Jessica A Leverett, John E Misiaszek, Craig S Chapman, David F Collins
{"title":"Grasping at illusions: stimulating cutaneous afferents to create kinesthetic illusions.","authors":"Jessica A Leverett, John E Misiaszek, Craig S Chapman, David F Collins","doi":"10.1007/s00221-025-07157-x","DOIUrl":"https://doi.org/10.1007/s00221-025-07157-x","url":null,"abstract":"","PeriodicalId":12268,"journal":{"name":"Experimental Brain Research","volume":"243 10","pages":"207"},"PeriodicalIF":1.6,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145023189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Patrick G Monaghan, Taylor N Takla, Maryam M Abbawi, Michael VanNostrand, Ana M Daugherty, Jeffrey A Stanley, Nora E Fritz
{"title":"Neural correlates of forward and backward walking in MS: insights from myelin water imaging.","authors":"Patrick G Monaghan, Taylor N Takla, Maryam M Abbawi, Michael VanNostrand, Ana M Daugherty, Jeffrey A Stanley, Nora E Fritz","doi":"10.1007/s00221-025-07156-y","DOIUrl":"10.1007/s00221-025-07156-y","url":null,"abstract":"<p><p>Mobility impairments and increased fall risk are common in multiple sclerosis (MS), resulting from myelin degradation in motor pathways. While forward walking is a common mobility assessment, backward walking shows greater sensitivity in distinguishing fallers due to its increased postural and cognitive demands. However, the neurobiological mechanisms underlying backward walking deficits remain unclear. This study examined associations among myelin water imaging (MWI) metrics-myelin water fraction (MWF) and geometric mean of intermediate-T2 relaxation times (geomT<sub>2IEW)-</sub>in motor pathways and forward and backward walking performance in MS. Forty-three individuals with relapsing-remitting MS completed forward and backward walking assessments. MWI assessed MWF and geomT<sub>2IEW</sub> in four motor tracts: corpus callosum body (CC<sub>body</sub>), superior and inferior cerebellar peduncles (SCP, ICP), and corticospinal tract (CST). Multiple regression models examined associations between regional MWF and geomT2IEW and walking velocity in each direction, controlling for age and disease severity, measured via the Patient-Determined Disease Steps (PDDS). Higher MWF in the SCP was significantly associated with faster backward velocity (b = 0.046, p = 0.026), while MWF in the CC<sub>body</sub> was the strongest predictor of forward velocity (b = 0.019, p = 0.030). GeomT<sub>2IEW</sub> was not significantly associated with walking velocity. PDDS was a significant covariate, with greater impairment linked to slower speeds (p < 0.001). Forward and backward walking involve distinct neural networks, with SCP myelin content linked to backward walking and CC<sub>body</sub> myelin to forward walking. Findings highlight the utility of backward walking assessments in identifying MS-related mobility deficits and suggest targeting cerebellar pathways in rehabilitation to improve gait and reduce fall risk.</p>","PeriodicalId":12268,"journal":{"name":"Experimental Brain Research","volume":"243 10","pages":"206"},"PeriodicalIF":1.6,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144948325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gregg Eschelmuller, J Timothy Inglis, Hyosub Kim, Romeo Chua
{"title":"Dual agonist and antagonist muscle vibration produces a bias in end point with no change in variability.","authors":"Gregg Eschelmuller, J Timothy Inglis, Hyosub Kim, Romeo Chua","doi":"10.1007/s00221-025-07143-3","DOIUrl":"https://doi.org/10.1007/s00221-025-07143-3","url":null,"abstract":"<p><p>Muscle spindles provide critical proprioceptive feedback about muscle length to the central nervous system (CNS). Single muscle tendon vibration can stimulate muscle spindles, causing illusory limb positions, while dual muscle tendon vibration is thought to produce a noisy proprioceptive system. It is currently unclear exactly how the CNS uses kinesthetic feedback from the agonist and antagonist muscles during target-directed reaches. The purpose of the current project was to investigate the effects of agonist, antagonist, and dual agonist/antagonist vibration during target-directed reaching. Using an elbow extension task, we found that antagonist muscle vibration produced an undershooting effect relative to the no-vibration control, while agonist muscle vibration produced an overshooting effect relative to the no-vibration control. Neither of the single muscle vibrations produced any change in the variable error of the movements. While it was originally hypothesized that dual agonist/antagonist vibration would increase participants' variable error with no change in bias, the opposite was found. Participants undershot relative to the no-vibration control with no change in variable error. Overall, the results from this study suggest that dual vibration does not necessarily create a noisy proprioceptive system but can produce a bias in end point.</p>","PeriodicalId":12268,"journal":{"name":"Experimental Brain Research","volume":"243 10","pages":"204"},"PeriodicalIF":1.6,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144948371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dylan J Carter, James R Forsyth, Joshua P M Mattock, Jonathan Shemmell
{"title":"Neuromuscular control of a five-finger pinch task is influenced by training history.","authors":"Dylan J Carter, James R Forsyth, Joshua P M Mattock, Jonathan Shemmell","doi":"10.1007/s00221-025-07147-z","DOIUrl":"10.1007/s00221-025-07147-z","url":null,"abstract":"<p><p>Hand control for dexterous and strength-based tasks involves several levels of the neuromuscular system which interact to produce force. We investigated hand force, motor unit (MU) control, and intermuscular coherence in specialist-trained groups to identify how training may affect neuromuscular force control and motor neuron activity. Equal groups of ten strength-trained (rock climbers) and dexterity-trained (musicians) individuals participated. Measures of forearm muscle structure were recorded and used to normalize maximal five-finger pinch force. Several submaximal trapezoidal pinch contractions were performed while force and electromyography (EMG) were recorded, and force steadiness was calculated. Motor unit firing rates were calculated from spike trains identified by surface EMG decomposition. Intermuscular coherence was calculated between two muscles controlling the hand (the abductor pollicis brevis and flexor digitorum superificialis), providing an estimate of the common synaptic inputs to these simultaneously activated muscles. Strength-trained participants had a higher force capacity (even when normalized to muscle size) and were steadier at controlling forces. The dexterity-trained group had faster MU discharge rates in the abductor pollicis brevis muscle at moderate force levels. Measures of synaptic inputs to the motor neuron pools were inconsistent. However, the largest peaks in the beta-band were at the lowest measured force level for the dexterity-trained group, while at the highest force intensity for the strength-trained group. These findings may indicate that the neuromuscular control of hand force differs between groups with different training histories.</p>","PeriodicalId":12268,"journal":{"name":"Experimental Brain Research","volume":"243 10","pages":"205"},"PeriodicalIF":1.6,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12405043/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144948338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aref Basereh, Hamid Rajabi, Shahriar Gharibzadeh, Joel Mason, Shapour Jaberzadeh
{"title":"Corticospinal drive modulation to agonist and antagonist arm muscles following strength training and detraining.","authors":"Aref Basereh, Hamid Rajabi, Shahriar Gharibzadeh, Joel Mason, Shapour Jaberzadeh","doi":"10.1007/s00221-025-07155-z","DOIUrl":"10.1007/s00221-025-07155-z","url":null,"abstract":"<p><p>This study aimed to investigate the corticospinal drive modulation to Agonist and Antagonist arm muscles following Strength training and detraining, as neural adaptations are critical for early strength gains. Seventeen healthy, untrained young adults underwent four weeks of unilateral dumbbell curl training (60-80% of one-repetition maximum) followed by four weeks of detraining. Transcranial magnetic stimulation (TMS) assessed corticospinal excitability and inhibition across multiple intensities (100-200% rMT). Strength training induced progressive 1-RM improvements in both agonist (BB: +37%, d = 4.18) and antagonist (TB: +15%, d = 0.32) muscles, with partial retention during detraining. The MEP increased selectively in the agonist (BB: +44%, d = 2.80) but not the antagonist muscle, while cSP decreased markedly in the agonist (BB: -42%, d = 2.0). No significant correlations emerged between strength changes and neural adaptations. Secondary outcomes showed transient increases in co-activation and arm circumference during training (p < 0.001). Strength training and detraining modulate corticospinal responses in agonist and antagonist muscles, highlighting their role in early strength acquisition and loss. These neural adaptations provide insight into the mechanisms underlying strength changes during training and detraining.</p>","PeriodicalId":12268,"journal":{"name":"Experimental Brain Research","volume":"243 9","pages":"203"},"PeriodicalIF":1.6,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144948355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Cognitive representations of multilevel buildings: two- or three-dimensional?","authors":"Otmar Bock","doi":"10.1007/s00221-025-07136-2","DOIUrl":"10.1007/s00221-025-07136-2","url":null,"abstract":"<p><p>Previous research suggests that conventional multilevel buildings are cognitively represented as a stack of horizontal planes, whereas an atrium-shaped architecture which allows easy visual access to other levels is represented as a volume. The present study investigated whether easy physical access to other levels also promotes a volumetric representation. Participants were examined in a virtual 3D grid maze in which they could access higher and lower levels at each intersection. During a learning phase, they were transported through the maze across twelve intersection, each featuring a unique object. In the subsequent test phase, they were asked to indicate the location of these objects on a schematic drawing of the maze. Response accuracy in the test phase was similar when the twelve visited objects were arranged in a horizontal plane and when they were laid out in a volume. In accordance with earlier reasoning, this suggests that easy physical access to other levels indeed can facilitate a volumetric cognitive representation of multilevel architectures. Additional findings suggest that this representation emerged gradually rather than abruptly like a sudden insight, and that transport through the maze without left and right turns facilitated the internal representation, probably by reducing the associated cognitive load.</p>","PeriodicalId":12268,"journal":{"name":"Experimental Brain Research","volume":"243 9","pages":"202"},"PeriodicalIF":1.6,"publicationDate":"2025-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144948293","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Galia Shaham, Irina Galperin, Amit Salomon, Eran Gazit, Aron S Buchman, Nir Giladi, James K Richardson, Jeffrey M Hausdorff
{"title":"Motor planning stage of gait initiation: effects of aging, Parkinson's disease, and associations with cognitive function.","authors":"Galia Shaham, Irina Galperin, Amit Salomon, Eran Gazit, Aron S Buchman, Nir Giladi, James K Richardson, Jeffrey M Hausdorff","doi":"10.1007/s00221-025-07151-3","DOIUrl":"10.1007/s00221-025-07151-3","url":null,"abstract":"<p><p>The response to a request to walk involves a motor planning phase followed by an execution phase. The initial phase of gait initiation, specifically the time to anticipatory postural adjustment (APA), can be viewed as a form of reaction time. However, it is not clear how to characterize the cognitive processes involved in this stage. To address this question, time-to-APA, simple and complex upper limb visuomotor reaction time (SRT, CRT), cognitive, and motor performance were evaluated in 27 people with Parkinson's disease (PD), 31 older adults (OA), and 34 young adults (YA). Our results showed that time-to-APA was significantly longer than SRT in all three groups (p < 0.001), indicating a more complex cognitive process. In YA, time-to-APA was significantly shorter than CRT (p < 0.001). In the OA and PD, time-to-APA was not significantly different from CRT. Mixed-effects analysis showed significant time (p < 0.001), group (p = 0.037), and group × time interaction effects (p = 0.002). Among all subjects, time-to-APA, but not APA duration, was associated with the Color-Trails Test (part B: r<sub>s</sub> = 0.406, p < 0.001). In PD, APA duration was correlated with MDS-UPDRS-part 3 (motor) scores (r<sub>s</sub> = 0.535, p = 0.004), but time-to-APA was not (p = 0.892). These findings suggest that time-to-APA is a cognitive process that is more complex than an SRT task and shares properties of a CRT task, especially among older adults and people with PD. In PD, this initial movement planning stage is not related to motor impairment, in contrast to APA duration. Further research is necessary to identify the factors underlying this initial stage of gait initiation.</p>","PeriodicalId":12268,"journal":{"name":"Experimental Brain Research","volume":"243 9","pages":"201"},"PeriodicalIF":1.6,"publicationDate":"2025-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12394281/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144948296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Humans take into account the consequences of motor control demands when making perceptual decisions between actions.","authors":"Élise Leroy, Éric Koun, David Thura","doi":"10.1007/s00221-025-07148-y","DOIUrl":"10.1007/s00221-025-07148-y","url":null,"abstract":"<p><p>Animals, including humans, are often faced with situations where they must decide between potential actions to perform based on various sources of information, including movement parameters that incur time and energy costs. Consistent with this fact, many behavioral studies indicate that decisions and actions show a high level of integration during goal-directed behavior. In particular, motor costs very often bias the choice process of human and non-human subjects experiencing successive decisions between actions. However, it appears as well that depending on the design in which the experiment occurs, the effect of motor costs on decisions can vary or even vanish. This suggests a contextual dependence of the influence of motor costs on decision-making. Moreover, it is not currently known whether or not the impact of motor costs on perceptual decisions depend on the difficulty of the decision. We addressed these two important issues by studying the behavior of healthy human subjects engaged in a new perceptual decision-making paradigm in which the constraint level associated with the movement executed to report a choice was volitionally chosen by the participants, and in which the difficulty of the perceptual decision to make continuously evolved depending on their motor performance. The results indicate that the level of constraint associated with a movement executed to express a perceptual decision strongly impacts the duration of these decisions, with a shortening of decisions when these are expressed by demanding movements. This influence appears most important when the decisions are difficult, but it is also present for easy decisions. We interpret this strategy as an adaptive way to optimize the participants' overall rate of success at the session level.</p>","PeriodicalId":12268,"journal":{"name":"Experimental Brain Research","volume":"243 9","pages":"200"},"PeriodicalIF":1.6,"publicationDate":"2025-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144948379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Paul McDonnell, Adam B Grimmitt, Jonaz Moreno Jaramillo, Wouter Hoogkamer, Douglas N Martini
{"title":"Posterior parietal cortex activity during visually cued gait: a preliminary study.","authors":"Paul McDonnell, Adam B Grimmitt, Jonaz Moreno Jaramillo, Wouter Hoogkamer, Douglas N Martini","doi":"10.1007/s00221-025-07146-0","DOIUrl":"10.1007/s00221-025-07146-0","url":null,"abstract":"<p><p>Safe gait requires visually cued (VC) step adjustments for negotiating targets and obstacles. Effective step adjustments rely on good visuospatial processing. The posterior parietal cortex (PPC) is implicated in visuospatial processing, yet empirical evidence is limited for the PPC's role during gait in humans. Increased cortical control of gait is associated with higher gait variability, a marker of gait performance and fall risk among older adults. However, the cortical underpinnings of gait variability in visually complex environments are not well established. The primary aim of this preliminary study was to assess PPC activity during VC gait and VC gait with perturbations (VCP). A secondary aim was to determine how PPC activity relates to gait variability during VC and VCP gait. Twenty-one healthy young adults completed three treadmill gait conditions at preferred speed: non-cued (NC) gait, VC gait, where stepping targets were presented in a regular pattern, and VCP gait, where stepping target positions were pseudorandomly shifted. Functional near-infrared spectroscopy quantified relative changes in deoxygenated and oxygenated hemoglobin (ΔHbO<sub>2</sub>) concentrations in the PPC. Inertial measurement units quantified gait variability. Moderate effects were observed for more positive ΔHbO<sub>2</sub> from NC to both VC and VCP gait, likely reflecting the increased visuospatial processing demands. Stride time variability was positively correlated with PPC ΔHbO<sub>2</sub> during VC gait, suggesting a potential role for the PPC in modulating temporal components of VC gait. Extending these findings to older adults will help to elucidate the PPC's role in gait adaptability and fall risk with aging.</p>","PeriodicalId":12268,"journal":{"name":"Experimental Brain Research","volume":"243 9","pages":"199"},"PeriodicalIF":1.6,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144948343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A novel finding on the sex-dependent role of BDNF and GSK-3beta in the medial prefrontal cortex in pain threshold changes in a rat model of fear conditioning with respect to the effect of extinction and the time period after conditioning.","authors":"Atefeh Motamedi-Manesh, Sepideh Khazaei, Anahita Bahrami, Meysam Moradi, Hamed Moradi, Ramel Sayad-Deghatkar, Salar Vaseghi","doi":"10.1007/s00221-025-07145-1","DOIUrl":"10.1007/s00221-025-07145-1","url":null,"abstract":"<p><p>Evidence has shown a wide range of changes in pain perception in posttraumatic stress disorder (PTSD). The present study aimed to explore changes in thermal pain threshold in both sexes of rats exposed to electrical footshocks in different periods after fear conditioning. Fear conditioning (PTSD-like model) was induced by three footshocks (0.8 mA, 3 s) paired with sounds (75 dB, 3 s). Extinction was performed using twenty sounds (75 dB, 3 s) with no footshocks, 1 h after footshocks. Freezing and pain threshold were measured 2 h, 2 days, 7 days, or 30 days after PTSD or extinction (there was not any recall session). The results showed freezing behavior showed a downward trend over time in males, while an upward trend over time in females. Extinction slightly decreased freezing behavior in males, while significantly decreased it in females. Pain threshold was increased in male PTSD rats, while after 30days, there was no change in pain perception. In females, pain threshold was restored in both PTSD-7d and - 30d groups. Extinction decreased pain threshold in males, with stronger effect in females. BDNF was decreased and GSK-3beta was increased in male PTSD rats, except PTSD-30d only for BDNF. In females, BDNF level was restored in both PTSD-7d and - 30d, and also, increased in PTSD-2d group, while GSK-3beta was increased. In conclusion, significant sex differences were observed in freezing behavior, pain threshold, and BDNF. Notably, it seems that GSK-3beta may be involved in freezing and pain perception changes only in females exposed to extinction session.</p>","PeriodicalId":12268,"journal":{"name":"Experimental Brain Research","volume":"243 9","pages":"196"},"PeriodicalIF":1.6,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144872128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}