Promoting neuroplasticity for motor rehabilitation after stroke: considering the effects of aerobic exercise and genetic variation on brain-derived neurotrophic factor

Delivering Intensive Rehabilitation in Stroke: Factors Influencing Implementation

BACKGROUND

The evidence base for stroke rehabilitation recommends intensive and repetitive task-specific practice, as well as aerobic exercise. However, translating these -evidence-based interventions from research into clinical practice remains a major -challenge.

OBJECTIVE

The objective of this study was to investigate factors influencing implementation of higher-intensity activity in stroke rehabilitation settings.

DESIGN

This qualitative study used a cross-sectional design.

METHODS

Semi-structured interviews were conducted with rehabilitation therapists from 4 sites across 2 Canadian provinces who had experience in delivering a higher-intensity intervention as part of a clinical trial (Determining Optimal post-Stroke Exercise [DOSE]). An interview guide was developed, and data were analyzed using implementation frameworks.

RESULTS

Fifteen therapists were interviewed before data saturation was reached. Therapists and patients generally had positive experiences regarding high-intensity interventions. However, therapists felt they would adapt the protocol to accommodate their beliefs about ensuring movement quality. The requirement for all patients to have a graded exercise test and the use of sensors (eg, heart rate monitors) gave therapists confidence to push patients harder than they normally would. Paradoxically, a system that enables routine graded exercise testing and the availability of staff and equipment contribute challenges for implementation in everyday practice.

CONCLUSIONS

Even therapists involved in delivering a high-intensity intervention as part of a trial wanted to adapt it for clinical practice; therefore, it is imperative that researchers are explicit regarding key intervention components and what can be adapted to help ensure implementation fidelity. Changes in therapists' beliefs and system-level changes (staffing and resources) are likely necessary to facilitate higher-intensity rehabilitation in practice.

The feasibility of an acute high-intensity exercise bout to promote locomotor learning after stroke

BACKGROUND

People post-stroke can learn a novel locomotor task but require more practice to do so. Implementing an approach that can enhance locomotor learning may therefore improve post-stroke locomotor recovery. In healthy adults, an acute high-intensity exercise bout before or after a motor task may improve motor learning and has thus been suggested as a method that could be used to improve motor learning in neurorehabilitation. However, it is unclear whether an acute high-intensity exercise bout, which stroke survivors can feasibly complete in neurorehabilitation session, would generate comparable results.

OBJECTIVE

To determine a feasible, high-intensity exercise protocol that could be incorporated into a post-stroke neurorehabilitation session and would result in significant exercise-induced responses.

METHODS

Thirty-seven chronic stroke survivors participated. We allocated subjects to either a control (CON) or one of the exercise groups: treadmill walking (TMW), and total body exercise (TBE). The main exercise-induced measures were: average intensity (% max intensity) and time spent (absolute: seconds; normalized: % total time) at target exercise intensity, and magnitudes of change in serum lactate (mmol/l) and brain-derived neurotrophic factor (BDNF; ng/ml).

RESULTS

Compared to CON, both exercise groups reached and exercised longer at their target intensities and had greater responses in lactate. However, the TBE group exercised longer at target intensity and with greater lactate response than the TMW group. There were no significant BDNF responses among groups.

CONCLUSIONS

An acute high-intensity exercise bout that could be incorporated into a neurorehabilitation learning-specific session and results in substantial exercise-induced responses is feasible post-stroke.

Time Course of Flow-Mediated Dilation and Vascular Endothelial Growth Factor following Acute Stroke

OBJECTIVES

People after stroke demonstrate alterations in vascular endothelial function measured by flow-mediated dilation. Limited information is available in the literature on possible protective factors following stroke. The aims of the secondary analysis were (1) to characterize the time course of vascular endothelial function using flow-mediated dilation at 72 hours after stroke and 1 week later during inpatient stroke rehabilitation and (2) to determine whether flow-mediated dilation was related to vascular endothelial growth factor, brain-derived neurotrophic factor, or estimated prestroke peak oxygen uptake.

METHODS

Flow-mediated dilation using Doppler ultrasound was assessed in bilateral brachial arteries at the defined time points. Flow-mediated dilation and blood draws occurred on the same day between 7:30 am and 9:00 am following an overnight fast. Enzyme-linked immunosorbent assay was used to quantify plasma vascular endothelial growth factor and brain-derived neurotrophic factor values. A nonexercise estimate was used to calculate prestroke peak oxygen uptake.

RESULTS

We have shown that between-limb differences are evident within 72 hours after stroke and remain 1 week later during inpatient rehabilitation. Higher values for vascular endothelial growth factor were associated with increased flow-mediated dilation at both time points. Higher estimated prestroke peak oxygen uptake was related to flow-mediated dilation. Brain-derived neurotrophic factor was not related to any outcome measures.

CONCLUSIONS

Unique vascular adaptations start early after stroke in the stroke-affected limb and remain through inpatient stroke rehabilitation. Vascular endothelial growth factor and prestroke physical activity may have a protective role in vascular function following stroke. Future work should focus on mechanistic pathways for preservation of vascular health.

Exercise-Induced Neuroprotection of the Nigrostriatal Dopamine System in Parkinson's Disease

Epidemiological studies indicate that physical activity and exercise may reduce the risk of developing Parkinson's disease (PD), and clinical observations suggest that physical exercise can reduce the motor symptoms in PD patients. In experimental animals, a profound observation is that exercise of appropriate timing, duration, and intensity can reduce toxin-induced lesion of the nigrostriatal dopamine (DA) system in animal PD models, although negative results have also been reported, potentially due to inappropriate timing and intensity of the exercise regimen. Exercise may also minimize DA denervation-induced medium spiny neuron (MSN) dendritic atrophy and other abnormalities such as enlarged corticostriatal synapse and abnormal MSN excitability and spiking activity. Taken together, epidemiological studies, clinical observations, and animal research indicate that appropriately dosed physical activity and exercise may not only reduce the risk of developing PD in vulnerable populations but also benefit PD patients by potentially protecting the residual DA neurons or directly restoring the dysfunctional cortico-basal ganglia motor control circuit, and these benefits may be mediated by exercise-triggered production of endogenous neuroprotective molecules such as neurotrophic factors. Thus, exercise is a universally available, side effect-free medicine that should be prescribed to vulnerable populations as a preventive measure and to PD patients as a component of treatment. Future research needs to establish standardized exercise protocols that can reliably induce DA neuron protection, enabling the delineation of the underlying cellular and molecular mechanisms that in turn can maximize exercise-induced neuroprotection and neurorestoration in animal PD models and eventually in PD patients.

An exploratory study of BDNF and oxidative stress marker alterations in subacute and chronic stroke patients affected by neuropathic pain

Patients affected by stroke, particularly subacute stroke patients, often complain of neuropathic pain (NP), which may severely impair their quality of life. The aim of this exploratory study was to characterize NP and to investigate whether there is a correlation between NP and serum brain-derived neurotrophic factor (BDNF) and serum markers of oxidative stress. We enrolled 50 patients divided in subacute (< 90 days from stroke onset) and chronic (> 90 and 180 < days from stroke onset). The Barthel Index, Deambulation Index, and Short Form 36 were used to assess the patients' degree of disability and quality of life. Pain-specific tools, namely the Numeric Rating Scale (NRS), Neuropathic Pain Diagnostic questionnaire (DN4), and Neuropathic Pain Symptom Inventory (NPSI), were also used. Serum levels of BDNF and markers of oxidative stress and of metal status were evaluated: copper, iron, transferrin, ferritin, ceruloplasmin concentration (iCp) and activity (eCp), Total Antioxidant status (TAS), Cp/Tf ratio, eCp/iCp ratio, and non-ceruloplasmin bound copper (Non-Cp Cu). We found the highest value of BDNF in subacute with NP (DN4 score ≥ 4). The TAS, Cp/Tf ratio, and eCp/iCp not only fell outside the normal reference range in a high percentage of subacute and chronic patients, but were also found to be related to specific NP symptoms. These preliminary results reveal altered BDNF and oxidative stress indices in subacute stroke patients who complain of NP. These investigative findings may shed more light on the mechanisms underlying NP and consequently lead to a more tailored therapeutic and/or rehabilitation procedure of subacute stroke patients.

The Effect of Aerobic Exercise on Brain-Derived Neurotrophic Factor in People with Neurological Disorders: A Systematic Review and Meta-Analysis

OBJECTIVE

To determine the effect of aerobic exercise on brain-derived neurotrophic factor (BDNF) levels in people with neurological disorders.

DATA SOURCES

Six electronic databases (CINAHL, PubMed, Cochrane, PsycINFO, SportDiscus, and Web of Science) were searched until the end of December 2016.

STUDY SELECTION

Experimental or observational studies of people with neurological disorders who undertook an exercise intervention with BDNF as an outcome measure. The search strategy yielded 984 articles.

DATA EXTRACTION

Study data were independently extracted from each article. Methodological quality of studies was assessed using the Physiotherapy Evidence Database (PEDro) scale. A meta-analysis was planned based on the assessment of predetermined criteria.

DATA SYNTHESIS

Eleven articles were included. Studies employed either a program of aerobic exercise, a single bout of aerobic exercise, or both. A meta-analysis of studies comparing a program of aerobic exercise against usual care/nil therapy showed a large effect (SMD: 0.84, 95% CI 0.47-1.20, p < 0.001) in favour of aerobic exercise to increase levels of BDNF. Findings for a single bout of aerobic exercise were mixed. Quality of studies was low (PEDro average score 4.3/10).

CONCLUSIONS

A program of aerobic exercise may contribute to increased levels of BDNF in neurological populations.

Does physical activity benefit motor performance and learning of upper extremity tasks in older adults? - A systematic review

Upper extremity motor performance declines with increasing age. However, older adults need to maintain, learn new and relearn known motor tasks. Research with young adults indicated that regular and acute physical activity might facilitate motor performance and motor learning processes. Therefore, this review aimed to examine the association between chronic physical activity and acute bouts of exercise on motor performance and motor learning in upper extremity motor tasks in older adults. Literature was searched via Cochrane library, PubMED, PsycINFO and Scopus and 27 studies met all inclusion criteria. All studies dealt with the influence of chronic physical activity on motor performance or motor learning, no appropriate study examining the influence of an acute bout of exercise in older adults was found. Results concerning the association of chronic physical activity and motor performance are mixed and seem to be influenced by the study design, kind of exercise, motor task, and exercise intensity. Regarding motor learning, a high physical activity or cardiovascular fitness level seems to boost the initial phase of motor learning; results differ with respect to motor retention. Overall, (motor-coordinative) intervention studies seem to be more promising than cross-sectional studies.

F. CARACTERIZACIÓN TEMPORO-ESPACIAL DEL PATRÓN DE MARCHA EN ROEDORES COMO MODELO ANIMAL DE LESIÓN CEREBRAL CEREBROVASCULAR

En la investigación sobre movimiento, la experimentación animal ha proporcionado fundamentación científica para la investigación clínica, mejorando procedimientos diagnósticos y de rehabilitación. Lesiones cerebrales en roedores pueden ser usadas para modelar síntomas locomotores, sensoriales y/o cognitivos. Con el propósito de determinar la funcionalidad locomotriz y sensorial en roedores, se han propuesto varios métodos de evaluación y pronóstico clínico para identificar y evaluar adaptaciones estructurales y mecanismos de neuro-recuperación. Esto ha permitido que métodos de intervención terapéutica, como el ejercicio físico, sean utilizados para restaurar funciones sensitivo-motoras y cognitivas en roedores y humanos. La extrapolación (translación) de los resultados de investigaciones en ciencias básicas a áreas clínicas supone la continua cooperación y retroalimentación entre investigadores y profesionales de la salud, favoreciendo la formulación de intervenciones terapéuticas más eficaces basadas en resultados obtenidos de la experimentación animal. El objetivo de esta revisión es exponer las principales deficiencias motoras y los métodos empleados para determinar la dificultad motriz en la marcha en roedores con lesión cerebrovascular, para lo cual se realizó una revisión de literatura, sobre términos definidos (MeSH), en las bases de datos PsychINFO, Medline y Web of Science, entre enero de 2000 y enero de 2017. Se excluyeron artículos de carácter cualitativo o narrativo, sin revisión por pares, disertaciones, tesis o trabajos de grado y resúmenes de conferencias. Se revisan algunas manifestaciones clínicas, su efecto en la locomotricidad en roedores, algunas metodologías usadas para generar lesiones y para estudiar la función motriz, los principales métodos de medición y algunos aspectos translacionales. 

AExaCTT - Aerobic Exercise and Consecutive Task-specific Training for the upper limb after stroke: Protocol for a randomised controlled pilot study

Motor function may be enhanced if aerobic exercise is paired with motor training. One potential mechanism is that aerobic exercise increases levels of brain-derived neurotrophic factor (BDNF), which is important in neuroplasticity and involved in motor learning and motor memory consolidation. This study will examine the feasibility of a parallel-group assessor-blinded randomised controlled trial investigating whether task-specific training preceded by aerobic exercise improves upper limb function more than task-specific training alone, and determine the effect size of changes in primary outcome measures. People with upper limb motor dysfunction after stroke will be allocated to either task-specific training or aerobic exercise and consecutive task-specific training. Both groups will perform 60 hours of task-specific training over 10 weeks, comprised of 3 × 1 hour sessions per week with a therapist and 3 × 1 hours of home-based self-practice per week. The combined intervention group will also perform 30 minutes of aerobic exercise (70-85%HRmax) immediately prior to the 1 hour of task-specific training with the therapist. Recruitment, adherence, retention, participant acceptability, and adverse events will be recorded. Clinical outcome measures will be performed pre-randomisation at baseline, at completion of the training program, and at 1 and 6 months follow-up. Primary clinical outcome measures will be the Action Research Arm Test (ARAT) and the Wolf Motor Function Test (WMFT). If aerobic exercise prior to task-specific training is acceptable, and a future phase 3 randomised controlled trial seems feasible, it should be pursued to determine the efficacy of this combined intervention for people after stroke.

The Role of the BDNF Val66Met Polymorphism in Recovery of Aphasia After Stroke

BACKGROUND

Brain-derived neurotrophic factor (BDNF) is assumed to play a role in mediating neuroplasticity after stroke. Carriers of the function-limiting Val66Met (rs6265) single nucleotide polymorphism (SNP) may have a downregulation in BDNF secretion, which may lead to a poorer prognosis after stroke compared to noncarriers in motor learning and motor function recovery. The present study investigates whether this polymorphism may also affect the recovery of poststroke aphasia (ie, language impairment).

OBJECTIVE

To study the influence of the BDNF Val66Met polymorphism on the recovery of poststroke aphasia.

METHODS

We included 53 patients with poststroke aphasia, all participating in an inpatient rehabilitation program with speech and language therapy. All patients were genotyped for the Val66Met SNP and subdivided into carriers (at least one Met allele) and noncarriers (no Met allele). Primary outcome measures included the improvement over rehabilitation time on the Amsterdam-Nijmegen Everyday Language Test (ANELT) and the Boston Naming Test (BNT).

RESULTS

The outcome measures showed a large variability in the improvement scores on both the ANELT and BNT. There was no significant difference between noncarriers and carriers in the primary outcome measures.

CONCLUSION

This study investigated the effect of the BDNF Val66Met polymorphism on clinical recovery of poststroke aphasia. In contrast to earlier studies describing a reducing effect of this polymorphism on motor function recovery after stroke, the present study does not support a reduction in language recovery for carriers compared to noncarriers with poststroke aphasia.

Moving Rehabilitation Research Forward: Developing Consensus Statements for Rehabilitation and Recovery Research

Stroke recovery is the next frontier in stroke medicine. While growth in rehabilitation and recovery research is exponential, a number of barriers hamper our ability to rapidly progress the field. Standardized terminology is absent in both animal and human research, methods are poorly described, recovery biomarkers are not well defined, and we lack consistent timeframes or measures to examine outcomes. Agreed methods and conventions for developing, monitoring, evaluating and reporting interventions directed at improving recovery are lacking, and current approaches are often not underpinned by biology. We urgently need to better understand the biology of recovery and its time course in both animals and humans to translate evidence from basic science into clinical trials. A new international partnership of stroke recovery and rehabilitation experts has committed to advancing the research agenda. In May 2016, the first Stroke Recovery and Rehabilitation Roundtable will be held, with the aim of achieving an agreed approach to the development, conduct and reporting of research. A range of methods will be used to achieve consensus in four priority areas: pre-clinical recovery research; biomarkers of recovery; intervention development, monitoring and reporting; and measurement in clinical trials. We hope to foster a global network of researchers committed to advancing this exciting field. Recovery from stroke is challenging for many survivors. They deserve effective treatments underpinned by our evolving understanding of brain recovery and human behaviour. Working together, we can develop game-changing interventions to improve recovery and quality of life in those living with stroke.

New insights about the putative role of myokines in the context of cardiac rehabilitation and secondary cardiovascular prevention

Exercise training prevents the onset and the development of many chronic diseases, acting as an effective tool both for primary and for secondary prevention. Various mechanisms that may be the effectors of these beneficial effects have been proposed during the past decades: some of these are well recognized, others less. Muscular myokines, released during and after muscular contraction, have been proposed as key mediators of the systemic effects of the exercise. Nevertheless the availability of an impressive amount of evidence regarding the systemic effects of muscle-derived factors, few studies have examined key issues: (I) if skeletal muscle cells themselves are the main source of cytokine during exercise; (II) if the release of myokines into the systemic circulation reach an adequate concentration to provide significant effects in tissues far from skeletal muscle; (III) what may be the role carried out by muscular cytokine regarding the well-known benefits induced by regular exercise, first of all the anti-inflammatory effect of exercise. Furthermore, a greater part of our knowledge regarding myokines derives from the muscle of healthy subjects. This knowledge may not necessarily be transferred per se to subjects with chronic diseases implicating a direct or indirect muscular dysfunction and/or a chronic state of inflammation with persistent immune-inflammatory activation (and therefore increased circulating levels of some cytokines): cachexia, sarcopenia due to multiple factors, disability caused by neurological damage, chronic congestive heart failure (CHF) or coronary artery disease (CAD). A key point of future studies is to ascertain how is modified the muscular release of myokines in different categories of unhealthy subjects, both at baseline and after rehabilitation. The purpose of this review is to discuss the main findings on the role of myokines as putative mediators of the therapeutic benefits obtained through regular exercise in the context of secondary cardiovascular prevention.

Sensorimotor Learning: Neurocognitive Mechanisms and Individual Differences

Here we provide an overview of findings and viewpoints on the mechanisms of sensorimotor learning presented at the 2016 Biomechanics and Neural Control of Movement (BANCOM) conference in Deer Creek, OH. This field has shown substantial growth in the past couple of decades. For example it is now well accepted that neural systems outside of primary motor pathways play a role in learning. Frontoparietal and anterior cingulate networks contribute to sensorimotor adaptation, reflecting strategic aspects of exploration and learning. Longer term training results in functional and morphological changes in primary motor and somatosensory cortices. Interestingly, re-engagement of strategic processes once a skill has become well learned may disrupt performance.

Efforts to predict individual differences in learning rate have enhanced our understanding of the neural, behavioral, and genetic factors underlying skilled human performance. Access to genomic analyses has dramatically increased over the past several years. This has enhanced our understanding of cellular processes underlying the expression of human behavior, including involvement of various neurotransmitters, receptors, and enzymes. Surprisingly our field has been slow to adopt such approaches in studying neural control, although this work does require much larger sample sizes than are typically used to investigate skill learning. We advocate that individual differences approaches can lead to new insights into human sensorimotor performance. Moreover, a greater understanding of the factors underlying the wide range of performance capabilities seen across individuals can promote personalized medicine and refinement of rehabilitation strategies, which stand to be more effective than “one size fits all” treatments.

A Single Bout of High-Intensity Interval Training Improves Motor Skill Retention in Individuals With Stroke

BACKGROUND

One bout of high-intensity cardiovascular exercise performed immediately after practicing a motor skill promotes changes in the neuroplasticity of the motor cortex and facilitates motor learning in nondisabled individuals.

OBJECTIVE

To determine if a bout of exercise performed at high intensity is sufficient to induce neuroplastic changes and improve motor skill retention in patients with chronic stroke.

METHODS

Twenty-two patients with different levels of motor impairment were recruited. On the first session, the effects of a maximal graded exercise test on corticospinal and intracortical excitability were assessed from the affected and unaffected primary motor cortex representational area of a hand muscle with transcranial magnetic stimulation. On the second session, participants were randomly assigned to an exercise or a nonexercise control group. Immediately after practicing a motor task, the exercise group performed 15 minutes of high-intensity interval training while the control group rested. Twenty-four hours after motor practice all participants completed a test of the motor task to assess skill retention.

RESULTS

The graded exercise test reduced interhemispheric imbalances in GABA_A-mediated short-interval intracortical inhibition but changes in other markers of excitability were not statistically significant. The group that performed high-intensity interval training showed a better retention of the motor skill.

CONCLUSIONS

The performance of a maximal graded exercise test triggers only modest neuroplastic changes in patients with chronic stroke. However, a single bout of high-intensity interval training performed immediately after motor practice improves skill retention, which could potentially accelerate motor recovery in these individuals.

Genetic Variation and Neuroplasticity: Role in Rehabilitation After Stroke

BACKGROUND AND PURPOSE

In many neurologic diagnoses, significant interindividual variability exists in the outcomes of rehabilitation. One factor that may impact response to rehabilitation interventions is genetic variation. Genetic variation refers to the presence of differences in the DNA sequence among individuals in a population. Genetic polymorphisms are variations that occur relatively commonly and, while not disease-causing, can impact the function of biological systems. The purpose of this article is to describe genetic polymorphisms that may impact neuroplasticity, motor learning, and recovery after stroke.

SUMMARY OF KEY POINTS

Genetic polymorphisms for brain-derived neurotrophic factor (BDNF), dopamine, and apolipoprotein E have been shown to impact neuroplasticity and motor learning. Rehabilitation interventions that rely on the molecular and cellular pathways of these factors may be impacted by the presence of the polymorphism. For example, it has been hypothesized that individuals with the BDNF polymorphism may show a decreased response to neuroplasticity-based interventions, decreased rate of learning, and overall less recovery after stroke. However, research to date has been limited and additional work is needed to fully understand the role of genetic variation in learning and recovery.

RECOMMENDATIONS FOR CLINICAL PRACTICE

Genetic polymorphisms should be considered as possible predictors or covariates in studies that investigate neuroplasticity, motor learning, or motor recovery after stroke. Future predictive models of stroke recovery will likely include a combination of genetic factors and other traditional factors (eg, age, lesion type, corticospinal tract integrity) to determine an individual's expected response to a specific rehabilitation intervention.

The influence of high intensity exercise and the Val66Met polymorphism on circulating BDNF and locomotor learning

Brain-derived neurotrophic factor (BDNF) has been directly related to exercise-enhanced motor performance in the neurologically injured animal model; however literature concerning the role of BDNF in the enhancement of motor learning in the human population is limited. Previous studies in healthy subjects have examined the relationship between intensity of an acute bout of exercise, increases in peripheral BDNF and motor learning of a simple isometric upper extremity task. The current study examined the role of high intensity exercise on upregulation of peripheral BDNF levels as well as the role of high intensity exercise in mediation of motor learning and retention of a novel locomotor task in neurologically intact adults. In addition, the impact of a single nucleotide polymorphism in the BDNF gene (Val66Met) in moderating the relationship between exercise and motor learning was explored. It was hypothesized that participation in high intensity exercise prior to practicing a novel walking task (split-belt treadmill walking) would elicit increases in peripheral BDNF as well as promote an increased rate and magnitude of within session learning and retention on a second day of exposure to the walking task. Within session learning and retention would be moderated by the presence or absence of Val66Met polymorphism. Fifty-four neurologically intact participants participated in two sessions of split-belt treadmill walking. Step length and limb phase were measured to assess learning of spatial and temporal parameters of walking. Serum BDNF was collected prior to and immediately following either high intensity exercise or 5min of quiet rest. The results demonstrated that high intensity exercise provides limited additional benefit to learning of a novel locomotor pattern in neurologically intact adults, despite increases in circulating BDNF. In addition, presence of a single nucleotide polymorphism on the BDNF gene did not moderate the magnitude of serum BDNF increases with high intensity exercise, nor did it moderate the relationship between high intensity exercise and locomotor learning.

Rehabilitation for Individuals With Genetic Degenerative Ataxia: A Systematic Review

BACKGROUND

Treatment of genetic degenerative ataxia is currently based on symptom management and maintenance of function. However, utilization of rehabilitation is limited due to a lack of evidence supporting its efficacy.

OBJECTIVE

This systematic review evaluated rehabilitation interventions for individuals with genetic degenerative ataxia. In addition, long-term outcomes from rehabilitation and optimal duration and intensity of rehabilitation were examined.

METHODS

A comprehensive search of 4 databases (MEDLINE, CINAHL, PEDro, and Cochrane) identified randomized, nonrandomized controlled, and cohort studies published from inception through to January 2016. The studies included at least one measure examining function, ataxia, balance, or gait. Methodological quality was assessed with the Australian National Health and Medical Research Council (NHMRC) Hierarchy of Evidence and the randomized controlled trials were rated according to the PEDro scale.

RESULTS

Seventeen studies met eligibility criteria. Five randomized controlled trials were included; however, the majority were classified as level III-3 and IV studies. Of 292 participants included, 148 had autosomal dominant ataxia, and 85 had autosomal recessive ataxia. Rehabilitation interventions included coordination and balance training, multifaceted inpatient rehabilitation, a cycling regime, balance exercises with technology assisted biofeedback, respiratory muscle training, and treadmill training. Two studies examined adjuncts to rehabilitation. Fifteen of the 17 studies demonstrated a statistically significant improvement in at least 1 outcome measuring ataxia, function, gait, or balance. Less than half of the studies included assessment of long-term outcomes and follow-up time frames varied considerably.

CONCLUSION

There is consistent evidence that rehabilitation improves function, mobility, ataxia, and balance in genetic degenerative ataxia.

Assessed and Emerging Biomarkers in Stroke and Training-Mediated Stroke Recovery: State of the Art

Since the increasing update of the biomolecular scientific literature, biomarkers in stroke have reached an outstanding and remarkable revision in the very recent years. Besides the diagnostic and prognostic role of some inflammatory markers, many further molecules and biological factors have been added to the list, including tissue derived cytokines, growth factor-like molecules, hormones, and microRNAs. The literatures on brain derived growth factor and other neuroimmune mediators, bone-skeletal muscle biomarkers, cellular and immunity biomarkers, and the role of microRNAs in stroke recovery were reviewed. To date, biomarkers represent a possible challenge in the diagnostic and prognostic evaluation of stroke onset, pathogenesis, and recovery. Many molecules are still under investigation and may become promising and encouraging biomarkers. Experimental and clinical research should increase this list and promote new discoveries in this field, to improve stroke diagnosis and treatment.

The role of brain-derived neurotrophic factor and its single nucleotide polymorphisms in stroke patients

Stroke is the main cause of motoric and neuropsychological disability in adults. Recent advances in research into the role of the brain-derived neurotrophic factor in neuroplasticity, neuroprotection and neurogenesis might provide important information for the development of new poststroke-rehabilitation strategies. It plays a role as a mediator in motor learning and rehabilitation after stroke. Concentrations of BDNF are lower in acute ischemic-stroke patients compared to controls. Lower levels of BDNF are correlated with an increased risk of stroke, worse functional outcomes and higher mortality. BDNF signalling is dependent on the genetic variation which could affect an individual's response to recovery after stroke. Several single nucleotide polymorphisms of the BDNF gene have been studied with regard to stroke patients, but most papers analyse the rs6265 which results in a change from valine to methionine in the precursor protein. Subsequently a reduction in BDNF activity is observed. There are studies indicating the role of this polymorphism in brain plasticity, functional and morphological changes in the brain. It may affect the risk of ischemic stroke, post-stroke outcomes and the efficacy of the rehabilitation process within physical exercise and transcranial magnetic stimulation. There is a consistent trend of Met alleles' being connected with worse outcomes and prognoses after stroke. However, there is no satisfactory data confirming the importance of Met allele in stroke epidemiology and the post-stroke rehabilitation process. We present the current data on the role of BDNF and polymorphisms of the BDNF gene in stroke patients, concentrating on human studies.

Contrasting roles of immune cells in tissue injury and repair in stroke: The dark and bright side of immunity in the brain

Despite considerable efforts in research and clinical studies, stroke is still one of the leading causes of death and disability worldwide. Originally, stroke was considered a vascular thrombotic disease without significant immune involvement. However, over the last few decades it has become increasingly obvious that the immune responses can significantly contribute to both tissue injury and protection following stroke. Recently, much research has been focused on the immune system's role in stroke pathology and trying to elucidate the mechanism used by immune cells in tissue injury and protection. Since the discovery of tissue plasminogen activator therapy in 1996, there have been no new treatments for stroke. For this reason, research into understanding how the immune system contributes to stroke pathology may lead to better therapies or enhance the efficacy of current treatments. Here, we discuss the contrasting roles of immune cells to stroke pathology while emphasizing myeloid cells and T cells. We propose that focusing future research on balancing the beneficial-versus-detrimental roles of immunity may lead to the discovery of better and novel stroke therapies.

Forced Aerobic Exercise Preceding Task Practice Improves Motor Recovery Poststroke

OBJECTIVE

To understand how two types of aerobic exercise affect upper-extremity motor recovery post-stroke. Our aims were to (1) evaluate the feasibility of having people who had a stroke complete an aerobic exercise intervention and (2) determine whether forced or voluntary exercise differentially facilitates upper-extremity recovery when paired with task practice.

METHOD

Seventeen participants with chronic stroke completed twenty-four 90-min sessions over 8 wk. Aerobic exercise was immediately followed by task practice. Participants were randomized to forced or voluntary aerobic exercise groups or to task practice only.

RESULTS

Improvement on the Fugl-Meyer Assessment exceeded the minimal clinically important difference: 12.3, 4.8, and 4.4 for the forced exercise, voluntary exercise, and repetitive task practice-only groups, respectively. Only the forced exercise group exhibited a statistically significant improvement.

CONCLUSION

People with chronic stroke can safely complete intensive aerobic exercise. Forced aerobic exercise may be optimal in facilitating motor recovery associated with task practice.

Effects of treadmill training on cognitive and motor features of patients with mild to moderate Parkinson's disease: a pilot, single-blind, randomized controlled trial

The aim of this pilot randomized controlled trial was to evaluate the effects of treadmill training on cognitive and motor performance in patients with Parkinson's disease (PD). Seventeen persons with mild to moderate PD were enrolled. Nine patients were allocated to the Intervention group and received twelve 45-minute sessions of treadmill training: one session a day, three days a week, for four consecutive weeks. Eight patients were allocated to the Control group; these patients did not undergo physical training but were required to have regular social interactions, following a specific lifestyle program. All the patients were evaluated at baseline and one month later. The primary outcome measures were the Frontal Assessment Battery-Italian version (FAB-it) and the 6-minute walking test (6MWT). At the one month evaluation significant differences were found between the groups in their performance on the FAB-it (p=0.005) and the 6MWT (p=0.018). Our findings support the hypothesis that treadmill training might effectively improve cognitive and motor features in patients with PD.

Nano-particle delivery of brain derived neurotrophic factor after focal cerebral ischemia reduces tissue injury and enhances behavioral recovery

BACKGROUND

Low levels of brain-derived neurotrophic factor (BDNF) are linked to delayed neurological recovery, depression, and cognitive impairment following stroke. Supplementation with BDNF reverses these effects. Unfortunately, systemically administered BDNF in its native form has minimal therapeutic value due to its poor blood brain barrier permeability and short serum half-life. In this study, a novel nano-particle polyion complex formulation of BDNF (nano-BDNF) was administered to mice after experimental ischemic stroke.

METHODS

Male C57BL/6J (8-10weeks) mice were randomly assigned to receive nano-BDNF, native-BDNF, or saline treatment after being subjected to 60min of reversible middle cerebral artery occlusion (MCAo). Mice received the first dose at 3 (early treatment), 6 (intermediate treatment), or 12h (delayed treatment) following stroke onset; a second dose was given in all cohorts at 24h after stroke onset. Post-stroke outcome was evaluated by behavioral, histological, and molecular analysis for 15days after stroke.

RESULTS

Early and intermediate nano-BDNF treatment led to a significant reduction in cerebral tissue loss. Delayed treatment led to improved memory/cognition, reduced post-stroke depressive phenotypes, and maintained myelin basic protein and brain BDNF levels, but had no effect on tissue atrophy.

CONCLUSIONS

The results indicate that administration of a novel nano-particle formulation of BDNF leads to both neuroprotective and neuro-restorative effects after stroke.

Paracrine Mechanisms of Intravenous Bone Marrow-Derived Mononuclear Stem Cells in Chronic Ischemic Stroke

Background

The emerging role of stem cell technology and transplantation has helped scientists to study their potential role in neural repair and regeneration. The fate of stem cells is determined by their niche, consisting of surrounding cells and the secreted trophic growth factors. This interim report evaluates the safety, feasibility and efficacy (if any) of bone marrow-derived mononuclear stem cells (BM-MNC) in chronic ischemic stroke by studying the release of serum vascular endothelial growth factor (VEGF) and brain-derived neurotrophic growth factor (BDNF).

Methods

Twenty stroke patients and 20 age-matched healthy controls were recruited with the following inclusion criteria: 3 months to 1.5 years from the index event, Medical Research Council (MRC) grade of hand muscles of at least 2, Brunnstrom stage 2-5, conscious, and comprehendible. They were randomized to one group receiving autologous BM-MNC (mean 60-70 million) and to another group receiving saline infusion (placebo). All patients were administered a neuromotor rehabilitation regime for 8 weeks. Clinical assessments [Fugl Meyer scale (FM), modified Barthel index (mBI), MRC grade, Ashworth tone scale] were carried out and serum VEGF and BDNF levels were assessed at baseline and at 8 weeks.

Results

No serious adverse events were observed during the study. There was no statistically significant clinical improvement between the groups (FM: 95% CI 15.2-5.35, p = 0.25; mBI: 95% CI 14.3-4.5, p = 0.31). VEGF and BDNF expression was found to be greater in group 1 compared to group 2 (VEGF: 442.1 vs. 400.3 pg/ml, p = 0.67; BDNF: 21.3 vs. 19.5 ng/ml) without any statistically significant difference.

Conclusion

Autologous mononuclear stem cell infusion is safe and tolerable by chronic ischemic stroke patients. The released growth factors (VEGF and BDNF) in the microenvironment could be due to the paracrine hypothesis of stem cell niche and neurorehabilitation regime.

Factors Influencing the Efficacy of Aerobic Exercise for Improving Fitness and Walking Capacity After Stroke: A Meta-Analysis With Meta-Regression

OBJECTIVE

To assess the influence of dosing parameters and patient characteristics on the efficacy of aerobic exercise (AEX) poststroke.

DATA SOURCES

A systematic review was conducted using PubMed, MEDLINE, Cumulative Index of Nursing and Allied Health Literature, Physiotherapy Evidence Database, and Academic Search Complete.

STUDY SELECTION

Studies were selected that compared an AEX group with a nonaerobic control group among ambulatory persons with stroke.

DATA EXTRACTION

Extracted outcome data included peak oxygen consumption (V˙o₂peak) during exercise testing, walking speed, and walking endurance (6-min walk test). Independent variables of interest were AEX mode (seated or walking), AEX intensity (moderate or vigorous), AEX volume (total hours), stroke chronicity, and baseline outcome scores.

DATA SYNTHESIS

Significant between-study heterogeneity was confirmed for all outcomes. Pooled AEX effect size estimates (AEX group change minus control group change) from random effects models were V˙o₂peak, 2.2mL⋅kg^-1⋅min^-1 (95% confidence interval [CI], 1.3-3.1mL⋅kg^-1⋅min^-1); walking speed, .06m/s (95% CI, .01-.11m/s); and 6-minute walk test distance, 29m (95% CI, 15-42m). In meta-regression, larger V˙o₂peak effect sizes were significantly associated with higher AEX intensity and higher baseline V˙o₂peak. Larger effect sizes for walking speed and the 6-minute walk test were significantly associated with a walking AEX mode. In contrast, seated AEX did not have a significant effect on walking outcomes.

CONCLUSIONS

AEX significantly improves aerobic capacity poststroke, but may need to be task specific to affect walking speed and endurance. Higher AEX intensity is associated with better outcomes. Future randomized studies are needed to confirm these results.

Decreased Brain-Derived Neurotrophic Factor Serum Concentrations in Chronic Post-Stroke Subjects

BACKGROUND

Brain-derived neurotrophic factor (BDNF) plays a critical role in sensorimotor recovery after a stroke. However, few studies have assessed the circulating BDNF levels in post-stroke humans to understand its changes. This study was conducted to measure BDNF serum concentrations in subjects with chronic hemiparesis, as well as to correlate serum concentrations with age, post-stroke time, total score of Stroke Specific Quality of Life Scale (SS-QOL), mobility subscale score, and motor function of SS-QOL.

METHODS

Seventeen chronic post-stroke subjects matched by age and gender with healthy controls took part in the study. Personal data (age, hemiparesis side, and post-stroke time) were collected, and a physical examination (weight, height, body mass index) and SS-QOL assessment were carried out. On the same day, after the initial evaluation, venous blood samples were collected from the chronic post-stroke subjects and the healthy subjects. The BDNF serum concentrations were measured blindly by enzyme-linked immunosorbent assay.

RESULTS

Subjects with chronic hemiparesis presented a decrease in BDNF serum compared with healthy subjects (P < .01). There was no correlation between BDNF serum levels with post-stroke time, age or quality of life, mobility, and the upper extremity motor function (P > .05). BDNF concentrations are related to structural and functional recovery after stroke; thus, this reduction is important to understand the rehabilitation process more clearly. However, more studies are needed considering the genetic variations and other tools to assess motor impairment and functional independence.

CONCLUSION

Chronic post-stroke subjects presented a decrease in BDNF serum concentrations, without a correlation with post-stroke time, age, and quality of life.

Bihemispheric Motor Cortex Transcranial Direct Current Stimulation Improves Force Steadiness in Post-Stroke Hemiparetic Patients: A Randomized Crossover Controlled Trial

Post-stroke patients usually exhibit reduced peak muscular torque (PT) and/or force steadiness during submaximal exercise. Brain stimulation techniques have been proposed to improve neural plasticity and help to restore motor performance in post-stroke patients. The present study compared the effects of bihemispheric motor cortex transcranial direct current stimulation (tDCS) on PT and force steadiness during maximal and submaximal resistance exercise performed by post-stroke patients vs. healthy controls. A double-blind randomized crossover controlled trial (identification number: TCTR20151112001; URL: http://www.clinicaltrials.in.th/) was conducted involving nine healthy and 10 post-stroke hemiparetic individuals who received either tDCS (2 mA) or sham stimulus upon the motor cortex for 20 min. PT and force steadiness (reflected by the coefficient of variation (CV) of muscular torque) were assessed during unilateral knee extension and flexion at maximal and submaximal workloads (1 set of 3 repetitions at 100% PT and 2 sets of 10 repetitions at 50% PT, respectively). No significant change in PT was observed in post-stroke and healthy subjects. Force steadiness during knee extension (~25–35%, P < 0.001) and flexion (~22–33%, P < 0.001) improved after tDCS compared to the sham condition in post-stroke patients, but improved only during knee extension (~13–27%, P < 0.001) in healthy controls. These results suggest that tDCS may improve force steadiness, but not PT in post-stroke hemiparetic patients, which might be relevant in the context of motor rehabilitation programs.

Depressive symptoms influence use of feedback for motor learning and recovery in chronic stroke

PURPOSE

Sensorimotor impairments and depressive symptoms (PSD) influence arm motor recovery post-stroke. Feedback provision improves upper limb motor learning in patients with chronic stroke but factors including PSD may affect ability to use feedback. We evaluated the influence of PSD on the ability to use auditory feedback for upper limb recovery and motor learning in patients with chronic stroke.

METHODS

Participants (n = 24) practiced 72 pointing movements/session (6 targets, 12 sessions, randomized) with auditory feedback on movement speed and trunk displacement. The presence of PSD (Beck's Depression Inventory; BDI-II) was assessed at pre-intervention (PRE). Arm motor impairment (Fugl-Meyer Assessment, shoulder horizontal adduction, shoulder flexion, elbow extension ranges, trunk displacement) and arm use (Motor Activity Log) were assessed at PRE, immediately after (POST) and retention (3 mos; RET). Participants were divided into two groups based on BDI-II scores: ≥ 14/63 (DEP group; n = 8; score: 20.5 ± 7.5) and ≤ 13/63 (no PSD (ND) group; n = 16; score: 5.0 ± 3.8). Changes in impairment and arm use levels were assessed (mixed-model ANOVAs).

RESULTS

All participants improved arm use. DEP had lower Fugl-Meyer scores, used more compensatory trunk displacement and had lower shoulder horizontal adduction range compared to ND.

CONCLUSION

The presence of PSD diminished the ability to use auditory feedback for arm motor recovery and motor learning.

Neuroplasticity: Insights from Patients Harboring Gliomas

Neuroplasticity is the ability of the brain to reorganize itself during normal development and in response to illness. Recent advances in neuroimaging and direct cortical stimulation in human subjects have given neuroscientists a window into the timing and functional anatomy of brain networks underlying this dynamic process. This review will discuss the current knowledge about the mechanisms underlying neuroplasticity, with a particular emphasis on reorganization following CNS pathology. First, traditional mechanisms of neuroplasticity, most relevant to learning and memory, will be addressed, followed by a review of adaptive mechanisms in response to pathology, particularly the recruitment of perilesional cortical regions and unmasking of latent connections. Next, we discuss the utility and limitations of various investigative techniques, such as direct electrocortical stimulation (DES), functional magnetic resonance imaging (fMRI), corticocortical evoked potential (CCEP), and diffusion tensor imaging (DTI). Finally, the clinical utility of these results will be highlighted as well as possible future studies aimed at better understanding of the plastic potential of the brain with the ultimate goal of improving quality of life for patients with neurologic injury.

Moving rehabilitation research forward: Developing consensus statements for rehabilitation and recovery research

Stroke recovery is the next frontier in stroke medicine. While growth in rehabilitation and recovery research is exponential, a number of barriers hamper our ability to rapidly progress the field. Standardized terminology is absent in both animal and human research, methods are poorly described, recovery biomarkers are not well defined, and we lack consistent timeframes or measures to examine outcomes. Agreed methods and conventions for developing, monitoring, evaluating and reporting interventions directed at improving recovery are lacking, and current approaches are often not underpinned by biology. We urgently need to better understand the biology of recovery and its time course in both animals and humans to translate evidence from basic science into clinical trials. A new international partnership of stroke recovery and rehabilitation experts has committed to advancing the research agenda. In May 2016, the first Stroke Recovery and Rehabilitation Roundtable will be held, with the aim of achieving an agreed approach to the development, conduct and reporting of research. A range of methods will be used to achieve consensus in four priority areas: pre-clinical recovery research; biomarkers of recovery; intervention development, monitoring and reporting; and measurement in clinical trials. We hope to foster a global network of researchers committed to advancing this exciting field. Recovery from stroke is challenging for many survivors. They deserve effective treatments underpinned by our evolving understanding of brain recovery and human behaviour. Working together, we can develop game-changing interventions to improve recovery and quality of life in those living with stroke.

Promoting Motor Cortical Plasticity with Acute Aerobic Exercise: A Role for Cerebellar Circuits

Acute aerobic exercise facilitated long-term potentiation-like plasticity in the human primary motor cortex (M1). Here, we investigated the effect of acute aerobic exercise on cerebellar circuits, and their potential contribution to altered M1 plasticity in healthy individuals (age: 24.8 ± 4.1 years). In Experiment   1, acute aerobic exercise reduced cerebellar inhibition (CBI) (n = 10, p = 0.01), elicited by dual-coil paired-pulse transcranial magnetic stimulation. In Experiment   2, we evaluated the facilitatory effects of aerobic exercise on responses to paired associative stimulation, delivered with a 25 ms (PAS25) or 21 ms (PAS21) interstimulus interval (n = 16 per group). Increased M1 excitability evoked by PAS25, but not PAS21, relies on trans-cerebellar sensory pathways. The magnitude of the aerobic exercise effect on PAS response was not significantly different between PAS protocols (interaction effect: p = 0.30); however, planned comparisons indicated that, relative to a period of rest, acute aerobic exercise enhanced the excitatory response to PAS25 (p = 0.02), but not PAS21 (p = 0.30). Thus, the results of these planned comparisons indirectly provide modest evidence that modulation of cerebellar circuits may contribute to exercise-induced increases in M1 plasticity. The findings have implications for developing aerobic exercise strategies to "prime" M1 plasticity for enhanced motor skill learning in applied settings.

BDNF Val66Met Polymorphism Is Related to Motor System Function After Stroke

BACKGROUND

The val(66)met polymorphism in brain-derived neurotrophic factor (BDNF) has been associated with poorer outcomes after stroke. The mechanism for this finding remains uncertain but might be related to the reduced motor system activation associated with this polymorphism in healthy people.

OBJECTIVE

The current study examined whether the presence of the BDNF val(66)met polymorphism is associated with reduced motor system activation after stroke.

DESIGN AND METHODS

Forty-two patients with stroke who were enrolled in 1 of 2 studies of robot-assisted arm motor therapy participated in the study. All participants were tested for the BDNF val(66)met polymorphism followed by functional magnetic resonance imaging during affected hand movement.

RESULTS

Participants averaged 12 months poststroke and had wide-ranging motor deficits (Fugl-Meyer scale scores=14-60). Brain activation in participants without the BDNF val(66)met polymorphism (n=26) spanned bilateral motor networks with a larger volume (total=334 cc) than that found in participants with this polymorphism (n=16) (97 cc). Regional analyses were consistent. Participants without this polymorphism showed larger ipsilesional primary sensorimotor cortex activation volume and magnitude compared with those in whom the polymorphism was present.

LIMITATIONS

The extent to which these findings generalize to other populations of people with stroke, such as those with stroke <7 days prior, remains uncertain.

CONCLUSIONS

Functional magnetic resonance imaging during affected hand movement showed decreased brain activation among participants with the BDNF val(66)met polymorphism compared with those lacking this polymorphism, especially in the ipsilesional primary sensorimotor cortex contralateral to movement. These results echo findings in healthy people and suggest that genetic factors affecting the normal brain continue to be operative after stroke. The findings suggest a potential imaging-based endophenotype for the BDNF val(66)met polymorphism's effect on the motor system that may be useful in a clinical trial setting.

The Effect of Aerobic Exercise on Neuroplasticity within the Motor Cortex following Stroke

Background

Aerobic exercise is associated with enhanced plasticity in the motor cortex of healthy individuals, but the effect of aerobic exercise on neuroplasticity following a stroke is unknown.

Objective

The aim of this study was to compare corticomotoneuronal excitability and neuroplasticity in the upper limb cortical representation following a single session of low intensity lower limb cycling, or a rest control condition.

Methods

We recruited chronic stroke survivors to take part in three experimental conditions in a randomised, cross-over design. Corticomotoneuronal excitability was examined using transcranial magnetic stimulation to elicit motor evoked potentials in the affected first dorsal interosseus muscle. Following baseline measures, participants either cycled on a stationary bike at a low exercise intensity for 30 minutes, or remained resting in a seated position for 30 minutes. Neuroplasticity within the motor cortex was then examined using an intermittent theta burst stimulation (iTBS) paradigm. During the third experimental condition, participants cycled for the 30 minutes but did not receive any iTBS.

Results

Twelve participants completed the study. We found no significant effect of aerobic exercise on corticomotoneuronal excitability when compared to the no exercise condition (P > 0.05 for all group and time comparisons). The use of iTBS did not induce a neuroplastic-like response in the motor cortex with or without the addition of aerobic exercise.

Conclusions

Our results suggest that following a stroke, the brain may be less responsive to non-invasive brain stimulation paradigms that aim to induce short-term reorganisation, and aerobic exercise was unable to induce or improve this response.

Neuroprotective Effects of Voluntary Exercise in an Inherited Retinal Degeneration Mouse Model

PURPOSE

Our previous investigations showed that involuntary treadmill exercise is neuroprotective in a light-induced retinal degeneration mouse model, and it may act through activation of tropomyosin-related kinase B (TrkB) receptors. This study investigated whether voluntary running wheel exercise can be neuroprotective in an inheritable model of the retinal degenerative disease retinitis pigmentosa (RP), rd10 mice.

METHODS

Breeding pairs of rd10 and C57BL/6J mice were given free-spinning (active) or locked (inactive) running wheels. Pups were weaned into separate cages with their parents' respective wheel types, and visual function was tested with ERG and a virtual optokinetic system at 4, 5, and 6 weeks of age. Offspring were killed at 6 weeks of age and retinal cross-sections were prepared for photoreceptor nuclei counting. Additionally, separate cohorts of active and inactive rd10 pups were injected daily for 14 days after eye opening with a selective TrkB receptor antagonist (ANA-12) or vehicle solution and assessed as described above.

RESULTS

Mice in the rd10 active group exhibited significant preservation of visual acuity, cone nuclei, and total photoreceptor nuclei number. Injection with ANA-12 precluded the preservation of visual acuity and photoreceptor nuclei number in rd10 mice.

CONCLUSIONS

Voluntary running partially protected against the retinal degeneration and vision loss that otherwise occurs in the rd10 mouse model of RP. This protection was prevented by injection of ANA-12, suggesting that TrkB activation mediates exercise's preservation of the retina. Exercise may serve as an effective, clinically translational intervention against retinal degeneration.

Effect of mesenchymal stem cell transplantation on brain-derived neurotrophic factor expression in rats with Tourette syndrome

The aim of the present study was to investigate the effect of bone marrow mesenchymal stem cell (MSC) transplantation on brain-derived neurotrophic factor (BDNF) expression in the striatum of Tourette syndrome (TS) rats. In addition, the possible mechanism of MSC transplantation in the treatment of TS was investigated. A total of 72 Wistar rats were randomly allocated into the control (sham surgery) group and the two experimental groups, including the TS+vehicle and TS+MSC. MSCs were co-cultured with 5-bromodeoxyuridine for 24 h for labeling prior to grafting. An autoimmune TS rat model was successfully established in the present study. Rat MSCs were cultured and expanded using density gradient centrifugation in vitro, identified by flow cytometry and then transplanted into the striata of the TS+MSC group rats. The mRNA and protein expression levels of BDNF were detected by RT-qPCR and ELISA, respectively. The results indicated that the stereotypic behavior of TS rats was reduced 7 days after MSC transplantation, while the mRNA and protein BDNF levels in the striatum increased, compared with the sham surgery group (P<0.05). In addition, the BDNF mRNA and protein expression level was lower in the striatum of TS+MSC transplantation, compared with that in TS+vehicle rats. In conclusion, intrastriatal transplantation of MSCs may provide relief from stereotypic TS behavior, since the BDNF level was reduced in TS rats after MSC transplantation.

Forced Aerobic Exercise Enhances Motor Recovery After Stroke: A Case Report

OBJECTIVE

Previously, we demonstrated that forced aerobic exercise (FE) increases the pattern of neural activation in Parkinson's disease. We sought to evaluate whether FE, when coupled with repetitive task practice, could promote motor recovery poststroke.

METHOD

A 46-yr-old man with ischemic stroke exhibited chronic residual upper-extremity deficits, scoring 35/66 on the Fugl-Meyer Assessment (FMA) at baseline. He completed 24 training sessions comprising 45 min of FE on a motorized stationary bicycle followed by 45 min of upper-extremity repetitive task practice.

RESULTS

From baseline to end of treatment, the FMA score improved by 20 points, perceived level of recovery on the Stroke Impact Scale increased by 20 percentage points, and cardiovascular function measured by peak oxygen uptake improved 30%. These improvements persisted 4 wk after the intervention ceased.

CONCLUSION

FE may be a safe and feasible rehabilitation approach to augment recovery of motor and nonmotor function while improving aerobic fitness in people with chronic stroke.

Endurance Exercise as an "Endogenous" Neuro-enhancement Strategy to Facilitate Motor Learning

Endurance exercise improves cardiovascular and musculoskeletal function and may also increase the information processing capacities of the brain. Animal and human research from the past decade demonstrated widespread exercise effects on brain structure and function at the systems-, cellular-, and molecular level of brain organization. These neurobiological mechanisms may explain the well-established positive influence of exercise on performance in various behavioral domains but also its contribution to improved skill learning and neuroplasticity. With respect to the latter, only few empirical and theoretical studies are available to date. The aim of this review is (i) to summarize the existing neurobiological and behavioral evidence arguing for endurance exercise-induced improvements in motor learning and (ii) to develop hypotheses about the mechanistic link between exercise and improved learning. We identify major knowledge gaps that need to be addressed by future research projects to advance our understanding of how exercise should be organized to optimize motor learning.

Physical Exercise as a Diagnostic, Rehabilitation, and Preventive Tool: Influence on Neuroplasticity and Motor Recovery after Stroke

Stroke remains a leading cause of adult motor disabilities in the world and accounts for the greatest number of hospitalizations for neurological disease. Stroke treatments/therapies need to promote neuroplasticity to improve motor function. Physical exercise is considered as a major candidate for ultimately promoting neural plasticity and could be used for different purposes in human and animal experiments. First, acute exercise could be used as a diagnostic tool to understand new neural mechanisms underlying stroke physiopathology. Indeed, better knowledge of stroke mechanisms that affect movements is crucial for enhancing treatment/rehabilitation effectiveness. Secondly, it is well established that physical exercise training is advised as an effective rehabilitation tool. Indeed, it reduces inflammatory processes and apoptotic marker expression, promotes brain angiogenesis and expression of some growth factors, and improves the activation of affected muscles during exercise. Nevertheless, exercise training might also aggravate sensorimotor deficits and brain injury depending on the chosen exercise parameters. For the last few years, physical training has been combined with pharmacological treatments to accentuate and/or accelerate beneficial neural and motor effects. Finally, physical exercise might also be considered as a major nonpharmacological preventive strategy that provides neuroprotective effects reducing adverse effects of brain ischemia. Therefore, prestroke regular physical activity may also decrease the motor outcome severity of stroke.

Effects of alternating current stimulation on the healthy and diseased brain

Cognitive and neurological dysfunctions can severely impact a patient's daily activities. In addition to medical treatment, non-invasive transcranial alternating current stimulation (tACS) has been proposed as a therapeutic technique to improve the functional state of the brain. Although during the last years tACS was applied in numerous studies to improve motor, somatosensory, visual and higher order cognitive functions, our knowledge is still limited regarding the mechanisms as to which type of ACS can affect cortical functions and altered neuronal oscillations seem to be the key mechanism. Because alternating current send pulses to the brain at predetermined frequencies, the online- and after-effects of ACS strongly depend on the stimulation parameters so that “optimal” ACS paradigms could be achieved. This is of interest not only for neuroscience research but also for clinical practice. In this study, we summarize recent findings on ACS-effects under both normal conditions and in brain diseases.

Aging, the Central Nervous System, and Mobility in Older Adults: Neural Mechanisms of Mobility Impairment

BACKGROUND

Mobility is crucial for successful aging and is impaired in many older adults. We know very little about the subtle, subclinical age-related changes in the central nervous system (CNS) that mediate mobility impairment.

METHODS

A conference series focused on aging, the CNS, and mobility was launched. The second conference addressed major age-associated mechanisms of CNS-mediated mobility impairment. Speakers and conference attendees recommended key areas for future research, identified barriers to progress, and proposed strategies to overcome them.

RESULTS

Priorities identified for future research include (a) studying interactions among different mechanisms; (b) examining effects of interventions targeting these mechanisms; (c) evaluating the effect of genetic polymorphisms on risks and course of age-related mobility impairment; and (d) examining the effect of age on CNS repair processes, neuroplasticity, and neuronal compensatory mechanisms. Key strategies to promote research include (a) establish standard measures of mobility across species; (b) evaluate the effect of aging in the absence of disease on CNS and mobility; and (c) use advanced computational methods to better evaluate the interactions between CNS and other systems involved in mobility.

CONCLUSIONS

CNS is a major player in the process, leading to mobility decline with aging. Future research in this area has the potential to prolong independence in older persons. Better interactions among disciplines and shared research paradigms are needed to make progress. Research priorities include the development of innovative approaches to integrate research on aging, cognition, and movement with attention to neurovascular function, neuroplasticity, and neurophysiological reserve.