Journal of neurophysiology最新文献

{"title":"Motor cortex contribution to dynamic force regulation in the index finger revealed by TMS interference.","authors":"Amit Kadosh, Orit Wonderman Bar Sela, Shay Ofir Geva, Afnan Muhana, Silvi Frenkel-Toledo, Nachum Soroker, Firas Mawase","doi":"10.1152/jn.00057.2026","DOIUrl":"10.1152/jn.00057.2026","url":null,"abstract":"<p><p>Lifting a paper cup without crushing it requires precise regulation of finger force. In humans, such control is thought to rely primarily on the contralateral corticospinal tract (CST), but the cortical mechanisms underlying graded force modulation remain unclear. To address this, we used online repetitive transcranial magnetic stimulation (rTMS) as a transient interference during an isometric index finger force-tracking task. Eleven healthy adults increased and decreased index finger isometric force at low (0-20% maximal voluntary contraction, MVC) and high (0-60% MVC) levels, while 2-s trains of 10-Hz rTMS were delivered over contralateral or ipsilateral primary motor cortex (M1; cM1, iM1) or a midline control site (Pz). Accuracy, consistency, and force smoothness were quantified using RMSE, SDAE, and normalized YankRMS within the 2-s stimulation windows, and outcomes were normalized to Pz. Factorial mixed-effects analysis showed a significant main effect of stimulation-site (Condition) across all three measures (all <i>P</i> < 0.0022). Holm-adjusted comparisons showed greater disruption during cM1 than iM1 stimulation and no-TMS, whereas iM1 did not differ from no-TMS. For YankRMS, the condition × intensity interaction was significant (<i>P</i> = 0.0031), with a larger cM1-iM1 difference at the higher force level (60% MVC) than at the lower force level (20% MVC; interaction contrast, <i>P</i> = 0.0033). No other task-dependent interactions were significant. These findings provide time-locked causal evidence that ongoing cM1 activity is essential for dynamic index finger force regulation, with the contralateral-ipsilateral asymmetry becoming more pronounced at higher force demands.<b>NEW & NOTEWORTHY</b> Fingertip force regulation underlies everyday grasping, lifting, and object release. Although the corticospinal tract supports skilled hand control, the causal role of motor cortex in graded force modulation is unclear. Using online rTMS during isometric tracking, we show that interference over contralateral M1 disrupts accuracy, consistency, and force smoothness more than ipsilateral M1 interference. The contralateral-ipsilateral difference in force smoothness was larger at higher forces, identifying force demand as a determinant of motor-cortical involvement in fine force control.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"1654-1665"},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149025103","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optogenetic control of activity in descending <i>Tdc²⁺</i> neurons modulates motor program bias in the <i>Drosophila</i> larval locomotor system.","authors":"William V Smith, Karen L Hibbard, Stefan R Pulver","doi":"10.1152/jn.00302.2026","DOIUrl":"10.1152/jn.00302.2026","url":null,"abstract":"<p><p>Motor systems must flexibly select between competing outputs while preserving stability of rhythmic outputs. In <i>Drosophila</i> larvae, the isolated central nervous system is capable of maintaining rhythmicity by generating multiple different fictive motor programs. The biogenic amines octopamine and tyramine are known to regulate larval locomotion, however, how the <i>tdc²⁺</i> octopaminergic/tyraminergic system regulates motor program competition is not well understood. Here, we combine dual-color calcium imaging and optogenetic manipulation to explore how <i>tdc²⁺</i> neurons track, permit, and bias fictive motor activity in third instar <i>Drosophila</i> larvae. We find that <i>tdc²⁺</i> activity in the larval ventral nerve cord is strongly coupled to motor neuron activity across multiple fictive behaviors, indicating that the system is recruited broadly across the motor repertoire. Optogenetic depolarization of <i>tdc²⁺</i>neurons increases motor root bursting and induces a robust fictive forward bias, whereas optogenetic hyperpolarization suppresses or abolishes fictive rhythms and generates a short-lasting, postinhibitory rebound in fictive activity. Spatially restricted stimulation reveals that posterior abdominal activation is especially effective at promoting fictive forward activity. Separating ventral nerve cord (VNC)-residing from brain-residing <i>tdc²⁺</i> populations further shows that activation of descending brain-residing <i>tdc²⁺</i> projections is sufficient to recapitulate this forward bias. Finally, <i>tdc²⁺</i> activation induces short-lived poststimulation changes in motor program probability, including transient elevation of competing fictive backward instantaneous frequency. Together, these findings suggest that <i>tdc²⁺</i> neurons act as a permissive and biasing modulatory layer within larval motor circuits, linking adrenergic-like signaling to motor program competition.<b>NEW & NOTEWORTHY</b> Rhythmically active motor systems must continually cycle between competing motor programs. How biogenic amines regulate competition among competing central pattern generating networks is not well understood. Here, we use calcium imaging and optogenetics to explore how a population of adrenergic-like neurons establishes and controls biases in motor programs. What is new and novel is that we uncover a modulatory layer that appears to control biases as well as form a core component of rhythm generation.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"1623-1639"},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149061846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Theta-gamma transcranial alternating current stimulation and complex visuomotor training in healthy young adults.","authors":"Noah J Tilley, John Cirillo, George M Opie, John G Semmler","doi":"10.1152/jn.00219.2026","DOIUrl":"10.1152/jn.00219.2026","url":null,"abstract":"<p><p>Theta-gamma (TG) transcranial alternating current stimulation (tACS) is a noninvasive brain stimulation technique that can improve performance of simple motor tasks when applied over the primary motor cortex (M1). However, the effects of TG tACS on performance of more complex motor tasks remain to be investigated. Forty healthy young (mean age 25.8 ± 5.1 yr) individuals were recruited to receive either 20 min of TG (75 Hz gamma burst nested at the peak of a 6 Hz theta wave) or sham tACS over M1 during training of a sequential visual isometric pinch force task (SVIPT). Skill was quantified as a function of speed and accuracy and was used to index changes in performance. Transcranial magnetic stimulation was used to assess corticomotor excitability and intracortical inhibition before and after the intervention. We found that skill increased during training (<i>P</i> < 0.001), but there was no difference between interventions (<i>P</i> = 0.729). Furthermore, training increased corticomotor excitability (<i>P</i> < 0.001), but did not modulate intracortical inhibition (<i>P</i> = 0.328), and this was not different between interventions (<i>P</i> > 0.196). Overall, our results suggest that the TG tACS applied over M1 has limited impact on neurophysiological and behavioral effects of complex visuomotor training in young healthy adults.<b>NEW & NOTEWORTHY</b> Application of theta-gamma transcranial alternating current stimulation (TG-tACS) over the primary motor cortex does not enhance visuomotor performance in young healthy adults. Given that visuomotor improvements likely rely on interactions across multiple nodes of the visuomotor network, future research should investigate the effects of TG-tACS targeting other brain regions to better define its potential for improving visuomotor performance.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"1489-1497"},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148990262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Far-periphery retinotopy reveals a nonlinear relationship between pRF size and eccentricity.","authors":"Pei-Yin Chen, Atsushi Wada","doi":"10.1152/jn.00256.2026","DOIUrl":"10.1152/jn.00256.2026","url":null,"abstract":"<p><p>The population receptive field (pRF) size is known to increase with the visual field eccentricity in the human visual cortex, and this relationship is generally assumed to be linear. However, conventional functional magnetic resonance imaging (fMRI) visual stimulation methods limit measurements largely to the central visual field, leaving the far periphery less explored. Here, we utilized wide-view stimulation to examine whether the linear pRF size-eccentricity relationship extends to the far periphery. The retinotopic stimuli consisted of rotating wedges and contracting concentric rings with checkerboard textures moving across the visual field. Observers viewed the stimuli through a wide-view binocular visual stimulation system in an MRI scanner, which allowed the visual presentation to cover approximately 90° in the visual field. We applied a two-dimensional (2-D) Gaussian pRF model to the blood oxygenation level-dependent (BOLD) activations of voxels in areas V1 to V3, hV4, and V3A/B. The relationship between the pRF size and eccentricity from the fovea to the far periphery is better captured by a nonlinear regression function than by the linear functions commonly used in previous central vision studies. Further analysis of the relationship between the pRF estimates and cortical surface location revealed that in areas V1 to V3, the pRF eccentricity and size increased with increasing cortical distance up to certain values before either saturating or decreasing. Notably, these transitions occurred at different cortical distances, revealing distinct cortical-distance dependencies of pRF eccentricity and size that characterize their nonlinear relationship in the far periphery.<b>NEW & NOTEWORTHY</b> We tested whether the generally assumed linear population receptive field (pRF) size-eccentricity relationship in the central visual field extends to the far periphery in the human visual cortex. Different from the central visual field observations, our wide-view pRF measurements revealed a nonlinear pRF size-eccentricity relationship in the early visual areas. This nonlinear relationship suggests different organizational patterns between the central and the far-peripheral visual fields.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"1498-1509"},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149001911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Direct cortical stimulation induces short-term modulation of neural oscillations in humans.","authors":"Saachi Munot, Naryeong Kim, Yuhao Huang, Corey J Keller","doi":"10.1152/jn.00011.2026","DOIUrl":"10.1152/jn.00011.2026","url":null,"abstract":"<p><p>Patterned brain stimulation is commonly employed to modulate brain circuits and treat neuropsychiatric disorders. Although it is widely used in clinical settings, there remains limited understanding of how stimulation alters neural oscillations and how these effects relate to baseline evoked network responses. To address this question, we applied 15 min of 10-Hz focal electrical stimulation delivered as 5-s trains separated by 10-s rest intervals, a pattern resembling \"excitatory\" transcranial magnetic stimulation, to 14 patients with epilepsy undergoing intracranial electroencephalography in premotor, parietal, and temporal cortical sites. We quantified spectral features of cortico-cortical evoked potentials (CCEPs) before and after stimulation. We hypothesized that the temporal and spectral components of the CCEP predicted the location and degree of stimulation-induced modulation. Across patients, low-frequency power (alpha, beta) showed the broadest change, whereas the magnitude of change was stronger in high frequencies (beta, gamma). Next, we demonstrated that regions with stronger prestimulation evoked spectral responses were more likely to exhibit larger poststimulation spectral changes. These findings were specific to frequency in a temporal window. Poststimulation power changes were driven by interaction between direction of change in prestimulation power and temporal window. Finally, regions exhibiting early increases and late decreases in prestimulation power exhibited power changes after stimulation. These patterns were consistent across premotor, parietal, and temporal sites, but the magnitude and latency varied by stimulation location. Together, these findings demonstrate that time-frequency prestimulation features predict poststimulation modulation of human neural oscillations and highlight temporally specific, state-dependent properties of stimulation responses in humans, thereby improving our understanding of stimulation-associated changes in human brain networks and helping inform more effective brain stimulation techniques.<b>NEW & NOTEWORTHY</b> Brain stimulation treats neuropsychiatric disorders, yet spectral changes remain poorly understood. We performed patterned stimulation in epilepsy patients, using intracranial recordings to study oscillatory plasticity. We found predictable changes: low frequencies were widespread, whereas high frequencies showed greater magnitude. These shifts were predicted by prestimulation activity. Our study reveals that baseline brain states determine spectral plasticity, providing insights to optimize stimulation techniques and understand human brain dynamics.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"1666-1679"},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149111032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Topical capsaicin produces secondary mechanical hyperalgesia without a group-level increase in tonic heat pain summation in healthy adults.","authors":"Spencer Potter, Edna Banjanovic, Nireen Abunahla, Jay Shah, John Srbely","doi":"10.1152/jn.00548.2025","DOIUrl":"10.1152/jn.00548.2025","url":null,"abstract":"<p><p>Central sensitization can produce secondary mechanical hyperalgesia; however, secondary thermal hyperalgesia remains controversial. This study investigated whether topical capsaicin alters temporal summation to tonic heat-pain within regions of secondary mechanical hyperalgesia. Twenty-six healthy adults (19 women, 7 men; 22.5 ± 3.5 yr) completed a participant- and investigator-masked, placebo-controlled, crossover protocol (≥1-wk washout) with topical capsaicin (0.075% Zostrix) or placebo (Lubriderm) applied to C5-C6 dermatomes. Temporal summation to tonic heat pain was assessed at 46.5°C for 120 s and quantified as the area under the pain-time curve (AUC). Mechanical summation used weighted pinprick (256 mN, 16 stimuli, 1 Hz) and was quantified using Sumscore. Outcomes were measured at baseline, 10-, 20-, and 30-min postintervention. Secondary mechanical hyperalgesia was induced postcapsaicin, with a significant main effect of intervention [<i>F</i>(1,24) = 4.77, <i>P</i> = 0.039]; the main effect of time and the time × intervention interaction were not significant, and no individual time point comparison survived multiplicity adjustment. Temporal summation to tonic heat pain within secondary hyperalgesic regions showed no significant effects of time, intervention, or time × intervention (<i>P</i> > 0.05). Within-subject analysis revealed 18/26 participants (69%; 95% CI: 0.48 to 0.86) with higher peak thermal AUC postcapsaicin versus placebo (two-sided <i>P</i> = 0.076), but exhibiting substantial individual heterogeneity. Topical capsaicin-induced central sensitization produced significant secondary mechanical hyperalgesia but no statistically significant group-level increase in temporal summation of heat pain. This modality-specific pattern using the current protocol does not exclude a moderate thermal effect. The substantial interindividual variability observed in this exploratory within-subject analysis was not statistically significant and is hypothesis generating.<b>NEW & NOTEWORTHY</b> This is, to our knowledge, the first double-blind, placebo-controlled, crossover study to quantify temporal summation of heat pain within regions of secondary hyperalgesia using an extended tonic thermal stimulus. Capsaicin-induced central sensitization produced significant secondary mechanical hyperalgesia without a statistically significant group-level increase in tonic heat summation. The findings describe a modality-specific pattern under this protocol and should not be interpreted as proof that thermal sensitization is absent.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"1544-1556"},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149061822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Adaptive eye movement behavior for actions in younger and older adults.","authors":"Anna Schroeger, Leonard Gerharz, Dimitris Voudouris","doi":"10.1152/jn.00023.2026","DOIUrl":"10.1152/jn.00023.2026","url":null,"abstract":"<p><p>Humans use eye movements to track and interact with moving objects. When motion trajectories are predictable, gaze shifts to future locations, such as a ball's bounce point, could help to overcome sensorimotor delays associated with the ball's future trajectory. These delays can become more pronounced with aging. This study examined whether older adults compensate for sensorimotor delays through stronger reliance on predictive gaze shifts to positions of interest. We recorded gaze and hand movements of younger and older adults playing an iPad version of \"Pong\" against an automated opponent. Participants moved either a large or a small paddle to intercept a ball that moved at two possible constant speeds and bounced off side walls. Both groups intercepted fewer balls when the paddle was small and the ball moved faster. Contrary to our hypothesis, older participants looked later than younger adults to the final wall bounce before the ball approached their paddle. However, they shifted their gaze earlier to their own paddle before interception, especially in the early phases of the experiment. Importantly, predictive gaze shifts to the ball's final bounce location were strongly linked to better performance. The adoption of predictive gaze shifts became more pronounced with more exposure to the experiment in both groups, indicating preserved learning and adaptive mechanisms across the lifespan. Overall, gaze allocation patterns remained similar across age groups, but aging specifically enhanced predictive gaze to where manual interactions are expected to happen.<b>NEW & NOTEWORTHY</b> Younger and older adults rely on similar visuomotor strategies. However, older adults exhibit delayed hand movements. They appear to compensate for motor slowing by maintaining predictive gaze shifts until the moment of acting, whereas younger adults reduce their predictions around that moment. Both groups showed learning of predictive gaze strategies over the time of the experiment.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"1475-1488"},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148919739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Major advances in carotid body research: then and now.","authors":"Rodrigo Iturriaga, David C Andrade, Julio Alcayaga","doi":"10.1152/jn.00180.2026","DOIUrl":"10.1152/jn.00180.2026","url":null,"abstract":"<p><p>The carotid body (CB) was anatomically described in the 18th century, and by the early 20th century, it was established as the principal peripheral chemoreceptor that senses arterial blood Po₂, Pco₂, and [H⁺], thereby mediating cardiorespiratory reflex responses. However, the absence of modern electrophysiological and molecular techniques limited the mechanistic insight into stimulus transduction. For decades, the research was dominated by unresolved debates over the mechanisms underlying O₂ and CO₂-H⁺ sensing and the role of putative excitatory transmitters such as dopamine, acetylcholine, and ATP. These uncertainties reflected a major gap between integrative physiology and molecular mechanisms. Since the late 1980s, the situation has changed considerably. Electrophysiological, molecular, and genetic studies have shown that O₂ sensing in glomus cells depends on the coupling between metabolic signals derived from the mitochondrial oxidative metabolism and K⁺ channels activity in the cell membrane. Over the past 20 years, a growing body of evidence has highlighted a novel role for the CB in autonomic-related diseases. An abnormal CB chemosensory overactivity has emerged as an active driver for autonomic dysfunction, featured by sympathetic excitation in conditions such as heart failure, obstructive sleep apnea, severe hypertension, and metabolic alterations. In this review, we will analyze major advances in CB research and the conceptual change from a passive sensor to a key contributor to sympathetic-mediated cardiometabolic diseases.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"1442-1463"},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148990273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing hearing and hearing loss in mice with OpenSABR (Open-source System for Auditory Brainstem Response)","authors":"Rowan Gargiullo, Cedric Bowe, Abigail F McElroy, Jessica Mai, William N Goolsby, Chris C Rodgers","doi":"10.1152/jn.00125.2026","DOIUrl":"10.1152/jn.00125.2026","url":null,"abstract":"<p><p>The auditory brainstem response (ABR) is a measure of the neurophysiological response to sound, widely used in clinical and research settings. Here, we describe OpenSABR (\"Open-source System for ABR\"), an open-source system for measuring the ABR that is more flexible and about 50 times cheaper than closed-source alternatives. The heart of our system is the commercially available Texas Instruments ADS1299 chip for multichannel differential recording. We designed auxiliary hardware and software to record and visualize the ABR. To demonstrate high-quality recording, we measured the response in mice to free-field auditory clicks from the left and right. We show that OpenSABR yields data consistent with prior work, introduce new methods for analyzing ABR waveforms, benchmark these methods against existing tools, compare variability within and between individuals, and detect the decreased auditory sensitivity associated with conductive hearing loss. Unlike proprietary alternatives, our system is highly flexible and could be customized for recording other biosignals like electromyography (EMG), electrocardiography (ECG), and sensory or motor evoked potentials. The low cost of OpenSABR (about $400) could broaden access to biosignal recording in research and education. This system is intended for research purposes and is not evaluated or approved for clinical use in humans, but if validated its low cost could broaden access to diagnosis of hearing and balance disorders.<b>NEW & NOTEWORTHY</b> We present Open-source System for ABR (OpenSABR), a new and open-source system for recording the auditory brainstem response (ABR) that costs about 50-fold less than some commercial alternatives. All hardware designs, software, and data are freely available. We demonstrate high-quality recordings in mice and new methods for quantifying the ABR, and we show that OpenSABR can detect threshold changes after hearing loss.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"1369-1386"},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13634598/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148919665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improved stability and interpretability of motor modules computed with an autoencoder.","authors":"Siddharth R Nathella, Bryant A Seamon, Aaron Young, Lena H Ting","doi":"10.1152/jn.00565.2025","DOIUrl":"10.1152/jn.00565.2025","url":null,"abstract":"<p><p>Motor module analysis is an important tool in the study of movement, particularly in people with impaired neural control. The most common method for computing motor modules is non-negative matrix factorization (NMF), which identifies a matrix of motor modules and their corresponding time-series activity from electromyography data. NMF has several limitations, including dependence of the muscle weightings on the number of modules selected. Approaches for selecting the number of modules vary between studies, making it difficult to compare and reproduce results. Some metrics of motor control complexity use the variance accounted for when extracting a single motor module (VAF₁), yet that module's structure offers little biomechanical interpretability. In this work, we present a method for computing motor modules using an autoencoder, a neural network architecture that can find latent representations of data. Using a single-layer autoencoder, we extracted motor modules from data in able-bodied individuals and poststroke individuals. The structure of autoencoder-computed modules was significantly less sensitive to the selected number of modules. With the autoencoder-computed modules, increasing the number of modules added new information, instead of splitting previous modules. Autoencoder-computed modules, especially at low module counts, had more distinct and interpretable biomechanical functions. Lastly, the autoencoder-computed modules are consistent with previous NMF studies in persons with stroke, which found fewer modules needed to explain the muscle activity of paretic limbs. Our autoencoder-based method offers a new approach for computing motor modules, with advantages of better stability in module structure across module counts, and a more biomechanically relevant interpretation of VAF₁.<b>NEW & NOTEWORTHY</b> This work presents an approach for computing motor modules using an autoencoder and comprehensively compares the stability of motor module structure, functional significance at low module counts, and interpretation of VAF₁ to the current state of the art. The AE-computed module structures were more stable at different module counts. The AE has the potential to improve confidence in module structure and make analysis less dependent on the specific number of modules selected.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"1431-1441"},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148919662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}