Motor Cortex Research Articles

Effects of anodal transcranial direct current stimulation on intracranial compliance in the subacute phase of stroke

ObjectivesTranscranial direct current stimulation (tDCS) increases cerebral blood flow. This study evaluated the effects of anodal tDCS (A-tDCS) on intracranial compliance (ICC) in patients with subacute stroke using a non-invasive method. MethodsThis was a randomized, proof-of-concept, double-blind, pilot study. Patients with ischemic stroke of the middle cerebral artery (MCA) were divided into the following two groups: 1) A-tDCS in the motor cortex on the affected side for 30min at 2mA, and 2) sham tDCS in the motor cortex on the affected side. The primary outcomes were intracranial compliance (P2/P1 ratio and time-to-peak [TTP]) and ICC normalization after the intervention (P2/P1 ratio <1). Secondary outcomes were systolic and diastolic blood pressures, heart rate, and peripheral oxygen saturation. ResultsNo significant differences were observed in the P2/P1 ratio (P = 0.509) and TTP (P = 0.480) between the groups. However, the A-tDCS group was significantly associated with a normal P2/P1 ratio after intervention (B = 2.583; standard error [SE]: 1.277; P = 0.043; corrected for age and stroke severity). No significant associations were observed between the groups and systolic blood pressure (F = 0.16; P = 0.902), diastolic blood pressure (F = 0.18; P = 0.892), heart rate (F = 0.11; P = 0.950), or peripheral oxygen saturation (F = 0.21; P = 0.750). ConclusionICC morphology normalization was observed in the A-tDCS group. However, no differences were observed in the P2/P1 ratio, TTP, or hemodynamic variables between the groups. A sample size of 66 patients with ischemic stroke of the MCA can be estimated using the observed effect size and standard α = 5% and β = 20% for future trials. Furthermore, this will aid in conducting the necessary randomized trials targeting these populations.

Does aberrant electrocortical dynamics pattern imply atypical balance control in adolescents with idiopathic scoliosis?

Adolescent idiopathic scoliosis (AIS) is a developmental disorder described as a three-dimensional spine deformity with multifactorial etiology. The multifactorial model of AIS suggests that the patient population is diverse. Identifying individuals with sensorimotor control impairments could enable personalized treatments, potentially leading to improved outcomes for those with AIS. We hypothesize that abnormal electrocortical dynamics within the sensorimotor cortex will be related to less efficient balance control in standing during ankle proprioception alteration in the absence or presence of vision. To test this hypothesis, the balance control performance of adolescents with AIS will be assessed on a force platform by computing the root mean square value of the scalar distance between the center of pressure and the center of gravity. Electroencephalography will be recorded while challenging balance control by altering ankle proprioception in the presence and absence of visual cues. Time-frequency analyses will be calculated to determine alpha, and beta band power in both conditions. Pilot data from 13 participants with AIS were analyzed to support our hypothesis. Three participants with less efficient balance control showed electrocortical dynamics changes, such as an increase in beta band power in the presence and absence of vision and a decrease in alpha band power in the presence of vision compared to the AIS group with efficient balance control. These findings support our hypothesis of suboptimal sensorimotor information processing in the subgroup of adolescents with AIS with less efficient balance control, which could have significant implications for developing personalized treatments for AIS.

Simple actions modulate context-dependent visual size perception at late processing stages

A simple button press towards a prime stimulus enhances subsequent visual search for objects that match the prime. The present study investigated whether this action effect is a general phenomenon across different task domains, and the underlying neural mechanisms. The action effect was measured in an unspeeded size-matching task, with the presentation of the central target and the surrounding inducers of the Ebbinghaus illusion together to one eye or separately to each eye, and when repetitive TMS was applied over right primary motor cortex (M1). The results showed that a prior key-press significantly reduced the illusion effect compared to passive viewing. Notably, the action effect persisted with dichoptic presentation of the Ebbinghaus configuration, but disappeared with the right M1 disruption. These results suggest that action guides visual perception to influence human behavior, which mainly affects the late visual processing stage and probably relies on feedback projections from the motor cortex.

Screening for Developmental Delays in Pediatric Cochlea Implant Candidates and Recipients.

Conduct a pilot clinical improvement project to effectively screen children with hearing loss for developmental delays. Children with hearing loss and cochlear implants (CIs) are at risk for additional developmental delays; however, screening to aid in early identification and referral for developmental delays is not routinely performed at CI centers. It is important to consider all aspects of child development to maximize CI outcomes and access to language. Caregivers of 31 children completed the Ages and Stages Questionnaire (ASQ) and the Sensory Profile-2 (SP2), which are standardized questionnaires that assess developmental milestones in areas of communication, gross motor, fine motor, problem solving, personal-social, and sensory integration. Participants were prospectively evaluated at a CI center in a tertiary medical center. Participants included children, aged ≤5 years old with bilateral hearing loss who use CIs or who were CI candidates, and their families. Scores on ASQ and SP2 questionnaires. Thirty-one children were screened, and approximately 40 to 50% screened positive for risk of developmental delay in areas excluding communication and received referrals for evaluations in occupational therapy (n = 16; 51.6%), physical therapy (n = 13; 41.9%), and developmental pediatrics (n = 13; 41.9%). Of children referred and seen for evaluations, six were diagnosed with developmental delays in at least one developmental area beyond the communication domains. Routine screening in children with significant hearing loss can successfully detect developmental delays, which may go unnoticed. This proactive approach enables timely and comprehensive treatment for developmental delays beyond those solely related to communication.

Chronic citalopram effects on the brain neurochemical profile and perfusion in a rat model of depression detected by the NMR techniques – spectroscopy and perfusion

BackgroundMajor depressive disorder (MDD) is a mental illness with a high worldwide prevalence and suboptimal pharmacological treatment, which necessitates the development of novel, more efficacious MDD medication. Nuclear magnetic resonance (NMR) can non-invasively provide insight into the neurochemical state of the brain using proton magnetic resonance spectroscopy (1H MRS), and an assessment of regional cerebral blood flow (rCBF) by perfusion imaging. These methods may provide valuable in vivo markers of the pathological processes underlying MDD. MethodsThis study examined the effects of the chronic antidepressant medication, citalopram, in a well-validated MDD model induced by bilateral olfactory bulbectomy (OB) in rats. 1H MRS was utilized to assess key metabolite ratios in the dorsal hippocampus and sensorimotor cortex bilaterally, and arterial spin labelling was employed to estimate rCBF in several additional brain regions. ResultsThe 1H MRS data results suggest lower hippocampal Cho/tCr and lower cortical NAA/tCr levels as a characteristic of the OB phenotype. Spectroscopy revealed lower hippocampal Tau/tCr in citalopram-treated rats, indicating a potentially deleterious effect of the drug. However, the significant OB model–citalopram treatment interaction was observed using 1H MRS in hippocampal mI/tCr, Glx/tCr and Gln/tCr, indicating differential treatment effects in the OB and control groups. The perfusion data revealed higher rCBF in the whole brain, hippocampus and thalamus in the OB rats, while citalopram appeared to normalise it without affecting the control group. ConclusionCollectively, 1H MRS and rCBF approaches demonstrated their capacity to capture an OB-induced phenotype and chronic antidepressant treatment effect in multiple brain regions.

Exploring motor cortex functional connectivity in Parkinson's disease using fNIRS

Exploring motor cortex functional connectivity in Parkinson's disease using fNIRS

Motor imagery technique for motor recovery of hand among sub-acute stroke patient: A randomized controlled trial

Stroke is the second leading cause of death globally, with a rising prevalence in line with increasing life expectancy. Hemiparesis, affecting up to 85% of stroke survivors, leads to impaired arm and hand movement, reduced strength, and limited coordination, significantly affecting daily activities. Despite rehabilitation efforts, many stroke survivors face persistent functional limitations or permanent disabilities. Intensive rehabilitation is often costly and constrained by the limited number of therapy sessions available in many centers. Therefore, strategies to enhance functional recovery while minimizing resource use are crucial. One promising approach is motor imagery (MI), a cognitive rehearsal of physical actions aimed at improving motor function. MI has been shown to activate similar brain areas as actual movement, such as the premotor cortex and supplementary motor area. While evidence supports MI's potential for enhancing motor recovery, clinical guidelines remain insufficient. This study aims to evaluate the effectiveness of motor imagery for improving hand function in subacute stroke patients. The primary objective is to assess the impact of MI on motor recovery using the Chedoke Arm and Hand Activity Inventory over a 4-week period.

Dorsal Column Spinal Cord Stimulation Attenuates Brain-Spine Connectivity through Locomotion and Visuospatial-Specific Area Activation in Progressive Freezing of Gait

Introduction: Freezing of gait (FOG) is a clinical phenomenon with major life impairments and significant reduction in quality of life for affected patients. FOG is a feature of Parkinson’s Disease and a hallmark of primary progressive freezing of gait (PPGF), currently reclassified as Progressive Supranuclear Palsy-progressive gait freezing (PSP-PGF). The pathophysiology of FOG and particularly PGF, which is a rare degenerative disorder with a progressive natural history of gait decline, are poorly understood. Mechanistically, changes in oscillatory activity and synchronization in frontal cortical regions, the basal ganglia, and the midbrain locomotor region have been reported, indicating that dysrhythmic oscillations and coherence could play a causal role in the pathophysiology of FOG. DBS and SCS have been tested as therapeutic neuromodulation avenues for FOG with mixed outcomes. Methods: We analyzed gait and balance in three patients with PSP-PGF who received percutaneous thoracic spinal cord stimulation (SCS) and utilized magnetoencephalography (MEG), electroencephalography (EEG), and electromyography (EMG) to evaluate functional connectivity between the brain and spine. Results: Gait and balance did not worsen over a 13-month period. This observation was accompanied by decreased beta-band spectral power in the whole brain and particularly in the basal ganglia. This was accompanied by increased functional connectivity in and between the sensorimotor cortices, basal ganglia, temporal cortex, and cerebellum, and a surge in corticomuscular coherence when SCS was paired with visual cues Conclusion: Our results suggest synergistic activity between brain and spinal circuits upon SCS for FOG in PGF, which may have implications for future brain-spine interfaces and closed-loop neuromodulation for patients with FOG.

Supplementary and Premotor Cortical Activation During Manual Dexterity Involving Motor Imagery in Multiple Sclerosis: A Functional Near-Infrared Spectroscopy Study

Background Investigating brain activation during motor imagery (MI) tasks in people with multiple sclerosis (pwMS) can increase the knowledge of the neural mechanisms underlying motor dysfunction in MS and, hopefully, aid in developing improved rehabilitation strategies. Objective To investigate brain activation in the supplementary motor area and premotor cortex via functional near-infrared spectroscopy (fNIRS) during a hand manipulation task, and comparing MI with actual practice (AP) in pwMS. Methods Each subject completed a sequence of 4 consecutive manual dexterity trials wearing an fNIRS device. The tasks included the following conditions: AP dominant hand, MI dominant hand, AP non-dominant hand, and MI non-dominant hand. Results Twenty pwMS (mean Expanded Disability Status Scale = 4.75 [3.0-6.5]) and 20 healthy controls (HC) participated in the study. According to the fNIRS timeline course, a similar increase (compared with baseline) was observed in the relative oxygenated hemoglobin (HbO) concentration during the MI and AP tasks, which was immediately followed by a decrease (for either hand) in the pwMS and the HC groups. A difference in the relative HbO concentration between the HC and pwMS was detected solely when the 2 groups mentally replicated the manual dexterity task movements in the MI condition (dominant hand). The increase was higher in the HC group ( P = .030). Conclusions Despite exhibiting manual dexterity difficulties, pwMS demonstrated comparable neural activation patterns as the HCs during MI tasks in regions associated with motor planning and complex movement control, thus, suggesting that deficits in manual dexterity among pwMS may not solely originate from impairments in the motor planning processes.

Association between tumor location and toxicity outcomes after stereotactic radiosurgery for brain metastases.

Toxicities associated with stereotactic radiosurgery (SRS) are important when considering treatment and supportive management for patients with brain metastases. We herein assessed the association between brain metastasis location and risk of toxicity after SRS. We conducted a retrospective institutional review of patients treated with SRS for brain metastases between 2008 and 2023. Outcomes included radiation necrosis, seizure, local failure, and overall survival (OS). We reviewed 215 patients treated to 605 metastases (median diameter 10mm, IQR 5-17 mm), in the frontal (34%), cerebellar (19%), parietal (16%), temporal (13%), and occipital (13%) regions. Median follow-up was 16 months (IQR 7-36). New-onset seizures developed in 11% (19/174) of patients without prior seizure and was higher in patients with motor or sensory cortex lesions (12/48, 25%) on multivariate analysis (MVA, P = 0.02). SRS-related grade ≥ 2 symptomatic radionecrosis occurred in 6% (33/605) of lesions and correlated with larger metastasis volume (P < 0.001) and renal cell carcinoma histology (P < 0.05), while supratentorial location was nearly significant (MVA, P = 0.06). Median OS across all patients was 16 months (95% CI 12-20). Patients with symptomatic radiation necrosis had a longer median survival compared to those who did not (43 vs. 14 months, P = 0.002), which remained significant alongside Karnofsky performance status and extracranial disease on MVA. Brain metastasis location in the motor or sensory cortex is associated with increased risk of new-onset seizure following SRS and may warrant consideration of steroid and/or anti-epileptic prophylaxis. Symptomatic radiation necrosis is uncommon in the cerebellum and may be increasing with improvements in survival.

EQUOTERAPIA: A CONEXÃO ENTRE EQUINOS E PACIENTES – A IMPORTÂNCIA DAS CARACTERÍSTICAS FÍSICAS E COMPORTAMENTAIS

Equine therapy is a technique that uses horses as a means of intervention between horse and patient, working with people who have special needs in the cognitive, affective, sensory or motor areas. This therapeutic method is composed of a team of veterinarians, doctors, psychologists, physiotherapists and a riding professional. The work is a literature review on equine therapy, highlighting the physical and behavioral characteristics of horses, the appropriate track for equine therapy, the importance of the horse’s gait so that the patient has a significant improvement and that the session is safe, the pace that helps the patient feel their emotions and their connection with the patient.

Altered parasympathetic outflow and central sensitization response to continuous pain in cyclic vomiting syndrome: a functional magnetic resonance imaging study.

Cyclic vomiting syndrome (CVS) is a disorder of brain-gut interaction characterized by recurrent episodes of nausea and vomiting interspersed with asymptomatic periods and associated with autonomic nervous system dysfunction. We examined the dysautonomic response to noxious stimuli seen in CVS patients using our previously validated approach to integrate peripheral autonomic outflow metrics, temporal summation of pain, and brain fMRI. BOLD fMRI and ECG were acquired from CVS patients and healthy adults during a rest condition and a sustained cuff pressure pain stimulus at the leg. After the latter scan, participants rated pain for the full 6-minute pain stimulus as well as first, middle, and last two-minutes to calculate temporal summation. During sustained pain, patients (n=13) exhibited greater reduction in heart rate variability within the high-frequency range (HF-HRV) and reduced anticorrelation between HF-HRV and fMRI signal in the anterior insula, pregenual anterior cingulate cortex, and ventrolateral and dorsolateral prefrontal cortex relative to healthy adults (n=13). Compared to healthy adults (n=14), patients (n=14) exhibited increasing pain intensity over the course of sustained cuff pressure. Seed-based functional connectivity analysis revealed for healthy adults (n=13), pain sensitization correlated with pain-induced increases in connectivity between primary somatosensory cortex and regions of interest in both left anterior insula/posterior orbitofrontal cortex and right pre-supplementary motor area, while this correlation was disrupted in CVS (n=10). Our results support altered central coding of nociceptive stimuli and autonomic responsivity of CVS patients in key brain regions implicated in autonomic control and interoception.

State dependent motor cortex stimulation reveals distinct mechanisms for corticospinal excitability and cortical responses.

Transcranial magnetic stimulation (TMS) is a non-invasive brain stimulation method that modulates brain activity by inducing electric fields in the brain. Real-time, state-dependent stimulation with TMS has shown that neural oscillation phase modulates corticospinal excitability. However, such motor-evoked potentials (MEPs) only indirectly reflect motor cortex activation and are unavailable at other brain regions of interest. The direct and secondary cortical effects of phase-dependent brain stimulation remain an open question. In this study, we recorded the cortical responses during single-pulse TMS using electroencephalography (EEG) concurrently with the MEP measurements in 20 healthy human volunteers (11 female). TMS was delivered at peak, rising, trough, and falling phases of mu (8-13 Hz) and beta (14-30 Hz) oscillations in the motor cortex. The cortical responses were quantified through TMS-evoked potential components N15, P50, and N100 as peak-to-peak amplitudes (P50-N15 and P50-N100). We further analyzed whether the pre-stimulus frequency band power was predictive of the cortical responses. We demonstrated that phase-specific targeting modulates cortical responses. The phase relationship between cortical responses was different for early and late responses. In addition, pre-TMS mu oscillatory power and phase significantly predicted both early and late cortical EEG responses in mu-specific targeting, indicating the independent causal effects of phase and power. However, only pre-TMS beta power significantly predicted the early and late TEP components during beta-specific targeting. Further analyses indicated distinct roles of mu and beta power on cortical responses. These findings provide insight to mechanistic understanding of neural oscillation states in cortical and corticospinal activation in humans.Significance Statement Understanding the effects of noninvasive neuromodulation on human brain provides valuable insights to its clinical utility. Brain state dependent stimulation helps us understand mechanisms leading to cortical responses and behavioral outcomes. Here we study the effects of the phase of ongoing oscillations in the motor cortex on cortical responses measured by electroencephalography. We also studied the relationship of phase preference between cortical responses and motor evoked potentials. Furthermore, we investigated the effects of the power of ongoing oscillations on cortical responses. These findings are important to understand the changes in biomarkers during state-dependent brain stimulation and their relationship to behavioral outcomes. At large, this helps the researchers to utilize state-dependent brain stimulation to enhance treatment efficacy.

Volumetric Analysis of Motor Cortex and Basal Ganglia in Pediatric Celiac Disease Patients Using volBrain: Implications for Neurological Dysfunction-Preliminary Results

Background/Objectives: Celiac disease (CD) is a common immune-mediated, chronic systemic disorder that is treated with a strict, life-long gluten-free diet (GFD). In addition to gastrointestinal manifestations, CD also presents with a variety of extraintestinal symptoms, including significant neurological and neuropsychiatric symptoms. Among these neurological manifestations, motor dysfunctions are particularly notable. The aim of this study is to investigate the potential volumetric differences in brain structures, particularly the motor cortex and basal ganglia, between pediatric CD patients and healthy controls using the volBrain software AssemblyNet version 1.0. Methods: This prospective study included pediatric patients with CD who complained of neurological symptoms and were scheduled for brain magnetic resonance imaging (MRI). All children had been previously diagnosed with CD and their adherence to GFD was evaluated using the Biagi score. Brain MRIs were performed on all included patients to obtain volumetry at the onset of the disease. For volumetric and segmentation data, the volBrain software was used. Results: In total, 12 pediatric patients with CD were included, with a median duration of a GFD of 5.3 years at the time of the MRI examination. There were no statistically significant differences between patients compliant with the GFD and those non-compliant in terms of age or duration of GFD. Volumetric analysis revealed deviations in all patients analyzed, which involved either a decrease or increase in the volume of the structures studied. Conclusion: Despite the limited number of patients in this study, the initial findings support previously described neurological manifestations in patients with CD. Newly developed MRI tools have the potential to enable a more detailed analysis of disease progression and its impact on the motor cortex.

Cortical areas for planning sequences before and during movement.

Production of rapid movement sequences relies on preparation before (pre-planning) and during (online planning) movement. Here, we compared these processes and asked whether they recruit different cortical areas. Human participants performed three single-finger and three multi-finger sequences in a delayed movement paradigm while undergoing 7T functional MRI. During preparation, primary motor (M1) and somatosensory (S1) areas showed pre-activation of the first movement, even without increases in overall activation. During production, the temporal summation of activity patterns corresponding to constituent fingers explained activity in these areas (M1 and S1). In contrast, the dorsal premotor cortex (PMd) and anterior superior parietal lobule (aSPL) showed substantial activation during the preparation (pre-planning) of multi-finger compared to single-finger sequences. These regions (PMd and aSPL) were also more active during production of multi-finger sequences, suggesting that pre- and online planning may recruit the same regions. However, we observed small but robust differences between the two contrasts, suggesting distinct contributions to pre- and online planning. Multivariate analysis revealed sequence-specific representations in both PMd and aSPL, which remained stable across both preparation and production phases. Our analyses show that these areas maintain a sequence-specific representation before and during sequence production, likely guiding the execution-related areas in the production of rapid movement sequences.Significance Statement Understanding how the brain orchestrates complex behavior remains a core challenge in human neuroscience. Here, we combine high-resolution neuroimaging and a carefully crafted design to study the neural control of rapid sequential finger movements, like typing or playing the piano. Advancing prior research, we show that the brain areas involved in planning these movements maintain those representations throughout the execution of the sequence. This representational stability across planning and execution suggests an intricate connection between these processes. Our results shed light on the nuanced contributions of different cortical areas to different aspects of coordinating skilled movement. This work is well placed to inform future research in animal models and the development of targeted interventions against movement disorders.

Molecular signaling predicts corticospinal axon growth state and muscle response plasticity induced by neuromodulation

Electrical motor cortex stimulation can produce corticospinal system plasticity and enhance motor function after injury. We investigate molecular mechanisms of structural and physiological plasticity following electrical neuromodulation, focusing on identifying molecular predictors, or biomarkers, for durable plasticity. We used two neuromodulation protocols, repetitive multipulse stimulation (rMPS) and patterned intermittent theta burst stimulation (iTBS), incorporating different stimulation durations and follow-up periods. We compared neuromodulation efficacy in promoting corticospinal tract (CST) sprouting, motor cortex muscle evoked potential (MEP) LTP-like plasticity, and their associated molecular underpinnings. Only iTBS produced CST sprouting after short-term neuromodulation (1 d of stimulation; 9-d survival for sprouting expression); both iTBS and rMPS produced sprouting with long-term (10-d) neuromodulation. Significant mTOR signaling activation and phosphatase and tensin homolog (PTEN) protein deactivation predicted axon growth across all neuromodulation conditions that produced significant sprouting. Both neuromodulation protocols, regardless of duration, were effective in producing MEP enhancement. However, persistent LTP-like enhancement of MEPs at 30 d was only produced by long-term iTBS. Statistical modeling suggests that Stat3 signaling is the key mediator of MEP enhancement. Cervical spinal cord injury (SCI) alone did not affect baseline molecular signaling. Whereas iTBS and rMPS after SCI produced strong mTOR activation and PTEN deactivation, only iTBS produced Stat3 activation. Our findings support differential molecular biomarkers for neuromodulation-dependent structural and physiological plasticity and show that motor cortex epidural neuromodulation produces molecular changes in neurons that support axonal growth after SCI. iTBS may be more suitable for repair after SCI because it promotes molecular signaling for both CST growth and MEP plasticity.

Hybrid Functional Near-Infrared Spectroscopy System and Electromyography for Prosthetic Knee Control

The increasing number of individuals with limb loss worldwide highlights the need for advancements in prosthetic knee technology. To improve control and quality of life, integrating brain–computer communication with motor imagery offers a promising solution. This study introduces a hybrid system that combines electromyography (EMG) and functional near-infrared spectroscopy (fNIRS) to address these limitations and enhance the control of knee movements for individuals with above-knee amputations. The study involved an experiment with nine healthy male participants, consisting of two sessions: real execution and imagined execution using motor imagery. The OpenBCI Cyton board collected EMG signals corresponding to the desired movements, while fNIRS monitored brain activity in the prefrontal and motor cortices. The analysis of the simultaneous measurement of the muscular and hemodynamic responses demonstrated that combining these data sources significantly improved the classification accuracy compared to using each dataset alone. The results showed that integrating both the EMG and fNIRS data consistently achieved a higher classification accuracy. More specifically, the Support Vector Machine performed the best during the motor imagery tasks, with an average accuracy of 49.61%, while the Linear Discriminant Analysis excelled in the real execution tasks, achieving an average accuracy of 89.67%. This research validates the feasibility of using a hybrid approach with EMG and fNIRS to enable prosthetic knee control through motor imagery, representing a significant advancement potential in prosthetic technology.

Brain functional connectivity under teleoperation latency: a fNIRS study

IntroductionLong-distance robot teleoperation faces high latencies that pose cognitive challenges to human operators. Latency between command, execution, and feedback in teleoperation can impair performance and affect operators’ mental state. The neural underpinnings of these effects are not well understood.MethodsThis study aims to understand the cognitive impact of latency in teleoperation and the related mitigation methods, using functional Near-Infrared Spectroscopy (fNIRS) to analyze functional connectivity. A human subject experiment (n = 41) of a simulated remote robot manipulation task was performed. Three conditions were tested: no latency, with visual and haptic latency, with visual latency and no haptic latency. fNIRS and performance data were recorded and analyzed.ResultsThe presence of latency in teleoperation significantly increased functional connectivity within and between prefrontal and motor cortexes. Maintaining visual latency while providing real-time haptic feedback reduced the average functional connectivity in all cortical networks and showed a significantly different connectivity ratio within prefrontal and motor cortical networks. The performance results showed the worst performance in the all-delayed condition and best performance in no latency condition, which echoes the neural activity patterns.ConclusionThe study provides neurological evidence that latency in teleoperation increases cognitive load, anxiety, and challenges in motion planning and control. Real-time haptic feedback, however, positively influences neural pathways related to cognition, decision-making, and sensorimotor processes. This research can inform the design of ergonomic teleoperation systems that mitigate the effects of latency.

A systematic review: enhancing stroke recovery through complementary interventions—Clinical outcomes and neural activity insights

The growing interest in complementary interventions for stroke recovery necessitates the need for neural insights to aid in making evidence-based clinical decisions. This systematic review examined the brain activation effects of complementary therapies, including acupuncture (n = 5), motor imagery therapy (MIT) (n = 5), music (n = 3), and virtual reality (VR) interventions (n = 3), on clinical outcomes and neural activity in stroke patients. All therapies engaged motor and sensory networks, frontal regions, parietal regions, and temporal regions, suggesting their potential to improve motor control, attention, memory, and cognitive function. Acupuncture activated motor areas in both hemispheres, while MIT stimulated frontoparietal regions in both sides of the brain, supporting whole-body integration in recovery. In contrast, VR therapy exhibited ipsilesional lateralization, while music therapy showed left-lateralization. The review also found that increased interhemispheric connectivity between motor regions, along with intrahemispheric ipsilesional connectivity between motor, cognitive, and sensory areas, is key to achieving better clinical outcomes.Systematic Review Registrationhttp://www.crd.york.ac.uk/PROSPERO, identifier (ID: CRD42023455192).

A combinatorial neural code for long-term motor memory.

Motor skill repertoire can be stably retained over long periods, but the neural mechanism that underlies stable memory storage remains poorly understood1-8. Moreover, it is unknown how existing motor memories are maintained as new motor skills are continuously acquired. Here we tracked neural representation of learned actions throughout a significant portion of the lifespan of a mouse and show that learned actions are stably retained in combination with context, which protects existing memories from erasure during new motor learning. We established a continual learning paradigm in which mice learned to perform directional licking in different task contexts while we tracked motor cortex activity for up to six months using two-photon imaging. Within the same task context, activity driving directional licking was stable over time with little representational drift. When learning new task contexts, new preparatory activity emerged to drive the same licking actions. Learning created parallel new motor memories instead of modifying existing representations. Re-learning to make the same actions in the previous task context re-activated the previous preparatory activity, even months later. Continual learning of new task contexts kept creating new preparatory activity patterns. Context-specific memories, as we observed in the motor system, may provide a solution for stable memory storage throughout continual learning.