Search Results (624)

Background: Adequate muscle perfusion, particularly at the level of muscle microcirculation (MM), is essential for muscle function, recovery, and tissue health. Percussive therapy (PT) is increasingly used to support recovery and injury prevention and has shown consistent benefits for range of motion and perceived recovery. However, the underlying physiological mechanisms remain insufficiently understood, and evidence regarding its effects on MM is limited. This study investigated the acute effect of a single PT session on MM and muscle oxygen saturation (SmO₂). Methods: Twenty-two healthy volunteers (24.2 ± 3.0 years) underwent a single PT application (two or four minutes) to the thigh using a handheld percussive device. MM, SmO₂, and the perceived somatosensory sensation (PSS) were assessed at baseline and at five-minute intervals up to 40 min post-application. Data were analyzed using linear mixed models adjusted for age, lower-body fat percentage, and intervention duration. Results: A significant main effect of time was found for both MM and SmO₂. MM increased significantly compared to baseline from 5 to 15 min post-application (all p < 0.001), while SmO₂ increased immediately after PT and remained elevated throughout the 40-min observation period (all p < 0.001). PSS increased significantly during the first 20 min (all p < 0.02) before returning to baseline. Conclusions: A single PT application was associated with transient increases in MM and sustained elevations in SmO₂, along with associated subjective sensations. These time-associated changes suggest that PT may enhance local muscle perfusion and therefore contribute to the understanding of its physiological mechanisms. Full article

Background/Objectives: Migraine with aura (MwA) is a heterogeneous disorder comprising pure visual aura (MwAv) and more complex phenotypes with additional somatosensory and/or dysphasic symptoms (MwAvsd). Previous structural magnetic resonance imaging (MRI) studies have demonstrated hippocampal subfield volume reductions associated with aura complexity, suggesting a role for the hippocampus in MwA pathophysiology. However, functional network mechanisms underlying these structural differences remain unclear. This study aimed to investigate hippocampal resting-state functional connectivity (FC) in MwA subtypes and healthy controls (HCs), and to determine whether hippocampal connectivity patterns differ according to aura complexity. Methods: In this comparative cross-sectional study, 27 patients with MwAvsd, 18 with MwAv, and 29 age- and sex-matched HCs underwent resting-state functional MRI on a 3T scanner. Seed-based FC analyses were performed using both hippocampi as regions of interest. Results: MwAvsd patients demonstrated significantly increased FC between the right hippocampus and the left dorsal parietal cortex and right sensory association cortex compared with MwAv patients. In contrast, MwAv patients showed increased FC between the left hippocampus and the right dorsolateral prefrontal cortex compared with MwAvsd patients. Additionally, MwAv patients exhibited stronger FC between the left hippocampus and bilateral anterior prefrontal cortices and the left angular cortex compared with HCs. No other significant hippocampal FC differences were observed. Conclusions: Hippocampal FC is altered in MwA and varies according to aura phenotype. Complex aura is characterized by enhanced hippocampal coupling with multisensory integration regions and reduced connectivity with executive control areas, whereas pure visual aura demonstrates increased hippocampal–prefrontal and hippocampal–parietal associative connectivity compared with HCs. These findings suggest that the hippocampus might serve as a target for future neuromodulatory and therapeutic investigations in MwA patients. Full article

Neuropathic pain represents a complex, prolonged pain state arising from lesions within the somatosensory nervous system. Despite significant advances in elucidating its pathophysiology, current therapeutic approaches remain largely symptomatic and frequently inadequate. MicroRNAs, a class of small non-coding RNAs that regulate gene expression post-transcriptionally, have recently emerged as critical modulators of neuronal excitability, neuroinflammation, and synaptic plasticity, which are crucial processes in the development and maintenance of neuropathic pain. This review summarizes the current evidence linking specific miRNAs to the onset and maintenance of neuropathic pain, with an emphasis on their roles in peripheral and central sensitization. The potential of miRNA-based biomarkers for diagnosis and prognostic evaluation is also highlighted. A thorough understanding of the complex miRNA regulatory networks underlying neuropathic pain could facilitate the development of novel, mechanism-based therapies and ultimately improve clinical outcomes. Full article

Background/Objectives: Tinnitus and hyperacusis can occur together or in isolation, with hyperacusis being associated with tinnitus much more frequently than vice versa. This striking correlation between tinnitus and hyperacusis prevalence implies that there might be a common origin, such as (hidden) hearing loss, and possibly interrelated neural mechanisms in the pathological development of those two conditions. Here, we propose such interrelated pathological mechanisms. Methods: This is a theoretical work based solely on considerations and published data. Results: We propose a model localized in the dorsal cochlear nucleus (DCN) of the brainstem, based on classical mechanisms of Hebbian and associative plasticity known from classical conditioning. Specifically, our model proposes that hyperacusis results from the synaptic enhancement of cochlear input to the DCN, whereas chronic tinnitus results from the synaptic enhancement of somatosensory input to the DCN. Specific conditions leading to one or the other condition are discussed. Conclusions: Our model predicts that hearing loss leads to chronic tinnitus, while noise exposure (which may also cause hearing loss) leads to hyperacusis. We would like to emphasize that our aim with the proposed model is not to provide a self-contained theoretical construct, but to stimulate thought regarding possible pathological causes of tinnitus and hyperacusis that have not yet been investigated. Individual assumptions that cannot yet be substantiated by the existing literature are intended to provide impetus for future experimental studies. Full article

Tactile somatosensory comfort is a critical factor in ergonomics research, particularly in designing assistive robots for geriatric care. Despite its importance, existing studies lack comprehensive comfort models tailored for optimizing system control in such applications. This study addresses this gap by introducing the first derivation of a tactile somatosensory comfort model that integrates Stevens’ law with the energy transfer function, establishing a link between physical stimuli and psychological responses. Through experimental data collection and parameter fitting, a quantitative relationship between comfort and psychological responses was established, facilitating the development of a novel optimal control model. The model parameters were fitted using the Physics-Informed Neural Networks (PINNs) algorithm, while the optimal scrubbing parameters for force (1.68 N) and velocity (36.47 mm/s) were determined via the Particle Swarm Optimization (PSO) algorithm. Validation experiments involving 20 participants, which monitored physiological parameters such as heart rate variability (HRV), confirmed the model’s effectiveness in enhancing comfort while ensuring robustness and generalizability. These findings contribute a novel theoretical framework for modelling and applying tactile somatosensory comfort, providing valuable insights for future research and development. Full article

Background/Objectives: This systematic review synthesizes MRI evidence to characterize neuromorphological alterations in somatosensory and vestibular brain regions among adolescents with idiopathic scoliosis (AIS). Methods: This systematic review was conducted in accordance with the PRISMA 2020 guidelines. We systematically searched five databases from inception to January 2026 for case–control MRI studies comparing AIS patients (10–18 years) with healthy controls. Two reviewers independently screened studies, extracted data, and assessed the risk of bias using the Newcastle–Ottawa Scale. Results: Across 15 studies (1270 participants), AIS patients demonstrated consistent neuromorphological alterations: (1) lower cerebellar tonsil position (0.9–2.8 mm below baseline), with ectopia incidence correlating with curve severity; (2) cortical thickening in bilateral medial regions but thinning in left paracentral areas; (3) left-dominant white matter volume increases and impaired microstructure in the corpus callosum; and (4) left-sided vestibular morphological changes, including a more vertical semicircular canal. Conclusions: AIS is associated with consistent neuromorphological alterations in key somatosensory and vestibular regions, supporting a potential neuroanatomical basis for impaired sensorimotor integration in its pathogenesis. It should be noted that substantial heterogeneity among the included studies prevented a meta-analysis, and the cross-sectional design limits causal interpretations Registration: This systematic review was registered in PROSPERO (CRD42024577195). Full article

Background/Objectives: The vibrotactile system, which is essential for guiding behavior in nocturnal rodents such as mice and rats, provides critical sensory input. To investigate the role of vibrotactile sensory inflow in neonatal locomotion, we used previsual rat pups that underwent bilateral vibrissectomy. Subsequently, their motor behavior was evaluated in an open field test. Methods: A total of 42 previsual pups from four litters were assigned to either bilateral vibrissectomy or sham surgery groups on postnatal days (PND) 9–12, with group allocation balanced across litters. Results: Open-field testing on PND 13 revealed that while vibrissectomy (VE) did not affect gross locomotor activity—such as distance traveled, speed, acceleration, or freezing episodes (all >0.05)—it significantly altered spatial behavior. To quantify spatial patterns of curvy tracks, we analyzed trajectorial compaction within the central zone, lacking the tactile guidance of the walls: trajectories were smoothed using virtual coatings scaled to the vibrissal length (16 mm). For each track, an individual linearized reference path was generated and subjected to identical smoothing. The compaction ratio—calculated as the coated area of the smoothed linearized reference divided by the coated area of the experimental track—was significantly greater in VE pups than in sham controls (p = 0.03). This effect was not attributable to differences in the path length traveled within the central zone. The increased compaction persisted when the smoothing scale was increased 2–3 fold (32–64 mm radii, approximating the pups’ mean body size), but not at smaller scales (2–4 mm). Conclusions: These results demonstrate that tactile input specifically modulates the spatial, rather than locomotor, components of nonvisual navigation. Consequently, the track compaction may serve as a sensitive marker for assessing vibrotactile function in developing laboratory rodents. Full article

Spreading depolarizations (SDs) are major pathophysiological events in several brain diseases, including migraine, brain ischemia, trauma, and epilepsy. However, the electrophysiological detection of SDs remains challenging. In this study, we examined changes in spikes (action potentials (APs) and action currents (ACs)) in layer 5 neurons of the somatosensory cortex of anesthetized rats during transient excitation at the onset of high-potassium-induced SDs. During whole-cell recordings, spike amplitude progressively decreased while spike duration increased during gradual neuronal depolarization at SD onset, culminating in depolarization block. A similar decrease in spike amplitude and increase in spike duration were observed during the pre-SD excitation phase in loose cell-attached recordings from single neurons and in cluster analysis of extracellular spikes. Multiple (non-clustered) unit activity also showed decrease in spike amplitude and spike broadening during pre-SD excitation. These findings suggest that dynamic changes in spike amplitude and duration at SD onset could serve as markers for SD detection. Full article

Postural control relies on the integration of visual, vestibular, and somatosensory inputs under biomechanical constraints. Conventional Romberg testing provides limited quantitative insight, particularly regarding directional control and sensory dependence. Wearable inertial measurement units (IMUs) enable portable, multidimensional assessment of postural sway. Thirty healthy adults (15 females, 15 males) completed a modified Romberg protocol with systematic manipulation of stance (normal, tandem), visual condition (eyes open, eyes closed), and arm position (arms at sides, arms forward), including both left and right leading foot during tandem stance. Whole-body kinematics were recorded using a full-body IMU system comprising 17 wireless sensors. Center-of-mass (CoM) trajectories were derived from a 23-segment biomechanical model, and linear, spatial, and nonlinear sway metrics were computed. Statistical analyses were conducted using repeated-measures ANOVA, with significance set at p < 0.05. Visual deprivation significantly increased sway path length, mean sway velocity, and sway area across all stance conditions (p < 0.001). Tandem stance elicited greater mediolateral sway than normal stance (p < 0.001). Romberg ratios exceeded unity for all metrics and were significantly higher in tandem stance (p < 0.01). Arm position effects were negligible in normal stance but showed significant Vision × Arm interactions during tandem stance (p < 0.05). Leading foot position had no significant main effects. Combining a modified Romberg protocol with full-body IMU-based CoM analysis enables sensitive characterization of sensory dependence and directional postural control. Tandem stance with visual deprivation increases mediolateral postural demands under reduced base-of-support conditions, providing a more challenging context for evaluating directional postural control. Full article

CDKL5 Deficiency Disorder (CDD) is a severe neurodevelopmental encephalopathy characterized by early disruptions of synaptic maturation and network stability, leading to persistent motor, cognitive, and behavioral impairments. Given the role of the endocannabinoid system in synaptic development, neuroinflammation, and neuronal resilience, we investigated whether the sustained enhancement of endogenous 2-arachidonoylglycerol (2-AG) signaling via monoacylglycerol lipase (MAGL) inhibition could mitigate key pathological features in adult Cdkl5 knockout (KO) mice. Using an intermittent 6-week treatment, the MAGL inhibitor JZL184 robustly increased plasma 2-AG levels, reduced MAGL protein levels, and activated CB1-AKT signaling without evidence of receptor desensitization. Despite this clear pharmacodynamic efficacy, behavioral effects were domain-specific: neither dose ameliorated core behavioral deficits, although the higher dose selectively reduced stereotypic jumping and modestly improved cue-dependent associative memory. At the cellular level, JZL184 induced biologically meaningful effects, partially restoring dendritic spine maturation in the primary somatosensory cortex and increasing neuronal survival in the vulnerable CA1 hippocampal region. In contrast, microglial responses were dose-dependent and divergent, with the lower dose exerting anti-inflammatory effects, while the higher dose increased cortical microglial density and Allograft Inflammatory Factor-1 (AIF-1) expression, suggesting engagement of compensatory or off-target mechanisms. Overall, these findings show that MAGL inhibition activates neuroprotective pathways and ameliorates select structural deficits in adult Cdkl5 KO mice, but is insufficient to produce broad behavioral recovery, highlighting the domain-specific effects of selective 2-AG enhancement via MAGL inhibition and the need for developmentally informed or multimodal therapeutic strategies in CDD. Full article

Introduction: Idiopathic adolescent scoliosis (IAS) is commonly managed non-surgically; however, patients with a Cobb angle >45° before skeletal maturity often require posterior spinal fusion. Because this procedure carries a risk of neurological complications, intraoperative neurophysiological monitoring (IONM) is essential for early detection of spinal cord compromise. Case report: We present a 13-year-old girl with rapidly progressing scoliosis (Cobb angle 78°) who developed intraoperative changes in motor evoked potentials (MEPs) during posterior fusion from L4 to Th2. Total intravenous anesthesia without muscle relaxants was used, and standard multimodal IONM with somatosensory evoked potentials (SSEPs), MEPs, and spontaneous/triggered electromyography was applied. After induction of general anesthesia and surgical exposure, pedicle preparation at Th8–Th9 was followed by increased bleeding from the vertebral bodies and an abrupt loss of MEPs in both lower limbs, most prominently in the tibialis anterior muscles, whilst SSEPs remained unchanged. Intraoperative radiography confirmed correct screw placement, and anesthetic variables were reassessed with no reversible cause identified. Because MEPs remained absent, a wake-up test was performed and demonstrated intact voluntary movement, allowing the surgery to continue. By the end of the procedure, MEPs recovered fully on the left side and partially on the right. The patient awoke without any postoperative motor deficit. Conclusion: It is well known that motor responses can show variability during surgery, including a gradual decrease due to prolonged anesthesia. After excluding anesthetic and mechanical factors, one of the hypothetical explanations for the transient MEP loss was temporary venous congestion and retrograde flow within the intravertebral and epidural/intraspinal venous networks, resulting in reversible spinal cord drainage impairment. Another hypothetical possibility was transient vasospasm from surgical manipulation without direct neural or vascular injury. This case highlights the critical role of continuous multimodal neuromonitoring in detecting reversible spinal cord dysfunction and guiding safe decision-making during complex scoliosis surgery. Full article

Central to the linkage of pain circuitry with the limbic system is its initial NAα2-mediated antinociceptive effect in acute pain models, followed by contradictory pronociceptive activation by the locus coeruleus seen in chronic pain models. Rats with a stable, long-term (>10 weeks) inflammatory compression of the trigeminal infraorbital nerve (FRICT-ION) preclinical model were given daily doxazosin, a slow-release NAα1 receptor antagonist, in weeks 8–10. Facial hypersensitivity was reversed back to baseline in male and female rats, but anxiety was only reduced in male animals. Doxazosin-decreased astrocytic activation was indicated by a decrease in both intracranial cathepsin B imaging in vivo and GFAP immunostaining in the somatosensory cortex and hippocampus. Doxazosin reduction in NAα1 receptor activation diminished glial-neuronal interactions, resulting in downstream reduction in pain-related behaviors. Other significant differences by sex included improved elevated zero maze anxiety measures only in males, and improved novel recognition scores only in females. Elevated thymus chemokine CXCL7 levels were reduced by doxazosin but only in male rats. These sexually dimorphic contradictions further complicate the understanding of the noradrenergic system’s involvement in nociception. The findings indicate that by reducing NAα1 receptor drive with doxazosin, the role of the locus coeruleus can be shifted back to NAα2-receptor-mediated pain inhibition. Full article

Objective: This study investigated the effects of a 10-week dancesport intervention on rhythm perception ability and its multisensory correlates in college students. Methods: Forty students were randomly assigned to an intervention group (dancesport) and a control group (Health Qigong). Rhythm perception was assessed across different task difficulties (Experiment 1) and through somatosensory, visual, and auditory channels (Experiment 2). Data were analyzed using repeated-measures ANOVA with Bonferroni-corrected pairwise comparisons. Results: The dancesport group showed significant improvement in rhythm perception accuracy at all difficulty levels. Furthermore, they achieved superior post-test performance compared to the control group on pooled-difficulty tasks. Significant enhancements were also found in somatosensory reaction time and in both the accuracy and reaction time of auditory processing. Visual channel improvement was restricted to accuracy. Conclusions: A 10-week dancesport training program led to significant within-group improvement in rhythm perception across all difficulty levels and enabled superior performance relative to the control group on pooled-difficulty tasks. It also enhances multisensory processing, particularly in somatosensory and auditory channels. Full article

Background: Resting-state functional MRI (rs-fMRI) studies typically rely on linear Pearson correlation to characterize brain connectivity, potentially overlooking the distributional characteristics of functional networks. This study introduces a kernel-transformed functional connectivity (FC) entropy framework to quantify network dedifferentiation in bipolar disorder (BD). Methods: We utilized a Gaussian kernel function to execute a nonlinear similarity transformation (referred to as reweighting) on standard linear correlation matrices. This approach acts as a functional filter to amplify the contrast between strong and weak connections. Multiscale entropy (global, modular, and nodal) was subsequently calculated to characterize the uniformity of connectivity weight distributions. Results: Compared to Normal Controls (NCs), patients with BD exhibited significantly higher entropy at the global level and within the Default Mode, Salience, and Somatosensory-Motor networks, indicating widespread network dedifferentiation (distributional flattening). These alterations were robust across different kernel widths and remained significant after rigorously controlling for head motion (Mean FD). Furthermore, manic symptom severity (YMRS) was negatively correlated with global entropy, suggesting a pathological “locking-in” or rigidity of specific neural circuits during manic states. Conclusions: The kernel-transformed FC entropy serves as a distribution-sensitive complement to conventional linear metrics. Our findings highlight network dedifferentiation as a key pathophysiological feature of BD and suggest this framework as a promising candidate metric for characterizing network dysregulation. Full article

Background/Objectives: From birth, infants learn how to interact with the world through exploration. It has been proposed that this early learning phase is driven by motor babbling: the spontaneous generation of exploratory movements that are progressively consolidated through associative mechanisms. This process leads to the acquisition of a repertoire of hand movements such as single- or multi-finger flexion, extension, touching, and pushing. Later, in a second phase, some of these movements (e.g., those that happen to enable access to biologically salient stimuli, such as grasping food) are further reinforced and consolidated through rewards obtained from the environment. However, the neural mechanisms underlying these processes remain unclear. Here, we used a fully neuroanatomically and neurophysiologically constrained neural network model to investigate the brain correlates of these processes. Methods: The model consists of six neural maps simulating six human brain areas, including three pre-central (motor-related) and three post-central (sensory-related) regions. Each map is composed of excitatory and inhibitory spiking neurons, with biologically constrained within- and between-area connectivity forming recurrent circuits. Hand action execution and corresponding haptic perception are simulated simply as activity in primary motor and somatosensory model areas, respectively. During an initial “exploratory” phase, the network learned, via Hebbian mechanisms, associations—as emerging distributed cell assembly (CA) circuits—linking “motor” to corresponding “haptic feedback” patterns. As a result of this initial training, the model began to exhibit spontaneous ignitions of these CA circuits, an emergent phenomenon taken to represent internally generated, non-stimulus-driven attempts at hand action exploitation. In a second phase, a global reward signal, simulating dopamine-mediated reward encoding, was applied to only a subset of “successful” actions upon their noise-driven ignition. Results: During the first exploratory phase, the neural architecture autonomously developed “action-perception” circuits corresponding to multiple possible hand actions. During the subsequent exploitation phase, positively reinforced circuits increased in size and, consequently, in frequency of spontaneous ignition, when compared to non-rewarded “actions”. Conclusions: These results provide a mechanistic account, at the cortical-circuit level, of the early acquisition of hand actions, of their subsequent consolidation, and of the spontaneous transition of an agent’s behavior from exploration to reward-seeking, as typically observed in humans and animals during development. Full article