Plasticity

Personalised Online Upper-Limb Physiotherapy for Stroke Survivors during the Inpatient Phase: A Feasibility Study

BACKGROUND

After a stroke, inpatients often receive less than the recommended dose of therapy. Telerehabilitation may assist by providing personalised rehabilitation programmes without face-to-face therapy time. This study aimed to evaluate the acceptability and feasibility of an individualised programme of upper-limb rehabilitation that is delivered via an online rehabilitation platform for inpatient stroke survivors.

METHODS

Stroke survivors were recruited from three stroke units in one NHS Board in Scotland and randomised to the intervention (personalised upper-limb exercise programme delivered via an online physiotherapy platform for four weeks, up to 30 min five times per week, in addition to usual care) or the control group (usual care). The main outcomes are related to recruitment, attrition, adherence and safety. The clinical measures were the Action Research Arm Test, Trunk Impairment Scale and Modified Ashworth Scale. The intervention participants, their carers and physiotherapists completed questionnaires on the acceptability of the intervention.

RESULTS

Twenty-six participants, 42% males, were recruited around three weeks post-stroke, on average. There were 13 participants in each group, with a mean age of 69 years (SD of 12) and 67 years (SD of 11) for the control and intervention groups, respectively. Overall, 47% of those screened for eligibility were randomised, and attrition was 23% in the intervention group mainly due to discharge before the end of the intervention. Participants who adhered to their programme (completed more than two-thirds), generally those with an engaged carer, demonstrated a trend toward improved clinical outcomes. Overall, the patients, carers and physiotherapists were positive regarding the intervention. There was a total of five reported adverse events, none of which were related to the study.

CONCLUSION

An upper-limb unsupervised exercise intervention using an online physiotherapy platform for inpatient stroke survivors is feasible, safe and acceptable to patients, carers and physiotherapists. A fully powered RCT is warranted to investigate the clinical- and cost-effectiveness of such interventions for this patient group.

Motor cortical functional connectivity changes due to short-term immobilization of upper limb: an fNIRS case report

Introduction

A short-term immobilization of one hand affects musculoskeletal functions, and the associated brain network adapts to the alterations happening to the body due to injuries. It was hypothesized that the injury-associated temporary disuse of the upper limb would alter the functional interactions of the motor cortical processes and will produce long-term changes throughout the immobilization and post-immobilization period.

Methods

The case participant (male, 12 years old, right arm immobilized for clavicle fracture) was scanned using optical imaging technology of fNIRS over immobilization and post-immobilization. Pre-task data was collected for 3 min for RSFC analysis, processed, and analyzed using the Brain AnalyzIR toolbox. Connectivity was measured using Pearson correlation coefficients (R) from NIRS Toolbox's connectivity module.

Results

The non-affected hand task presented an increased ipsilateral response during the immobilization period, which then decreased over the follow-up visits. The right-hand task showed a bilateral activation pattern following immobilization, but the contralateral activation pattern was restored during the 1-year follow-up visit. Significant differences in the average connection strength over the study period were observed. The average Connection strength decreased from the third week of immobilization and continued to be lower than the baseline value. Global network efficiency decreased in weeks two and three, while the network settled into a higher efficient state during the follow-up periods after post-immobilization.

Discussion

Short-term immobilization of the upper limb is shown to have cortical changes in terms of activations of brain regions as well as connectivity. The short-term dis-use of the upper limb has shifted the unilateral activation pattern to the bilateral coactivation of the motor cortex from both hemispheres. Resting-state data reveals a disruption in the motor cortical network during the immobilization phase, and the network is reorganized into an efficient network over 1 year after the injury. Understanding such cortical reorganization could be informative for studying the recovery from neurological disorders affecting motor control in the future.

Integrating neuroplasticity and evolution

Neuroplasticity and evolutionary biology have been prominent fields of study for well over a century. However, they have advanced largely independently, without consideration of the benefits of integration. We propose a new framework by which researchers can begin to examine the evolutionary causes and consequences of neuroplasticity. Neuroplasticity can be defined as changes to the structure, function or connections of the nervous system in response to individual experience. Evolution can alter levels of neuroplasticity if there is variation in neuroplasticity traits within and between populations. Neuroplasticity may be favored or disfavored by natural selection depending on the variability of the environment and the costs of neuroplasticity. Additionally, neuroplasticity may affect rates of genetic evolution in many ways: for example, decreasing rates of evolution by buffering against selection or increasing them via the Baldwin effect, by increasing genetic variation or by incorporating evolved peripheral changes to the nervous system. These mechanisms can be tested using comparative and experimental approaches and by examining patterns and consequences of variation in neuroplasticity among species, populations and individuals.

Effects of moderate-intensity aerobic exercise on serum BDNF and motor learning in the upper-limb in patients after chronic-stroke: A randomized, controlled feasibility study with embedded health economic evaluation

BACKGROUND

Brain-derived neurotrophic factor (BDNF) promotes activity-dependent neuroplasticity and is released following aerobic-exercise.

OBJECTIVE

Feasibility and efficacy of 1.Moderate-Intensity Cycle-Ergometer-Training (MI-ET) and 2.Low-Intensity Circuit-Training (LI-CT) on BDNF-serum-concentration in chronic-stroke and consequently efficacy of motor-learning in varying BDNF-concentrations (neuroplasticity being the substrate for motor-learning) via upper-limb robotic-training (RT) in both groups.

METHODS

Randomised-control feasibility-study. 12-week, 3x/week intervention, 17 chronic-stroke-survivors randomized into: (1) MI-ET&RT or (2) LI-CT&RT. Both groups completed 40 mins MI-ET or LI-CT followed by 40 mins RT. Feasibility outcomes: (1) screening and enrollment-rates, (2) retention-rates, (3) adherence: (i) attendance-rates, (ii) training-duration, (4) adverse events. Primary clinical outcomes: 1. serum-BDNF changes pre-post training (immediate) and pre-training basal-levels over 12-weeks (long-term). 2.upper-limb performance with Action-Research-Arm-Test (ARAT). Additionally, feasibility of an embedded health economic evaluation (HEE) to evaluate health-costs and cost-effectiveness.

OUTCOMES

cost-questionnaire return-rates, cost-of-illness (COI) and Health-Utitility-Index (HUI).

RESULTS

21.5% of eligible and contactable enrolled. 10 randomized to MI-ET and 7 to LI-CT. 85% of training-sessions were completed in MI-ET (306/360) and 76.3% in LI-CT-group (165/216). 12-weeks: Drop-outs MI-ET-10%, LI-CT-43%.

CLINICAL OUTCOMES

No significant changes in immediate or long-term serum-BDNF in either group. Moderate-intensity aerobic-training did not increase serum-BDNF post-stroke. Individual but no group clinically-relevant changes in ARAT-scores. HEE outcomes at 12-weeks: 100% cost-questionnaires returned. Group-costs baseline and after treatment, consistently favouring MI-ET group. COI: (1-year-time-frame): MI-ET 67382 SD (43107) Swiss-Francs and LI-CT 95701(29473) Swiss-Francs.

CONCLUSION

The study is feasible with modifications. Future studies should compare high-intensity versus moderate-intensity aerobic-exercise combined with higher dosage arm-training.

The role of feedback in the robotic-assisted upper limb rehabilitation in people with multiple sclerosis: a systematic review

INTRODUCTION

Robotic-assisted upper limb rehabilitation might improve upper limb recovery in people with multiple sclerosis (PwMS) with moderate-to-severe disability. In the few existing studies, the training effects have been related to the type of intervention, if intensive, repetitive, or task-oriented training might promote neuroplasticity and recovery. Notably, most of these devices operate within a serious game context providing different feedback. Since feedback is a key component of motor control and thus involved in motor and cognitive rehabilitation, clinicians cannot desist from considering the potential contribution of feedback in the upper limb robot-assisted rehabilitation effects.

AREA COVERED

In this systematic review, we reported the rehabilitation protocols used in the robot-assisted upper limb training in PwMS to provide state-of-the-art on the role of feedback in robotic-assisted Upper Limb rehabilitation. PubMed, the Cochrane Library, and the Physiotherapy Evidence Database databases were systematically searched from inception to March 2022. After a literature search, the classification systems for feedback and the serious game were applied.

EXPERT OPINION

There is a need for sharing standard definitions and components of feedback and serious game in technologically assisted upper limb rehabilitation. Indeed, improving these aspects might further improve the effectiveness of such training in the management of PwMS.

A Tailored Music-Motor Therapy and Real-Time Biofeedback Mobile Phone App (‘GotRhythm’) to Promote Rehabilitation Following Stroke: A Pilot Study

Background:

Stroke persists as an important cause of long-term disability world-wide with the need for rehabilitation strategies to facilitate plasticity and improve motor function in stroke survivors. Rhythm-based interventions can improve motor function in clinical populations. This study tested a novel music-motor software application ‘GotRhythm’ on motor function after stroke.

Methods:

Participants were 22 stroke survivors undergoing inpatient rehabilitation in a subacute stroke ward. Participants were randomised to the GotRhythm intervention (combining individualised music and augmented auditory feedback along with wearable sensors to deliver a personalised rhythmic auditory stimulation training protocol) or usual care. Intervention group participants were offered 6-weeks of the GotRhythm intervention, consisting of a supervised 20-minute music-motor therapy session using GotRhythm conducted 3 times a week for 6 weeks. The primary feasibility outcomes were adherence to the intervention and physical function (change in the Fugl-Meyer Assessment of Motor Recovery score) measured at baseline, after 3-weeks and at end of the intervention period (6-weeks).

Results:

Three of 10 participants randomised to the intervention did not receive any of the GotRhythym music-motor therapy. Of the remaining 7 intervention group participants, only 5 completed the 3-week mid-intervention assessment and only 2 completed the 6-week post-intervention assessment. Participants who used the intervention completed 5 (IQR 4,7) sessions with total ‘dose’ of the intervention of 70 (40, 201) minutes.

Conclusion:

Overall, adherence to the intervention was poor, highlighting that application of technology assisted music-based interventions for stroke survivors in clinical environments is challenging along with usual care, recovery, and the additional clinical load.

Effects of Computer-Based Cognitive Rehabilitation on Attention, Executive Functions, and Quality of Life in Patients with Parkinson's Disease: A Randomized, Controlled, Single-Blinded Pilot Study

BACKGROUND

Cognitive decline in Parkinson's disease (PD) has become increasingly recognized in recent years, and there is a need to identify methods for cognitive rehabilitation in PD patients.

OBJECTIVE

The aim of this study was to explore the feasibility and effects of 2 different computer-based cognitive rehabilitation (CBCR) interventions on attention, executive functions, and quality of life (QoL) in PD patients.

METHODS

Thirty nondemented PD patients were randomly assigned to one of 3 groups: one passive control group and 2 intervention groups with 2 different CBCR programmes. The intervention period was 8 weeks with follow-up visits in clinic every second week. Before and after the intervention period, patients were tested with a neuropsychological battery of attention, executive functions, and QoL.

RESULTS

Twenty-four patients completed the study. Patients in one of the CBCR groups experienced a significant within-group increase on the primary measures of attention, executive functions, and QoL. However, this effect was not significant between groups. No significant differences were observed for the other CBCR group or the control group.

CONCLUSIONS

CBCR is a feasible intervention for cognitive rehabilitation in nondemented PD patients. The effects of training were modest and should be further explored in larger clinical trials. Some CBCR programmes might be more effective than others for PD patients. The protocol for this study was published prospectively at ClinicalTrials.gov on September 18, 2017 with ID: NCT03285347.

General principles of brain electromagnetic rhythmic oscillations and implications for neuroplasticity

Neuro-plasticity describes the ability of the brain in achieving novel functions, either by transforming its internal connectivity, or by changing the elements of which it is made, meaning that, only those changes, that affect both structural and functional aspects of the system, can be defined as "plastic." The concept of plasticity can be applied to molecular as well as to environmental events that can be recognized as the basic mechanism by which our brain reacts to the internal and external stimuli. When considering brain plasticity within a clinical context-that is the process linked with changes of brain functions following a lesion- the term "reorganization" is somewhat synonymous, referring to the specific types of structural/functional modifications observed as axonal sprouting, long-term synaptic potentiation/inhibition or to the plasticity related genomic responses. Furthermore, brain rewires during maturation, and aging thus maintaining a remarkable learning capacity, allowing it to acquire a wide range of skills, from motor actions to complex abstract reasoning, in a lifelong expression. In this review, the contribution on the "neuroplasticity" topic coming from advanced analysis of EEG rhythms is put forward.

Effect of Motor Skill Training in Functional Activities vs Strength and Flexibility Exercise on Function in People With Chronic Low Back Pain: A Randomized Clinical Trial

Importance

Chronic low back pain (LBP) is the most prevalent chronic pain in adults, and there is no optimal nonpharmacologic management. Exercise is recommended, but no specific exercise-based treatment has been found to be most effective.

Objective

To determine whether an exercise-based treatment of person-specific motor skill training (MST) in performance of functional activities is more effective in improving function than strength and flexibility exercise (SFE) immediately, 6 months, and 12 months following treatment. The effect of booster treatments 6 months following treatment also was examined.

Design, Setting, and Participants

In this single-blind, randomized clinical trial of people with chronic, nonspecific LBP with 12-month follow-up, recruitment spanned December 2013 to August 2016 (final follow-up, November 2017), and testing and treatment were performed at an academic medical center. Recruitment was conducted by way of flyers, physician and physical therapy offices, advertisements, and media interviews at Washington University in St Louis, Missouri. Of 1595 adults screened for eligibility, 1301 did not meet the inclusion criteria and 140 could not be scheduled for the first visit. A total of 154 people with at least 12 months of chronic, nonspecific LBP, aged 18 to 60 years, with modified Oswestry Disability Questionnaire (MODQ) score of at least 20% were randomized to either MST or SFE. Data were analyzed between December 1, 2017, and October 6, 2020.

Interventions

Participants received 6 weekly 1-hour sessions of MST in functional activity performance or SFE of the trunk and lower limbs. Half of the participants in each group received up to 3 booster treatments 6 months following treatment.

Main Outcomes and Measures

The primary outcome was the modified Oswestry Disability Questionnaire (MODQ) score (0%-100%) evaluated immediately, 6 months, and 12 months following treatment.

Results

A total of 149 participants (91 women; mean [SD] age, 42.5 [11.7] years) received some treatment and were included in the intention-to-treat analysis. Following treatment, MODQ scores were lower for MST than SFE by 7.9 (95% CI, 4.7 to 11.0; P < .001). During the follow-up phase, the MST group maintained lower MODQ scores than the SFE group, 5.6 lower at 6 months (95% CI, 2.1 to 9.1) and 5.7 lower at 12 months (95% CI, 2.2 to 9.1). Booster sessions did not change MODQ scores in either treatment.

Conclusions and Relevance

People with chronic LBP who received MST had greater short-term and long-term improvements in function than those who received SFE. Person-specific MST in functional activities limited owing to LBP should be considered in the treatment of people with chronic LBP.

Trial Registration

ClinicalTrials.gov Identifier: NCT02027623.

Neuroplasticity and brain reorganization associated with positive outcomes of multidisciplinary rehabilitation in progressive multiple sclerosis: A fMRI study

BACKGROUND

Multiple sclerosis (MS) is characterized by a range of symptoms, including motor, sensorimotor and cognitive impairments, that limit the quality of life. A multidisciplinary rehabilitation approach in people affected by multiple sclerosis was recently reported to improve the functional abilities of MS patients in daily activities. The purpose of the study was to assess the effect of multidisciplinary rehabilitation on the whole brain of MS patients by means of functional magnetic resonance imaging (fMRI).

METHODS

Thirty individuals affected by MS (49.9 ± 12.1 years; disease duration: 16.0 ± 8.5 years) with a medium-high severity of disease were enrolled. The fMRI examination assessed a range of action-related tasks involving passive movement, mental simulation of action and miming of action triggered by external stimuli, such as object photography. The three tasks were performed using each arm separately. The fMRI acquisitions were performed at T1 (inclusion in the study), T2 (3 months later, at the start of rehabilitation) and T3 (after 3 months of multidisciplinary rehabilitation).

RESULTS

The fMRI results revealed a significant reduction in the activity of brain areas related to task-specific networks as well as the activation of cerebral regions not usually involved in task-specific related network, such as the medial prefrontal area.

CONCLUSIONS

The effectiveness of multidisciplinary rehabilitation on activity and participation has been established in previous studies. Our study sheds new light on the effect of such treatment on brain reorganization.

No evidence for enhanced processing of speech that is low-pass filtered near the edge frequency of cochlear dead regions in children

OBJECTIVES

Cochlear dead regions (DRs) are regions in the cochlea where the inner hair cells and/or neurons are not functioning. Adults with extensive high-frequency DRs have enhanced abilities in processing sounds with frequencies just below the edge frequency, f_edge, of the DR. It was assessed whether the same is true for children.

DESIGN

Performance was compared for children aged 8 to 13 years with: DRs (group DR), hearing impairment but without DRs (group NODR), and normal hearing (group NH). Seven ears in each group were tested. Each ear in the DR group was matched in age and low-frequency hearing with an ear in the NODR group, and in age with an ear in the NH group, giving seven "triplets". Within each triplet, the percent correct identification of vowel-consonant-vowel stimuli was measured using stimuli that were low-pass filtered at f_edge and 0.67f_edge, based on the ear with a DR. For the hearing-impaired ears, stimuli were given frequency-selective amplification as prescribed by DSL 4.1.

RESULTS

No significant differences in performance were found between groups for either low-pass cut-off frequency.

CONCLUSION

Unlike adults, the children with DRs did not show enhanced discrimination of speech stimuli with frequencies below f_edge.

Enhancing endogenous capacity to repair a stroke-damaged brain: An evolving field for stroke research

Stroke represents a severe medical condition that causes stroke survivors to suffer from long-term and even lifelong disability. Over the past several decades, a vast majority of stroke research targets neuroprotection in the acute phase, while little work has been done to enhance stroke recovery at the later stage. Through reviewing current understanding of brain plasticity, stroke pathology, and emerging preclinical and clinical restorative approaches, this review aims to provide new insights to advance the research field for stroke recovery. Lifelong brain plasticity offers the long-lasting possibility to repair a stroke-damaged brain. Stroke impairs the structural and functional integrity of entire brain networks; the restorative approaches containing multi-components have great potential to maximize stroke recovery by rebuilding and normalizing the stroke-disrupted entire brain networks and brain functioning. The restorative window for stroke recovery is much longer than previously thought. The optimal time for brain repair appears to be at later stage of stroke rather than the earlier stage. It is expected that these new insights will advance our understanding of stroke recovery and assist in developing the next generation of restorative approaches for enhancing brain repair after stroke.

Immediate effects of a single session of robot-assisted gait training using Hybrid Assistive Limb (HAL) for cerebral palsy

[Purpose] Robot-assisted gait training (RAGT) using Hybrid Assistive Limb (HAL, CYBERDYNE) was previously reported beneficial for stroke and spinal cord injury patients. Here, we investigate the immediate effect of a single session of RAGT using HAL on gait function for cerebral palsy (CP) patients. [Subjects and Methods] Twelve patients (average age: 16.2 ± 7.3 years) with CP received a single session of RAGT using HAL. Gait speed, step length, cadence, single-leg support per gait cycle, hip and knee joint angle in stance, and swing phase per gait cycle were assessed before, during, and immediately after HAL intervention. [Results] Compared to baseline values, single-leg support per gait cycle (64.5 ± 15.8% to 69.3 ± 12.1%), hip extension angle in mid-stance (149.2 ± 19.0° to 155.5 ± 20.1°), and knee extension angle in mid-stance (137.6 ± 20.2° to 143.1 ± 19.5°) were significantly increased immediately after intervention. Further, the knee flexion angle in mid-swing was significantly decreased immediately after treatment (112.0 ± 15.5° to 105.2 ± 17.1°). Hip flexion angle in mid-swing also decreased following intervention (137.2 ± 14.6° to 129.7 ± 16.6°), but not significantly. Conversely, gait speed, step length, and cadence were unchanged after intervention. [Conclusion] A single-time RAGT with HAL improved single-leg support per gait cycle and hip and knee joint angle during gait, therapeutically improving gait function in CP patients.

Movement goals encoded within the cortex and muscle synergies to reduce redundancy pre and post-stroke. The relevance for gait rehabilitation and the prescription of walking-aids. A literature review and scholarly discussion

Current knowledge of neural and neuromuscular processes controlling gait and movement as well as an understanding of how these mechanisms change following stroke is an important basis for the development of effective rehabilitation interventions. To support the translation of findings from basic research into useful treatments in clinical practice, up-to-date neuroscience should be presented in forms accessible to all members of the multidisciplinary team. In this review we discuss aspects of cortical control of gait and movement, muscle synergies as a way of translating cortical commands into specific muscle activity and as an efficient means of reducing neural and musculoskeletal redundancy. We discuss how these mechanisms change following stroke, potential consequences for gait rehabilitation, and the prescription and use of walking-aids as well as areas requiring further research.

The sensory side of post-stroke motor rehabilitation

Contemporary strategies to promote motor recovery following stroke focus on repetitive voluntary movements. Although successful movement relies on efficient sensorimotor integration, functional outcomes often bias motor therapy toward motor-related impairments such as weakness, spasticity and synergies; sensory therapy and reintegration is implied, but seldom targeted. However, the planning and execution of voluntary movement requires that the brain extracts sensory information regarding body position and predicts future positions, by integrating a variety of sensory inputs with ongoing and planned motor activity. Neurological patients who have lost one or more of their senses may show profoundly affected motor functions, even if muscle strength remains unaffected. Following stroke, motor recovery can be dictated by the degree of sensory disruption. Consequently, a thorough account of sensory function might be both prognostic and prescriptive in neurorehabilitation. This review outlines the key sensory components of human voluntary movement, describes how sensory disruption can influence prognosis and expected outcomes in stroke patients, reports on current sensory-based approaches in post-stroke motor rehabilitation, and makes recommendations for optimizing rehabilitation programs based on sensory stimulation.

Stroke

Stroke, or cerebrovascular accident, involves injury to the central nervous system as a result of a vascular cause, and is a leading cause of disability worldwide. People with stroke often experience sensory, cognitive, and motor sequelae that can lead to difficulty walking, controlling balance in standing and voluntary tasks, and reacting to prevent a fall following an unexpected postural perturbation. This chapter discusses the interrelationships between stroke-related impairments, problems with control of balance and gait, fall risk, fear of falling, and participation in daily physical activity. Rehabilitation can improve balance and walking function, and consequently independence and quality of life, for those with stroke. This chapter also describes effective interventions for improving balance and walking function poststroke, and identifies some areas for further research in poststroke rehabilitation.

Withdrawn: Bilateral versus ipsilesional cortico-subcortical activity patterns in stroke show hemispheric dependence

Vidal AC, Banca P, Pascoal AG, Cordeiro G, Sargento-Freitas J, Gouveia A and Castelo-Branco M. Bilateral versus ipsilesional corticosubcortical activity patterns in stroke show hemispheric dependence. Int J Stroke. Epub ahead of print 5 April 2018. DOI: https://doi.org/10.1177/1747493018767164. Ahead of Print article withdrawn by publisher. Due to an administrative error, this article was accidentally published Online First and in Volume 12 Issue 1 with different DOIs. Vidal AC, Banca P, Pascoal AG, Cordeiro G, Sargento-Freitas J, Gouveia A and Castelo-Branco M. Bilateral versus ipsilesional corticosubcortical activity patterns in stroke show hemispheric dependence. Int J Stroke. Epub ahead of print 5 April 2018. The correct and citable version of the article remains: Vidal AC, Banca P, Pascoal AG, Cordeiro G, Sargento-Freitas J, Gouveia A and Castelo-Branco M. Bilateral versus ipsilesional corticosubcortical activity patterns in stroke show hemispheric dependence. Int J Stroke 2017; 12(1): 71–83. DOI: https://doi.org/10.1177/1747493016672087.

Assessment of serotonergic system in formation of memory and learning

We evaluated the involvement of the serotonergic system on memory formation and learning processes in healthy adults Wistar rats. Fifty-seven rats of 5 groups had one serotonergic nuclei damaged by an electric current. Electrolytic lesion was carried out using a continuous current of 2mA during two seconds by stereotactic surgery. Animals were submitted to learning and memory tests. Rats presented different responses in the memory tests depending on the serotonergic nucleus involved. Both explicit and implicit memory may be affected after lesion although some groups showed significant difference and others did not. A damage in the serotonergic nucleus was able to cause impairment in the memory of Wistar. The formation of implicit and explicit memory is impaired after injury in some serotonergic nuclei.

Evaluation of Functional Correlation of Task-Specific Muscle Synergies with Motor Performance in Patients Poststroke

The central nervous system produces movements by activating specifically programmed muscle synergies that are also altered with injuries in the brain, such as stroke. In this study, we hypothesize that there exists a positive correlation between task-specific muscle synergy and motor functions at joint and task levels in patients following stroke. The purpose here is to define and evaluate neurophysiological metrics based on task-specific muscle synergy for assessing motor functions in patients. A patient group of 10 subjects suffering from stroke and a control group of nine age-matched healthy subjects were recruited to participate in this study. Electromyography (EMG) signals and movement kinematics were recorded in patients and control subjects while performing arm reaching tasks. Muscle synergies of individual patients were extracted off-line from EMG records of each patient, and a baseline pattern of muscle synergy was obtained from the pooled EMG data of all nine control subjects. Peak velocities and movement durations of each reaching movement were computed from measured kinematics. Similarity indices of matching components to those of the baseline synergy were defined by synergy vectors and time profiles, respectively, as well as by a combined similarity of vector and time profile. Results showed that pathological synergies of patients were altered from the characteristics of baseline synergy with missing components, or varied vector patterns and time profiles. The kinematic performance measured by peak velocities and movement durations was significantly poorer for the patient group than the control group. In patients, all three similarity indices were found to correlate significantly to the kinematics of movements for the reaching tasks. The correlation to the Fugl-Meyer score of arm was the highest with the vector index, the lowest with the time profile index, and in between with the combined index. These findings illustrate that the analysis of task-specific muscle synergy can provide valuable insights into motor deficits for patients following stroke, and the task-specific similarity indices are useful neurophysiological metrics to predict the function of neuromuscular control at the joint and task levels for patients.

Developing and Evaluating a Flexible Wireless Microcoil Array Based Integrated Interface for Epidural Cortical Stimulation

Stroke leads to serious long-term disability. Electrical epidural cortical stimulation has made significant improvements in stroke rehabilitation therapy. We developed a preliminary wireless implantable passive interface, which consists of a stimulating surface electrode, receiving coil, and single flexible passive demodulated circuit printed by flexible printed circuit (FPC) technique and output pulse voltage stimulus by inductively coupling an external circuit. The wireless implantable board was implanted in cats’ unilateral epidural space for electrical stimulation of the primary visual cortex (V1) while the evoked responses were recorded on the contralateral V1 using a needle electrode. The wireless implantable board output stable monophasic voltage stimuli. The amplitude of the monophasic voltage output could be adjusted by controlling the voltage of the transmitter circuit within a range of 5–20 V. In acute experiment, cortico-cortical evoked potential (CCEP) response was recorded on the contralateral V1. The amplitude of N2 in CCEP was modulated by adjusting the stimulation intensity of the wireless interface. These results demonstrated that a wireless interface based on a microcoil array can offer a valuable tool for researchers to explore electrical stimulation in research and the dura mater-electrode interface can effectively transmit electrical stimulation.

Bilateral versus ipsilesional cortico-subcortical activity patterns in stroke show hemispheric dependence

Background Understanding of interhemispheric interactions in stroke patients during motor control is an important clinical neuroscience quest that may provide important clues for neurorehabilitation. In stroke patients, bilateral overactivation in both hemispheres has been interpreted as a poor prognostic indicator of functional recovery. In contrast, ipsilesional patterns have been linked with better motor outcomes. Aim We investigated the pathophysiology of hemispheric interactions during limb movement without and with contralateral restraint, to mimic the effects of constraint-induced movement therapy. We used neuroimaging to probe brain activity with such a movement-dependent interhemispheric modulation paradigm. Methods We used an fMRI block design during which the plegic/paretic upper limb was recruited/mobilized to perform unilateral arm elevation, as a function of presence versus absence of contralateral limb restriction ( n = 20, with balanced left/right lesion sites). Results Analysis of 10 right-hemispheric stroke participants yielded bilateral sensorimotor cortex activation in all movement phases in contrast with the unilateral dominance seen in the 10 left-hemispheric stroke participants. Superimposition of contralateral restriction led to a prominent shift from activation to deactivation response patterns, in particular in cortical and basal ganglia motor areas in right-hemispheric stroke. Left-hemispheric stroke was in general characterized by reduced activation patterns, even in the absence of restriction, which induced additional cortical silencing. Conclusion The observed hemispheric-dependent activation/deactivation shifts are novel and these pathophysiological observations suggest short-term neuroplasticity that may be useful for hemisphere-tailored neurorehabilitation.

Portable Myoelectric Brace Use Increases Upper Extremity Recovery and Participation But Does Not Impact Kinematics in Chronic, Poststroke Hemiparesis

The authors examined the efficacy of an 8-week regimen combining repetitive task-specific practice (RTP) with a myoelectric brace (RTP+Myomo) on paretic upper extremity (UE; use in valued activities, perceived recovery, and reaching kinematics) in 12 subjects (4 men; M age = 53.5 years; mean time poststroke = 61.7 months). Seven subjects were administered RTP+Myomo therapy, and 5 were administered RTP only. Both groups participated in individualized, 45-min therapy sessions occurring 3 days/week over an 8-week period. The arm, hand ability, activities of daily living, and perceptions of recovery subscales of the Stroke Impact Scale (SIS), as well as UE reaching kinematics, assessed before and after the intervention. Subjects in the RTP+Myomo group showed greater improvements on all SIS subscales, with the recovery scale reaching statistical significance (p = .03). Subjects in the RTP-only group showed a greater increase in hand velocity in the reach up task (p = .02), but no changes were observed in the range of shoulder flexion or elbow extension during reaching. None of the changes in kinematic outcome measures significantly correlated with any of the changes in SIS subscales. RTP integrating myoelectric bracing may be more beneficial than RTP only in improving self-reported function and perceptions of overall recovery. The authors observed no changes in the range of elbow extension, and no relationship between self-reported improvements and changes in reaching kinematics.

Computational models and motor learning paradigms: Could they provide insights for neuroplasticity after stroke? An overview

Computational approaches for modelling the central nervous system (CNS) aim to develop theories on processes occurring in the brain that allow the transformation of all information needed for the execution of motor acts. Computational models have been proposed in several fields, to interpret not only the CNS functioning, but also its efferent behaviour. Computational model theories can provide insights into neuromuscular and brain function allowing us to reach a deeper understanding of neuroplasticity. Neuroplasticity is the process occurring in the CNS that is able to permanently change both structure and function due to interaction with the external environment. To understand such a complex process several paradigms related to motor learning and computational modeling have been put forward. These paradigms have been explained through several internal model concepts, and supported by neurophysiological and neuroimaging studies. Therefore, it has been possible to make theories about the basis of different learning paradigms according to known computational models. Here we review the computational models and motor learning paradigms used to describe the CNS and neuromuscular functions, as well as their role in the recovery process. These theories have the potential to provide a way to rigorously explain all the potential of CNS learning, providing a basis for future clinical studies.

Moving Forward by Stimulating the Brain: Transcranial Direct Current Stimulation in Post-Stroke Hemiparesis

Stroke remains a leading cause of disability worldwide, with a majority of survivors experiencing long term decrements in motor function that severely undermine quality of life. While many treatment approaches and adjunctive strategies exist to remediate motor impairment, many are only efficacious or feasible for survivors with active hand and wrist function, a population who constitute only a minority of stroke survivors. Transcranial direct current stimulation (tDCS), a type of non-invasive brain stimulation, has been increasingly utilized to increase motor function following stroke as it is able to be used with stroke survivors of varying impairment levels, is portable, is relatively inexpensive and has few side effects and contraindications. Accordingly, in recent years the number of studies investigating its efficacy when utilized as an adjunct to motor rehabilitation regimens has drastically increased. While many of these trials have reported positive and promising efficacy, methodologies vary greatly between studies, including differences in stimulation parameters, outcome measures and the nature of physical practice. As such, an urgent need remains, centering on the need to investigate these methodological differences and synthesize the most current evidence surrounding the application of tDCS for post-stroke motor rehabilitation. Accordingly, the purpose of this paper is to provide a detailed overview of the most recent tDCS literature (published 2014-2015), while highlighting these variations in methodological approach, as well to elucidate the mechanisms associated with tDCS and post-stroke motor re-learning and neuroplasticity.

Non-Invasive Brain Stimulation to Enhance Post-Stroke Recovery

Brain plasticity after stroke remains poorly understood. Patients may improve spontaneously within the first 3 months and then more slowly in the coming year. The first day, decreased edema and reperfusion of the ischemic penumbra may possibly account for these phenomena, but the improvement during the next weeks suggests plasticity phenomena and cortical reorganization of the brain ischemic areas and of more remote areas. Indeed, the injured ischemic motor cortex has a reduced cortical excitability at the acute phase and a suspension of the topographic representation of affected muscles, whereas the contralateral motor cortex has an increased excitability and an enlarged somatomotor representation; furthermore, contralateral cortex exerts a transcallosal interhemispheric inhibition on the ischemic cortex. This results from the imbalance of the physiological reciprocal interhemispheric inhibition of each hemisphere on the other, contributing to worsening of neurological deficit. Cortical excitability is measurable through transcranial magnetic stimulation (TMS) and prognosis has been established according to the presence of motor evoked potentials (MEP) at the acute phase of stroke, which is predictive of better recovery. Conversely, the lack of response to early stimulation is associated with a poor functional outcome. Non-invasive stimulation techniques such as repetitive TMS (rTMS) or transcranial direct current stimulation (tDCS) have the potential to modulate brain cortical excitability with long lasting effects. In the setting of cerebrovascular disease, around 1000 stroke subjects have been included in placebo-controlled trials so far, most often with an objective of promoting motor recovery of the upper limb. High frequency repetitive stimulation (>3 Hz) rTMS, aiming to increase excitability of the ischemic cortex, or low frequency repetitive stimulation (≤1 Hz), aiming to reduce excitability of the contralateral homonymous cortex, or combined therapies, have shown various effects on the functional disability score and neurological scales of treated patients and on the duration of the treatment. We review here the patients’ characteristics and parameters of stimulation that could predict a good response, as well as safety issues. At last, we review what we have learnt from experimental studies and discuss potential directions to conduct future studies.

Brain plasticity and migraine transformation: fMRI evidences

INTRODUCTION

Chronification transforms episodic migraine into the pathologic chronic form. Biological characteristics of the migrainous brain progressively change, in predisposed subjects, under the repetition of external and internal stimuli. Modifications involve neurons, synapses, neurotransmitters, receptors, connectivity and pain control. f-MRI is a promising way to explore the still unclear biology of this progression. Areas covered: Data included were obtained from the most relevant and updated works available on PubMed about this topic. We summarized the pathophysiology of migraine chronification and of brain plasticity, and we described the different fMRI techniques and their main evidences about migraine transformation. Expert commentary: Functional-MRI has revealed many aspects regarding the peculiarity of the migrainous brain and its tendency toward chronicity but a series of questions are still open: What are the hallmarks of the predisposition to chronification? Which elements are the cause and which the consequence of this process?

Transcranial direct current stimulation: before, during, or after motor training?

Noninvasive brain stimulation has recently been used to augment motor training-induced plasticity. However, the exact time during which noninvasive brain stimulation can be combined with motor therapy to maximize neuroplasticity and behavioral changes is unknown. We conducted a randomized sham-controlled crossover trial to examine when (before, during, or after training) transcranial direct current stimulation (tDCS) should be applied to best reinforce motor training-induced plasticity in 12 healthy right-handed participants (mean age: 21.8±1.6) who underwent active or sham tDCS combined with motor training. Transcranial magnetic stimulation-elicited motor-evoked potentials from the right first dorsal interosseous muscle were recorded before (baseline) and immediately after each session. The training task comprised four practice trials - 3 min each (30 s pause between trials) - of repetitive finger movements (thumb abduction/adduction) with the right hand. Anodal tDCS (1 mA, 13 min, on the motor primary cortex) was applied before, during, and after the training. Compared with baseline motor-evoked potentials and the sham condition, tDCS that was applied before, but not during or after, the motor task enhanced corticospinal excitability. These data suggest that tDCS performed before - not during or after - promotes optimization of motor training-induced plasticity.

Who May Benefit From Armeo Power Treatment? A Neurophysiological Approach to Predict Neurorehabilitation Outcomes

BACKGROUND

The Armeo Power, a rehabilitation exoskeleton that allows early treatment of motor disabilities, provides intelligent arm support in a large 3-dimensional work space, thus enabling patients to perform intensive, repetitive, and goal-oriented exercises. This device could efficiently induce new connections and facilitate plasticity phenomena potentiation. Knowledge of the potential brain plasticity reservoir after brain damage constitutes a prerequisite for an optimal rehabilitation strategy.

OBJECTIVE

To identify potential neurophysiologic markers predicting the responsiveness of stroke patients to upper limb robotic treatment.

DESIGN

Prospective cohort study.

SETTING

Behavioral and Robotic Neurorehabilitation Laboratory of IRCCS Centro Neurolesi Bonino-Pulejo, Messina, Italy.

PATIENTS

We enrolled 35 patients who had sustained a first-ever ischemic supratentorial stroke at least 2 months before enrollment and had unilateral hemiplegia.

METHODS

All patients underwent 40 Armeo Power training sessions that lasted 1 hour each (ie, 5 times a week for 8 weeks).

MAIN OUTCOME MEASUREMENTS

We assessed the spasticity and motor function of the upper limb by means of the Modified Ashworth scale and Fugl-Meyer assessment, respectively. Moreover, we evaluated the cortical excitability and plasticity potential of the bilateral primary motor areas in response to the repetitive paired associative stimulation paradigm using transcranial magnetic stimulation and Armeo Power kinematic parameters.

RESULTS

The patients who showed significant repetitive paired associative stimulation aftereffects at baseline exhibited an evident increase of cortical plasticity in the affected hemisphere (motor evoked potential amplitude increase, P = .03), a decrease of interhemispheric inhibition (affected hemisphere cortical silent period duration decrease, P = .01; unaffected hemisphere cortical silent period duration increase, P = .004; repetitive paired associative stimulation aftereffect increase, P = .008). Such findings were paralleled by clinical improvements (Fugl-Meyer, P = .04) and Armeo Power kinematic improvements (elbow flexion/extension, P = .02; shoulder range of movement, P = .002).

CONCLUSIONS

Our data suggest that use of Armeo Power may improve upper limb motor function recovery as predicted by reshaping of cortical and transcallosal plasticity, according to the baseline cortical excitability.

LEVEL OF EVIDENCE

IV.

Neuroplasticity in post-stroke gait recovery and noninvasive brain stimulation

Gait disorders drastically affect the quality of life of stroke survivors, making post-stroke rehabilitation an important research focus. Noninvasive brain stimulation has potential in facilitating neuroplasticity and improving post-stroke gait impairment. However, a large inter-individual variability in the response to noninvasive brain stimulation interventions has been increasingly recognized. We first review the neurophysiology of human gait and post-stroke neuroplasticity for gait recovery, and then discuss how noninvasive brain stimulation techniques could be utilized to enhance gait recovery. While post-stroke neuroplasticity for gait recovery is characterized by use-dependent plasticity, it evolves over time, is idiosyncratic, and may develop maladaptive elements. Furthermore, noninvasive brain stimulation has limited reach capability and is facilitative-only in nature. Therefore, we recommend that noninvasive brain stimulation be used adjunctively with rehabilitation training and other concurrent neuroplasticity facilitation techniques. Additionally, when noninvasive brain stimulation is applied for the rehabilitation of gait impairment in stroke survivors, stimulation montages should be customized according to the specific types of neuroplasticity found in each individual. This could be done using multiple mapping techniques.

Effects of Tetramethylpyrazine on Functional Recovery and Neuronal Dendritic Plasticity after Experimental Stroke

The 2,3,5,6-tetramethylpyrazine (TMP) has been widely used in the treatment of ischemic stroke by Chinese doctors. Here, we report the effects of TMP on functional recovery and dendritic plasticity after ischemic stroke. A classical model of middle cerebral artery occlusion (MCAO) was established in this study. The rats were assigned into 3 groups: sham group (sham operated rats treated with saline), model group (MCAO rats treated with saline) and TMP group (MCAO rats treated with 20 mg/kg/d TMP). The neurological function test of animals was evaluated using the modified neurological severity score (mNSS) at 3 d, 7 d, and 14 d after MCAO. Animals were euthanized for immunohistochemical labeling to measure MAP-2 levels in the peri-infarct area. Golgi-Cox staining was performed to test effect of TMP on dendritic plasticity at 14 d after MCAO. TMP significantly improved neurological function at 7 d and 14 d after ischemia, increased MAP-2 level at 14 d after ischemia, and enhanced spine density of basilar dendrites. TMP failed to affect the spine density of apical dendrites and the total dendritic length. Data analyses indicate that there was significant negative correlation between mNSS and plasticity measured at 14 d after MCAO. Thus, enhanced dendritic plasticity contributes to TMP-elicited functional recovery after ischemic stroke.

Proprioceptive Based Training for stroke recovery. Proposal of new treatment modality for rehabilitation of upper limb in neurological diseases

Background

The central nervous system (CNS) has plastic properties allowing its adaptation through development. These properties are still maintained in the adult age and potentially activated in case of brain lesion. In the present study authors hypothesized that a significant recovery of voluntary muscle contraction in post stroke patients experiencing severe upper limb paresis can be obtained, when proprioceptive based stimulations are provided. Proprioceptive based training (PBT) is based on performing concurrent movements with both unaffected and affected arm, with the aim to foster motor recovery through some mutual connections of interhemispheric and transcallosal pathways. The aim of this pre-post pilot study was to evaluate the feasibility of PBT on recovery of voluntary muscle contraction in subacute phase after stroke.

Methods

The treatment lasted 1 h daily, 5 days per week for 3 weeks. The PBT consisted of multidirectional exercises executed synchronously with unaffected limb and verbal feedback. The Medical Research Council scale (MRC), Dynamometer, Fugl-Meyer Upper Extremity scale (F-M UE), Functional Independence Measure scale (FIM) and modified Ashworth scale were administered at the beginning and at the end of training. Statistical significance was set at p < 0.05.

Results

Six patients with severe paresis of the upper limb within 6 months after stroke were enrolled in the study (5 ischemic and 1 hemorrhagic stroke, 3 men and 3 women, mean age 65.7 ± 8.7 years, mean distance from stroke 4.1 ± 1.5 months) and all of them well tolerated the training. The clinical changes of voluntary muscle contraction after PBT were statistically significant at the MRC scale overall (p = 0.028), and dynamometer assessment overall (p = 0.028). Each patient improved muscle contraction of one or more muscles and in 4 out of 6 patients voluntary active movement emerged after therapy. The functional outcomes (i.e. F-M UE and FIM) did not show significant change within group.

Conclusions

The findings of this preliminary research revealed that PBT may be a feasible intervention to improve the motricity of upper limb in stroke survivors.

Non-invasive brain stimulation: an interventional tool for enhancing behavioral training after stroke

Stroke is the leading cause of disability among adults. Motor deficit is the most common impairment after stroke. Especially, deficits in fine motor skills impair numerous activities of daily life. Re-acquisition of motor skills resulting in improved or more accurate motor performance is paramount to regain function, and is the basis of behavioral motor therapy after stroke. Within the past years, there has been a rapid technological and methodological development in neuroimaging leading to a significant progress in the understanding of the neural substrates that underlie motor skill acquisition and functional recovery in stroke patients. Based on this and the development of novel non-invasive brain stimulation (NIBS) techniques, new adjuvant interventional approaches that augment the response to behavioral training have been proposed. Transcranial direct current, transcranial magnetic, and paired associative (PAS) stimulation are NIBS techniques that can modulate cortical excitability, neuronal plasticity and interact with learning and memory in both healthy individuals and stroke patients. These techniques can enhance the effect of practice and facilitate the retention of tasks that mimic daily life activities. The purpose of the present review is to provide a comprehensive overview of neuroplastic phenomena in the motor system during learning of a motor skill, recovery after brain injury, and of interventional strategies to enhance the beneficial effects of customarily used neurorehabilitation after stroke.

Hearing colors: an example of brain plasticity

Sensory substitution devices (SSDs) are providing new ways for improving or replacing sensory abilities that have been lost due to disease or injury, and at the same time offer unprecedented opportunities to address how the nervous system could lead to an augmentation of its capacities. In this work we have evaluated a color-blind subject using a new visual-to-auditory SSD device called “Eyeborg”, that allows colors to be perceived as sounds. We used a combination of neuroimaging techniques including Functional Magnetic Resonance Imaging (fMRI), Diffusion Tensor Imaging (DTI) and proton Magnetic Resonance Spectroscopy (¹H-MRS) to study potential brain plasticity in this subject. Our results suggest that after 8 years of continuous use of this device there could be significant adaptive and compensatory changes within the brain. In particular, we found changes in functional neural patterns, structural connectivity and cortical topography at the visual and auditive cortex of the Eyeborg user in comparison with a control population. Although at the moment we cannot claim that the continuous use of the Eyeborg is the only reason for these findings, our results may shed further light on potential brain changes associated with the use of other SSDs. This could help to better understand how the brain adapts to several pathologies and uncover adaptive resources such as cross-modal representations. We expect that the precise understanding of these changes will have clear implications for rehabilitative training, device development and for more efficient programs for people with disabilities.

Appraisal of brain connectivity in radiologically isolated syndrome by modeling imaging measures

We hypothesized that appraisal of brain connectivity may shed light on the substrate of the radiologically isolated syndrome (RIS), a term applied to asymptomatic subjects with brain MRI abnormalities highly suggestive of multiple sclerosis. We thus used a multimodal MRI approach on the human brain by modeling measures of microstructural integrity of white matter (WM) tracts with those of functional connectivity (FC) at the level of resting state networks in RIS subjects, demographically matched normal controls (NC), and relapsing-remitting (RR) MS patients, also matched with RIS for brain macrostructural damage (i.e., lesions and atrophy). Compared with NC, in both RIS subjects and MS patients altered integrity of WM tracts was present. However, RIS subjects showed, at a less conservative threshold, lower diffusivities than RRMS patients in distinct cerebral associative, commissural, projection, and cerebellar WM tracts, suggesting a relatively better anatomical connectivity. FC was similar in NC and RIS subjects, even in the presence of important risk factors for MS (spinal cord lesions, oligoclonal bands, and dissemination in time on MRI) and increased in RRMS patients in two clinically relevant networks subserving "processing" (sensorimotor) and "control" (working memory) functions. In RIS, the lack of functional reorganization in key brain networks may represent a model of "functional reserve," which may become upregulated, with an adaptive or maladaptive role, only at a later stage in case of occurrence of clinical deficit.

Epidural Electrical Stimulation for Stroke Rehabilitation: Results of the Prospective, Multicenter, Randomized, Single-Blinded Everest Trial

BACKGROUND

This prospective, single-blinded, multicenter study assessed the safety and efficacy of electrical epidural motor cortex stimulation (EECS) in improving upper limb motor function of ischemic stroke patients with moderate to moderately severe hemiparesis.

METHODS

Patients ≥ 4 months poststroke were randomized 2:1 to an investigational (n = 104) or control (n = 60) group, respectively. Investigational patients were implanted (n = 94) with an epidural 6-contact lead perpendicular to the primary motor cortex and a pulse generator. Both groups underwent 6 weeks of rehabilitation, but EECS was delivered to investigational patients during rehabilitation. The primary efficacy endpoint (PE) was defined as attaining a minimum improvement of 4.5 points in the upper extremity Fugl-Meyer (UEFM) scale as well as 0.21 points in the Arm Motor Ability Test (AMAT) 4 weeks postrehabilitation. Follow-up assessments were performed 1, 4, 12, and 24 weeks postrehabilitation. Safety was evaluated by monitoring adverse events (AEs) that occurred between enrollment and the end of rehabilitation.

RESULTS

Primary intent-to-treat analysis showed no group differences at 4 weeks, with PE being met by 32% and 29% of investigational and control patients, respectively (P = .36). Repeated-measures secondary analyses revealed no significant treatment group differences in mean UEFM or AMAT scores. However, post hoc comparisons showed that a greater proportion of investigational (39%) than control (15%) patients maintained or achieved PE (P = .003) at 24 weeks postrehabilitation. Investigational group mean AMAT scores also improved significantly (P < .05) when compared to the control group at 24 weeks postrehabilitation. Post hoc analyses also showed that 69% (n = 9/13) of the investigational patients who elicited movement thresholds during stimulation testing met PE at 4 weeks, and mean UEFM and AMAT scores was also significantly higher (P < .05) in this subgroup at the 4-, 12-, and 24-week assessments when compared to the control group. Headache (19%), pain (13%), swelling (7%), and infection (7%) were the most commonly observed implant procedure-related AEs. Overall, there were 11 serious AEs in 9 investigational group patients (7 procedure related, 4 anesthesia related).

CONCLUSIONS

The primary analysis pertaining to efficacy of EECS during upper limb motor rehabilitation in chronic stroke patients was negative at 4 weeks postrehabilitation. A better treatment response was observed in a subset of patients eliciting stimulation induced upper limb movements during motor threshold assessments performed prior to each rehabilitation session. Post hoc comparisons indicated treatment effect differences at 24 weeks, with the control group showing significant decline in the combined primary outcome measure relative to the investigational group. These results have the potential to inform future chronic stroke rehabilitation trial design.

The timing and amount of vagus nerve stimulation during rehabilitative training affect poststroke recovery of forelimb strength

Loss of upper arm strength after stroke is a leading cause of disability. Strategies that can enhance the benefits of rehabilitative training could improve motor function after stroke. Recent studies in a rat model of ischemic stroke have demonstrated that vagus nerve stimulation (VNS) paired with rehabilitative training substantially improves recovery of forelimb strength compared with extensive rehabilitative training without VNS. Here we report that the timing and amount of stimulation affect the degree of forelimb strength recovery. Similar amounts of Delayed VNS delivered 2 h after daily rehabilitative training sessions resulted in significantly less improvement compared with that on delivery of VNS that is paired with identical rehabilitative training. Significantly less recovery also occurred when several-fold more VNS was delivered during rehabilitative training. Both delayed and additional VNS confer moderately improved recovery compared with extensive rehabilitative training without VNS, but fail to enhance recovery to the same degree as VNS that is timed to occur with successful movements. These findings confirm that VNS paired with rehabilitative training holds promise for restoring forelimb strength poststroke and indicate that both the timing and the amount of VNS should be optimized to maximize therapeutic benefits.

[The motor organization of cerebral cortex and the role of the mirror neuron system. Clinical impact for rehabilitation]

The basic characteristics of Penfield homunculus (somatotopy and unique representation) have been questioned. The existence of a defined anatomo-functional organization within different segments of the same region is controversial. The presence of multiple motor representations in the primary motor area and in the parietal lobe interconnected by parieto-frontal circuits, which are widely overlapped, form a complex organization. Both features support the recovery of functions after brain injury. Regarding the movement organization, it is possible to yield a relevant impact through the understanding of actions and intentions of others, which is mediated by the activation of mirror-neuron systems. The implementation of cognitive functions (observation, image of the action and imitation) from the acute treatment phase allows the activation of motor representations without having to perform the action and it plays an important role in learning motor patterns.