern over time, even in the resting state. We hypothesized that analysis of continuously captured time-varying instantaneous phase synchronization between signals from different brain regions might add another dimension to already identified network dynamics. To validate this hypothesis as an aid to elucidating the physiological mechanisms of aging, we examined time-series of instantaneous phase synchronization events in resting-state EEG activity across the brain, in healthy younger and healthy older subjects. We then characterized the temporal dynamics of phase synchronization using multiscale entropy, which quantifies the complexity of brain signal dynamics over multiple time scales. The results of surrogate analyses confirmed that the temporal dynamics of phase synchronization arise from deterministic processes in the neural network system. Group comparison showed region-specific enhanced complexity of temporal dynamics of phase synchronization in older subjects in alpha band predominantly in frontal brain regions, which was not identified by a comparative phase synchronization approach such as phase lag index. Enhanced complexity of temporal dynamics of functional connectivity in older subjects might reflect a general network alteration theory in aging. This is a first report describing the importance of capturing the dynamics of instantaneous phase synchronization and characterizing its temporal organization. Applying this method to neurophysiologic data may provide a novel understanding of dynamical neural network processes in both healthy and pathological conditions.

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YNICL Journal 2016 Journal Article

Synchrony of auditory brain responses predicts behavioral ability to keep still in children with autism spectrum disorder

Yuko Yoshimura
Mitsuru Kikuchi
Hirotoshi Hiraishi
Chiaki Hasegawa
Tetsuya Takahashi
Gerard B. Remijn
Manabu Oi
Toshio Munesue

The auditory-evoked P1m, recorded by magnetoencephalography, reflects a central auditory processing ability in human children. One recent study revealed that asynchrony of P1m between the right and left hemispheres reflected a central auditory processing disorder (i.e., attention deficit hyperactivity disorder, ADHD) in children. However, to date, the relationship between auditory P1m right-left hemispheric synchronization and the comorbidity of hyperactivity in children with autism spectrum disorder (ASD) is unknown. In this study, based on a previous report of an asynchrony of P1m in children with ADHD, to clarify whether the P1m right-left hemispheric synchronization is related to the symptom of hyperactivity in children with ASD, we investigated the relationship between voice-evoked P1m right-left hemispheric synchronization and hyperactivity in children with ASD. In addition to synchronization, we investigated the right-left hemispheric lateralization. Our findings failed to demonstrate significant differences in these values between ASD children with and without the symptom of hyperactivity, which was evaluated using the Autism Diagnostic Observational Schedule, Generic (ADOS-G) subscale. However, there was a significant correlation between the degrees of hemispheric synchronization and the ability to keep still during 12-minute MEG recording periods. Our results also suggested that asynchrony in the bilateral brain auditory processing system is associated with ADHD-like symptoms in children with ASD.

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YNIMG Journal 2014 Journal Article

A longitudinal study of auditory evoked field and language development in young children

Yuko Yoshimura
Mitsuru Kikuchi
Sanae Ueno
Kiyomi Shitamichi
Gerard B. Remijn
Hirotoshi Hiraishi
Chiaki Hasegawa
Naoki Furutani

The relationship between language development in early childhood and the maturation of brain functions related to the human voice remains unclear. Because the development of the auditory system likely correlates with language development in young children, we investigated the relationship between the auditory evoked field (AEF) and language development using non-invasive child-customized magnetoencephalography (MEG) in a longitudinal design. Twenty typically developing children were recruited (aged 36–75months old at the first measurement). These children were re-investigated 11–25months after the first measurement. The AEF component P1m was examined to investigate the developmental changes in each participant's neural brain response to vocal stimuli. In addition, we examined the relationships between brain responses and language performance. P1m peak amplitude in response to vocal stimuli significantly increased in both hemispheres in the second measurement compared to the first measurement. However, no differences were observed in P1m latency. Notably, our results reveal that children with greater increases in P1m amplitude in the left hemisphere performed better on linguistic tests. Thus, our results indicate that P1m evoked by vocal stimuli is a neurophysiological marker for language development in young children. Additionally, MEG is a technique that can be used to investigate the maturation of the auditory cortex based on auditory evoked fields in young children. This study is the first to demonstrate a significant relationship between the development of the auditory processing system and the development of language abilities in young children.

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YNICL Journal 2013 Journal Article

Altered brain connectivity in 3-to 7-year-old children with autism spectrum disorder

Mitsuru Kikuchi
Kiyomi Shitamichi
Yuko Yoshimura
Sanae Ueno
Hirotoshi Hiraishi
Tetsu Hirosawa
Toshio Munesue
Hideo Nakatani

Autism spectrum disorder (ASD) is often described as a disorder of aberrant neural connectivity and/or aberrant hemispheric lateralization. Although it is important to study the pathophysiology of the developing ASD cortex, the physiological connectivity of the brain in young children with ASD under conscious conditions has not yet been described. Magnetoencephalography (MEG) is a noninvasive brain imaging technique that is practical for use in young children. MEG produces a reference-free signal and is, therefore, an ideal tool for computing the coherence between two distant cortical rhythms. Using a custom child-sized MEG, we recently reported that 5- to 7-year-old children with ASD (n = 26) have inherently different neural pathways than typically developing (TD) children that contribute to their relatively preserved performance of visual tasks. In this study, we performed non-invasive measurements of the brain activity of 70 young children (3-7 years old, of which 18 were aged 3-4 years), a sample consisting of 35 ASD children and 35 TD children. Physiological connectivity and the laterality of physiological connectivity were assessed using intrahemispheric coherence for 9 frequency bands. As a result, significant rightward connectivity between the parietotemporal areas, via gamma band oscillations, was found in the ASD group. As we obtained the non-invasive measurements using a custom child-sized MEG, this is the first study to demonstrate a rightward-lateralized neurophysiological network in conscious young children (including children aged 3-4 years) with ASD.

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YNIMG Journal 2010 Journal Article

Antipsychotics reverse abnormal EEG complexity in drug-naive schizophrenia: A multiscale entropy analysis

Tetsuya Takahashi
Raymond Y. Cho
Tomoyuki Mizuno
Mitsuru Kikuchi
Tetsuhito Murata
Koichi Takahashi
Yuji Wada

Multiscale entropy (MSE) analysis is a novel entropy-based approach for measuring dynamical complexity in physiological systems over a range of temporal scales. To evaluate this analytic approach as an aid to elucidating the pathophysiologic mechanisms in schizophrenia, we examined MSE in EEG activity in drug-naive schizophrenia subjects pre- and post-treatment with antipsychotics in comparison with traditional EEG analysis. We recorded eyes-closed resting-state EEG from frontal, temporal, parietal, and occipital regions in drug-naive 22 schizophrenia and 24 age-matched healthy control subjects. Fifteen patients were re-evaluated within 2–8 weeks after the initiation of antipsychotic treatment. For each participant, MSE was calculated on one continuous 60-s epoch for each experimental session. Schizophrenia subjects showed significantly higher complexity at higher time scales (lower frequencies) than did healthy controls in fronto-centro-temporal, but not in parieto-occipital regions. Post-treatment, this higher complexity decreased to healthy control subject levels selectively in fronto-central regions, while the increased complexity in temporal sites remained higher. Comparative power analysis identified spectral slowing in frontal regions in pre-treatment schizophrenia subjects, consistent with previous findings, whereas no antipsychotic treatment effect was observed. In summary, multiscale entropy measures identified abnormal dynamical EEG signal complexity in anterior brain areas in schizophrenia that normalized selectively in fronto-central areas with antipsychotic treatment. These findings show that entropy-based analytic methods may serve as a novel approach for characterizing and understanding abnormal cortical dynamics in schizophrenia and elucidating the therapeutic mechanisms of antipsychotics.

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YNIMG Journal 2010 Journal Article

Smaller insula and inferior frontal volumes in young adults with pervasive developmental disorders

Hirotaka Kosaka
Masao Omori
Toshio Munesue
Makoto Ishitobi
Yukiko Matsumura
Tetsuya Takahashi
Kousuke Narita
Tetsuhito Murata

Enlarged head circumference and increased brain weight have been reported in infants with pervasive developmental disorders (PDD), and volumetric studies suggest that children with PDD have abnormally enlarged brain volumes. However, little is known about brain volume abnormalities in young adults with PDD. We explored gray matter (GM) volume in young adults with PDD. T1-weighted volumetric images were acquired with a 3-T magnetic resonance scanner from 32 males with high-functioning PDD (23. 8±4. 2 years; Full Scale Intelligence Quotient [FSIQ]=101. 6±15. 6) and 40 age-matched normal male control subjects (22. 5±4. 3 years; FSIQ=109. 7±7. 9). Regional GM volumes were compared between the two groups using voxel-based morphometry (VBM) with the Diffeomorphic Anatomical Registration using Exponentiated Lie algebra (DARTEL). Compared with the control group, the high-functioning PDD group showed significantly less GM in the right insula, the right inferior frontal gyrus, and the right inferior parietal lobule. A conservative threshold confirmed considerably smaller volumes in the right insula and inferior frontal gyrus. In these areas, negative correlations were found between Autism Spectrum Quotient scores and GM volume, although no significant correlations were found between each subject's FSIQ and GM volume. No regions showed greater GM volumes in the high-functioning PDD group. The insular cortex, which works as a relay area for multiple neurocognitive systems, may be one of the key regions underlying the complex clinical features of PDD. These smaller GM volumes in high-functioning PDD subjects may reflect the clinical features of PDD itself, rather than FSIQ.

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