Neuromodulation: Technology at the Neural Interface

Low-intensity focused ultrasound (LIFU) is a non-invasive neuromodulation technique with a favorable safety profile in healthy volunteers. Participant-experienced symptoms however remain inconsistently measured, and prospective benchmarks are lacking. Here, we prospectively characterized symptoms associated with LIFU neuromodulation across eight studies using a standardized Report of Symptoms (ROS). We compiled 629 sessions (472 LIFU, 157 sham) in 106 healthy adults (28.1 +/- 9.8 years) across eight cortical and subcortical targets (500 kHz; extracranial ISPPA 3.9-33.3 W/cm2; mechanical index 0.5-1.4). The ROS rated 17 symptom domains from 0 (absent) to 3 (severe) before and after each session. New-onset incidence, symptom severity, and total symptom burden were compared between LIFU and sham. The same instrument was applied in 35 patients with chronic pain. Symptom profiles after LIFU were indistinguishable from sham across all 17 domains. Total symptom burden averaged approximately one domain per session and did not increase after LIFU (0.94 to 1.03; p = 0.120). Post-intervention burden was predicted by baseline burden (beta = 0.347, p < 0.001) but not by stimulation condition (p = 0.222). New-onset symptoms did not increase across up to 27 LIFU sessions (OR = 0.99, p = 0.73) and were weakly, non-significantly related to acoustic intensity (rho = 0.37). Across a prospective, sham-controlled dataset, LIFU added no measurable symptom burden and was well tolerated in healthy adults, with comparable tolerability in patients. These findings establish a benchmark for the safety of human LIFU neuromodulation and a foundation for its therapeutic translation.

Background: Deep brain stimulation (DBS) is a widely used therapy for neurologic and psychiatric disorders. Conventional DBS delivers highly regular stimulation patterns that suppress pathological activity but can induce stimulation-related side effects, limiting the therapeutic window. Introducing controlled temporal variability through stochastic pulse timing may represent an alternative programming dimension to improve tolerability while preserving clinical benefit. Methods: An adult in their 60's with bilateral Vim DBS underwent evaluation of tonic, pink-noise, and white-noise stimulation patterns delivered through his chronically implanted Boston Scientific Genus system using the Chronos research platform. We assessed tremor and stimulation-induced side effects using accelerometry, spiral drawing tasks, standardized speech recordings, and patient-reported paresthesias. Results: Pink noise stimulation preserved meaningful tremor suppression while improving tolerability compared with conventional tonic 130 Hz stimulation. Under tonic stimulation, dysarthria and paresthesias were prominent at 2.0 mA, narrowing the usable therapeutic window. In contrast, pink noise maintained tremor control across the same amplitude range with reduced side-effect burden. White noise stimulation demonstrated intermediate effects, providing improved tolerability relative to tonic stimulation but less tremor suppression than pink noise. Findings were consistent across accelerometry and functional drawing tasks. Conclusion: This study provides first-in-human evidence that temporally structured stochastic pulse timing can preserve therapeutic benefit while expanding the tolerable stimulation range relative to tonic DBS. These findings suggest that temporal structure represents a clinically meaningful programming dimension that may broaden the DBS therapeutic window using software based updates to existing hardware. Further evaluation in larger cohorts is warranted

Myofascial pain syndrome (MPS) is a major cause of chronic neck pain, with tissue ischemia implicated as a contributing factor. This prospective, single-arm interventional study evaluated the analgesic effect of ultrasound-guided fascia hydrorelease (US-FHR) performed around arteries supplying the neck in patients with chronic neck MPS. Thirteen adults (median age 53.0 years; 38.5% female) underwent US-FHR targeting the perivascular fascia of either the transverse cervical or dorsal scapular artery using 2 mL of normal saline. Pain intensity was assessed by visual analog scale (VAS) at rest and during movement; disability by the 5-item Pain Disability Index, Japanese version (PDI-5-J); and arterial blood flow volume before and after the procedure. The primary outcome, pain VAS during movement, decreased from 49.0 mm (interquartile range [IQR], 44.5-64.0) at baseline to 22.0 mm (IQR, 14.5-31.5) at 15 min and 22.0 mm (IQR, 14.0-34.0) at 1 week (Hodges&-Lehmann median difference, 30.5 mm [95% CI, 24.5 to 36.5] and 28.5 mm [95% CI, 18.5 to 37.0]; both P < 0.001). Pain VAS at rest improved from 21.0 mm (IQR, 13.0-43.5) to 8.0 mm at 15 min and 1 week (median difference, 14.5 mm [95% CI, 9.0 to 24.0; P = 0.001] and 13.5 mm [95% CI, 6.0 to 21.0; P = 0.007]). PDI-5-J decreased from 17.0 (IQR, 10.5-23.0) to 13.0 (IQR, 4.0-17.5) at 1 week (median difference, 5 [95% CI, 2 to 8; P = 0.004]). Blood flow volume increased from 11.2 mL/min (IQR, 4.5-14.4) to 17.2 mL/min (IQR, 6.1-23.7) immediately after US-FHR (median difference, +4.1 mL/min [95% CI, +2.5 to +8.9; P = 0.001]), although transient. One patient experienced transient bleeding that was promptly controlled. In this single-arm feasibility study, US-FHR around the target artery was simple and safe to perform and was associated with reduced neck pain. Because the study lacked a control group, these preliminary findings should be regarded as hypothesis-generating and require confirmation in controlled trials; they may also inform the future evaluation of MPS in other anatomical regions. Trial registration: UMIN Clinical Trials Registry, UMIN000053612.

ObjectiveLateral spinal cord stimulation (LSCS) is a promising approach for restoring somatosensory feedback in lower-limb amputees, but its spatial selectivity remains limited. Percepts often spread to unintended regions of the residual limb, and reducing electrode contact size may not improve focality. This study investigated whether the anatomical organization of lumbar dorsal rootlets (DR) imposes fundamental constraints on LSCS selectivity. ApproachAcute neurophysiology experiments were performed in six adult cats. Both LSCS and individual DR stimulation were conducted in the same animals. For DR stimulation, bipolar hook electrodes were used to stimulate individual DR, while antidromic compound action potentials (CAPs) were recorded from femoral and sciatic nerve branches instrumented with nerve cuffs. For LSCS, custom 32-contact epidural paddle electrodes were placed over the lateral surface of the spinal cord at corresponding vertebral levels. Recruitment thresholds, dynamic ranges, and response patterns were analyzed across spinal levels, and DR recruitment patterns were directly compared to those evoked by LSCS within the same animals. Main resultsA clear rostrocaudal organization was observed across spinal levels during stimulation of individual DR, with femoral branches predominantly recruited at L4-L5 and sciatic branches at L6-L7. However, no somatotopic organization was found across DR within each spinal level; individual DR frequently co-activated multiple branches within the same group, and selective recruitment could only be maintained over a narrow dynamic range (median [~]10 {micro}A). LSCS exhibited even a narrower dynamic range ([~]5 {micro}A) but closely mirrored DR recruitment patterns, indicating that LSCS activates sensory afferents in a manner determined by the organizational structure of the DR. SignificanceThese findings demonstrate that the limited spatial selectivity of LSCS can largely be attributed to the coarse organization of DR within each root level rather than due to limitations of epidural electrode design. Moving electrodes intradurally or reducing contact size further is unlikely to substantially improve focality. Instead, improving paddle stability to ensure consistent placement over the appropriate spinal levels may be a more effective strategy for enhancing percept localization.

Background: Chronic pain is a multidimensional condition that often persists despite conventional treatment and adversely affects multiple domains of daily life. Music listening has emerged as a promising non-pharmacological intervention, with accumulating evidence supporting its beneficial effects on pain and associated psychological outcomes. However, despite growing evidence of efficacy, the translation of music listening into routine clinical practice remains limited, partly because intervention reporting has received comparatively little attention. Objective: To evaluate the effectiveness of music listening interventions for chronic pain and systematically assess the methodological quality and completeness of intervention reporting to identify barriers to reproducibility and clinical implementation. Methods: Systematic searches were conducted in PubMed, Cochrane Library, CINAHL, and Web of Science through June 2025, with no date restrictions on publication. Randomized controlled trials involving adults with chronic pain receiving music listening interventions were included. Two independent reviewers screened studies, extracted data, and assessed risk of bias. Intervention reporting was evaluated using the TIDieR checklist, and a random-effects meta-analysis was performed for pain intensity outcomes. Results: Ten RCTs involving 538 participants were included. Music listening interventions varied substantially in delivery, duration, and music selection procedures, reflecting considerable heterogeneity in intervention design. Most studies reported significant improvements in pain and psychological outcomes. Meta-analysis of eight trials (10 effect estimates), demonstrated a moderate reduction in pain intensity (SMD = -0.53, 95% CI: -0.96 to -0.11, p = 0.014; I2 = 76.2%). Although intervention rationale and procedures were generally well described, reporting of intervention modifications, treatment fidelity, and adherence was frequently incomplete. These reporting deficiencies may compromise reproducibility and limit translation into clinical practice. Conclusions: Music listening appears to be a safe, accessible, and scalable non-pharmacological intervention for chronic pain management, with benefits extending beyond pain reduction to psychological wellbeing, quality of life, and functioning. However, incomplete reporting of key intervention components may limit reproducibility and hinder clinical implementation. Future trials should adopt standardized and transparent reporting standards to facilitate implementation into clinical practice.

The anterior cingulate cortex (ACC) is a key brain center involved in cognitive and emotional processing that is implicated in a variety of neuropsychiatric disorders including chronic pain and depression. Circuit-targeted diagnosis and treatment of these disorders will require the capacity to precisely modulate ACC subregions. Toward that end, we recently developed and validated a novel low-intensity transcranial focused ultrasound device that can noninvasively and directly modulate ACC subdivisions in humans with millimeter precision. Here we describe the subjective reports of 36 individuals diagnosed with either chronic pain or major depression who received repeated brief stimulation trials (807 active, 797 sham; duration 30s-3min) spanning the dorsoventral extent of the ACC. Sonication immediately altered cognitive-emotional states (odds ratio 5.6, active versus sham), eliciting a positive-valence experience more often than negative (29% versus 8%) in both diagnostic groups. Sham-adjusted response rate varied across ACC targets, with the largest effects (Cohen's d ~ 0.8) observed in pregenual and subgenual ACC in subjects with chronic pain and depression, respectively. These rapid trial-by-trial responses to ACC stimulation predicted subsequent improvements in pain and depression severity at 24 hours. Collectively, these findings reveal that transcranial ultrasound can robustly evoke immediate, target-specific, clinically meaningful changes in cognitive-emotional state, demonstrating the potential of ultrasonic neuromodulation as a tool for individualized probing of circuit function and dysfunction.

Modern cochlear implants (CIs) use pulsatile stimulation to restore hearing for individuals with severe hearing loss. CIs provide robust speech recognition in quiet but poorly represent temporal fine structure (TFS), needed for challenging listening situations. Analog stimulation preserves the acoustic waveform and may better encode TFS, yet it has not been evaluated combined with modern current-focusing strategies. We compared neural responses in the inferior colliculus (IC) evoked by CI stimuli consisting of 100 pulses/s biphasic pulse trains and 100 cycles/s sinusoidal analog stimulation with monopolar, bipolar, and tripolar electrode configurations in urethane-anesthetized guinea pigs. Following cochlear implantation, multiunit activity was recorded from the tonotopic axis of the central nucleus of the IC using 16-channel silicon probes. Detection thresholds, spread of excitation, vector strength, sustained response percentage, and temporal response properties were quantified. Analog stimulation consistently evoked significantly lower activation thresholds than pulsatile stimulation while maintaining comparable or sometimes narrower spatial selectivity across stimulation modes. In contrast, analog stimulation generated lower vector strength, larger tonic response components, and a pronounced level-dependent polarity effect. At low stimulus levels, responses were dominated by the cathodic phase of the sinusoidal waveform, whereas increasing stimulus level responses were elicited by both phases, producing synchronization at twice the stimulus frequency. These findings demonstrate that stimulation waveform strongly influences temporal coding while having relatively little effect on the spatial distribution of neural activation. These results provide a physiological basis for reexamining analog stimulation as an alternative strategy for cochlear implant sound coding.

Finding suitable therapies for treatment-refractory neuropsychiatric disorders constitutes a major goal for translational neuroscience. Deep brain stimulation shows promise for treatment resistant depression, but treatment efficacy varies substantially across patients. Objective, electrophysiologically driven strategies to optimize deep brain stimulation for treatment resistant depression could greatly improve clinical efficacy by minimizing the trial-and-error approach needed to personalize stimulation settings. This may not only reduce the delay between the start of the treatment and symptom improvement, but also enable acute, real-time verification of circuit engagement, advancing our understanding of the mechanism mediating antidepressant effects. Here, we investigate whether cerebro-cerebral evoked potentials elicited through different deep brain stimulation configurations could be used to guide stimulation personalization for treatment resistant depression. Cerebro-cerebral evoked potentials offer a fast, objective way to identify regions engaged by stimulation, revealing the effective connectivity pattern of the stimulated location. Data were collected from eight patients with treatment resistant depression who received dual bilateral deep brain stimulation devices targeting the subcallosal cingulate and ventral capsule/ventral striatum. During an initial in-hospital monitoring period, single-pulse electrical stimulation was delivered through the deep brain stimulation devices and cerebro-cerebral evoked potentials were recorded through temporary stereo-electroencephalography probes across fronto-temporal regions. Patients underwent several outpatient stimulation programming sessions over the course of 9 months to identify the stimulation configurations leading to the greatest improvement in depressive symptoms. We retrospectively analysed cerebro-cerebral evoked potentials obtained in response to stimulation of different stimulation configurations to identify features distinguishing the clinically effective configurations. The deep brain stimulation configurations leading to the greatest improvement in depressive symptoms were associated with significantly larger evoked potentials in the orbitofrontal cortex and showed an increased number of evoked potentials across dorsal and ventral prefrontal regions. Waveform similarity analysis revealed a gradient in therapeutic effects, such that multiple alternative stimulation configurations led to similar symptom improvement. The vast deep brain stimulation parameter space might contain a configuration subspace defined by comparable therapeutic effects. In addition, evoked potentials obtained from single-pulse and from bursts of high-frequency stimulation displayed similar spatial patterns, suggesting that either method might be able to identify the configuration best engaging the circuit mediating the clinical response. Together, these findings provide proof-of-principle evidence that stimulation-evoked prefrontal responses reflect network engagement associated with antidepressant effects. Cerebro-cerebral evoked potentials may offer an objective and acute strategy to guide contact selection in deep brain stimulation for treatment resistant depression.

Stroboscopic light stimulation (SLS) is a candidate non-pharmacological intervention that induces transient visual and affective experiences, with potential application in depression. Before efficacy testing, clinical development requires safety, tolerability and feasibility data. We report a staged, single-site programme in adults reporting depressive symptoms. Work Package (WP) 1 tested 11 SLS parameter sets for safety and tolerability. An interim bridge study assessed whether a low-phenomenology SLS control reduced subjective visual effects while preserving session context. WP2 randomised 84 participants to four weekly supervised 31-minute sessions of the intervention or a low-phenomenology control. In WP1, 31 participants were analysed; no severe adverse reactions occurred, mean discomfort was low (0.49/10), and the highest session-level upper 80% confidence limit was 1.13/10, well below the prespecified threshold. The interim study supported experiential separation between intervention and control. In WP2, endpoint data were available for 70/84 participants (83.3%): 39/42 in the intervention arm and 31/42 in the control arm. Overall retention met the criterion, but lower control-arm retention remains a design issue; protocol adherence was high, discomfort remained low, and no serious SLS-attributable adverse events occurred. Exploratory depressive-symptom changes suggested a possible BDI-II signal, but do not establish efficacy. Supervised SLS met key safety, tolerability, and feasibility criteria, and a lower visual-phenomenology active control can be carried forward, while masking and comparator credibility remain to be established. The next step is a diagnostically defined, CTU-governed Phase 2a feasibility trial that pre-registers a locked protocol and tests masking, credibility, retention and endpoint precision.

Background: Stroke often causes Upper Limb (UL) functional impairments. The Primary Somatosensory Cortex (S1) plays an important role in motor learning. Repetitive Transcranial Magnetic Stimulation (rTMS) over S1 could enhance UL recovery. We aimed to explore its preliminary effects on UL motor activity and function post-stroke. Methods: An exploratory parallel-group randomized controlled trial in people with chronic stroke (>3 months) and moderate hemiparesis was conducted. Participants received 20 sessions of active or sham 5Hz rTMS over affected S1, with Robot-Assisted Therapy and Task-Oriented Training, 5 days/week for 4 weeks. The primary endpoint was UL motor activity (Action Research Arm Test, ARAT). Secondary measures were the UL Fugl-Meyer Assessment (UL-FMA) and sensory outcomes. Results: The baseline-adjusted mean difference (MD) in ARAT was 4.05 points [0.78, 7.33], favoring active stimulation. Secondary measures did not favor active stimulation (UL-FMA: MD = 2.62 [-1.51, 6.76]; sensory outcomes showed no between-group differences). Conclusion: High-frequency rTMS over S1 may enhance UL motor activity (ARAT), but no evidence for motor impairment (UL-FMA) or sensory domains was found. Compensation rather than restoration may underlie this improvement. Stimulation targets should match the intended recovery domain, although larger trials are needed to confirm these preliminary findings.

Transcranial photobiomodulation (PBM) is an emerging non-invasive brain stimulation method that is thought to increase neural metabolism by stimulating ATP production by the mitochondria. However, the mechanisms of action and the effects on the human brain are still unclear. In the present study, we investigated the potential of this method to enhance Blood Oxygen Level Dependent (BOLD) responses during the execution of a motor task in young and aged participants. Sixty young and aged participants were included in this single-blinded, sham-controlled, randomised, crossover study. They underwent an fMRI recording before and after 24-min stimulation with a 80-LEDs helmet emitting transcranially red and near infrared light. Post vs Pre BOLD signal was compared between PBM and SHAM, in each group. At baseline, aged participants showed reduced BOLD signal compared to young ones, in key regions of the sensorimotor processing, principally the left primary motor cortex and striatum. Transcranial PBM did not have a real impact in the young group. However in aged participants it increased BOLD signal in some regions that were underactivated compared to the young group at baseline. In particular, regional analysis showed increased BOLD response in the left primary motor cortex, and right dorsal and ventral premotor regions and striatum. These results suggest that transcranial PBM can increase fMRI BOLD activity in the task-related regions, particularly in aged subjects. Further research are needed to distinguish neural from vascular effects in transcranial PBM.

Background: Down syndrome (DS) is associated with persistent language and cognitive impairments and with abnormalities in cortical oscillatory activity, including in the gamma range. Transcranial photobiomodulation (tPBM) is a noninvasive neuromodulatory intervention with potential benefits for cortical physiology, language, and cognition. Methods: We conducted a pilot randomized, double-blind, sham-controlled trial of repeated 40-Hz near-infrared tPBM in adolescents and young adults with DS. Fourteen participants were randomized 1:1 to active tPBM or sham and received 18 sessions over 6 weeks, followed by short-term and long-term follow-up. Outcomes included resting-state EEG gamma power, connected-speech measures, language and cognitive indices, and selected computerized tasks. Results: Active tPBM did not significantly increase global resting-state EEG gamma power relative to sham at either follow-up. Pre-registered analyses did not show broad treatment benefit across outcomes, although they did identify a significant short-term advantage for active tPBM on grammatical morpheme accuracy in connected speech; in contrast, picture naming favored sham at long-term follow-up. Exploratory mechanistic analyses did not show a robust biological treatment signal. Both active and sham procedures were well tolerated, with no serious adverse events. Conclusions: In this underpowered pilot sample, 6 weeks of 40-Hz near-infrared tPBM--delivered unilaterally, at low power, on target areas--did not demonstrate a meaningful effect size in DS. A dose-finding study for tPBM in DS, also accounting for age of participants, is recommended.

This study examined whether connectivity-guided accelerated intermittent theta-burst stimulation (iTBS) improves depressive symptoms beyond routine multimodal inpatient care in hospitalized patients with treatment-resistant depression (TRD). In this randomized, double-blind, sham-controlled trial, patients with unipolar TRD received active or sham iTBS. Stimulation targeted an individualized left dorsolateral prefrontal cortex site showing most functional anticorrelation with the subgenual anterior cingulate cortex on resting-state functional MRI. Treatment was delivered as 3 daily sessions over 10 weekdays (30 sessions; 54,000 pulses) as an inpatient augmentation strategy. Primary and secondary outcomes were changes in Montgomery-Asberg Depression Rating Scale (MADRS) and Beck Depression Inventory-II (BDI-II) scores during the 2-week stimulation phase. Exploratory endpoints included response and remission rates. Of the 57 randomized patients, 51 completed treatment (active, n=27; sham, n=24). The cohort exhibited moderate-to-severe treatment resistance (mean Maudsley Staging Method score, 10.9) and high psychiatric comorbidity. Active iTBS was associated with significantly steeper MADRS improvement than sham (-3.54 points/week; 95% CI, -5.53 to -1.55; PFDR=.02), corresponding to model-estimated reductions of 12.06 versus 4.98 points with a large effect size (d=-0.89). BDI-II trajectories similarly favored active treatment, though with a smaller effect (group-by-time estimate, -0.23 points/day; 95% CI, -0.41 to -0.05; PFDR=.04; d=-0.22). MADRS response rates were higher with active iTBS (42.3% vs 13.0%), while remission rates were numerically but not significantly higher (26.9% vs 12.5%). No serious adverse events occurred. In conclusion, connectivity-guided iTBS produced significant add-on antidepressant effects during acute inpatient treatment of TRD. Larger multicenter trials are needed to establish durability and optimize implementation.

Cochlear implants (CIs) restore hearing by stimulating auditory neurons to encode amplitude envelopes across frequency bands, providing essential cues for speech recognition. This study investigated how stimulation pulse rate constrains temporal envelope processing and speech cue perception in ten post-lingually deaf CI users by evaluating amplitude modulation (AM) detection thresholds and consonant identification performance across pulse rates. The effects of pulse rate on temporal processing and speech perception were examined using both standard clinical multi-channel strategies and single-channel strategies designed to isolate within-channel envelope representations. Results revealed a significant decline in AM detection and consonant recognition performance at the lowest tested pulse rate of 125 pulses per second (pps), consistent with perceptual constraints on temporal processing at low carrier rates, rather than inadequate envelope sampling. At the highest pulse rate of 4000pps, a non-significant reduction in AM detection was observed which may be consistent with previously reported reductions in amplitude discrimination at high pulse rates. Consonant recognition performance remained stable across clinically relevant pulse rates (250-2000pps), though listener-specific pulse rate effects were observed. Notably, significant correlations were found between single-channel and multi-channel performance in AM detection and consonant recognition tasks. These findings support an important contribution of within-electrode temporal envelope processing to multi-channel speech perception and highlight the clinical relevance of individual variability in pulse rate effects.

Background: Subthalamic nucleus deep brain stimulation (STN-DBS) improves levodopa-induced motor complications and cardinal motor symptoms of Parkinson's disease (PD), but stimulation frequency may differentially shape outcomes. This is evident for axial and gait symptoms, which may respond differently to lower-frequency stimulation. Whether frequency-dependent effects extend to cognition remains unclear. Objective: To investigate the cognitive effects of DBS at distinct frequencies in PD. Methods: We conducted a systematic review and meta-analysis (PROSPERO - CRD42024618253). PubMed, Web of Science, and EMBASE were searched for studies assessing cognitive outcomes under different stimulation frequencies. Eight cognitive domains were defined: verbal fluency, cognitive flexibility, executive control, working memory, attention, processing speed, episodic memory, and time processing. Multilevel random-effects meta-analyses were performed, with effect sizes expressed as Hedges' g. Results: Forty-three studies met the inclusion criteria, the majority (n = 31) involving STN-DBS. Twenty-one STN-DBS studies, including 355 patients, were included in the meta-analysis. Compared with HFS ([&ge;] 130 Hz), lower frequencies (4-80 Hz) were associated with better verbal fluency (g = 0.27) and cognitive flexibility (g = 0.38), with consistent effects across sensitivity and leave-one-out analyses. Accuracy-based executive control measures also favored lower-frequency stimulation. OFF-stimulation comparisons showed a concordant pattern. Evidence for other targets (PPN and NBM) was limited. Conclusions: Lower-frequency STN-DBS was associated with modest benefits in specific cognitive domains compared with HFS. These findings highlight the need for future research to determine how frequency interacts with stimulation location and symptom-specific networks to shape cognitive and cognitive-motor outcomes in PD.

There is growing interest and need for non-invasive stimulation approaches for the treatment of Parkinson's disease (PD) and other neurological conditions. Pilot studies indicate that vibrotactile stimulation on the fingertips may reduce PD motor symptoms (Pfeifer et al., 2021; Syrkin-Nikolau et al., 2018). PD motor symptoms (e.g., rigidity, bradykinesia) are correlated with exaggerated beta power in the subthalamic nucleus (STN), where neurons are excessively synchronized (Brown 2003; Kuhn et al., 2006; Neumann et al., 2016; Yin et al., 2021), but the effect of vibrotactile stimulation on the STN has not been determined. Here, in 12 PD participants in the OFF deep brain stimulation (DBS) and OFF medication state, we investigated how unilateral vibrotactile stimulation applied to the fingertips affects local field potential (LFP) power in STN. We used a within-participants design to expose each participant to a treatment stimulation pattern, termed randomized vibrotactile stimulation (RVS), and a control stimulation pattern, with the order randomized and with intermittent acquisition of STN LFP. RVS yielded a modest but statistically significant 12% (SEM 4.6%) reduction in mean normalized STN beta power and a 48% (SEM 19%) reduction in peak beta power compared to the DBS-off baseline condition and was significantly different when compared to our control stimulus. Furthermore, we identified a biomarker in STN beta power that predicts which participants may benefit from RVS. We observed that participants that exhibited prominent beta peaks had stronger reductions in mean beta power (17% reduction, SEM 6.1%) and peak beta power (55% reduction, SEM 10%). Regressing against the magnitude of the peak in beta provides a moderate prediction of change in mean and peak beta power due to RVS (R2 = 0.58 for mean and 0.52 for peak). We then used our observations to construct a computational model where beta peaks in a simulated STN varied from prominent to diminished. We found that the efficacy of randomized treatments was dependent on the magnitude of beta peaking, mirroring our clinical findings, and showing that RVS may act by reducing intra-neuronal synaptic strengths in STN. Despite robust changes in STN LFP in our study population, we did not observe a significant change in motor symptoms. These results suggest that peripheral vibrotactile stimulation can reduce STN beta power and motivate additional studies to investigate its long-term effects on motor symptoms across a large population of participants.

Effective modulation of cortical-subcortical motor circuits is essential for post-stroke recovery, yet progress has been constrained by the absence of non-invasive tools capable of precisely targeting deep brain structures. In this pilot proof of concept study, we explored the feasibility and preliminary neuromodulatory effects of a 12-minute transcranial focused ultrasound (tFUS) protocol targeting the ipsilesional ventral lateral posterior (VLp) thalamus in ischemic stroke patients. Six individuals with upper-limb hemiparesis received individualized, neuronavigation-guided tFUS. Sensorimotor tracking performance improved signiffcantly after a single session. Concurrent EEG revealed reversible beta-power suppression over the ipsilesional motor cortex and enhanced theta-phase synchronization in frontoparietal networks, both of which were associated with behavioral gains. Resting-state fMRI indicated rebalancing of inter-hemispheric motor networks. These preliminary ffndings suggest that thalamic tFUS can modulate both local and networklevel neural activity and is associated with immediate functional improvement, highlighting its potential as a feasible neuromodulation approach for deep motor circuit engagement in post-stroke rehabilitation.

Evaluation of the effectiveness of therapeutic interventions for dentine hypersensitivity is limited by a lack of standardisation and objectivity in measuring the associated pain. To address this, we investigated whether electroencephalography (EEG) can provide an objective, quantitative measure of the condition. Participants with and without dentine hypersensitivity underwent evaporative (air puff) and thermal (cooling probe) tooth stimulation during continuous recording of EEG activity. Sensitivity scores (Schiff Sensitivity score for air puff stimuli, and Visual Analogue Scale score (VAS) for thermal stimuli) were recorded, and participants' responses to the Dentine Hypersensitivity Experience Questionnaire (DHEQ) collected. There were strong positive correlations between the Schiff and VAS scores, and also between both sensitivity scores and the impact of dentine hypersensitivity on quality of life (DHEQ). Additionally, EEG data analysis revealed significant differences in event-related potentials (ERP) following evaporative stimulation between participants with different Schiff scores, and in cortical activity between traces where participants indicated discomfort and those where participants did not indicate discomfort during thermal stimulation trials. Topographical maps of EEG band power during thermal stimulation showed progressive cortical recruitment and focal activation emerging in the 3 seconds prior to indication of discomfort. Comparison of EEG band power between response and no response trials to thermal stimulation showed significantly higher delta frequency band power in response trials than in no-response trials. Peak-to-peak amplitude of cortical response during thermal stimulation correlated with DHEQ and VAS scores, and the probe temperature at which participants indicated discomfort. These findings suggest that components of EEG responses align with other measures of dentine sensitivity (DHEQ, Schiff and VAS scores) and can serve as objective neurophysiological markers for evaluating the severity of dentine hypersensitivity.

Background: Despite the common use of local heating and intradermal microdialysis perfusion of acetylcholine (ACh) to probe cutaneous endothelium and nitric oxide (NO)-dependent dilation, sex differences in microvascular responsiveness to these stimuli in healthy young adults remain incompletely understood. Methods: Cutaneous vasodilation was assessed in response to local heating to 39{degrees}C and 42{degrees}C and graded perfusion of ACh (10-10 to 10-1 mol/L) alone or concurrently with 15 mM NG-nitro-L-arginine methyl ester (L-NAME; NO synthase inhibitor) using laser-Doppler flowmetry coupled with intradermal microdialysis in 80 young adults (40 females). Results: Local heating to 42{degrees}C elicited greater endothelium- and NO-dependent dilation than heating to 39{degrees}C in both groups (p<0.001), but no sex differences were observed at either temperature (p=0.65). ACh-induced endothelium-dependent dilation also was not different between sexes (p=0.08), but the NO-dependent component was greater in females than in males (p=0.01). In young females, menstrual cycle day (range: day 2-33) was not associated with endothelium- or NO-dependent dilation in response to any stimulus (all p[&ge;]0.19), regardless of hormonal contraceptive use. Conclusions: Taken together, these findings suggest that sex differences in microvascular NO bioavailability in healthy young adults depend on the stimulus used to elicit cutaneous vasodilation and, in females, microvascular endothelium- and NO-dependent dilation are not meaningfully influenced by menstrual cycle phase.

Accumulating evidence suggests alterations in neurocognitive, affective, interoceptive and autonomic processing in functional neurological disorder (FND), yet interventions targeting these processes remain underexplored. This study investigated the possible immediate and longer-term effects of a somatic yoga intervention on cognitive control, emotion regulation, state dissociation and affect, autonomic arousal, and interoceptive processing in FND. Twenty-three adults with FND completed six weeks of somatic yoga (N=12) or six weeks of a music-based relaxation control (N=11). At baseline, post-single session, and post-six weeks, participants completed laboratory measures of sustained attention, response inhibition, interoception, emotion regulation, and state dissociation and affect. Electrocardiography and galvanic skin conductance were recorded throughout. Linear mixed effects models assessed potential change on day one, immediately pre/post a single session, and from day 1 to the end of the six-week programme. After one session, stop signal reaction time, negative affect, and heartrate decreased in both groups ({Delta}=.69-.75). After one session and at six weeks, improved sustained attention, elevated positive affect, and reduced dissociation were seen in both groups, with a larger magnitude of change in yoga ({Delta}=.50-1.10). The yoga group exhibited fewer direction errors on the response inhibition task and shorter response times on the sustained attention task, with the opposite seen in the music group ({Delta}=.50-1.17). Both in the short- and longer-term, somatic yoga might lead to adaptive changes in attention and executive functioning, arousal, state affect and dissociation.