Impaired Motor Control Research Articles

Neuroprotective Effects of N - Acetyl - Methoxytryptamine in a Neurotoxic Mice Model of Huntington’s Disease Induced by Quinolinic Acid

Huntington’s Disease (HD) is an autosomal dominant neuropathology associated with severe degeneration in neurons of the basal ganglia. It is characterized by progressive motors symptoms, cognitive deficits and dementia. The genetic mutation induces trinucl eotide repeat expansion (TNR) of cytosine, adenine and guanine (CAG). The CAG - repeat is translated into a poly glutamine (polyQ) stretch caused by molding of DNA “loop out” structures and DNA slippage during the replication. This expanded sequence encodes a mutant huntingtin (mHtt), which is associated to neuronal dysfunction, cellular death, ubiquitous molecular and cellular anomalies. Furthermore, there are progressive impairments in motor control, cognitive function and mood. Quinolinic acid (QA) is an e xcitotoxic compound in humans and animals that has been linked to HD. N - acetyl - methoxytryptamine (MLT) is a hormone that produce anti - oxidant and anti - inflammatory effects on cell damage. The principal aim of this study is to know if QA induces damage in s triatal astrocytes and neurons and to evidence how MLT can participate as a neuroprotectant agent against the neurotoxic injury. We inoculate QA intrastriatal in 8 weeks old wild type (WT) female mice as endogenous neurotoxic model of HD. Here, we worked w ith three different groups of mice, and the striatal injection was administrated in all animals. PBS were inoculated in control mice; the second group was injected only QA; and the last group was pre - treated with MLT 30 min before the QA injection. Immunob lots, oxidative stress biomarkers, histological assay of astrocytes and neurons were evaluated as well as rotarod and open field tests. There was a reduction in proteins levels of BDNF and NeuN in QA mice. Contrary effects in lysates showed NF - κB, IκB α , HT T, GFAP and NRs. The analysis of CAT, SOD, Gpx and GSH showed decreased activity, while MDA displayed increased activation in QA mice. The animals pre - treated with MLT revers the tendency of proteins and antioxidant biomarkers; the HTT perinuclear staining in neurons was reduced. NeuN histochemistry showed a greater number of NeuN + cells; the astrogliosis was attenuated; and locomotor activities improved. Analysis of RT - PCR do no show significant diferences between teatments. This study suggests that MLT c an induce a compensatory response to neurotoxic stress againts neuro - glial injury. Thus, increasing MLT levels may be a promising treatment for HD disorder.

EMG Analysis of Trunk Muscle Recruitment Patterns of Anticipatory Postural Adjustments during Unilateral Arm Flexion in Chronic Neck Pain Patients

Introduction: EMG recruitment pattern of trunk muscles can change to compensate pain. One of these pattern alterations occurs in anticipatory postural adjustments (APAs) or feedforward activity of trunk muscles prior to arm movements. No study has determined the EMG pattern alterations of trunk muscle recruitments during the arm movement in patients with chronic neck pain (CNP). This study was examined the effect of CNP on EMG activities of trunk muscles for APAs during rapid arm flexion. Material and Methods: Sixteen patients with CNP for at least 3 months and sixteen healthy individuals matched in gender, age and weight were selected in this semi-experimental study. Surface EMG was utilized to evaluate 8 trunk muscles bilaterally and right anterior fibers of deltoid muscle during a unilateral rapid arm flexion. Anticipatory muscle activity was calculated by EMG onset latency of the trunk muscle from 100 ms before deltoid activity to 100 ms after it. Also, the values of root mean square (RMS) in 4 epochs around the onset of deltoid EMG were measured and compared. A two-tailed t-test and repeated-measure ANOVA were used for statistical analyses.Results: The onset latency of muscles in left and right side, except left erector spine muscle, in patients showed a significantly higher delay compared to healthy controls (P<0.05). The analysis of RMS in the 4 epochs revealed that in the control group, the values of RMS for rectus abdominus and erector spine in both sides, left external oblique and left transverse abdominus/internal oblique increased significantly during Epochs 3 and 4 , but in CNP subjects, the RMS of these muscles did not change significantly in 4 epochs.Conclusion: The patients with CNP had alterations in their recruitment patterns of particular trunk muscles in response to arm movement.Therefore, these patients have impaired motor control of trunk muscles during internal perturbation. These results indicated that not only the alterations in recruitment of trunk muscles occur, but also the intensity of their contractions decreases. In conclusion, CNP may alter in order to control the reactive forces resulting from limb movement.

Asymmetric Dopaminergic Degeneration and Attentional Resources in Parkinson's Disease.

Background: Attention is crucial to voluntary perform actions in Parkinson’s disease (PD), allowing patients to bypass the impaired habitual motor control. The asymmetrical degeneration of the dopaminergic system could affect the attentional functions.Objective: To investigate the relationship between the asymmetric dopaminergic degeneration and the attentional resources in Parkinsonian patients with right-side (RPD) and left-side (LPD) motor symptoms predominance.Methods: 50 RPD, 50 LPD, and 34 healthy controls underwent visual (V), auditory (A), and multiple choices (MC) reaction time (RTs) tasks. For PD patients, these tasks were performed before and after a 4-week intensive, motor-cognitive rehabilitation treatment (MIRT). The effectiveness of treatment was evaluated assessing Unified Parkinson’s disease Rating Scale (UPDRS) III and Timed-up and Go Test (TUG).Results: RTs did not differ between PD patients and healthy controls. Before MIRT, no differences between LPD and RPD patients were observed in RTs (p = 0.20), UPDRS III (p = 0.60), and TUG (p = 0.38). No differences in dopaminergic medication were found between groups (p = 0.44 and p = 0.66 before and after MIRT, respectively). After MIRT, LPD patients showed a significant reduction in MC RTs (p = 0.05), V RTs (p = 0.02), and MC-V RTs. A significant association between changes in RTs and improvements in UPDRS III and TUG was observed in LPD patients.Conclusion: attention does not differ among RPD patients, LPD patients and healthy controls. Only LPD patients improved their performances on attentional tasks after MIRT. We argue that the increased early susceptibility of the left nigrostriatal system to degeneration affects differently the cognitive modifiability and the neuroplastic potential. Our results could provide insight into new therapeutic approaches, highlighting the importance to design different treatments for RPD patients and LPD patients.

Vocal motor control and central auditory impairments in unilateral vocal fold paralysis.

To evaluate differences in vocal motor control and central auditory processing between treated unilateral vocal fold paralysis (UVFP) and healthy control cohorts. Cross-sectional. Ten UVFP study patients treated by type I thyroplasty with stable voices were compared to 12 control subjects for vocal motor control using a pitch perturbation response task and central auditory processing performance using a battery of complex sound intelligibility assays that included adverse temporal and noise conditions. Standard clinical evaluations of voice production and peripheral audiometric sensitivity were performed. Vocal motor control was impaired in treated UVFP. The UVFP cohort exhibited a 32.5% reduction in the instantaneous, subconscious compensatory response to pitch feedback perturbation in the interval between 150 ms and 550 ms following onset (P < 0.0001, linear mixed effects model). This impairment cannot simply be ascribed to vocal motor capacity insufficiency in the UVFP cohort because both cohorts demonstrated comparable functional capacity to perform the vocal motor task. The UVFP cohort also showed greater propensity for central auditory processing impairment (P < 0.05), notably for temporal compression and added noise challenges. Combined central vocal motor control and auditory processing impairments in treated UVFP highlight reciprocal interdependency of sensory and motor systems. This pilot study suggests that peripheral motor impairment of the larynx can degrade central auditory processing, which in turn may contribute to vocal motor control impairment. A more complete restoration communicative function in UVFP will require deeper understanding of sensory, motor, and sensorimotor aspects of the human communication loop. 3b Laryngoscope, 129:2112-2117, 2019.

Chronic Non-specific Low Back Pain and Motor Control During Gait.

Background: Chronic non-specific low back pain (LBP) poses a major socioeconomic problem, although the mechanisms are not yet clear. Impaired motor control is one of the mechanisms being discussed.Objectives: The purpose of this review is to provide an overview of motor control parameter differences between individuals with and without non-specific LBP during gait.Methods: A literature search on Medline, SportDiscus, PsychInfo, PsychArticels, EMBASE, and Scopus was performed. Twenty-nine articles comparing healthy adults and adults with chronic non-specific LBP in neuromuscular and/or biomechanical parameters during walking or running were examined. Data extraction and quality assessment were independently performed by two persons. Among others, we extracted population, conditions, outcome measures, and results.Results: The results showed that persons with and without non-specific LBP differed in several parameters of motor control, which was indicated by a lower movement amplitude of the pelvis, more in-phase coordination, lower ground reaction forces, higher stride-to-stride variability and a higher activity in ES in the LBP group.Conclusion: Despite no strong evidence for any of the parameters, a combination of biomechanical and neuromuscular parameters provides a conclusive explanation. Impaired motor control during walking is reflected in higher activity of the erector spinae, which leads to a stiffened lumbar-pelvic region. Different acquisition and processing of data renders making comparisons difficult, whereby standards for future research are necessary.

The Effect of Hydrotherapy on Pain, Joint Position Sense, and Two-Point Discrimination in Women with Nonspecific Chronic Low Back Pain

Introduction: Patients with nonspecific chronic low back pain experience deficit in joint position sense acuity and two-point discrimination, and these deficits are associated with pain in these patients. The aim of present study was to evaluate the effect of hydrotherapy on pain, joint position sensee, and two-point discrimination in patients with nonspecific chronic low back pain and motor control impairment. Material and Methods: 25 women with nonspecific chronic low back pain were selected using Oswestry Disability Questionnaire, and randomly assigned into 2 groups of hydrotherapy (n = 12) and control (n = 13). The experimental group performed an eight weeks of hydrotherapy exercises, and control group did not perform exercise. Before and after complementation of intervention, visual analogue scale, goniometer, and caliper were used to assess pain, joint position sense, and two-point discrimination, respectively. Within and between group comparisons were done using paired t and independent t tests. Results: In hydrotherapy group, there were significant differences between pretest and posttest in pain (P = 0.007), joint positon sense (P = 0.005), and two-point discrimination (P = 0.008); whereas there was not any significant difference in control group. Conclusion: Hydrotherapy exercises result in decreasing pain, improvement in joint position sense, and two-point discrimination of women with nonspecific chronic low back pain and motor control impairment. So, use of these exercises is recommended for treatment of nonspecific chronic low back pain.

Influence of impaired selective motor control on stance phase knee kinematics and stride characteristics in cerebral palsy

Influence of impaired selective motor control on stance phase knee kinematics and stride characteristics in cerebral palsy

Impaired white matter integrity between premotor cortex and basal ganglia in writer's cramp.

IntroductionWriter’s cramp (WC) as a focal hand dystonia is characterized by abnormal postures of the hand during writing. Impaired inhibition and maladaptive plasticity in circuits linking the basal ganglia and sensorimotor cortices have been described. In particular, a dysfunction of lateral premotor cortices has been associated with impaired motor control in WC. We applied diffusion tensor imaging to identify changes in white matter connectivity between premotor regions and important cortical and subcortical structures.MethodsWhole brain white matter tracts were reconstructed in 18 right‐handed WC patients and 18 matched controls, using probabilistic fiber tracking. We restricted our analyses to left‐hemispheric fibers between the middle frontal gyrus (MFG) and basal ganglia, thalamus, primary motor, and sensory cortex. Diffusion parameters (fractional anisotropy and linear anisotropy) were compared between both groups.ResultsA significant reduction in fractional anisotropy values was shown for patients (mean ± SD: 0.37 ± 0.02) vs. controls (0.39 ± 0.03) regarding fibers between the left‐sided MFG and the putamen (p < 0.05). The same applied for linear anisotropy values in this connection (p < 0.05).ConclusionsOur results suggest an impaired structural connectivity between the left‐hemispheric MFG and putamen with a loss of equally aligned fibers in WC patients. This could reflect a structural basis for functional findings interpreted as altered inhibition and plasticity, both within the premotor cortex and the basal ganglia, that at last lead to the clinical symptoms of WC.

Neurological gait disorders in childhood

Abstract There are an enormous number of neurological illnesses that can manifest with gait disturbance in childhood. Whilst experience and clinical acumen are helpful in diagnosing these disorders, some basic principles in assessment and diagnosis are helpful in determining the phenomenology, time course, and neuro-anatomical localisation. In this review we focus on some of the more common movement disorders resulting in inserted postures (including spasticity and dystonia), inserted movements (including chorea and myoclonus), and impairment of motor control (including ataxia and neuro-muscular disorders). A number of case studies are included to illustrate the factual descriptions.

Studying Huntington's Disease in Yeast: From Mechanisms to Pharmacological Approaches.

Huntington’s disease (HD) is a neurodegenerative disorder that leads to progressive neuronal loss, provoking impaired motor control, cognitive decline, and dementia. So far, HD remains incurable, and available drugs are effective only for symptomatic management. HD is caused by a mutant form of the huntingtin protein, which harbors an elongated polyglutamine domain and is highly prone to aggregation. However, many aspects underlying the cytotoxicity of mutant huntingtin (mHTT) remain elusive, hindering the efficient development of applicable interventions to counteract HD. An important strategy to obtain molecular insights into human disorders in general is the use of eukaryotic model organisms, which are easy to genetically manipulate and display a high degree of conservation regarding disease-relevant cellular processes. The budding yeast Saccharomyces cerevisiae has a long-standing and successful history in modeling a plethora of human maladies and has recently emerged as an effective tool to study neurodegenerative disorders, including HD. Here, we summarize some of the most important contributions of yeast to HD research, specifically concerning the elucidation of mechanistic features of mHTT cytotoxicity and the potential of yeast as a platform to screen for pharmacological agents against HD.

Brain network connectivity associated with anticipatory postural control in children and adults

Internal models provide a coherent framework for understanding motor behavior. Examples for the use of internal models include anticipatory postural adjustments (APAs), where the individual anticipates and cancels out the destabilizing effect of movement on body posture. Yet little is known about the functional changes in the brain supporting the development of APAs. Here, we addressed this issue by relating individual differences in APAs as assessed during bimanual load lifting to interindividual variation in brain network interactions at rest. We showed that the strength of the connectivity between three main canonical brain networks, namely the cingulo-opercular, the fronto-parietal and the somatosensory-motor networks, is an index of the ability to implement APAs from late childhood (9- to 11-year-old children). We also found an effect of age on the relationship between APAs and coupling strength between these networks, consistent with the notion that APAs are near but not yet fully mature in children. We discuss the implications of these findings for our understanding of learning disorders with impairment in predictive motor control.

StartReact during gait initiation reveals differential control of muscle activation and inhibition in patients with corticospinal degeneration

Corticospinal lesions cause impairments in voluntary motor control. Recent findings suggest that some degree of voluntary control may be taken over by a compensatory pathway involving the reticulospinal tract. In humans, evidence for this notion mainly comes from StartReact studies. StartReact is the acceleration of reaction times by a startling acoustic stimulus (SAS) simultaneously presented with the imperative stimulus. As previous StartReact studies mainly focused on isolated single-joint movements, the question remains whether the reticulospinal tract can also be utilized for controlling whole-body movements. To investigate reticulospinal control, we applied the StartReact paradigm during gait initiation in 12 healthy controls and 12 patients with ‘pure’ hereditary spastic paraplegia (HSP; i.e., retrograde axonal degeneration of corticospinal tract). Participants performed three consecutive steps in response to an imperative visual stimulus. In 25% of 16 trials a SAS was applied. We determined reaction times of muscle (de)activation, anticipatory postural adjustments (APA) and steps. Without SAS, we observed an overall delay in HSP patients compared to controls. Administration of the SAS accelerated tibialis anterior and rectus femoris onsets in both groups, but more so in HSP patients, resulting in (near-)normal latencies. Soleus offsets were accelerated in controls, but not in HSP patients. The SAS also accelerated APA and step reaction times in both groups, yet these did not normalize in the HSP patients. The reticulospinal tract is able to play a compensatory role in voluntary control of whole-body movements, but seems to lack the capacity to inhibit task-inappropriate muscle activity in patients with corticospinal lesions.

Altered Gamma Oscillations during Motor Control in Children with Autism Spectrum Disorder.

Autism is hypothesized to result in a cortical excitatory and inhibitory imbalance driven by inhibitory interneuron dysfunction, which is associated with the generation of gamma oscillations. On the other hand, impaired motor control has been widely reported in autism. However, no study has focused on the gamma oscillations during motor control in autism. In the present study, we investigated the motor-related gamma oscillations in autism using magnetoencephalography. Magnetoencephalographic signals were recorded from 14 right-handed human children with autism (5 female), aged 5–7 years, and age- and IQ-matched 15 typically developing children during a motor task using their right index finger. Consistent with previous studies, the autism group showed a significantly longer button response time and reduced amplitude of motor-evoked magnetic fields. We observed that the autism group exhibited a low peak frequency of motor-related gamma oscillations from the contralateral primary motor cortex, and these were associated with the severity of autism symptoms. The autism group showed a reduced power of motor-related gamma oscillations in the bilateral primary motor cortex. A linear discriminant analysis using the button response time and gamma oscillations showed a high classification performance (86.2% accuracy). The alterations of the gamma oscillations in autism might reflect the cortical excitatory and inhibitory imbalance. Our findings provide an important clue into the behavioral and neurophysiological alterations in autism and a potential biomarker for autism.SIGNIFICANCE STATEMENT Currently, the diagnosis of autism has been based on behavioral assessments, and a crucial issue in the diagnosis of autism is to identify objective and quantifiable clinical biomarkers. A key hypothesis of the neurophysiology of autism is an excitatory and inhibitory imbalance in the brain, which is associated with the generation of gamma oscillations. On the other hand, motor deficits have also been widely reported in autism. This is the first study to demonstrate low motor performance and altered motor-related gamma oscillations in autism, reflecting a brain excitatory and inhibitory imbalance. Using these behavioral and neurophysiological parameters, we classified autism and control group with good accuracy. This work provides important information on behavioral and neurophysiological alterations in patients with autism.

Association of spasticity and motor dysfunction in chronic stroke.

The prevalence of increased muscle tone after stroke is frequently reported as 30% to 40%, and the condition is often concurrent with motor control deficits, manifesting as an inability to isolate paretic-limb joint movements. The objectives of this retrospective analysis were to 1) report the prevalence of increased muscle tone in a convenience sample of 128 chronic stroke survivors with moderate/severe motor deficits and 2) quantify the relation between tone and motor impairment in chronic stroke survivors. Analyses included descriptive statistics and multiple regression modeling, with the modified Ashworth Scale score (MAS; tone) as a predictor of isolated joint movement control (Fugl-Meyer score [FM]; motor impairment). Increased muscle tone was present in 97% of subjects. Increased muscle tone was associated with impaired motor control (FM; upper extremity, P=0.008; lower extremity, P=0.03) after adjusting for age, time since stroke and sex. We found a significant difference between flexor and extensor strength for finger, elbow, hip and knee joints (P<0.002). Participants were classified in high and low MAS score groups. With high MAS score and for muscles of finger flexion and forearm pronation, we found a trend toward impaired strength of antagonist muscles (finger extensors and forearm supinators, respectively) as compared with low MAS score for these same muscle pairings. The prevalence of increased tone was higher in this study than in previous reports. Increased muscle tone in chronic stroke survivors with persistent motor dysfunction could be associated with impaired motor control and differential muscle strength of antagonistic muscles.

Relative phase measures of intersegmental coordination describe motor control impairments in children with cerebral palsy who exhibit stiff-knee gait

BackgroundThe purpose of this retrospective study was to explore lower limb intersegmental coordination as a clinically important indicator of motor control mechanisms in individuals with cerebral palsy exhibiting stiff-knee gait. We used the relative phase of thigh and foot segments around foot-off to describe motor control, given the relevance of the pre-swing phase of gait to the existence of stiff-knee gait. MethodsTraditional gait parameters and thigh/foot intersegmental coordination were calculated using pre-and postoperative kinematic data from a cohort of 54 subjects (92 legs) with spastic cerebral palsy. All participants had stiff-knee gait, walked without assistive devices, and underwent rectus femoris transfer surgery to improve swing period knee flexion. Analyses included correlations between a) preoperative intersegmental coordination and gait variables (knee flexion range, rate and gait performance) and b) pre-to-postoperative intersegmental coordination change and change in gait variables. FindingsThigh/foot intersegmental coordination significantly (P < 0.001) correlated with knee flexion range, rate and walking speed. Postoperative intersegmental coordination was significantly more uncoupled than preoperative. Pre-to-postoperative intersegmental coordination improvement also significantly correlated with improvements in knee flexion range, rate and walking speed. Pre-to-postoperative changes in intersegmental coordination accounted for 43% and 36% of variance in knee flexion range change and knee flexion rate change respectively. InterpretationIntersegmental coordination is a clinically important factor in knee flexion limitations associated with stiff-knee gait for individuals with cerebral palsy. These findings are a foundation for further study of intersegmental coordination measures as complements to traditional instrumented gait analysis.

Dysfunctional inhibitory control in Parkinson's disease patients with levodopa-induced dyskinesias.

Chronic dopamine replacement therapies in Parkinson's disease can induce side effects, such as levodopa-induced dyskinesias and impulse control disorders. A dysfunction of inhibitory brain networks has been related to both disorders; however, there is no clear behavioral evidence supporting this hypothesis. We aimed to determine whether PD patients with levodopa-induced dyskinesias show features of increased impulsivity in parallel with altered motor inhibition. Two matched samples of Parkinson's disease patients with (n = 14) or without (n = 14) levodopa-induced dyskinesias and a control group (n = 10) participated in the study. All groups were evaluated by the Barratt Impulsiveness Scale-11 to assess impulsivity traits. Furthermore, participants performed a stop signal task to evaluate reactive-motor inhibition and a Go/NoGo task to evaluate proactive-inhibitory control. PD patients were tested both in OFF and ON levodopa medication. Parkinson's disease patients with levodopa-induced dyskinesias showed higher impulsivity scores than PD patients without levodopa-induced dyskinesias. Dyskinetic patients presented also delayed stop signal reaction times indicating a worse performance in reactive inhibition. The slowness in inhibiting a motor command correlated with the impulsiveness scores. Furthermore, in the dyskinetic group, a positive correlation was found between stop reaction times and the severity of involuntary movements. Under the effect of levodopa, all patients were faster but dyskinetic patients were significantly less accurate in proactive inhibition. Inhibitory control is compromised in dyskinetic patients in parallel with increased impulsivity, revealing an impairment of motor and behavioral inhibitory control in Parkinson's disease patients with levodopa-induced dyskinesias.

Building interactive computer play games with youth with cerebral palsy: Improving practice efficacy through biofeedback and user-centered design

Interactive computer play (ICP), or serious games, can provide motivational and flexible rehabilitation environments. This is useful for the 1 in 400 children born with Cerebral Palsy (CP) each year, whose daily activities are impacted by impaired motor control. Improvement through traditional rehabilitation is often hindered by low adherence and limited repetitions. This study aims to build an ICP game which offers a motivational and effective environment to supplement reaching and grasping rehabilitation in youth with CP. Through a user-centered design process, we first met with five youth with CP and four occupational therapists to establish reach and grasp movement priorities. Then, seven youth, age 16–23 years with hemiplegic CP, participated in 1–3 game design sessions. During each design session, participants extended and relaxed their hand to control an ICP game using a forearm muscle activity sensor (Myo Armband). Participants played games with different types of feedback and control mechanisms (detailed in Fig. 1 ). Game versions were iterated between design sessions. The top priority identified by youth and therapists was increasing amplitude and endurance of wrist extension while fingers open. Thus, this action was used as the primary game control. At each design session, participants played an average of 15 levels, each lasting 129 ± 56 seconds and requiring 43 ± 19 wrist extension repetitions. In total, during a typical session, participants practiced 645 ± 285 repetitions through the ICP game. User input showed participants were most responsive when feedback directly followed wrist extension (e.g. increased power bar or bonus points). The user-centered design process engages participants to build practice tools that they find motivating. The ICP game can offer youth with CP the high quantity of repetitions required to improve reach and grasp activities. Next, the game will be used in a home-based pilot study to demonstrate its efficacy for improving reach and grasp activities.

Effects induced by motor cortex anodal transcranial direct current stimulation on wrist muscles in stroke patients

Transcranial direct current stimulation is used to modify noninvasively cortical brain excitability in humans. It consists in delivering a weak current trough two electrodes: one applied over the motor cortex and a second in supra-orbital position. Recently we showed in healthy subjects that anodal tDCS applied over the motor cortex can be used to modify descending inputs relayed by corticospinal tract on reciprocal inhibition pathways innervating wrist muscles [1] . We found that effects induced by anodal tDCS in wrist extensors and in wrist flexors are opposite: tDCS increases reciprocal inhibition in extensors but decreases reciprocal inhibition in flexors. It appears that modulations induced by anodal tDCS on reciprocal inhibition pathways favor the contraction in wrist extensors. Motor deficit in wrist extensors is usual in hemiplegic patients and the aim of this study is to combine spinal cord MRI and electrophysiological methods to explore effects of tDCS at wrist level in patients with impaired wrist motor control. Anodal tDCS is applied over the non-lesional hemisphere (ipsilateral motor cortex). Its effects at spinal level are explored using electrophysiological techniques based on EMG recordings and percutaneous stimulations of peripheral nerves to elicit reciprocal inhibition at wrist level. MRI study relies on diffusion tensor imaging (DTI) and magnetization transfer (MT) [2] . Preliminary results in hemiplegic patients suggest an increase of reciprocal inhibition contrary to the results found in healthy subjects. They also show a relationship between motor impairment and MRI metrics. It opens new vista for motor rehabilitation of stroke patients.

Effects of Multi-Session Repetitive Transcranial Magnetic Stimulation on Motor Control and Spontaneous Brain Activity in Multiple System Atrophy: A Pilot Study.

Background: Impaired motor control is one of the most common symptoms of multiple system atrophy (MSA). It arises from dysfunction of the cerebellum and its connected neural networks, including the primary motor cortex (M1), and is associated with altered spontaneous (i.e., resting-state) brain network activity. Non-invasive repetitive transcranial magnetic stimulation (rTMS) selectively facilitates the excitability of supraspinal networks. Repeated rTMS sessions have been shown to induce long-term changes to both resting-state brain dynamics and behavior in several neurodegenerative diseases. Here, we hypothesized that a multi-session rTMS intervention would improve motor control in patients with MSA, and that such improvements would correlate with changes in resting-state brain activity.Methods: Nine participants with MSA received daily sessions of 5 Hz rTMS for 5 days. rTMS targeted both the cerebellum and the bilateral M1. Before and within 3 days after the intervention, motor control was assessed by the motor item of the Unified Multiple System Atrophy Rating Scale (UMSARS). Resting-state brain activity was recorded by blood-oxygen-level dependency (BOLD) functional magnetic resonance imaging. The “complexity” of resting-state brain activity fluctuations was quantified within seven well-known functional cortical networks using multiscale entropy, a technique that estimates the degree of irregularity of the BOLD time-series across multiple scales of time.Results: The rTMS intervention was well-attended and was not associated with any adverse events. Average motor scores were lower (i.e., better performance) following the rTMS intervention as compared to baseline (t8 = 2.3, p = 0.003). Seven of nine participants exhibited such pre-to-post intervention improvements. A trend toward an increase in resting-state complexity was observed within the motor network (t8 = 1.86, p = 0.07). Participants who exhibited greater increases in motor network resting-state complexity demonstrated greater improvement in motor control (r2= 0.72, p = 0.004).Conclusion: This pilot study demonstrated that a five-session rTMS intervention targeting the cerebellum and bilateral M1 is feasible and safe for those with MSA. More definitive, well-controlled trials are warranted to confirm our preliminary results that rTMS may alleviate the severity of motor dysfunction and modulate the multiscale dynamics of motor network brain activity.

What If Low Back Pain Is the Most Prevalent Parkinsonism in the World?

Low back pain (LBP) has a point prevalence of nearly 10% and ranks highest in global disease burden for years lived with disability; Parkinson’s disease (PD) ranks in the top 100 most disabling health conditions for years lost and years lived with disability (1). Recent evidence suggests that people with chronic, recurrent LBP exhibit many postural impairments reminiscent of a neurological postural disorder such as PD. We compare and contrast postural impairments associated with LBP and PD in order to inform treatment strategies for both conditions. The literature suggests that both LBP and PD associate with impaired proprioceptive function, sensory orientation during standing balance, anticipatory postural adjustments, automatic postural responses, and striatal-cortical function. Although postural impairments are similar in nature for LBP and PD, the postural impairments with LBP appear more specific to the trunk than for PD. Likewise, although both health conditions associate with altered striatal-cortical function, the nature of the altered neural structure or function differ for PD and LBP. Due to the high prevalence of LBP associated with PD, focused treatment of LBP in people with PD may render benefit to their postural impairments and disabilities. In addition, LBP would likely benefit from being considered more than just a musculoskeletal injury; as such, clinicians should consider including approaches that address impairments of postural motor control.