Proprioceptive senses, particularly movement-position and force-effort senses enable individuals to perform essential motor functions. Despite their crucial role in the acquisition and execution of motor skills, proprioceptive assessment methods and the specific modalities they evaluate are clearly defined in the literature. Furthermore, there is a lack of consensus regarding the laterality of proprioceptive senses in upper extremities. The primary objective of this study is to examine the laterality and differences in movement-position and force-effort senses between the hands and to evaluate the relationship between motor skill laterality and various proprioceptive modalities in right-handers. 60 healthy, right handed participants aged 18-30 were included in the study. The Finger Tapping Test (FTT) and Purdue Pegboard Test (PPT) were used to assess motor skills. Active Movement Extent Discrimination Assessment (AMEDA) and Targeted Pinch Force Grading Assessment (TPFGA) were used to assess proprioceptive senses. Proprioceptive tests did not show a significant difference between the hands. The dominant right hand performed better than the non-dominant hand in both motor tasks (p <0.001). No relationship was observed between motor and proprioceptive test results. Despite the dominant right hand's superior motor performance, no significant proprioceptive differences between hands were found. This suggests motor and proprioceptive asymmetries might differ between hands, and when the findings of this study is evaluated with previous studies, we claim that the current methods are insufficient in the thorough assessment of proprioceptive senses. Classifying proprioceptive measurement methods by active/passive movement and static/dynamic processes could greatly improve our understanding of sensorimotor issues and rehabilitation strategies.

Parkinson's disease (PD) is characterized by progressive degeneration of dopaminergic neurons, leading to motor dysfunction and cognitive impairment. Although levodopa (l-DOPA)/carbidopa remains the gold standard therapy for PD, its efficacy declines over time, highlighting the need for adjuvant strategies that improve functional outcomes. This study evaluated whether freeze-dried bee venom (BV) enhances the behavioral effects of l-DOPA/carbidopa in a murine model of PD. Adult male mice (age: 3.0-3.5 months) were randomly assigned using a computer-generated randomization sequence to the following experimental groups: SHAM, animals that were injected with saline in the dorsomedial striatum (STR) (n = 6); 6-hydroxydopamine (6-OHDA) lesion, animals that received an injection of 6-OHDA in the STR (n = 7); l-DOPA/carbidopa, lesioned animals that were treated with l-DOPA/carbidopa from day 13 (D13) to day 30 (D30) after the lesion (n = 7); and l-DOPA/carbidopa + BV, lesioned animals treated with a combination of l-DOPA/carbidopa and BV from D13 to D30 after the lesion (n = 7). Motor asymmetry and paw dragging were assessed using the cylinder test, and lateralized function was assessed using the corridor test. Cognitive performance was evaluated with the novel object recognition (NOR) test. Behavioral data were analyzed using the Kruskal-Wallis test followed by Dunn's post hoc comparisons. Compared with 6-OHDA treatment, the combined treatment with BV and l-DOPA/carbidopa significantly improved forelimb motor symmetry (H = 15.16, p = 0.001) and reduced contralateral paw dragging (H = 19.91, p < 0.001). In the corridor test, compared with l-DOPA/carbidopa alone, BV cotreatment increased the retrieval index (H = 16.43, p < 0.001). Moreover, BV prevented 6-OHDA-induced cognitive impairment in the NOR test, restoring the discrimination index to levels comparable to those of the SHAM group (H = 17.48, p < 0.001). These findings provide behavioral evidence that BV may serve as a promising adjuvant to l-DOPA/carbidopa, improving both motor and cognitive outcomes in a mouse model of PD and supporting further investigation in studies incorporating histological and molecular endpoints.

The pathological mechanisms underlying neurodegenerative diseases remain poorly defined, largely due to the lack of tools capable of detecting molecular alterations before the onset of clinical symptoms. Here we successfully achieve targeted profiling of dopamine (DA) and nontargeted profiling of amino acid (AA) molecules in the lesioned substantia nigra of Parkinson's disease (PD) mouse by intergrating ex vivo surface-enhanced Raman spectroscopy (SERS) probes with concurrent in vivo electrophysiological recordings in the primary motor cortex. The PD model was established by stereotaxic unilateral injection of 6-hydroxydopamine (6-OHDA) into the right striatum of mice, while the left sham side was used as the reference. At early stage of PD model, a sandwich-structured SERS tag enables highly specific targeted profiling of picomolar-level DA, and a feedforward neural network resolves highly overlapping AA spectra, allowing reliable identification of AA components at physiological micromolar concentrations. In the lesioned substantia nigra, results reveal a rapid decline in DA levels within 6 h after 6-OHDA injection, followed by a marked elevation of glutamate (Glu) at 9 h; while the primary motor cortex at 9 h starts to emerge pathological β-band hypersynchronization and abnormal β-γ phase amplitude coupling. These molecular and circuit-level disturbances clearly precede overt motor asymmetry that becomes evident only at 27 h postlesion. Integrated transcriptomic and qPCR analysis identifies Glu as a central molecular hub linking early neurochemical imbalance to subsequent neural circuit dysfunction. The findings indicate a DA-depletion-triggered and Glu-centered excitotoxic cascade, and also prospect a early therapeutic window during which restoring Glu homeostasis, enhancing metabolic resilience, or mitigating oxidative stress may help prevent subsequent network destabilization. This synergistic SERS-electrophysiology suite enables time-resolved chemical-to-neurophysiological mapping and provides a general framework for investigating molecular-to-circuit transitions in neurodegenerative disorders.

Is being asymmetric a bad thing? Insights from a longitudinal observational study on STN-DBS Parkinson's disease.

ABSTRACT Background Motor asymmetry and axial symptoms represent partially distinct dimensions of the Parkinson’s disease (PD) motor phenotype. Although subthalamic nucleus deep brain stimulation (STN-DBS) and dopaminergic therapy are known to influence motor presentation, the clinical expression of lateralized and axial motor domains under different treatment strategies remains incompletely characterized in real-world settings. Objectives To compare motor asymmetry and axial involvement between PD patients treated with STN-DBS and those receiving medical therapy alone, and to examine OFF – ON levodopa-related modulation of these motor domains. Methods In this retrospective cross-sectional study, 184 consecutive PD patients (44 with STN-DBS and 140 without DBS) underwent standardized evaluations in medication ‘OFF’ and ‘ON’ states. Motor Asymmetry Index (MAI) and Axial-to-Appendicular Ratio (AAR) were calculated using MDS-UPDRS-III subscores. Between-group comparisons and within-group OFF – ON changes were analyzed, adjusting for disease duration and baseline motor severity. Results Unadjusted analyses showed lower MAI values in the STN-DBS group in the OFF state (p = 0.045), suggesting greater symmetry; however, this association was not significant after adjustment. Levodopa was associated with a consistent shift toward increased motor asymmetry and higher axial-to-appendicular ratios across both groups (all p < 0.01). The magnitude of AAR change was greater in the STN-DBS cohort. Conclusions In this retrospective cross-sectional study, levodopa was associated with a shift in motor phenotype characterized by increased asymmetry and axial-to-appendicular burden, independent of DBS status. These findings suggest that dopaminergic therapy may reshape motor expression rather than uniformly improve motor function.

BackgroundBilateral motor asymmetry is a hallmark feature of Parkinson’s disease (PD). However, few studies have quantitatively examined this feature in patients with scans without evidence of dopaminergic deficit (SWEDD). This study aimed to investigate upper limb asymmetry in bradykinesia among PD and SWEDD patients using gyro sensors, focusing on finger tapping and forearm rotation task.MethodsWe recruited 23 early‐stage, drug‐naïve PD patients, 23 SWEDD patients, and 20 age‐matched healthy controls. We recorded gyro sensor signals during 15‐s finger tapping and forearm rotation tasks. Bilateral asymmetry indices were calculated and compared among groups. In addition, repeated measure analysis of variance (ANOVA) was used to examine the interaction of task and group, and Spearman correlation analysis was conducted with clinical motor scores.ResultsNo significant group differences were found during finger tapping. However, during forearm rotation, PD patients exhibited significantly greater asymmetry than SWEDD patients in several indices, including RMS angular velocity, peak angular displacement, peak power, and total power. Task × group interaction effects were significant only in forearm rotation, and asymmetry indices from forearm rotation showed significant correlations with clinical motor scores.ConclusionsForearm rotation is a sensitive task for detecting motor asymmetry in PD and for differentiating PD from SWEDD. These results suggest that quantitative motor asymmetry indices using wearable sensors could aid clinicians in the identification of potential SWEDD.

Substantial asymmetries of motor dysfunction are evident in patients with Parkinson's disease (PD), the mechanisms of which remain largely unexplored. This study investigated how deep brain stimulation (DBS) targeting the globus pallidus interna (GPi) and subthalamic nucleus (STN) modulates characteristics of hemispheric lateralization in PD patients, with particular emphasis on motor asymmetries and hemispheric integration (via homotopic functional connectivity) and segregation (via hemispheric asymmetry in connectivity). Resting-state functional magnetic resonance imaging (fMRI) and Unified Parkinson's Disease Rating Scale (UPDRS) III scores were analyzed from 55 PD patients who underwent either bilateral GPi- or STN-DBS. Both targets produced significant improvements in motor function. Notably, stimulation effects on motor asymmetry depend on patients' baseline asymmetry direction (DBS OFF): STN-DBS consistently reduced asymmetry in the leftward-asymmetry patients, whereas GPi-DBS has stronger effects in rightward patients. In both cases, stimulation led to a more symmetric pattern. Beyond motor outcomes, motor gains were associated with changes in homotopic connectivity in the lateral occipital region, overlapping the extrastriate body area, suggesting a compensatory role of visual networks. These findings highlight the contribution of the visual networks to motor improvement and reveal target-dependent effects of DBS on both motor asymmetry and non-motor cognitive domains.

This study investigated whether the dominant hand would exhibit faster nerve conduction velocity, lower muscle activation latency, and superior Coincidence Anticipation Timing (CAT) performance compared to the non-dominant hand, reflecting enhanced neuromuscular efficiency and perceptual accuracy due to sport-specific training adaptations. This study employed a single-group, between subject comparative design to examine perceptual–motor performance and neuromuscular activation characteristics of the dominant and non-dominant hands. CAT and basal electromyographic (EMG) measurements were obtained separately for each hand, followed by task-related CAT performance during which EMG signals were recorded simultaneously. Comparisons between dominant and non-dominant hands were performed using independent samples t-tests. The dominant hand exhibited significantly greater AE and VE across general and nerve-specific measures (p < 0.01), with large to very large effect sizes, indicating differences in perceptual timing accuracy and consistency. Median nerve latency was shorter in the dominant hand, whereas median nerve amplitude did not differ significantly between hands. In contrast, ulnar nerve latency was longer and ulnar nerve amplitude was lower in the dominant hand, reflecting asymmetrical peripheral neural characteristics. Task-induced changes analyses demonstrated significant increases in nerve latency and reductions in amplitude in both limbs (p < 0.001), suggesting neuromuscular strain following task execution. Correlation analyses revealed weak-to-moderate associations between CAT errors and EMG parameters (r = 0.25–0.45), indicating that perceptual–motor performance is only partially explained by peripheral neuromuscular activation. Elite basketball players demonstrate distinct perceptual–motor and neurophysiological asymmetries between dominant and non-dominant hands. The integration of CAT outcomes with sEMG and nerve conduction measures provides a comprehensive approach for characterizing perceptual–motor performance and neuromuscular function. These findings may inform bilateral training strategies and neuromuscular monitoring practices aimed at optimizing performance and reducing neural strain in basketball players. ClinicalTrials.gov NCT07253623, Date: 11.19.2025. Retrospectively registered.

Motor asymmetry is a hallmark of Parkinson's disease (PD), but ~20% of patients present with symmetric motor signs, which are associated with faster disease progression and poorer dopaminergic response. The impact of motor symmetry on activities of daily living (ADL) outcomes following subthalamic deep brain stimulation (STN-DBS) remains unclear. We hypothesised that patients with symmetric PD experience less ADL improvement post-STN-DBS than asymmetric PD patients. This was a prospective, quasi-experimental, non-randomised, controlled, international multicentre study with a 6-month follow-up. The primary outcome was the Scales for Outcomes in Parkinson's Disease-Motor ADL scale. Secondary outcomes included Unified Parkinson's Disease Rating Scale motor examination and Parkinson's Disease Questionnaire-8 (PDQ-8). We defined symmetric PD as a right-to-left hemibody motor score equalling 1. We analysed within-group longitudinal changes, between-group outcome differences, effect size and correlations between PDQ-8 and motor changes. We confirmed results in a propensity-score matched subcohort with well-balanced demographic and clinical parameters. We included 200 patients with asymmetric and 54 with symmetric PD. In symmetric PD, ADL remained stable, which was not associated with the observed PDQ-8 improvement. In contrast, in asymmetric PD, ADL improved with a moderate effect size, which correlated moderately with PDQ-8 improvement. In symmetric PD, the absolute risk of experiencing no clinically relevant postoperative ADL improvement was 23.8% higher. This study provides class IIb evidence of worse ADL outcome of STN-DBS in patients with symmetric compared with asymmetric PD. Clinicians should counsel patients with symmetric PD on their elevated risk of ADL non-response when discussing STN-DBS as a treatment option.

Parkinson's disease (PD) is characterized by asymmetric motor symptoms (MSs), which may influence non-motor symptoms (NMSs). This study investigated the relationship between NMSs and the neurometabolic profile of the substantia nigra (SN) and globus pallidus (GP) of patients with PD, examining how these associations vary according to MS asymmetry. Forty-three PD patients (20 with right-predominant motor symptoms-RPD, and 23 with left-predominant motor symptoms-LPD) and 20 healthy controls (HCs) underwent single-voxel proton magnetic resonance spectroscopy, along with comprehensive clinical assessments of MSs and NMSs. Compared with HCs, PD patients showed higher N-acetylaspartate (NAA) levels in the SN, lower myo-inositol (Ins) levels in both sides of the SN, and higher glutamate/glutamine (Glx) levels in the right GP. Choline (Cho) in the left GP was positively associated with cognitive performance. In LPD patients, compared with HCs, NAA levels were increased in the right SN, whereas Ins levels were reduced in both hemispheres. These patients reported higher anxiety and exhibited marked hemispheric asymmetry of SN NAA. In this group, higher NAA levels in the right SN were associated with fewer sleep disturbances, while Ins in the right GP was related to both cognitive function and NMS severity. RPD patients showed elevated Glx levels in the right GP compared with HCs, with no significant hemispheric differences in metabolite levels. Nevertheless, Cho in the right SN was positively associated with sleep disturbances. Overall, these findings suggest that motor asymmetry in PD influences the neurometabolic correlates of NMSs, revealing distinct metabolic-clinical profiles in RPD and LPD patients.

Paw preference, or handedness, is a widely studied behavioral trait used to assess lateralization and motor function in rodents. This study aimed to determine the consistency and reliability of three commonly used behavioral tests to rigorously assess paw preference: the Collins Test, the Staircase Test, and the Pawedness Trait Test. Thirty Sprague Dawley rats (12-48 weeks; 20 females, 10 males) were subjected to all three behavioral tests. Paw uses were recorded, and the laterality index was calculated for each test. Additional cohorts of younger rats (6-9 weeks; 45 females, 45 males) and older rats (12-48 weeks; 38 females, 45 males) were tested to assess the effects of age and sex on paw preference. ANOVA, Fleiss' and pairwise Cohen's Kappa were used for statistical analysis. All three tests yielded comparable measures of paw preference (ANOVA, p = 0.801). Substantial inter-test agreement was demonstrated by Fleiss' kappa (κ = 0.761, p = 3.93 × 1012). Paw preference did not significantly vary by age or sex, and the distribution of left, right, and ambidextrous preference categories aligned with existing literature. The Collins, Staircase, and Pawedness Trait Tests provide consistent, reliable assessments of paw preference in Sprague Dawley rats. These validated behavioral assays can serve as essential tools for preclinical research, including but not limited to models of motor asymmetry observed in stroke, cerebral palsy, traumatic brain injury, and language lateralization, as well as neurodegenerative diseases.

Circadian Motor Asymmetry and Homeostatic Dysregulation in Adults with ADHD: An Actigraphic Study

The objective of this opinion paper is to highlight, based on recent studies, the importance of considering motor symptom (a)symmetry in the progression and management of non-motor symptoms in Parkinson's disease.

Abstract.Research Background. Spastic hemiparesis determines a persistent deficit in the motor sphere due to upper motor neuron lesions. This pathology manifests through a specific symptom complex: pyramidal hypertonicity (spasticity), coordination impairment, proprioceptive deficiency, and pronounced motor asymmetry. Material and Methods. The study involved children aged 7–8 years diagnosed with spastic hemiparesis (n=11). To achieve the research objectives, the following methods were employed: analysis of specialized scientific and methodological literature, pedagogical experimentation, and methods of mathematical statistics. Results. The synthesis of research findings regarding the muscular endurance indicators of children in the experimental group allows for the conclusion of a positive transformation in their functional state. Following the experimental intervention, a statistically significant increase in mean and median values (p &lt; 0.05) was recorded for key parameters of the axial musculature. It was demonstrated that the development of proximal stability through the strengthening of trunk muscles is a determinant of improvement in children's motor status. It was established that the developed muscular corset minimizes motor asymmetry and creates a biomechanical foundation for the restoration of coordination mechanisms in spastic hemiparesis. Conclusions. The implemented author's technology ensured a reliable improvement in the muscular endurance of the axial musculature (trunk and back) among children in the experimental group (p &lt; 0.05). This result is considered a pathogenetic basis for the enhancement of postural control, as spinal stabilization is a primary link in the restoration of motor function in cerebral palsy. It was found that the traditional physical education system does not exert a statistically significant influence on the muscular endurance of children with spastic hemiparesis. This verifies the scientific hypothesis regarding the necessity for the intensification and specialization of rehabilitation protocols for this specific nosology. The absence of statistically significant intergroup differences at the final stage–despite pronounced intragroup progress within the experimental group–indicates two strategic vectors for further research: 1) increasing exposure (the necessity of extending the duration of the rehabilitation impact to consolidate the cumulative effect); 2) scaling the sample (expanding the number of respondents to increase statistical power and achieve a clearer differentiation of effects between groups).

High-precision applications using brushless direct current (BLdc) motors demand accurate angular measurements. However, minor mechanical flaws in commercial sensors introduce nonlinear distortions in position readings, causing torque ripple. Further ripple is generated by slight asymmetries in stator windings and rotor magnets. Typically, sensor nonlinearities are addressed using external equipment, while motor asymmetries are often overlooked and left to the current control loop, which, due to limited bandwidth, cannot fully suppress their effects. This article analyzes both sensor and motor nonlinearities and proposes a compensation technique that requires no additional hardware. It leverages the intrinsic properties of BLdc motors to derive an algebraic correction function for angular measurements. Exploiting the periodicity of the distortions, this function is expressed as a Fourier series. Lower order terms address sensor errors, while higher order terms compensate for motor asymmetries. The experimental validation confirms that the method enhances control performance by reducing current ripple, mechanical vibrations, and energy consumption.

This study aimed to evaluate the effects of hand dominance and gender on auditory reaction times under blindfolded and randomized conditions, while also examining bilateral motor coordination through simultaneous response evaluation. Twenty-eight healthy participants (16 female, 12 male) completed auditory reaction time tasks under three conditions: dominant hand, non-dominant hand, and simultaneous bilateral responses. Each condition was repeated 10 times. Mean and standard deviation (SD) values were calculated from all trials. Paired and independent t-tests were used for statistical comparison. The dominant hand produced significantly faster responses than the non-dominant hand (p = 0.022) and also exhibited lower intra-individual variability (p = 0.030), indicating higher consistency. Gender had no significant effect on reaction time (p = 0.249). Interestingly, in the simultaneous condition, the mean difference in reaction time between hands was −1.44 milliseconds, with the non-dominant hand often responding faster—a result that challenges conventional assumptions about motor asymmetry. Auditory reaction time is influenced by hand dominance in both speed and consistency. The surprising dominance of the non-dominant hand during simultaneous responses raises important questions about interhemispheric coordination and sensorimotor integration and warrants further neurophysiological investigation.

Dietary Supplementation with Six Percent Blueberries (Vaccinium corymbosum L.) Attenuates Neurodegeneration and Motor Deficits in a Parkinson's Disease Model.

Striatal injection of aminochrome in Wistar rats induces early-stage behavioral changes of Parkinson's disease and dopaminergic degeneration in the caudal and medial regions of the nigra pars compacta.

Parkinson's disease (PD) is a neurodegenerative disorder associated with a progressive loss of dopaminergic cells and as of now, there is no established definitive treatment available for this condition. In this study, the focus was on investigating the impact of SVAK-12, a small molecule that can cross the blood-brain barrier and remain stable without structural changes. The effect of SVAK-12 was investigated in vitro on neurotoxicity, in vivo model of Parkinson's diseases and in silico. Through in vitro and in vivo experiments, as well as molecular docking simulations, it was found that SVAK-12 (375 ng.ml) led to increased cell viability, reduced cellular damage, and decreased production of NO and ROS. Additionally, it boosted levels of important neurotrophic factors like BDNF (130.49%) and GDNF (116.38%), potentially aiding in alleviating motor disability and depression. The study also highlighted SVAK-12's potential as a therapeutic candidate for neurological disorders due to its ability to increase tyrosine hydroxylase expression and dopamine levels (4.84 times). While it did not significantly improve motor symptoms in vivo, it did enhance motor asymmetry in the forelimbs and gene expression related to brain regions. Besides, it induced significant BMP-2 gene expression in substantial nigra regions without significant changes in GDNF and Nurr1 gene expression in the striatum expression. The docking of SVAK-12, Levodopa, Amantadine, Biperiden, Selegiline, and Rasagiline to the binding site of GFRα1, sortilin, and TrkB showed that SVAK-12 had greater MolDock score than Selegiline and Amantadine for GFRα1 and greater than amantadine for Sortilin and TrKB. Overall, the study suggests that SVAK-12's neuro-biocompatibility, ability to reduce free radicals, and enhanced neurotrophic factors make it a promising candidate as a neuroprotective drug.

SummaryBehavioral laterality is a prominent Bilateria feature, where motor functions are performed with a directional preference. Underlying such behaviors is thought to be hemispheric specializations that improve behavioral performance. Despite the prevalence, how behavioral lateralization is modulated throughout evolution is poorly understood. Comparative approaches are a powerful strategy for addressing fundamental biological questions from individual to evolutionary scales. Previously, we described a robust visuomotor asymmetry in larval zebrafish search pattern behavior. Here, we compare visuomotor asymmetry across several larval teleost species, demonstrating that general motor patterns are variable while behavioral asymmetry is conserved across sighted teleosts, yet not naturally blind cavefish. Our data indicate that visuomotor asymmetry in larval teleosts is a conserved behavior that can be modulated by natural selection against vision. This establishes larval teleosts as a powerful system for dissecting the molecular and evolutionary forces that govern behavioral lateralization, bridging the gap between mechanism and adaptation.