Journal of neurophysiology最新文献

{"title":"Influence of gamma transcranial alternating current stimulation frequency and intensity on motor cortex excitability in young and older adults.","authors":"John Cirillo, Brodie J Hand, Wei-Yeh Liao, George M Opie, Ryoki Sasaki, John G Semmler","doi":"10.1152/jn.00147.2025","DOIUrl":"10.1152/jn.00147.2025","url":null,"abstract":"<p><p>Gamma transcranial alternating current stimulation (tACS) over primary motor cortex (M1) has been shown to reduce gamma-aminobutyric acid (GABA)-mediated inhibition during stimulation. However, the effectiveness of gamma tACS may be influenced by various factors, such as stimulation frequency, current intensity, and age. The aim of this study was to examine whether corticomotor excitability and GABA-mediated inhibition is influenced by gamma tACS when applied at different frequencies and intensities over M1 of young and older adults. Electromyographic recordings were obtained from the right hand first dorsal interosseous muscle of 18 young and 17 older adults. Motor-evoked potential (MEP) amplitudes elicited by single- and paired-pulse transcranial magnetic stimulation were used to examine corticomotor excitability and short-interval intracortical inhibition (SICI) during gamma and sham tACS. Gamma tACS was applied at three frequencies (60 Hz, 75 Hz, and 90 Hz) and three current intensities (1.0 mA, 1.5 mA, and 2.0 mA). Corticomotor excitability during tACS was not altered by the different gamma frequencies and intensities in young and older adults. Modulation of SICI during gamma tACS was both frequency- and intensity-dependent, with more inhibition than sham for 75 Hz and at 1.5-2.0 mA, but neither was influenced by age. These findings contrast with previous studies, showing that reduced SICI during gamma tACS is not a consistent outcome. Further investigation that includes a greater range of frequencies and intensities is needed to identify the optimal dose for modulating human M1 excitability and intracortical inhibition with gamma tACS.<b>NEW & NOTEWORTHY</b> Mid-gamma transcranial alternating current stimulation (tACS) may modulate primary motor cortex (M1) GABA-mediated inhibition in a frequency- and intensity-dependent manner in both healthy young and older adults. However, reduced intracortical inhibition during gamma tACS is not a consistent finding and further investigation is needed to better understand how gamma tACS influences human M1 function across age groups.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"619-627"},"PeriodicalIF":2.1,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144682709","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":"Aging leads to predictive gaze allocation during interception.","authors":"Leonard Gerharz, Dimitris Voudouris","doi":"10.1152/jn.00029.2025","DOIUrl":"10.1152/jn.00029.2025","url":null,"abstract":"<p><p>Healthy aging is associated with a general compromise in cognitive, sensory, and motor functions, often reflected in slower and more variable sensorimotor processes. Here, we demonstrate that aging is not only marked by sensorimotor decline but is also accompanied by adaptive sensory sampling strategies during complex motor tasks. Specifically, we examined how healthy aging influences gaze allocation when intercepting a moving object within a narrow spatiotemporal margin, and hypothesized that older adults would rely more on predictive gaze allocation to the interception area. Younger (20-34 yr) and older adults (>55 yr) were asked to hit a moving target at specific hit zones on a monitor that could be inferred either with high (disk) or low (arc) spatial certainty. In two separate experiments, the target moved along unpredictable or predictable paths toward those hit zones. Older adults initiated their interceptive movement earlier than younger adults, but both achieved high interception performance. Remarkably, older adults executed predictive saccades toward the hit zones earlier than younger adults and fixated those hit zones for longer. This was particularly the case when the hit zone was of high spatial certainty. We did not find evidence for a relationship between gaze allocation patterns and interception performance. We suggest that aging can lead to a shift in gaze allocation patterns when performing spatiotemporal constrained tasks, possibly to optimize the acquisition of task-relevant visual information in the presence of age-related sensorimotor limitations.<b>NEW & NOTEWORTHY</b> Healthy aging comes with poorer sensory processing and pronounced sensorimotor delays that can impair behavior. Here, we demonstrate that older adults rely on predictive gaze allocation during interception, which enables them to maintain high motor performance. Specifically, older adults made earlier predictive gaze shifts to future interception locations compared with younger adults, while maintaining high interception performance. We suggest that gaze allocation is adaptable in aging to maintain high performance despite age-related sensorimotor limitations.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"728-740"},"PeriodicalIF":2.1,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144698815","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":"Movement-related activity in the internal globus pallidus of the parkinsonian macaque.","authors":"Daisuke Kase, Andrew J Zimnik, Yan Han, Devin R Harsch, Sarah Bacha, Karin M Cox, Andreea C Bostan, R Mark Richardson, Robert S Turner","doi":"10.1152/jn.00611.2024","DOIUrl":"10.1152/jn.00611.2024","url":null,"abstract":"<p><p>Although the basal ganglia (BG) play a central role in the motor symptoms of Parkinson's disease, few studies have investigated the influence of parkinsonism on movement-related activity in the BG. Here, we studied the perimovement activity of neurons in globus pallidus internus (GPi) of nonhuman primates (NHPs) during performance of a choice reaction time reaching task before and after the induction of parkinsonism by administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Neuronal responses, including increases or decreases in firing rate, were equally common in the parkinsonian brain as seen before MPTP, and the distribution of different response types was largely unchanged. The slowing of behavioral reaction times and movement durations following the induction of parkinsonism was accompanied by a prolongation of the time interval between neuronal response onset and movement initiation. Neuronal responses were also reduced in magnitude and prolonged in duration after the induction of parkinsonism. Importantly, those two effects were more pronounced among decrease-type responses, and they persisted after controlling for MPTP-induced changes in the between-trial variability in response timing. Following MPTP, the trial-to-trial timing of neuronal responses also became uncoupled from the time of movement onset and more variable in general. Overall, the effects of MPTP on temporal features of GPi responses were related to the severity of parkinsonian motor impairments, whereas changes in response magnitude and duration did not reflect symptom severity consistently. These findings point to a previously underappreciated potential role for abnormalities in the timing of GPi task-related activity in the generation of parkinsonian motor signs.<b>NEW & NOTEWORTHY</b> Although the globus pallidus internus (GPi) plays a central role in the cardinal symptoms of Parkinson's disease (PD), how parkinsonism alters the movement-related activity of GPi neurons remains understudied. Using a monkey model of PD, we found that: <i>1</i>) the timing of GPi responses became uncoupled from movement onset; and <i>2</i>) responses, especially decrease-type responses, became attenuated and prolonged. These abnormalities in GPi perimovement activity may contribute to the generation of parkinsonian motor signs.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"741-765"},"PeriodicalIF":2.1,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12370004/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144690570","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":"Bayesian estimation of sensory priors in human spatial orientation.","authors":"Jing Tian, Min Jung Kim, Ha-Jun Yoon, Qadeer Arshad, W Pieter Medendorp, Amir Kheradmand","doi":"10.1152/jn.00223.2025","DOIUrl":"https://doi.org/10.1152/jn.00223.2025","url":null,"abstract":"<p><p>Perception of spatial orientation relies on integration of sensory information encoding body position with external cues, such as visual inputs from the environment. Inherent variability in sensory inputs plays a critical role in how sensory information is processed. Unlike physical stimuli, neural encoding and transformation of these signals is subject to noise introduced at multiple levels within the sensory pathway. The Bayesian observer model provides a robust computational framework for understanding how the brain accommodates uncertainty to generate earth-vertical perception. Within the Bayesian framework, Gaussian <i>prior</i> distributions serve to constrain noisy sensory signals, allowing the brain to generate reliable estimates even in the presence of ambiguous input. These sensory <i>priors</i> are typically assumed to be centred at zero based on the premise that the brain defaults to upright body orientation when interpreting sensory signals. In this study, we compute the sensory <i>priors</i> associated with the eye and head orientation as two key sensory contributors to spatial orientation. These <i>priors</i> were estimated as free parameters within the Bayesian spatial model by combining measurements of subjective visual vertical (SVV) with perceived head and eye orientations. Our findings reveal that the Bayesian framework can effectively identify the sensory <i>priors</i> for eye and head orientation that contribute to spatial orientation. The results demonstrate the potential of using sensory <i>priors</i> as individualized functional markers for the neural mechanisms underlying spatial orientation.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144682690","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":"Task relevance selectively modulates sensorimotor adaptation in the presence of multiple prediction errors.","authors":"Somesh N Shingane, Nishant Rao, Neeraj Kumar, Pratik K Mutha","doi":"10.1152/jn.00511.2024","DOIUrl":"https://doi.org/10.1152/jn.00511.2024","url":null,"abstract":"<p><p>Adaptation to consistently occurring sensorimotor errors is considered obligatory in nature. We probed the robustness of this finding by asking if humans can selectively attenuate adaptation based on the task-relevance of error signals. Subjects made planar reaches to three different targets: an arc (experiment 1), a bar (experiment 2), and a point (experiment 3). During the reach, perturbations in extent (visuomotor gain), direction (visuomotor rotation) or both simultaneously were employed. In experiment 1, subjects showed robust adaptation to the rotation when reaching to the arc even though the presence of this perturbation was irrelevant for achievement of the task goal. Interestingly however, rotation adaptation was strongly attenuated when it was presented simultaneously with a task-relevant gain perturbation. In experiment 2, which involved reaches to the bar, again, subjects successfully adapted to the task-irrelevant gain perturbation when it occurred in isolation. However, adaptation was attenuated when the gain co-occurred with a task-relevant rotation. Experiment 3 revealed that the attenuation observed in the first two experiments was not due to an inability to adapt to co-occurring rotation and gain perturbations. Collectively, our results suggest that the sensorimotor system selectively tunes learning in the presence of multiple error signals, a finding that can potentially be explained by a biased competition mechanism. That is, given limited processing capacity, a salient attribute - the relevance of the error to the task goal in this case - is prioritized for processing and drives subsequent adaptive changes in motor output.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144649746","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":"Spinally Projecting Serotonergic Neurons in Motor Network Modulation.","authors":"Andrea Giorgi, C J Heckman, Marie-Claude Perreault","doi":"10.1152/jn.00139.2025","DOIUrl":"10.1152/jn.00139.2025","url":null,"abstract":"<p><p><i>Spinally projecting</i> serotonergic (5-HTsp) neurons represent a heterogeneous population of neurons in the brainstem whose relevance in the control of movement has largely been inferred. Numerous studies across a variety of species have suggested that 5-HTsp neurons exert a widespread influence on spinal sensorimotor networks, operating at multiple levels (primary afferents, interneurons, and motoneurons) through various serotonin receptor subtypes. However, despite the anatomical and neurochemical complexity of the 5-HTsp system, most supporting evidence has largely been derived from indirect approaches (e.g., exogenous application of 5-HT and agonists/antagonists of 5-HT receptors). Direct demonstrations of specific anatomical and functional connectivity have been limited, occasionally yielding apparent discrepant results. Consequently, as the primary provider of serotonin to the spinal cord, the exact contributions of the 5-HTsp neurons remain to be fully elucidated. For this mini-review, we sifted through the literature of the last six decades, starting after the characterization of the brainstem raphe nuclei and monoaminergic systems [1-3], to provide a clearer picture of what is currently known of the anatomy and influences of the different populations of 5-HTsp neurons on sensorimotor circuits and motor behaviors. We focused on studies reporting direct manipulation of brainstem 5-HTsp neurons, excluding those targeting 5-HT neurotransmission by exogenous application of 5-HT. This emphasis aims to highlight the urgency of resolving how 5-HTsp neuron subpopulations differentiate anatomically and functionally, so that they can be integrated as dedicated components in current models of supraspinal control of movement and motor diseases such as Parkinson's and amyotrophic lateral sclerosis. Along the way, we point out gaps in knowledge that may be filled using newly available research tools.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144649745","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":"Unified measures quantifying intensity and similarity of pain and somatosensory percepts.","authors":"Eric J Earley, Malin Ramne, Johan Wessberg","doi":"10.1152/jn.00031.2025","DOIUrl":"10.1152/jn.00031.2025","url":null,"abstract":"","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"292-302"},"PeriodicalIF":2.1,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144310058","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":"Iota oscillations (25-35 Hz) during wake and REM sleep in children and young adults.","authors":"Sophia Snipes","doi":"10.1152/jn.00081.2025","DOIUrl":"10.1152/jn.00081.2025","url":null,"abstract":"<p><p>High-frequency brain oscillations in humans are currently categorized into beta (13-30 Hz) and gamma (>30 Hz). Here, I introduce a new class of oscillations between 25 and 35 Hz, which I propose to call \"iota.\" Iota oscillations have low amplitudes but can still be measured with surface electroencephalography (EEG). Within an individual, iota activity has a narrow spectral bandwidth typically less than 3 Hz, thus distinguishing it from broadband beta and gamma. Iota oscillations occur in sustained bursts during both wakefulness and rapid eye movement (REM) sleep. They are only found in a subset of individuals, more in children than in adults. Overall, iota oscillations are challenging to detect but could serve as a marker of both brain development and states of vigilance.<b>NEW & NOTEWORTHY</b> Electrical brain waves are some of the only neuronal signals that can be measured noninvasively in humans. Until now, only six classes of waves have been identified. Here I introduce a new class, iota, specific to wakefulness and rapid eye movement (REM) sleep. This makes iota just the second class of brain wave known to characterize REM sleep (after theta), and opens up new opportunities to investigate this elusive state.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"1-9"},"PeriodicalIF":2.1,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144025200","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":"Case studies in neuroscience: movement-related cortical stimulation to enhance corticospinal transmission in chronic incomplete spinal cord injury.","authors":"David A Cunningham, Christina V Oleson, P Hunter Peckham, Kevin L Kilgore","doi":"10.1152/jn.00083.2025","DOIUrl":"10.1152/jn.00083.2025","url":null,"abstract":"<p><p>Incomplete spinal cord injury (iSCI) disrupts signal transmission at the level of injury (LOI) and in higher brain structures, weakening intracortical circuits and impairing movement initiation. A potential approach to target intracortical circuits is to deliver transcranial magnetic stimulation (TMS) during motor intention, known as movement-related cortical stimulation (MRCS). We hypothesize that delivering TMS during motor intention will enhance corticospinal excitability (CE) and improve muscle activation below the LOI. One participant with chronic severe iSCI participated in a crossover study followed by five consecutive treatment sessions. First, we investigated the impact of TMS intensity (subthreshold vs. suprathreshold) on CE when delivered 50 ms before movement. The participant then received five consecutive days of MRCS with active subthreshold TMS for 15-20 min. <i>Experiment 1:</i> CE was assessed before and after sham, suprathreshold, and subthreshold MRCS (1-wk washout), targeting the abductor hallucis muscle. <i>Experiment 2</i>: CE and volitional motor unit recruitment were measured at baseline, the start of each session and 3- and 7-day follow-up. Corticomotor maps were assessed at baseline and post 3- and 7-day follow-up. Subthreshold MRCS increased CE compared with sham and suprathreshold MRCS. Five days of subthreshold MRCS increased CE, motor maps, and volitional motor unit recruitment, with improvements lasting up to the 3-day follow-up and remaining above baseline at <i>day 7</i>. These findings suggest that timed cortical stimulation with movement intention may enhance signal transmission in iSCI below the LOI. Future research is needed to determine if MRCS can prime intracortical circuitry before therapy to improve motor function.<b>NEW & NOTEWORTHY</b> We demonstrate that five consecutive days of movement-related cortical stimulation can enhance corticospinal excitability, expand motor maps, and improve volitional motor unit recruitment in a person with severe incomplete spinal cord injury. These results support the brain's adaptive capacity following spinal cord injury, despite limited motor drive to the muscle, and corroborate the potential to improve motor function by targeting higher-order networks during volitional motor intention with noninvasive brain stimulation.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"397-406"},"PeriodicalIF":2.1,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144560426","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":"Ineffective cues for contextual saccade adaptation.","authors":"Maxime Martel, Laurent Madelain","doi":"10.1152/jn.00148.2025","DOIUrl":"10.1152/jn.00148.2025","url":null,"abstract":"<p><p>Contextual saccadic adaptation is investigated through a variant of the double-step paradigm, where two directions of intrasaccadic steps are signaled by two cues. This enables the simultaneous induction of two distinct saccadic adaptations. Surprisingly, contextual adaptation is effective only with motor-related cues, whereas visual cues such as target color and shape do not elicit significant adaptation. We tested nine different contextual cues to signal intrasaccadic steps in a contextual double-step paradigm: visual stimulus duration, lateralization of a sound, various statistical regularities across trials, symbolic cues, starting location of the target, and the amplitude of the first step or the target color and shape. Robust systematic contextual learning was found under the amplitude and the starting location experiments, whereas no learning occurred with any other cues. This lack of contextual learning further confirms that the prediction of the intrasaccadic steps depends on the nature of the context. In two additional experiments replicating those using target color and shape, and symbolic cues, participants were periodically prompted to explicitly report the contextual cue they had just experienced. Again, no systematic contextual adaptation was observed despite participants achieving reporting the contextual cue accurately. This dissociation between perceptual reports and motor tasks involving the same visual information aligns with previous results on the constraints for contextual learning. The saccadic system, evolutionarily specialized for spatial targeting, exhibits selective learning that prioritizes localization cues, effectively ignoring nonmotor cues in its learning processes, even when such cues are explicitly perceived.<b>NEW & NOTEWORTHY</b> This study demonstrates that motor-related cues drive contextual saccadic adaptation, whereas purely perceptual cues fail to do so. We observed a dissociation between the ability to report nonmotor cues and their failure to induce contextual adaptation. The results underscore the importance of spatially relevant cues for guiding contextual saccadic adaptation. These findings deepen our understanding of the selective mechanisms underlying motor learning.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"237-249"},"PeriodicalIF":2.1,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144225755","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}