Background Transcranial ultrasound stimulation (TUS) with various parameters can modulate cortical excitability, but its neuromodulatory effects on excitability and behavior have not been consistently replicated across independent labs or compared within subjects. Objective To examine the neuromodulatory effects of four TUS protocols against sham on motor cortical excitability and inhibitory control. Methods Twenty-six healthy adults were enrolled to complete up to five sessions (four active TUS protocols and one sham); 24 completed all the five sessions, separated by at least one week. Motor evoked potentials (MEPs) were recorded at 20 min and 0 min before stimulation, and at 0, 20, and 40 min after stimulation. Stop-signal task (SST) performance was assessed before and after stimulation, and simultaneous EEG was recorded during the SST to extract event-related potentials (ERP). Linear mixed-effects models with false-discovery-rate correction were used for statistical analysis. Results The intermittent and continuous theta-burst TUS protocols (iTBUS/cTBUS), adapted from an animal protocol, produced excitatory and inhibitory MEP effects, respectively, that were directionally consistent with the effects commonly associated with iTBS- and cTBS-patterned TMS; however, this physiological similarity did not translate into the expected behavioral outcomes. The excitatory effects of two TUS protocols on motor cortex were replicated, yet MEPs and ERP changes were associated with divergent SST outcomes. ERP analysis showed that cTBUS significantly reduced P3 amplitudes, whereas other protocols produced no significant group-level ERP changes. Conclusion The bidirectional iTBUS/cTBUS effects observed here provide preliminary human evidence partially consistent with observations from animal models, although mechanistic equivalence and full translational validity across species remain to be established. The excitatory effects observed with two previously described TUS protocols were directionally consistent with earlier reports. Nevertheless, TUS-induced MEP facilitation does not necessarily enhance inhibitory control in the SST, underscoring the need for task-specific multimodal frameworks to advance TUS as a precise neuromodulation technique.
Background Chronic inflammatory itch is sustained by reciprocal interactions among pruriceptive circuits, scratching-induced skin injury, immune-cell infiltration, and autonomic neuroimmune signaling. Spinal cord stimulation is known to reshape dorsal horn sensory processing, but whether it modulates neuroimmune inflammation during dermatitis-associated itch remains unclear. Methods Using acute pruritogen-evoked itch and DNFB-induced chronic dermatitis models in mice, we examined the effects of low- and high-frequency spinal cord stimulation on itch-like behavior, skin inflammation, spinal GRPR-associated neuronal activation, and sympathetic-associated neuroimmune changes. Activity-dependent FosTRAP2 labeling combined with chemogenetic activation or inhibition was used to test the functional contribution of the HF-SCS/TRAP-defined neuronal ensemble. Results Spinal cord stimulation reduced pruritogen-evoked licking/biting and chronic DNFB-associated itch-like behavior, accompanied by decreased epidermal hyperplasia, T-cell infiltration, and IL-1β/TNF-α-associated inflammatory signals in lesional skin. HF-SCS increased c-Fos activity within a prominent Pax2+ inhibitory neuronal component in the dorsal horn. Chemogenetic reactivation of the HF-SCS/TRAP-defined neuronal ensemble recapitulated the behavioral and cutaneous effects associated with SCS, whereas chemogenetic inhibition impaired the protective efficacy of stimulation. Spinal cord stimulation was also associated with reduced GRPR-related neuronal activation and Grpr expression. Anatomical tracing indicated an association between the HF-SCS/TRAP-defined neuronal ensemble and ChAT+ sympathetic preganglionic neurons, while HF-SCS was accompanied by reduced sympathetic-associated markers in skin and the spinal intermediolateral region. Conclusion These findings identify spinal cord stimulation as a preclinical neuromodulatory approach that attenuates dermatitis-associated itch and cutaneous neuroinflammation. The data support a functional contribution of the HF-SCS/TRAP-defined neuronal ensemble, which is enriched in Pax2+ inhibitory neurons, while the reductions in GRPR-related activity and sympathetic-associated signaling remain associative findings.
BACKGROUND:Transcranial Magnetic Stimulation (TMS) is an established non-invasive neuromodulation technique, with growing evidence suggesting that targeting multiple interconnected nodes may enable more selective network-level control. However, multisite stimulation remains constrained by the fixed field geometry and limited focality of conventional coils. OBJECTIVE:To introduce and characterize a modular multichannel transcranial magnetic stimulation (mTMS) array capable of electronically steering the induced electric field (E-field) without mechanical coil movement. METHODS:The array consists of two custom-made 3-axis TMS coils arranged with a slight tilt to approximate head curvature and enhance stimulation depth and efficiency. This modular architecture allows flexible adjustment of coils spacing and orientation. Computational simulations and in vivo experiments demonstrate that independently driven coil elements can be combined to form distinct "virtual coils", enabling controlled electronic shifts of the E-field hotspot. RESULTS:Using a physical-versus-electronic hotspot displacement paradigm with repeated resting motor threshold (rMT) estimation, we show that electronic E-field shifts of ±1 cm produce effects comparable to physically moving the coil. Computational modeling analysis confirms that the electronically synthesized virtual coil configurations elicit systematic E-field shifts in precentral gyrus that are spatially consistent with the measured rMT at each physical coil array location. The system achieved functional resolution consistent with the known spatial accuracy of TMS, with variability within expected limits of neuronavigation and calibration errors. CONCLUSION:These findings establish the feasibility and physiological relevance of electronically controlled E-field steering using a modular coil array. This platform provides a scalable foundation for next generation mTMS systems supporting multifocal stimulation of distributed brain networks.
BACKGROUND:After a motor stroke, brain networks mediating reaching and grasping undergo functional reorganization, particularly in the parietal cortex. Online repetitive transcranial magnetic stimulation (rTMS) can probe the behavioral relevance of stimulated cortical territories. However, anatomical interpretation is limited because the induced electric field is spatially distributed and may not correspond precisely to the nominal stimulation target. OBJECTIVE:To investigate how individual rTMS-induced E-field distributions relate to interference effects of online rTMS over the anterior intraparietal sulcus (IPS) on grasping in stroke patients and healthy controls. METHODS:Eighteen chronic stroke patients and eighteen matched controls performed a reach-grasp-lift task during online rTMS of the IPS. Individual E-fields were modeled and correlated with rTMS-induced changes in 3D kinematic measures. The overlap between E-field maxima and a meta-analytically defined grasping network, as well as cytoarchitectonic parietal regions, was quantified. RESULTS:In both groups, spatial overlap between the induced E-field and the grasping-related network was linked to rTMS effects on movement smoothness. Changes in grip shaping and smoothness were associated with E-field overlap in the IPS in healthy controls. In patients, the analogous association was observed for the inferior parietal lobule (IPL) rather than the IPS, a pattern compatible with reorganization of parietal specialization after stroke. CONCLUSIONS:E-field-based analyses may improve the interpretation of rTMS effects on grasping in healthy and reorganized neural circuits. This can provide a framework for neuromodulation strategies that focus on individually defined functional targets rather than standard landmarks.
OBJECTIVE:To develop and validate an ultrasound-guided low-intensity focused ultrasound (USg-LIFU) platform for subject-specific deep-brain neuromodulation and test whether ventral tegmental area (VTA) targeting modulates alcohol-related behaviour in a mouse model of alcohol use disorder. METHODS:USg-LIFU uses ultrasound tomography (UT)-assisted acoustic velocity mapping and subject-specific finite element method (FEM) simulations to incorporate reconstructed acoustic-property information into FEM-based focal prediction and guide mechanical alignment of the predicted focal zone toward the target. Targeting accuracy is verified ex-vivo using high-intensity focused ultrasound (HIFU) to create thermal lesions in mouse brain tissue. In-vivo neuromodulatory effects were tested in cHAP mice (n=10) that underwent six USg-LIFU sessions targeting the VTA on alternating days and compared with sham controls (n=5). Daily measures were recorded to assess alcohol and water intake, and blood alcohol concentration (BAC) was assessed before, during, and after treatment. RESULTS:Simulations showed that changes in brain acoustic velocity shifted focal position and altered pressure distribution, underscoring the need for subject-specific correction. Ex-vivo studies demonstrated that the optimized focus converged on the predefined intracranial target, with visible thermal damage at the intended location after sonication. In-vivo, most LIFU-treated mice showed reduced ethanol intake and increased water consumption after treatment initiation, whereas sham animals maintained or strengthened alcohol preference. Across the treatment period, mean alcohol intake decreased by approximately 51% in the treated group, consistent with reductions in BAC measurements. CONCLUSION:USg-LIFU achieved accurate subject-specific targeting and produced measurable modulation of alcohol-related behaviour, supporting its potential as an accessible platform for non-invasive deep-brain neuromodulation.
INTRODUCTION:Apathy is a common and disabling non-motor symptom in Parkinson's disease (PD) that can diminish the therapeutic benefit of subthalamic nucleus deep brain stimulation (STN-DBS). We previously demonstrated that co-stimulation of the left ventromedial prefrontal cortex (vmPFC) can alleviate apathy following levodopa withdrawal in PD patients treated with STN-DBS. Building on these findings, we investigated whether presurgical white matter integrity of the vmPFC-STN pathway constitutes a structural correlate of clinically significant apathy prior to DBS. METHODS:Preoperative T1-weighted and diffusion MRI data from 119 PD patients undergoing STN-DBS were analyzed. Based on Starkstein Apathy Scale (SAS) scores, patients were classified as apathetic (SAS ≥ 14; n = 67) or non-apathetic (n = 52). Fractional anisotropy (FA) maps were processed using FSL's Tract-Based Spatial Statistics pipeline. Voxel-wise group comparisons were performed with threshold-free cluster enhancement (5000 permutations), restricted to a bilateral vmPFC-STN mask derived from probabilistic tractography from the previously published cohort. RESULTS:A significant cluster (74 voxels) within the left vmPFC-STN ROI showed reduced FA in apathetic patients (TFCE-corrected p = 0.0294). Post-hoc analyses revealed higher mean diffusivity (p = 0.0206) and radial diffusivity (p = 0.001) in the apathetic group, while axial diffusivity did not differ. Exploratory subset analysis suggested baseline vmPFC-STN integrity may influence apathy response to vmPFC DBS. CONCLUSION:Clinically significant apathy in PD prior to STN-DBS is associated with reduced white matter integrity in the left internal capsule involving the broader left-sided vmPFC projection system. Identifying this structural substrate may contribute to future optimization of apathy management with STN-DBS.
BACKGROUND:High-frequency deep-brain stimulation can reduce seizure burden but imposes a large stimulation load on the tissue, and its effects depend on both frequency and temporal patterning. We tested whether a compact reservoir model could generate a hippocampal-inspired event schedule and whether that schedule could modulate neuronal activity in vitro with fewer nominal pulses than 50-Hz stimulation. METHODS:A 10-unit leaky reservoir with a one-dimensional affine ridge readout transformed cortical input recordings into CA3-inspired outputs. Retrospective computational validation used paired cortical-CA3 recordings, training-only scaling, removal of at least the first 10 s of every generated trace, date-grouped held-out evaluation, multiple spectral and temporal metrics, objective-function ablation and surrogate signals. One offline biomimetic schedule was then delivered open loop to primary rat cortical cultures on multielectrode arrays and compared with periodic 0.16-Hz and 50-Hz stimulation. RESULTS:17 of 19 paired recordings passed the pre-specified transient diagnostic. In 11 scorable date-grouped held-out recordings, the reservoir had modestly lower median log-PSD RMSE and autocorrelation error than linear and lagged-ridge baselines. When applied to primary cortical cultures, the primary pooled analysis of all 11 biomimetic-stimulated MEAs yielded a mean firing-rate slope of 0.7655 relative to the null value of 1 (95% CI for the mean slope, 0.491-1.040; p = 0.0865). In separate MEA-level fold-change analyses of all 11 biomimetic-stimulated MEAs, normalized firing rate was 0.8458 and normalized burst rate was 0.7792, both significantly reduced relative to baseline. A post hoc exploratory classification identified reduced firing-rate slopes in 4 of 11 MEAs. CONCLUSION:These results provide an open-loop in vitro proof of concept that a low-event, irregular stimulation schedule can be associated with heterogeneous modulation of cortical-network activity. Periodic stimulation at the same nominal mean event rate did not produce a statistically significant modulation under the conditions tested. The irregular schedule may contain timing-related properties that contribute to the observed response, but the specific contribution of ESN-derived temporal ordering remains unresolved. Future work should test appropriate temporal controls and evaluate the approach in closed-loop and epilepsy-model experiments.
BACKGROUND:Transcranial photobiomodulation (t-PBM) with near-infrared light stimulates mitochondria and may have antidepressant effects. We evaluated dose-dependent effects of t-PBM on the hemodynamic blood-oxygenation-level-dependent (BOLD) power in major depressive disorder (MDD). METHODS:31 MDD subjects underwent randomly assigned t-PBM sessions, 1/week, in the MRI scanner, with 1) Sham; 2) High dose: pulse wave, irradiance ∼300 mW/cm2; 3) Medium dose: continuous wave, ∼300 mW/cm2; and 4) Low dose: continuous wave, ∼50 mW/cm2 t-PBM (808 nm) was delivered to the prefrontal cortex, bilaterally. fMRI was recorded at 3T before, during, and after t-PBM. We used mixed-effects linear regression to evaluate changes in BOLD power during stimulation, compared to sham. The analysis was repeated for the middle frontal gyrus (MFG), the prefrontal areas irradiated by t-PBM, and the entire brain cortex. RESULTS:We found similar results in the MFG, the prefrontal cortex directly irradiated, and the entire brain cortex: medium dose t-PBM was associated with a statistically significant increase in BOLD power, whereas low dose t-PBM was associated with a significant decrease in BOLD. There were no significant changes in BOLD power with the high (pulsed) t-PBM dose or with sham. Single administrations of any t-PBM dose did not result in significant changes in depression severity (versus sham). All 3 t-PBM doses were well tolerated. CONCLUSION:The acute effect of t-PBM on the hemodynamic BOLD power is robust, dose-dependent, bidirectional, and extends beyond the areas directly illuminated. These findings may provide a reference for future dose selection and clinical efficacy studies.
BACKGROUND:The substantia nigra (SN) is an emerging deep brain stimulation (DBS) target for Parkinson's disease (PD). However, its independent therapeutic profile remains obscured by concurrent subthalamic nucleus (STN) stimulation in clinical practice. We systematically evaluated the frequency-dependent efficacy, longitudinal feasibility, and clinical boundaries of direct SN DBS to optimize both targeted nigral modulation and STN-SN combined stimulation. METHODS:Phase 1 comprised an acute randomized crossover assessment in which 30 participants underwent both SN stimulation at 10, 30, and 130 Hz and standard STN stimulation at 130 Hz. Outcomes included the Movement Disorder Society Unified Parkinson's Disease Rating Scale Part III (MDS-UPDRS III), objective gait kinematics, and episodic memory. Phase 2 was an exploratory, non-randomized 3-month feasibility cohort. Seven participants initiated chronic SN stimulation; two discontinued because of treatment-limiting adverse events, and longitudinal outcomes were available for five treatment-tolerant completers, with descriptive comparison to five STN-DBS comparator participants. RESULTS:SN-DBS produced clear, frequency-dependent acute motor improvements. High-frequency (130 Hz) stimulation yielded the most pronounced clinical benefits, including a 43.6% reduction in MDS-UPDRS III and a 13.5% increase in stride length. The motor and spatial gait effects at 130 Hz were of similar magnitude to those observed with standard STN-DBS, while episodic memory performance remained stable across stimulation conditions. Patient-specific VTA mapping identified an outcome-associated region predominantly within the dorsal SN, and greater spatial overlap was associated with greater motor improvement. In Phase 2, chronic SN stimulation was maintained for 3 months in five of seven participants; two discontinued because of treatment-limiting adverse events. CONCLUSION:Direct SN stimulation produced a clear frequency-dependent acute response in PD, with 130 Hz yielding the strongest motor and spatial gait benefits among the tested frequencies and effects of similar magnitude to standard STN stimulation. VTA mapping localized the strongest response-associated region predominantly within the dorsal SN, and the 3-month observations provided a basis for further development of anatomically precise and individualized SN neuromodulation.
BACKGROUND:Transcranial magnetic stimulation-evoked potentials (TEPs) propagate from the stimulation site to distributed brain networks, with early propagation thought to occur predominantly through feedforward processes and later propagation through recurrent processes. We employed pharmacological manipulation to probe mechanisms that underlie feedforward and recurrent signal propagation in the human brain. METHODS:We manipulated TEP propagation using GABAAergic drugs in placebo-controlled randomized crossover experiments in healthy participants. Experiment 1 tested zolpidem and alprazolam, while Experiment 2 tested diazepam. Experiment 3 compared active and sham TMS-EEG to verify the specificity of diazepam effects on TEPs. RESULTS:Alprazolam decreased β-band phase coupling within large-scale neural networks in the early feedforward stage. During the late recurrent stage, it reduced significant current density (SCD), significant current scattering (SCS) and the perturbational complexity index (PCI-lz). In contrast, zolpidem increased early-stage SCD and TMS-induced event-related spectral perturbations, but did not affect β-band phase coupling, SCS, or PCI-lz. Structural equation modeling revealed that the early-stage changes in β-band phase coupling predicted directly or indirectly the late-stage changes in SCD, SCS, PCI-lz and saccadic peak velocity, a marker of GABAAergic sedation. Diazepam replicated the alprazolam effects. The active vs. sham TMS-EEG comparison showed that the reductions in late-stage SCD and SCS induced by diazepam reflected specific modulation of TEPs. CONCLUSIONS:Findings provide a novel framework of how local neural dynamics shape signal propagation to large-scale networks and identify early-stage β-band phase coupling as a key mechanism. Consequently, considering propagation dynamics is important when interpreting PCI alterations in brain disorders.
BACKGROUND:The motor cortex exhibits a somatotopic organization that enables skilled control of lower limbs during locomotion. Following spinal cord injury (SCI), descending cortical commands are completely or partially disrupted, resulting in impaired volitional walking. We previously developed a closed-loop paradigm delivering intracortical microstimulation (ICMS) to hindlimb motor representations in synchrony with locomotion, which immediately improves walking deficits and enhances long-term recovery of voluntary locomotor control in rodent models. However, as clinical efforts prioritize less invasive neurostimulation approaches, the necessity of functionally specific cortical targeting remains a critical question. OBJECTIVE:Here, we tested whether stimulation of hindlimb-specific cortical territories provides superior recovery compared to non-specific stimulation or no stimulation in a feline model of severe thoracic spinal contusion (T10) producing chronic bilateral locomotor deficits. METHODS:Following recovery of weight-supported stepping, cats underwent a three-week locomotor training intervention, with or without concurrent ICMS depending on group assignment: no stimulation (n = 5); ICMS targeting the specific contralateral hindlimb representation (n = 2); or non-specific ICMS recruiting multiple body parts (n = 3). Locomotor performance was assessed on a flat treadmill, ladder treadmill, and during obstacle avoidance up to four weeks post-therapy. RESULTS:Our results indicate that while all groups exhibited improvements in basic treadmill locomotion, only hindlimb-specific ICMS restored voluntary locomotor control to near-intact levels, particularly during tasks requiring high-precision paw placement. CONCLUSIONS:These findings provide preclinical evidence that the functional specificity of cortical stimulation is essential for optimizing skilled locomotor recovery, highlighting the importance of precise spatial targeting in neuroprosthetic interventions.
This systematic review summarized findings on the association between screen time and bruxism in children and adolescents (PROSPERO- CRD42023429775). Two researchers conducted the search and selection of studies, extracted the data, and analyzed the risk of bias. The quality of the evidence was assessed using the GRADE tool. Five databases were screened on September 25th, 2025. Studies exploring the association between bruxism and the use of screen devices in individuals aged 0-18 were included, considering different and valid study designs, screen devices, and methods of detection of bruxism behavior with or without circadian distinction. Qualitative data synthesis was performed. Eleven cross-sectional and two cohort studies were included. Eight studies found an association between bruxism and the use of screen devices in children and adolescents, while five studies did not find a significant association. In conclusion, an association between screen use or duration and bruxism in children and adolescents cannot be established. Although some studies reported positive associations for awake, sleep, and unspecified bruxism, particularly in research evaluating longer daily screen time or indicators of problematic digital use, the certainty of the evidence was very low. Further well-designed longitudinal studies should be conducted to broaden the overview of this association.
Abstract Radiotherapy is the cornerstone of head and neck cancer (HNC) treatment, but it has been frequently associated with changes in the acquired enamel pellicle (AEP), potentially affecting the early stages of dental biofilm formation. Thus, this study aimed to characterize the bacterial proteomic profiles of early colonizers adhering to the AEP in patients with HNC undergoing radiotherapy, with emphasis on radiation-induced changes that may influence oral biofilm development and oral health outcomes. AEP samples were collected from nine patients with HNC before radiotherapy (BRT), during radiotherapy (DRT), and after radiotherapy (ART), as well as from nine orally healthy individuals. Pellicles were obtained 120 min after formation and analyzed by shotgun label-free proteomics using nanoLC-ESI-MS/MS. Protein expression levels were compared between groups using the t test (p < 0.05). AEP showed elevated levels of bacterial proteins predominantly attributed to Actinomyces, mainly associated with DNA binding, chromatin organization, and glucose metabolism. The bacterial proteomic profile shifted markedly DRT, with exclusive detection of proteins involved in carbohydrate transport and metabolism, oxidative stress response, and protein folding, including several ATP-binding cassette transporters and glycolytic enzymes. Proteins related to stress tolerance, transcriptional regulation, and secretion systems were detected ART, many of them associated with bacterial species commonly linked to periodontal diseases, such as Tannerella and Oribacterium. Notably, Cysteine synthase was identified exclusively BRT in all comparisons, suggesting its potential as a biomarker. These findings indicate that radiotherapy induces dynamic changes in the AEP bacterial proteome, potentially favoring dysbiotic biofilm development and increasing susceptibility to oral diseases in patients with HNC.
Abstract This study aimed to evaluate the in vitro cytotoxicity and bioactivity, and the in vivo biocompatibility, collagen maturation, and bioactivity, of PBS Cimmo HP and Bio-C Repair Ion+ in comparison with white MTA-Angelus. Osteoblast-like cell viability was assessed using the Alamar Blue assay, while bioactivity was assessed by alkaline phosphatase (ALP) activity and Alizarin Red staining. For the in vivo analysis, polyethylene tubes containing the materials or empty tubes (control) were implanted in the dorsum of mice. After 7 and 30 days (n = 8), the animals were euthanised and the specimens were processed for haematoxylin-eosin, Picrosirius Red, von Kossa (VK), and polarised light (PL) analyses. Data were statistically analysed (p < 0.05). Most materials extracts were cytocompatible (P > 0.05), except for the PBS Cimmo HP 1:4 extract at 48-h (p < 0.05). All materials showed increased ALP activity (p < 0.05). Mineralized nodules were significantly present in most material extracts (p < 0.05), except in the undiluted PBS Cimmo HP extract and in the white MTA-Angelus 1:4 extract. At 7 days, PBS Cimmo HP induced moderate-to-severe inflammation, whereas the other groups induced moderate inflammation (p > 0.05). At 30 days, all groups showed reduced inflammation (p > 0.05). Overall, the fibrous capsule was thick at 7 days and thin at 30 days. At 7 days, the control and PBS Cimmo HP groups showed a greater presence of immature collagen (p < 0.05); at 30 days, more mature collagen was observed in all groups (p > 0.05). The materials exhibited positivity for VK or PL in both periods. In conclusion, PBS Cimmo HP and Bio-C Repair Ion+ were cytocompatible and biocompatible, and demonstrated bioactivity and collagen maturation similar to those of white MTA-Angelus.
