Biology subjects

Takemi, M.

Publications and source records attributed to Takemi, M..

14 recordsLinked to original sources

bioRxiv2026

Modulating supplementary motor area excitability enhances groove-related pleasure during music listening

Pleasurable urge to move to music is often referred to as groove. Although previous studies have shown an association between the supplementary motor area (SMA) and the groove experience, its causal role remains unclear. Here, we investigated whether the SMA is causally involved in groove experience during music listening using repetitive transcranial magnetic stimulation. Fifteen healthy participants completed three sessions on separate days: excitatory stimulation (intermittent theta burst stimulation; iTBS) over the SMA, inhibitory stimulation (continuous theta burst stimulation; cTBS) over the SMA, and sham stimulation (iTBS or cTBS) over the vertex. After each stimulation session, participants listened to five high-groove and five low-groove musical excerpts and rated urge-to-move and pleasure on a 0-100 scale. Heart rate was additionally recorded as an exploratory physiological measure during music listening. Linear mixed-effects models (LMM) showed that pleasure ratings, but not urge-to-move ratings, were higher following both iTBS and cTBS compared with sham stimulation. In exploratory LMMs, reduced log-transformed heart rate variability (HRV) significantly predicted higher pleasure ratings. These findings suggest that SMA stimulation modulates the pleasurable component of the groove experience, likely via network-level mechanisms rather than a simple linear relationship between SMA excitability and pleasure. They also raise the possibility that reduced parasympathetic activity, reflected by lower HRV, mediates the stimulation-related increase in musical pleasure. Future studies should investigate the causal roles of other brain regions as well as clarify the directionality between autonomic changes and the groove experience.

neuroscience↗

bioRxiv2025

Does wearable neurofeedback training improve memory aptitudes in healthy adults?--A systematic review and meta-analysis

Neurofeedback training (NFT) provides individuals with real-time feedback on their brain activity, enabling voluntary modulation. Interest in NFT for memory enhancement has surpassed the cumulative evidence in healthy adults, especially for modalities feasible outside of laboratory settings. To address this gap, this systematic review and meta-analysis focused on electroencephalography (EEG) and functional near- infrared spectroscopy (fNIRS), both of which are portable and widely accessible. Randomized controlled trials published between January 1990 and September 2022 were retrieved from PubMed, Scopus, Web of Science, and APA PsycInfo. Of the 44 eligible studies, 24 reported sufficient data for inclusion in the meta-analysis. Using a random-effects model, we found that NFT produced a small-to-moderate improvement in memory performance (standardized mean difference = 0.28; 95% confidence interval = 0.065-0.48; t(11.9) = 2.86; p = 0.014), with moderate heterogeneity. No publication bias was detected. Subgroup meta-analyses revealed significant effects in younger adults, for EEG-based protocols, and in tasks assessing verbal and short-term memory tasks. Meta-regression identified a positive association between daily session duration and effect size, with sessions longer than 30 minutes more likely to produce positive effects. As effects also varied by targeted brain regions and EEG frequency bands used for neurofeedback, protocol differences likely contributed to the observed variability in outcomes. Long- term follow-up is warranted to determine the persistence of NFT effects.

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bioRxiv2025

Target engagement in human motor cortex induced by constant sinusoidal and amplitude-modulated transcranial AC stimulation

Transcranial alternating current stimulation (tACS) is a noninvasive technique for modulating brain oscillations. While sinusoidal tACS (sin-tACS) delivers current at a constant amplitude, amplitude-modulated tACS (AM-tACS) uses a high-frequency carrier modulated by a low-frequency envelope. We systematically compared the acute effects of sin-tACS at theta (5 Hz), alpha (10 Hz), beta (20 Hz), and gamma (140 Hz) frequencies, and AM-tACS (140 Hz carrier frequency modulated at theta, alpha, or beta) on corticospinal excitability. Healthy participants received 2 mA peak-to-peak tACS to the primary motor hand area (M1HAND) via a bipolar montage (M1HAND-Pz). Each tACS block consisted of ten 30-second stimulation periods interleaved with 6-second pauses, followed by 11 minutes without stimulation. Corticospinal excitability was assessed during each block using single-pulse transcranial magnetic stimulation (TMS), delivered at the peak and trough of tACS. MEP amplitudes were generally larger at the trough. Only beta sin-tACS and theta AM-tACS significantly modulated corticospinal excitability. Beta sin-tACS increased MEP amplitudes in early stimulation epochs, while theta AM-tACS facilitated MEPs in later stimulation epochs and this facilitation persisted briefly after stimulation ended. Participants with stronger early responses to beta sin-tACS also tended to show greater delayed effects with theta AM-tACS. These excitability changes during tACS were not predicted by simulated electric field strength. A follow-up EEG experiment revealed that beta sin-tACS increased beta power over left sensorimotor cortex, while theta AM-tACS decreased beta power over midline parietal cortex. These EEG changes were restricted to tACS pauses. The results show that sin-tACS and AM-tACS can both modulate corticospinal excitability, but functional changes differ in temporal dynamics, frequency specificity, and cortical region engagement.

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bioRxiv2025

Neural correlates of individual variability in reward-based motor learning

Individual differences in motor learning are linked to variability in the neural processes associated with feedback processing and motor memory retention. This study investigated the neural correlates of reward-based motor learning and focused on two electrophysiological markers: event-related desynchronization (ERD) in the sensorimotor cortex and feedback-related negativity (FRN) from frontal EEG channels. Sixty-four healthy adults performed a visuomotor rotation task with monetary reward or punishment feedback. Learning amount, defined as the degree of error compensation, and retention amount, defined as the maintenance of adapted motor behavior in a no-vision condition, were quantified. Scalp EEG was recorded to assess alpha (8-13 Hz) and beta (15-30 Hz) ERD over the primary motor cortex (M1) during movement preparation and FRN amplitude following feedback presentation. Stepwise regression revealed that FRN amplitude in the late adaptation phase was associated with learning amount, but only among participants with robust event-related potential (ERP) responses (amplitude > {+/-}5 {micro}V). This finding suggests that greater neural sensitivity to feedback supports better learning. In contrast, alpha ERD magnitude in the late adaptation phase, along with reinforcement conditions, was a significant predictor of motor skill retention in the full sample, although no interaction effect was observed. These findings suggest that FRN and alpha ERD reflect dissociable neural mechanisms underlying learning and retention, respectively, with FRN indexing feedback sensitivity and alpha ERD reflecting cortical excitability related to memory consolidation. The absence of interaction effects between neural markers and reinforcement conditions further supports the idea that these processes contribute independently to motor adaptation. Practically, combining reward-based training with interventions that increase M1 excitability may enhance retention, while tailoring feedback strategies to maximize FRN responses may improve learning efficiency. These findings provide novel insights into the neural basis of individual variability in motor learning and suggest avenues for personalized approaches in rehabilitation and skill learning.

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bioRxiv2025

Transcranial electrical stimulation for memory enhancement: A systematic review and meta-analysis

BackgroundNon-invasive brain stimulation techniques have received increasing interest for their potential to enhance memory function, a fundamental cognitive aspect of daily life. MethodsThis systematic review and meta-analysis investigated the efficacy of transcranial electrical stimulation (tES) in enhancing memory function in healthy adults, following the pre-registered strategy at PROSPERO (CRD42022353630). ResultsA total of 66 articles (119 trials, 3,786 participants) focusing on transcranial direct current stimulation and transcranial alternating current stimulation were identified. Meta-analysis revealed a significant overall effect of tES on memory function compared with sham stimulation (standardized mean difference [95% confidence interval] = 0.19 [0.12-0.27]), with anodal transcranial direct current stimulation showing the most consistent enhancement. In particular, stimulation of the frontal regions effectively improved working and declarative memories. While the effects remained significant within hours post-stimulation, they diminished after one day or longer. Regarding adverse events, tingling and itching sensations on the scalp occurred more frequently in the active group than in the sham group, but no severe adverse events were reported. Challenges, including publication bias, heterogeneity, and bias toward specific aspects of memory were noted, emphasizing the need for improved experimental rigor and diversification of memory tasks. ConclusionThese findings highlight the potential of tES as a safe and effective tool for memory enhancement while emphasizing areas for future research to develop its applications.

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bioRxiv2025

Quantifying state-dependent control properties of brain dynamics from perturbation responses

The brain can be conceptualized as a control system facilitating transitions between states, such as from rest to motor activity. Applying network control theory to measurements of brain signals enables characterization of brain dynamics through control properties. However, most prior studies that have applied network control theory have evaluated brain dynamics under unperturbed conditions, neglecting the critical role of external perturbations in accurate system identification. In this study, we combine a perturbation input paradigm with a network control theory framework and propose a novel method for estimating the controllability Gramian matrix in a simple, theoretically grounded manner. This method provides insights into brain dynamics, including overall controllability (quantified by the Gramians eigenvalues) and specific controllable directions (represented by its eigenvectors). As a proof of concept, we applied our method to transcranial magnetic stimulationinduced electroencephalographic responses across four motor-related states and two resting states. We found that states such as open-eye rest, closed-eye rest, and motor-related states were more effectively differentiated using controllable directions than overall controllability. However, certain states, like motor execution and motor imagery, remained indistinguishable using these measures. These findings indicate that some brain states differ in their intrinsic control properties as dynamical systems, while others share similarities that make them less distinguishable. This study underscores the value of control theory-based analyses in quantitatively how intrinsic brain states shape the brains responses to stimulation, providing deeper insights into the dynamic properties of these states. This methodology holds promise for diverse applications, including characterizing individual response variability and identifying conditions for optimal stimulation efficacy. Significant statementThe brain can be viewed as a control system transitioning between states, such as from rest to motor activity. Previous studies using network control theory mostly evaluated brain dynamics without external perturbations, neglecting their role in accurate system identification. This study integrates perturbation inputs with network control theory to propose a method for estimating the controllability Gramian, thereby providing insights into brain dynamics. We applied this approach to TMS-induced EEG responses in motor-related and resting states. Our findings show that controllable directions (eigenvectors) allow better discrimination between states than overall controllability. Our method can quantitatively assess brain state differences, and has potential applications in characterizing individual response variability and optimizing stimulation efficacy.

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bioRxiv2025

Successive failure triggered by motor exploration in a reinforcement-based reaching task

Motor exploration, a key process in reinforcement-based motor learning, is triggered by suboptimal performance and leads to increased movement variability. Consequently, failure in one trial may increase the likelihood of failure in subsequent trials. If this pattern emerges, successive failures (SFs) are not merely events to be avoided but part of the trial-and-error process of identifying optimal movements, which can facilitate motor learning. This study investigated whether and how SFs occur above chance levels during a motor learning task with binary success/failure feedback and explored the relationship between SFs and motor learning outcomes. Thirty-three healthy young adults participated in the study, performing a reaching task to pass through a target without visual feedback of their hand position. Binary feedback was provided after each trial, indicating whether the hand trajectory overlapped with the target. The results showed that the probability of two SFs was significantly higher than the square of the overall failure probability, indicating that failure streaks occurred above chance levels. A computational model, in which motor variability comprised constant motor noise and exploratory variability regulated by recent reward history (where variability increased following failure), successfully explained SF emergence. However, the learning index, defined as the difference in failure probability between the first and latter halves of the experiment, was unrelated to SF emergence. Additionally, failure streaks disappeared when participants were asked to reach one of seven randomly selected targets in each trial, suggesting that introducing environmental variability can help alleviate SFs.

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bioRxiv2024

Electroencephalographic Biomarkers of Relaxation: A Systematic Review and Meta-analysis

The human electroencephalogram (EEG) is composed of synchronous oscillations within characteristic frequency bands, including 8-13 Hz alpha oscillations that often appear during relaxation. Relaxation is critical for physical and mental health, but the extent to which various EEG components reflect relaxation remains uncertain. This systematic review and meta-analysis investigated associations between EEG components and concurrently measured reference indices of relaxation in healthy adults. A comprehensive database search and screening using preset criteria identified 38 studies involving 1,120 participants published between January 1940 and January 2022 for qualitative synthesis. These studies used various reference relaxation measures such as electrocardiographic indices related to parasympathetic nervous system activity and introspective indices obtained through questionnaires. Risks of bias were evaluated following the risk of bias assessment tool for nonrandomized studies. A meta-analysis of 23 studies using a random-effects model revealed positive correlations between relaxation index and the power of alpha oscillations at central channels (Fishers z-transformed correlation coefficient and [95% confidence interval]: 0.23 [0.10-0.36]) and frontal channels (0.16 [0.02-0.31]). The correlation was significantly higher for the central channel compared with other channels. No significant correlations were detected between relaxation indices and other EEG frequencies or channels. The causal relationships between relaxation and alpha power at central and frontal channels warrant further study.

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bioRxiv2024

Posture-dependent modulation of marmoset cortical motor maps detected via rapid multichannel epidural stimulation

In this study, rapid topographical changes were detected in the forelimb motor maps in the primary motor cortex (M1) of awake marmoset monkeys using our previously developed accurate short-time stimulation mapping procedure (Takemi et al. 2017; Kosugi et al. 2018). The results revealed that although the hotspot (the location in M1 that elicited a forelimb muscle twitch with the lowest stimulus intensity) remained constant across postures, the stimulus intensity required to elicit the forelimb muscle twitch in the perihotspot region and the size of motor representations were posture-dependent. Hindlimb posture was particularly effective in inducing these modulations. The angle of the body axis relative to the gravitational vertical line did not alter the motor maps. These results provide a proof of concept that a rapid stimulation mapping system with chronically implanted cortical electrodes can capture the dynamic regulation of forelimb motor maps in natural conditions. The flexible nature of the motor maps necessitates the reconsideration of the results of motor control and neuroplasticity studies. Neural mechanisms regulating forelimb muscle representations in M1 by the hindlimb sensorimotor state warrant further exploration.

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bioRxiv2023

Efficacy of neurofeedback training for improving attentional performance in healthy adults: A systematic review and meta-analysis

This systematic review and meta-analysis examined the NFT effects on attentional performance in healthy adults. Six databases were searched until June 2022 to identify parallel randomized controlled trials (RCTs) evaluating attentional improvements after NFT. Risk of bias was assessed using the Cochrane Collaboration tool. We identified 41 RCTs for qualitative synthesis and 15 RCTs (569 participants) for meta-analysis. The overall NFT effect on attentional performance was significant (standardized mean difference = 0.27, 95% confidence interval = 0.10-0.44). However, no significant pooled effect was found within the trials comparing its effect with sham NFT (8 RCTs). Additionally, variable effects were observed on individual subsets of attentional performance. Further sham-controlled RCTs are required to validate the improvement of attentional performance with NFT.

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bioRxiv2022

Two common issues in synchronized multimodal recordings with EEG: Jitter and Latency

Multimodal recording using electroencephalogram (EEG) and other biological signals (e.g., electromyograms, eye movement, pupil information, or limb kinematics) is ubiquitous in human neuroscience research. However, the precise time alignment of data from heterogeneous sources is limited due to variable recording parameters of commercially available research devices and experimental setups. Here, we introduced the versatility of a Lab Streaming Layer (LSL)-based application for multimodal recordings of high-density EEG and other devices such as eye trackers or hand kinematics. To introduce the benefit of recording multiple devices in a time-synchronized manner, we discuss two common issues in measuring multimodal data: jitter and latency. The LSL-based system can be used for research on precise time-alignment of datasets, such as detecting stimulus-induced transient neural responses and testing hypotheses well-formulated in time by leveraging the millisecond time resolution of the system.

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bioRxiv2022

Looking for a sign forecasting failure in actions: reaching errors triggered by a slowdown of movement and specific brain activity in preceding trials

Even experts can sometimes fail while performing fully learned movements. Do such failures suddenly arise, or are there any forecasting signs? It has been reported that the kinematics of the early phase of movements can predict the failure, and brain activity patterns specific to failures are observed just before the movement onset. The presence of abnormal brain activity patterns long before (> 30 s) a failure in a cognitive task leads us to question if signs of a failure in action could exist in trials preceding the failure. Here, we examined this question using a reaching movement adaptation paradigm conventionally used to test motor learning dynamics. Firstly, the presence of a behavioral sign that preceded failures was observed: the peak velocity of the reaching movement significantly decreased in the preceding two trials. Secondly, specific theta and alpha band activity of EEG were observed in the failure trials and the trials preceding the failure. These results suggest that a failure in actions does not occur suddenly, and some signs preceding failures can be observed in the prior trials. Our approach may pave the way to investigate how we prevent failures and improve motor performance.

neuroscience↗

bioRxiv2022

Neurofeedback training for improving motor performance in healthy adults: A systematic review and meta-analysis

Neurofeedback training (NFT) refers to a training where the participants voluntarily aim to manipulate their own brain activity using the sensory feedback abstracted from their brain activity. NFT has attracted attention in the field of motor learning for its potential to become an alternative or additional training method for general physical training. In this study, a systematic review of NFT studies for motor performance improvements in healthy adults and a meta-analysis on the effectiveness of NFT were conducted. To identify relevant studies published between January 1st, 1990 to August 3rd, 2021, a computerized search was performed using the databases, Web of Science, Scopus, PubMed, JDreamIII, and Ichushi-Web. Thirty-two studies were identified for the qualitative synthesis and 13 randomized controlled trials (286 subjects) for the meta-analysis. The meta-analysis revealed significant effects of NFT for motor performance improvement examined at the timing after the last NFT session (standardized mean difference = 0.96, 95% CI = 0.40-1.53), but with the existence of publication biases and substantial heterogeneity among the trials. Subsequent subgroup meta-analysis demonstrated reliable benefits when the NFT is performed longer than 1 week. The effectiveness of NFT for each motor performance measurement (e.g., speed, accuracy, and hand dexterity) remains unclear because of high heterogeneity or due to small sample size. Further accumulation of empirical NFT studies for motor performance improvement will be necessary to provide reliable evidence about the NFT effects on specific motor skills and to safely incorporate NFT into real-world scenarios.

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bioRxiv2022

Multi-pulse transcranial magnetic stimulation of human motor cortex produces short-latency corticomotor facilitation via two distinct mechanisms

BackgroundSingle-pulse transcranial magnetic stimulation of the precentral hand representation (M1HAND) can elicit indirect waves in the corticospinal tract at a periodicity of ~660 Hz, called indirect or I-waves. These synchronized descending volleys are produced by transsynaptic excitation of fastconducting monosynaptic corticospinal axons in M1-HAND. Paired-pulse TMS can induce short-interval intracortical facilitation (SICF) of motor evoked potentials (MEPs) at inter-pulse intervals that match I-wave periodicity. ObjectiveTo examine whether short-latency corticospinal facilitation engages additional mechanisms independently of I-wave periodicity. MethodsIn 19 volunteers, one to four biphasic TMS pulses were applied to left M1-HAND with interpulse interval was adjusted to the first peak or first trough of the individual SICF curve. TMS was applied at different intensities to probe the intensity-response relationship. ResultsPairs, triplets, or quadruplets at individual peak-latency facilitated MEP amplitudes across a wide range of TMS intensities compared to single pulses. Multi-pulse TMSHAND at individual troughlatency also produced a consistent facilitation of MEP amplitude. Short-latency facilitation at trough-latency was less pronounced than short-latency facilitation at peak-latency, but the relative difference in facilitation decreased with increasing stimulus intensity. Increasing the number of pulses from two to four pulses had only a modest effect on MEP facilitation. ConclusionTwo mechanisms underly short-latency corticomotor facilitation caused by biphasic multi-pulse TMS. An intracortical mechanism is related to I-wave periodicity and engages fast-conducting direct projections to spinal motoneurons. A second corticospinal mechanism does not rely on I-wave rhythmicity and may be mediated by slower conducting indirect pyramidal tract projections from M1-HAND to spinal interneurons. The latter mechanism deserves more attention in TMS studies of the corticomotor system.

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