Biology subjects

Takemi, M.

Publications and source records attributed to Takemi, M..

6 recordsLinked to original sources

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.

neuroscience↗

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.

neuroscience↗

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.

neuroscience↗

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.

neuroscience↗

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.

neuroscience↗