Recovery of function in humans: cortical stimulation and pharmacological treatments after stroke

Non-invasive brain stimulation in the treatment of post-stroke aphasia: a scoping review

PURPOSE

Aphasia is an acquired language impairment that commonly results from stroke. Non-invasive brain stimulation (NIBS) might accelerate aphasia recovery trajectories and has seen mounting popularity in recent aphasia rehabilitation research. The present review aimed to: (1) summarise all existing literature on NIBS as a post-stroke aphasia treatment; and (2) provide recommendations for future NIBS-aphasia research.

MATERIALS AND METHODS

Databases for published and grey literature were searched using scoping review methodology. 278 journal articles, conference abstracts/posters, and books, and 38 items of grey literature, were included for analysis.

RESULTS

Quantitative analysis revealed that ipsilesional anodal transcranial direct current stimulation and contralesional 1-Hz repetitive transcranial magnetic stimulation were the most widely used forms of NIBS, while qualitative analysis identified four key themes including: the roles of the hemispheres in aphasia recovery and their relationship with NIBS; heterogeneity of individuals but homogeneity of subpopulations; individualisation of stimulation parameters; and much remains under-explored in the NIBS-aphasia literature.

CONCLUSIONS

Taken together, these results highlighted systemic challenges across the field such as small sample sizes, inter-individual variability, lack of protocol optimisation/standardisation, and inadequate focus on aphasiology. Four key recommendations are outlined herein to guide future research and refine NIBS methods for post-stroke aphasia treatment.

Aberrant neural oscillations in poststroke aphasia

Neural oscillations are electrophysiological indicators of synchronous neuronal activity in the brain. Recent work suggests aberrant patterns of neuronal activity in patients with poststroke aphasia. Yet, there is a lack of systematic explorations of neural oscillations in poststroke aphasia. Investigating changes in the dynamics of neuronal activity after stroke may be helpful to identify neural markers of aphasia and language recovery and increase the current understanding of successful language rehabilitation. This review summarizes research on neural oscillations in poststroke aphasia and evaluates their potential as biomarkers for specific linguistic processes. We searched the literature through PubMed, Web of Science, and EBSCO, and selected 31 studies that met the inclusion criteria. Our analyses focused on neural oscillation activity in each frequency band, brain connectivity, and therapy-induced changes during language recovery. Our review highlights potential neurophysiological markers; however, the literature remains confounded, casting doubt on the reliability of these findings. Future research must address these confounds to confirm the robustness of cross-study findings on neural oscillations in poststroke aphasia.

Supporting Post-Stroke Language and Cognition with Pharmacotherapy: Tools for Each Phase of Care

PURPOSE OF REVIEW

There is enormous enthusiasm for the possibility of pharmacotherapies to treat language deficits that can arise after stroke. Speech language therapy remains the most frequently utilized and most strongly evidenced treatment, but the numerous barriers to patients receiving the therapy necessary to recover have motivated the creation of a relatively modest, yet highly cited, body of evidence to support the use of pharmacotherapy to treat post-stroke aphasia directly or to augment traditional post-stroke aphasia treatment. In this review, we survey the use of pharmacotherapy to preserve and support language and cognition in the context of stroke across phases of care, discuss key ongoing clinical trials, and identify targets that may become emerging interventions in the future.

RECENT FINDINGS

Recent trials have shifted focus from short periods of drug therapy supporting therapy in the chronic phase to longer terms approaching pharmacological maintenance beginning more acutely. Recent innovations in hyperacute stroke care, such as tenecteplase, and acute initiation of neuroprotective agents and serotonin reuptake inhibitors are important areas of ongoing research that complement the ongoing search for effective adjuvants to later therapy. Currently there are no drugs approved in the United States for the treatment of aphasia. Nevertheless, pharmacological intervention may provide a benefit to all phases of stroke care.

Research hotspots and frontiers of post-stroke aphasia rehabilitation: a bibliometric study and visualization analysis

Background

Aphasia is a common complication of stroke and is associated with high morbidity and mortality rates. Rehabilitation plays a crucial role in the comprehensive management of post-stroke aphasia and its consequences. However, bibliometric analysis in the field of post-stroke aphasia rehabilitation is still lacking. This study aimed to comprehensively identify assistance networks, analyze research trends, focus on hot and cutting-edge health topics related to post-stroke aphasia rehabilitation, and inform future research guidelines.

Methods

The Web of Science Core Collection (WoSCC) electronic database was searched from inception to January 4, 2023 to identify studies related to post-stroke aphasia rehabilitation. Bibliometric analysis and visualization of country, institution, journal, author, reference, and keywords were performed using CiteSpace and VOSviewer software.

Results

A total of 2,325 papers were included in the analysis, with a progressive increase in the number of articles published each year. The USA was the country with the most publications (809 articles), and the University of Queensland was the institution with the most publications (137 articles). The subject area of post-stroke aphasia rehabilitation is dominated by clinical neurology (882 articles). Aphasiology was the journal with the most publications (254 articles) and the most cited journal (6,893 citations). Worrall L was the most prolific author (51 publications), and Frideriksson J was the most cited author (804 citations).

Conclusion

By using bibliometrics, we provided a comprehensive review of studies related to post-stroke aphasia rehabilitation. Future research hotspots on topics related to post-stroke aphasia rehabilitation will mainly focus on the plasticity mechanisms of neurolinguistics networks, language function assessment, language rehabilitation modalities, and patients' rehabilitation needs and participation experiences in post-stroke aphasia. This paper provides systematic information that is worth exploring in the future.

Clinical Implementation of Noninvasive Brain Stimulation in an Outpatient Neurorehabilitation Program

ABSTRACT

Motor, speech, and cognitive impairments are the most common consequences of neurological disorders. There has been an increasing interest in the use of noninvasive brain stimulation techniques such as transcranial direct current stimulation and transcranial magnetic stimulation to augment the effects of neurorehabilitation. Numerous research studies have shown that transcranial direct current stimulation and transcranial magnetic stimulation are highly promising neuromodulation tools that can work as adjuvants to standard neurorehabilitation services, including physical therapy, occupational therapy, and speech-language pathology. However, to date, there are vast differences in methodology in studies including noninvasive brain stimulation parameters, patient characteristics, time point of intervention after injury, and outcome measures, making it difficult to translate and implement transcranial direct current stimulation and transcranial magnetic stimulation in the clinical setting. Despite this, a series of principles are thought to underlie the effectiveness of noninvasive brain stimulation techniques. We developed a noninvasive brain stimulation rehabilitation program using these principles to provide best practices for applying transcranial direct current stimulation and/or transcranial magnetic stimulation as rehabilitation adjuvants in the clinical setting to help improve neurorehabilitation outcomes. This article outlines our approach, philosophy, and experience.

Long-term effects of transcranial direct current stimulation (tDCS) combined with speech language therapy (SLT) on post-stroke aphasia patients: A systematic review and network meta-analysis of randomized controlled trials

BACKGROUND

Transcranial direct current stimulation (tDCS) is a noninvasive neuromodulation tool for improving language performance in patients with aphasia after stroke. However, it remains unclear whether it has long-term effects. After consulting a large number of relevant studies, it was found that there are no definitive conclusions about the long-term effects of tDCS on post-stroke aphasia patients.

OBJECTIVE

To determine whether tDCS has long-term effects on post-stroke aphasia patients (PAPs) and which type of tDCS has the most beneficial treatment effects on language performance (especially naming ability).

METHODS

A network meta-analysis was conducted by searching for randomized controlled trials (RCTs) published until April 2023 in the following databases: Web of Science, Embase, Medline (from OVID and PubMed), PsycInfo and PsycARTICLES (from OVID). We only included RCTs published in English. PAPs treated by tDCS combined with speech-language therapy were selected. Sham tDCS was the control group. Naming ability or other language performance must be assessed at follow-up states. Two reviewers independently used checklists to assess the primary outcome (the long-term effects on naming ability) and the secondary outcome (other language performance, such as communication). Cochrane Collaboration guidelines were used to assess the risk of bias.

RESULTS

Seven studies with 249 patients were included for data synthesis. For primary outcomes (naming nous), there was no obvious evidence to show a difference between interventions (C-tDCS vs. S-tDCS SMD = 0.06, 95% CI = -1.01, 1.12; A-tDCS vs. S-tDCS SMD = 0.00, 95% CI = -0.66, 0.65; D-tDCS vs. S-tDCS SMD = 0.77, 95% CI = -0.71, 2.24; A-tDCS vs. C-tDCS SMD = -0.06, 95% CI = -1.31,1.19; D-tDCS vs. C-tDCS SMD = 0.71, 95% CI = -1.11,2.53; D-tDCS vs. A-tDCS SMD = 0.77, 95% CI = -0.84, 2.39). In addition, no evidence showed differences in communication ability (C-tDCS vs. S-tDCS SMD = 0.08 95% CI = -1.77, 1.92; A-tDCS vs. S-tDCS SMD = 1.23 95% CI = -1.89, 4.34; D-tDCS vs. S-tDCS SMD = 0.70; 95% CI = -1.93, 3.34; A-tDCS vs. C-tDCS SMD = 1.15 95% CI = -2.48, 4.77; D-tDCS vs. C-tDCS SMD = 0.62 95% CI = -2.59, 3.84; D-tDCS vs. A-tDCS SMD = -0.52 95% CI = -4.60, 3.56).

CONCLUSION

It seems that tDCS has no long-term effects on post-stroke aphasia patients in naming nouns and communication in terms of the results of our network meta-analysis. However, the results should be interpreted with caution. In the future, more RCTs with long follow-up times should be included in the research to conduct subgroup or meta-regression analyses to obtain a sufficient effect size.

Feasibility of Cognitive Training in Combination With Transcranial Direct Current Stimulation in a Home-Based Context (TrainStim-Home): study protocol for a randomised controlled trial

INTRODUCTION

With the worldwide increase of life expectancy leading to a higher proportion of older adults experiencing age-associated deterioration of cognitive abilities, the development of effective and widely accessible prevention and therapeutic measures has become a priority and challenge for modern medicine. Combined interventions of cognitive training and transcranial direct current stimulation (tDCS) have shown promising results for counteracting age-associated cognitive decline. However, access to clinical centres for repeated sessions is challenging, particularly in rural areas and for older adults with reduced mobility, and lack of clinical personnel and hospital space prevents extended interventions in larger cohorts. A home-based and remotely supervised application of tDCS would make the treatment more accessible for participants and relieve clinical resources. So far, studies assessing feasibility of combined interventions with a focus on cognition in a home-based setting are rare. With this study, we aim to provide evidence for the feasibility and the effects of a multisession home-based cognitive training in combination with tDCS on cognitive functions of healthy older adults.

METHODS AND ANALYSIS

The TrainStim-Home trial is a monocentric, randomised, double-blind, placebo-controlled study. Thirty healthy participants, aged 60-80 years, will receive 2 weeks of combined cognitive training and anodal tDCS over left dorsolateral prefrontal cortex (target intervention), compared with cognitive training plus sham stimulation. The cognitive training will comprise a letter updating task, and the participants will be stimulated for 20 min with 1.5 mA. The intervention sessions will take place at the participants' home, and primary outcome will be the feasibility, operationalised by two-thirds successfully completed sessions per participant. Additionally, performance in the training task and an untrained task will be analysed.

ETHICS AND DISSEMINATION

Ethical approval was granted by the ethics committee of the University Medicine Greifswald. Results will be available through publications in peer-reviewed journals and presentations at national and international conferences.

TRIAL REGISTRATION NUMBER

NCT04817124.

Better language through chemistry: Augmenting speech-language therapy with pharmacotherapy in the treatment of aphasia

Speech and language therapy is the standard treatment of aphasia. However, many individuals have barriers in seeking this measure of extensive rehabilitation treatment. Investigating ways to augment therapy is key to improving poststroke language outcomes for all patients with aphasia, and pharmacotherapies provide one such potential solution. Although no medications are currently approved for the treatment of aphasia by the United States Food and Drug Administration, numerous candidate mechanisms for pharmaceutical manipulation continue to be identified based on our evolving understanding of the neurometabolic experience of stroke recovery across molecular, cellular, and functional levels of inquiry. This chapter will review evidence for catecholaminergic, glutamatergic, cholinergic, and serotonergic drug therapies and discuss future directions for both candidate drug selection and pharmacotherapy practice in people with aphasia.

Diagnosing and managing post-stroke aphasia

Introduction: Aphasia is a debilitating language disorder and even mild forms of aphasia can negatively affect functional outcomes, mood, quality of life, social participation, and the ability to return to work. Language deficits after post-stroke aphasia are heterogeneous. Areas covered: The first part of this manuscript reviews the traditional syndrome-based classification approach as well as recent advances in aphasia classification that incorporate automatic speech recognition for aphasia classification. The second part of this manuscript reviews the behavioral approaches to aphasia treatment and recent advances such as noninvasive brain stimulation techniques and pharmacotherapy options to augment the effectiveness of behavioral therapy. Expert opinion: Aphasia diagnosis has largely evolved beyond the traditional approach of classifying patients into specific syndromes and instead focuses on individualized patient profiles. In the future, there is a great need for more large scale randomized, double-blind, placebo-controlled clinical trials of behavioral treatments, noninvasive brain stimulation, and medications to boost aphasia recovery.

Adjunctive Approaches to Aphasia Rehabilitation: A Review on Efficacy and Safety

Aphasia is one of the most socially disabling post-stroke deficits. Although traditional therapies have been shown to induce adequate clinical improvement, aphasic symptoms often persist. Therefore, unconventional rehabilitation techniques which act as a substitute or as an adjunct to traditional approaches are urgently needed. The present review provides an overview of the efficacy and safety of the principal approaches which have been proposed over the last twenty years. First, we examined the effectiveness of the pharmacological approach, principally used as an adjunct to language therapy, reporting the mechanism of action of each single drug for the recovery of aphasia. Results are conflicting but promising. Secondly, we discussed the application of Virtual Reality (VR) which has been proven to be useful since it potentiates the ecological validity of the language therapy by using virtual contexts which simulate real-life everyday contexts. Finally, we focused on the use of Transcranial Direct Current Stimulation (tDCS), both discussing its applications at the cortical level and highlighting a new perspective, which considers the possibility to extend the use of tDCS over the motor regions. Although the review reveals an extraordinary variability among the different studies, substantial agreement has been reached on some general principles, such as the necessity to consider tDCS only as an adjunct to traditional language therapy.

Transcranial direct current stimulation (tDCS) for improving activities of daily living, and physical and cognitive functioning, in people after stroke

BACKGROUND

Stroke is one of the leading causes of disability worldwide. Functional impairment, resulting in poor performance in activities of daily living (ADL) among stroke survivors is common. Current rehabilitation approaches have limited effectiveness in improving ADL performance, function, muscle strength, and cognitive abilities (including spatial neglect) after stroke, with improving cognition being the number one research priority in this field. A possible adjunct to stroke rehabilitation might be non-invasive brain stimulation by transcranial direct current stimulation (tDCS) to modulate cortical excitability, and hence to improve these outcomes in people after stroke.

OBJECTIVES

To assess the effects of tDCS on ADL, arm and leg function, muscle strength and cognitive abilities (including spatial neglect), dropouts and adverse events in people after stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register, CENTRAL, MEDLINE, Embase and seven other databases in January 2019. In an effort to identify further published, unpublished, and ongoing trials, we also searched trials registers and reference lists, handsearched conference proceedings, and contacted authors and equipment manufacturers.

SELECTION CRITERIA

This is the update of an existing review. In the previous version of this review, we focused on the effects of tDCS on ADL and function. In this update, we broadened our inclusion criteria to compare any kind of active tDCS for improving ADL, function, muscle strength and cognitive abilities (including spatial neglect) versus any kind of placebo or control intervention.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and risk of bias, extracted data, and applied GRADE criteria. If necessary, we contacted study authors to ask for additional information. We collected information on dropouts and adverse events from the trial reports.

MAIN RESULTS

We included 67 studies involving a total of 1729 patients after stroke. We also identified 116 ongoing studies. The risk of bias did not differ substantially for different comparisons and outcomes. The majority of participants had ischaemic stroke, with mean age between 43 and 75 years, in the acute, postacute, and chronic phase after stroke, and level of impairment ranged from severe to less severe. Included studies differed in terms of type, location and duration of stimulation, amount of current delivered, electrode size and positioning, as well as type and location of stroke. We found 23 studies with 781 participants examining the effects of tDCS versus sham tDCS (or any other passive intervention) on our primary outcome measure, ADL after stroke. Nineteen studies with 686 participants reported absolute values and showed evidence of effect regarding ADL performance at the end of the intervention period (standardised mean difference (SMD) 0.28, 95% confidence interval (CI) 0.13 to 0.44; random-effects model; moderate-quality evidence). Four studies with 95 participants reported change scores, and showed an effect (SMD 0.48, 95% CI 0.02 to 0.95; moderate-quality evidence). Six studies with 269 participants assessed the effects of tDCS on ADL at the end of follow-up and provided absolute values, and found improved ADL (SMD 0.31, 95% CI 0.01 to 0.62; moderate-quality evidence). One study with 16 participants provided change scores and found no effect (SMD -0.64, 95% CI -1.66 to 0.37; low-quality evidence). However, the results did not persist in a sensitivity analysis that included only trials with proper allocation concealment. Thirty-four trials with a total of 985 participants measured upper extremity function at the end of the intervention period. Twenty-four studies with 792 participants that presented absolute values found no effect in favour of tDCS (SMD 0.17, 95% CI -0.05 to 0.38; moderate-quality evidence). Ten studies with 193 participants that presented change values also found no effect (SMD 0.33, 95% CI -0.12 to 0.79; low-quality evidence). Regarding the effects of tDCS on upper extremity function at the end of follow-up, we identified five studies with a total of 211 participants (absolute values) without an effect (SMD -0.00, 95% CI -0.39 to 0.39; moderate-quality evidence). Three studies with 72 participants presenting change scores found an effect (SMD 1.07; 95% CI 0.04 to 2.11; low-quality evidence). Twelve studies with 258 participants reported outcome data for lower extremity function and 18 studies with 553 participants reported outcome data on muscle strength at the end of the intervention period, but there was no effect (high-quality evidence). Three studies with 156 participants reported outcome data on muscle strength at follow-up, but there was no evidence of an effect (moderate-quality evidence). Two studies with 56 participants found no evidence of effect of tDCS on cognitive abilities (low-quality evidence), but one study with 30 participants found evidence of effect of tDCS for improving spatial neglect (very low-quality evidence). In 47 studies with 1330 participants, the proportions of dropouts and adverse events were comparable between groups (risk ratio (RR) 1.25, 95% CI 0.74 to 2.13; random-effects model; moderate-quality evidence).  AUTHORS' CONCLUSIONS: There is evidence of very low to moderate quality on the effectiveness of tDCS versus control (sham intervention or any other intervention) for improving ADL outcomes after stroke. However, the results did not persist in a sensitivity analyses including only trials with proper allocation concealment. Evidence of low to high quality suggests that there is no effect of tDCS on arm function and leg function, muscle strength, and cognitive abilities in people after stroke. Evidence of very low quality suggests that there is an effect on hemispatial neglect. There was moderate-quality evidence that adverse events and numbers of people discontinuing the treatment are not increased. Future studies should particularly engage with patients who may benefit the most from tDCS after stroke, but also should investigate the effects in routine application. Therefore, further large-scale randomised controlled trials with a parallel-group design and sample size estimation for tDCS are needed.

Cognitive training and brain stimulation in prodromal Alzheimer's disease (AD-Stim)-study protocol for a double-blind randomized controlled phase IIb (monocenter) trial

BACKGROUND

Given the growing older population worldwide, and the associated increase in age-related diseases, such as Alzheimer's disease (AD), investigating non-invasive methods to ameliorate or even prevent cognitive decline in prodromal AD is highly relevant. Previous studies suggest transcranial direct current stimulation (tDCS) to be an effective method to boost cognitive performance, especially when applied in combination with cognitive training in healthy older adults. So far, no studies combining tDCS concurrent with an intense multi-session cognitive training in prodromal AD populations have been conducted.

METHODS

The AD-Stim trial is a monocentric, randomized, double-blind, placebo-controlled study, including a 3-week tDCS-assisted cognitive training with anodal tDCS over left DLPFC (target intervention), compared to cognitive training plus sham (control intervention). The cognitive training encompasses a letter updating task and a three-stage Markov decision-making task. Forty-six participants with subjective cognitive decline (SCD) or mild cognitive impairment (MCI) will be randomized block-wise to either target or control intervention group and participate in nine interventional visits with additional pre- and post-intervention assessments. Performance in the letter updating task after training and anodal tDCS compared to sham stimulation will be analyzed as primary outcome. Further, performance on the second training task and transfer tasks will be investigated. Two follow-up visits (at 1 and 7 months post-training) will be performed to assess possible maintenance effects. Structural and functional magnetic resonance imaging (MRI) will be applied before the intervention and at the 7-month follow-up to identify possible neural predictors for successful intervention.

SIGNIFICANCE

With this trial, we aim to provide evidence for tDCS-induced improvements of multi-session cognitive training in participants with SCD and MCI. An improved understanding of tDCS effects on cognitive training performance and neural predictors may help to develop novel approaches to counteract cognitive decline in participants with prodromal AD.

TRIAL REGISTRATION

ClinicalTrials.gov , NCT04265378 . Registered on 07 February 2020. Retrospectively registered. Protocol version: Based on BB 004/18 version 1.2 (May 17, 2019).

SPONSOR

University Medicine Greifswald.

Visual motion perception improvements following direct current stimulation over V5 are dependent on initial performance

Transcranial direct current stimulation (tDCS) can improve visual perception. However, the effect of tDCS on visual perception is largely variable, possibly due to individual differences in initial performance. The goal of the present study was to evaluate the dependency of visual motion perception improvements on initial performance. Twenty-eight observers were randomly divided into two groups. Anodal tDCS and sham stimulation were separately applied to V5 (1.5 mA, 20 min), while observers performed a coherent motion direction identification task. The results showed that compared to sham stimulation, anodal tDCS induced a significant improvement in motion perception that lasted at least 20 min. In addition, the degree of improvement was dependent on initial performance, with a greater improvement magnitude observed for those with poorer initial performance. These results may have implications for understanding the nature of the stimulation rule and for the use of a customised stimulation protocol to enhance tDCS efficiency in practical applications.

Neuromodulation in post-stroke aphasia treatment

PURPOSE OF REVIEW

This paper aims to review non-invasive brain stimulation (NIBS) methods to augment speech and language therapy (SLT) for patients with post-stroke aphasia.

RECENT FINDINGS

In the past five years there have been more than 30 published studies assessing the effect of transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS) for improving aphasia in people who have had a stroke. Different approaches to NIBS treatment have been used in post-stroke aphasia treatment including different stimulation locations, stimulation intensity, number of treatment sessions, outcome measures, type of aphasia treatment, and time post-stroke.

SUMMARY

This review of NIBS for post-stroke aphasia shows that both tDCS and TMS can be beneficial for improving speech and language outcomes for patients with stroke. Prior to translating NIBS to clinical practice, further studies are needed to determine optimal tDCS and TMS parameters as well as the mechanisms underlying tDCS and TMS treatment outcomes.

Recovery from tactile agnosia: a single case study

In a patient suffering from tactile agnosia a comparison was made (using the ABABAB paradigm) between three blocks of neuropsychological rehabilitation sessions involving off-line anodal transcranial direct current stimulation (anodal-tDCS) and three blocks of rehabilitation sessions without tDCS. During the blocks with anodal-tDCS, the stimulation was administered in counterbalanced order to two sites: i) the perilesional parietal area (specific stimulation) and ii) an occipital area far from the lesion (nonspecific stimulation).Rehabilitation associated with anodal-tDCS (in particular in the perilesional areas) is more efficacious than without stimulation.

The experimental research on neuroplasticity in rats' hippocampus subjected to chronic cerebral hypoperfusion and interfered by Modified Dioscorea Pills

Background

Chronic Cerebral Hypoperfusion (CCH) is a common, crucial and tough problem for old people. It easily leads to Lacunar Infarction and even Vascular Dementia (VD). Western medicine has the advantage to relieve some VD symptoms but fails to cure it. Some classic Chinese medicines have good efficacies to treat and delay the cerebral functional decline resulted from CCH. Among them Modified Dioscorea Pills (MDP) has been proven to have a convincing effect in curing VD. So far the knowledge about neuroplasticity in CCH is little known and the underlying interfered mechanism by MDP on neuroplasticity has not yet been explored. This study explores the changes of neuroplasticity involving neurogenesis, angiogenesis and synaptogenesis in CCH and interfered by MDP.

Methods

40 male SD rats were divided into the Sham operated Group, the Model Group and the MDP Group according to a Random Number Table. Bilateral Common Carotid Arteries Occlusion (BCCAO) was adopted to prepare CCH models. MDP condense decoction had been administered by gavage to rats in the MDP Group (10g·Kg-1·d-1) for 45 days; Rats in the other two groups were accepted normal salts as substitution with same dosage and course. Through Morris Water Maze (MWM) test, pathological observation of hippocampus, ultrastructural study on synapse, Real Time Polymerase Chain Reaction (RT-PCR) and immunohistochemistry detection, the capacities of intelligence of rats, the morphological character of hippocampus CA1 zone and the synapse associated protein and gene such as Growth Associated Protein (GAP-43) mRNA, Vascular Endothelial Growth Factor (VEGF) mRNA, Microtubule-associated Protein (MAP)-2, Synaptophysin (SYP), Postsynaptic Density protein (PSD)-95 and Micro Vessel Density (MVD) were determined. Through one-way ANOVA the data was analyzed and when P＜0.05 the result was considered significant.

Results

Compared to the Model Group, rats in the MDP Group achieved much better behavioral performance (P＜0.05); more neurons and more synapses regenerated; the expression of SYP, PSD-95and MAP-2 up-regulated (P＜0.05); The expressions of GAP-43 mRNA and VEGF mRNA in the Model Group were higher than those in the Sham operated Group (P＜0.05), but they reached the highest in the MDP Group (P＜0.05); The count of MVD in the Sham operated Group is the lowest, it is higher in the MDP Group and it reaches highest in the Model Group (P＜0.05).

Conclusions

Some key genes promoting neuroplasticity such as GAP-43 mRNA and VEGF mRNA remarkably up-regulated in CCH, they only boost angiogenesis but fail to facilitate neurogenesis and synaptogenesis in CCH. However, accompanied by furtherly up-regulation of these two key genes, MDP obviously improves neurogenesis, synaptogenesis and temperate angiogenesis in CCH which may be underlying its good efficacy.

Consensus Paper: Experimental Neurostimulation of the Cerebellum

The cerebellum is best known for its role in controlling motor behaviors. However, recent work supports the view that it also influences non-motor behaviors. The contribution of the cerebellum towards different brain functions is underscored by its involvement in a diverse and increasing number of neurological and neuropsychiatric conditions including ataxia, dystonia, essential tremor, Parkinson's disease (PD), epilepsy, stroke, multiple sclerosis, autism spectrum disorders, dyslexia, attention deficit hyperactivity disorder (ADHD), and schizophrenia. Although there are no cures for these conditions, cerebellar stimulation is quickly gaining attention for symptomatic alleviation, as cerebellar circuitry has arisen as a promising target for invasive and non-invasive neuromodulation. This consensus paper brings together experts from the fields of neurophysiology, neurology, and neurosurgery to discuss recent efforts in using the cerebellum as a therapeutic intervention. We report on the most advanced techniques for manipulating cerebellar circuits in humans and animal models and define key hurdles and questions for moving forward.

Effects of Transcranial Direct Current Stimulation on Apraxia of Speech and Cortical Activation in Patients With Stroke: A Randomized Sham-Controlled Study

Purpose The study aims to investigate, using anodal transcranial direct current stimulation (A-tDCS), over which site, the left lip region of primary motor cortex (M1) or the Broca's area, there would be better recovery from apraxia of speech (AoS) in patients with poststroke aphasia and to examine for altered activation in speech-related areas after tDCS with nonlinear electroencephalography (EEG). Method Fifty-two patients with AoS were randomized into A-tDCS over the left M1 (A-tDCS-M1), Broca's area, and sham tDCS groups who underwent 10 sessions of tDCS and speech treatment for 5 days. The EEG nonlinear index of approximate entropy was calculated for 6 subjects in each group before and after treatment. Results After treatment, the change in speech-language performance improved more significantly in the A-tDCS-M1 group than the other 2 groups (p < .05). EEG approximate entropy indicated that both A-tDCS groups could activate the stimulated sites; the improvement in the A-tDCS-M1 group was correlated with high activation in the dorsal lateral prefrontal cortex and Broca's areas of the left hemisphere in addition to the stimulated site. Conclusion A-tDCS over the left M1 can improve the speech function in patients with poststroke aphasia and severe AoS and excite and recruit more areas in the motor speech network.

Plasticity and recovery of function

The frontal lobe plays a crucial role in human motor behavior. It is one of the last areas of the brain to mature, especially the prefrontal regions. After a brief historical perspective on the perceived dichotomy between the view of the brain as a static organ and that of a plastic, constantly changing structure, we discuss the stability/plasticity dilemma including examples of documented cortical reorganization taking place at multiple spatial and temporal scales. We pose that while plasticity is needed for motor learning, stability of the system is necessary for storage and maintenance of memorized skills. We discuss how this plasticity/stability dilemma is resolved along the life span and after a brain injury. We then examine the main challenges that clinicians have to overcome to promote recovery of function in patients with brain lesions, including attempts to use neurostimulation techniques as adjuvant to training-based customary neurorehabilitation.

Effects of a Multi-Session Cognitive Training Combined With Brain Stimulation (TrainStim-Cog) on Age-Associated Cognitive Decline - Study Protocol for a Randomized Controlled Phase IIb (Monocenter) Trial

Background

With increasing aging populations worldwide, developing interventions against age-associated cognitive decline is particularly important. Evidence suggests that combination of brain stimulation with cognitive training intervention may enhance training effects in terms of performance gain or transfer to untrained domains. This protocol describes a Phase IIb clinical trial that investigates the intervention effects of training combined with brain stimulation in older adults.

Methods

The TrainStim-Cog study is a monocentric, randomized, single-blind, placebo-controlled intervention. The study will investigate cognitive training with concurrent anodal transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (target intervention) compared to cognitive training with sham stimulation (control intervention) over nine sessions in 3 weeks, consisting of a letter updating task, and a three-stage Markov decision-making task. Fifty-six older adults will be recruited from the general population. Baseline assessment will be performed including neuropsychological screening and performance on training tasks. Participants will be allocated to one of the two study arms using block-wise randomization stratified by age and baseline performance with a 1:1 allocation ratio. Primary outcome is performance in the letter updating task after training under anodal tDCS compared to sham stimulation. Secondary outcomes include performance changes in the decision-making task and transfer tasks, as well as brain structure and functional networks assessed by structural, and functional magnetic resonance imaging (MRI) that are acquired pre- and post-intervention.

Significance

The main aim of the TrainStim-Cog study is to provide evidence for behavioral and neuronal effects of tDCS-accompanied cognitive training and to elucidate the underlying mechanisms in older adults. Our findings will contribute toward developing efficient interventions for age-associated cognitive decline.

Trial registration

This trial was retrospectively registered at Clinicaltrials.gov Identifier: NCT03838211 at February 12, 2019, https://clinicaltrials.gov/ct2/show/NCT03838211.

Protocol version

Based on BB 004/18 version 1.2 (May 17, 2019).

Transcranial direct current stimulation (tDCS) for improving aphasia in adults with aphasia after stroke

BACKGROUND

Stroke is one of the leading causes of disability worldwide and aphasia among survivors is common. Current speech and language therapy (SLT) strategies have only limited effectiveness in improving aphasia. A possible adjunct to SLT for improving SLT outcomes might be non-invasive brain stimulation by transcranial direct current stimulation (tDCS) to modulate cortical excitability and hence to improve aphasia.

OBJECTIVES

To assess the effects of tDCS for improving aphasia in people who have had a stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (June 2018), CENTRAL (Cochrane Library, June 2018), MEDLINE (1948 to June 2018), Embase (1980 to June 2018), CINAHL (1982 to June 2018), AMED (1985 to June 2018), Science Citation Index (1899 to June 2018), and seven additional databases. We also searched trial registers and reference lists, handsearched conference proceedings and contacted authors and equipment manufacturers.

SELECTION CRITERIA

We included only randomised controlled trials (RCTs) and randomised controlled cross-over trials (from which we only analysed the first period as a parallel group design) comparing tDCS versus control in adults with aphasia due to stroke.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and risk of bias, and extracted data. If necessary, we contacted study authors for additional information. We collected information on dropouts and adverse events from the trials.

MAIN RESULTS

We included 21 trials involving 421 participants in the qualitative synthesis. Three studies with 112 participants used formal outcome measures for our primary outcome measure of functional communication - that is, measuring aphasia in a real-life communicative setting. There was no evidence of an effect (standardised mean difference (SMD) 0.17, 95% confidence interval (CI) -0.20 to 0.55; P = 0.37; I² = 0%; low quality of evidence; inverse variance method with random-effects model; higher SMD reflecting benefit from tDCS; moderate quality of evidence). At follow-up, there also was no evidence of an effect (SMD 0.14, 95% CI -0.31 to 0.58; P = 0.55; 80 participants ; 2 studies; I² = 0%; very low quality of evidence; higher SMD reflecting benefit from tDCS; moderate quality of evidence).For our secondary outcome measure, accuracy in naming nouns at the end of intervention, there was evidence of an effect (SMD 0.42, 95% CI 0.19 to 0.66; P = 0.0005; I² = 0%; 298 participants; 11 studies; inverse variance method with random-effects model; higher SMD reflecting benefit from tDCS; moderate quality of evidence). There was an effect for the accuracy in naming nouns at follow-up (SMD 0.87, 95% CI 0.25 to 1.48; P = 0.006; 80 participants; 2 studies; I² = 32%; low quality of evidence); however the results were not statistically significant in our sensitivity analysis regarding the assumptions of the underlying correlation coefficient for imputing missing standard deviations of change scores. There was no evidence of an effect regarding accuracy in naming verbs post intervention (SMD 0.19, 95% CI -0.68 to 1.06; P = 0.67; I² = 0%; 21 participants; 3 studies; very low quality of evidence). We found no studies examining the effect of tDCS on cognition in people with aphasia after stroke. We did not find reported serious adverse events and the proportion of dropouts and adverse events was comparable between groups (odds ratio (OR) 0.54, 95% CI 0.21 to 1.37; P = 0.19; I² = 0%; Mantel-Haenszel method with random-effects model; 345 participants; 15 studies; low quality of evidence).

AUTHORS' CONCLUSIONS

Currently there is no evidence of the effectiveness of tDCS (anodal tDCS, cathodal tDCS and Dual-tDCS) versus control (sham tDCS) for improving functional communication in people with aphasia after stroke (low quality of evidence). However, there is limited evidence that tDCS may improve naming performance in naming nouns (moderate quality of evidence), but not verbs (very low quality of evidence) at the end of the intervention period and possibly also at follow-up. Further methodologically rigorous RCTs with adequate sample size calculation are needed in this area to determine the effectiveness of this intervention. Data on functional communication and on adverse events should routinely be collected and presented in further publications as well as data at follow-up. Further study on the relationship between language/aphasia and cognition may be required, and improved cognitive assessments for patients with aphasia developed, prior to the use of tDCS to directly target cognition in aphasia. Authors should state total values at post-intervention as well as their corresponding change scores with standard deviations.

The Intersection of Central Dopamine System and Stroke: Potential Avenues Aiming at Enhancement of Motor Recovery

Dopamine, a major neurotransmitter, plays a role in a wide range of brain sensorimotor functions. Parkinson's disease and schizophrenia are two major human neuropsychiatric disorders typically associated with dysfunctional dopamine activity levels, which can be alleviated through the druggability of the dopaminergic systems. Meanwhile, several studies suggest that optimal brain dopamine activity levels are also significantly impacted in other serious neurological conditions, notably stroke, but this has yet to be fully appreciated at both basic and clinical research levels. This is of utmost importance as there is a need for better treatments to improve recovery from stroke. Here, we discuss the state of knowledge regarding the modulation of dopaminergic systems following stroke, and the use of dopamine boosting therapies in animal stroke models to improve stroke recovery. Indeed, studies in animals and humans show stroke leads to changes in dopamine functioning. Moreover, evidence from animal stroke models suggests stimulation of dopamine receptors may be a promising therapeutic approach for enhancing motor recovery from stroke. With respect to the latter, we discuss the evidence for several possible receptor-linked mechanisms by which improved motor recovery may be mediated. One avenue of particular promise is the subtype-selective stimulation of dopamine receptors in conjunction with physical therapy. However, results from clinical trials so far have been more mixed due to a number of potential reasons including, targeting of the wrong patient populations and use of drugs which modulate a wide array of receptors. Notwithstanding these issues, it is hoped that future research endeavors will assist in the development of more refined dopaminergic therapeutic approaches to enhance stroke recovery.

Adaptability and reproducibility of a memory disruption rTMS protocol in the PharmaCog IMI European project

Transcranial magnetic stimulation (TMS) can interfere with cognitive processes, such as transiently impairing memory. As part of a multi-center European project, we investigated the adaptability and reproducibility of a previously published TMS memory interfering protocol in two centers using EEG or fMRI scenarios. Participants were invited to attend three experimental sessions on different days, with sham repetitive TMS (rTMS) applied on day 1 and real rTMS on days 2 and 3. Sixty-eight healthy young men were included. On each experimental day, volunteers were instructed to remember visual pictures while receiving neuronavigated rTMS trains (20 Hz, 900 ms) during picture encoding at the left dorsolateral prefrontal cortex (L-DLPFC) and the vertex. Mixed ANOVA model analyses were performed. rTMS to the L-DLPFC significantly disrupted recognition memory on experimental day 2. No differences were found between centers or between fMRI and EEG recordings. Subjects with lower baseline memory performances were more susceptible to TMS disruption. No stability of TMS-induced memory interference could be demonstrated on day 3. Our data suggests that adapted cognitive rTMS protocols can be implemented in multi-center studies incorporating standardized experimental procedures. However, our center and modality effects analyses lacked sufficient statistical power, hence highlighting the need to conduct further studies with larger samples. In addition, inter and intra-subject variability in response to TMS might limit its application in crossover or longitudinal studies.

HSPA12B promotes functional recovery after ischaemic stroke through an eNOS-dependent mechanism

Stroke is the leading cause of disability worldwide. HSPA12B, a heat-shock protein recently identified expression specifically in endothelial cells, is able to promote angiogenesis. Here, we have investigated its effects on functional recovery at chronic phase of ischaemic stroke. Ischaemic stroke was induced by 60 min. of middle cerebral artery occlusion in transgenic mice with overexpression of HSPA12B (HSPA12B Tg) and wild-type littermates (WT). HSPA12B Tg mice demonstrated a significant higher survival rate than WT mice within 28 days post-stroke. Significant improved neurological functions, increased spontaneous locomotor activity and decreased anxiety were detected inHSPA12B Tg mice compared with WT controls within 21 days post-stroke. Stroke-induced hippocampal degeneration was attenuated in HSPA12B Tg mice examined at day 28 post-stroke. Interestingly, HSPA12B Tg mice showed enhanced peri-infarct angiogenesis (examined 28 days post-stroke) and hippocampal neurogenesis (examined 7 days post-stroke), respectively, compared to WT mice. The stroke-induced eNOS phosphorylation and TGF-β1 expression were augmented in HSPA12B Tg mice. However, administration with eNOS inhibitor L-NAME diminished the HSPA12B-induced protection in neurological functional recovery and mice survival post-stroke. The data suggest that HSPA12B promoted functional recovery and survival after stroke in an eNOS-dependent mechanism. Targeting HSPA12B expression may have a therapeutic potential for the stroke-evoked functional disability and mortality.

Treatments to Promote Neural Repair after Stroke

Stroke remains a major cause of human disability worldwide. In parallel with advances in acute stroke interventions, new therapies are under development that target restorative processes. Such therapies have a treatment time window measured in days, weeks, or longer and so have the advantage that they may be accessible by a majority of patients. Several categories of restorative therapy have been studied and are reviewed herein, including drugs, growth factors, monoclonal antibodies, activity-related therapies including telerehabilitation, and a host of devices such as those related to brain stimulation or robotics. Many patients with stroke do not receive acute stroke therapies or receive them and do not derive benefit, often surviving for years thereafter. Therapies based on neural repair hold the promise of providing additional treatment options to a majority of patients with stroke.

Neuroimaging of stroke recovery from aphasia - Insights into plasticity of the human language network

The role of left and right hemisphere brain regions in language recovery after stroke-induced aphasia remains controversial. Here, we summarize how neuroimaging studies increase the current understanding of functional interactions, reorganization and plasticity in the language network. We first discuss the temporal dynamics across the time course of language recovery, with a main focus on longitudinal studies from the acute to the chronic phase after stroke. These studies show that the functional contribution of perilesional and spared left hemisphere as well as contralesional right hemisphere regions to language recovery changes over time. The second section introduces critical variables and recent advances on early prediction of subsequent outcome. In the third section, we outline how multi-method approaches that combine neuroimaging techniques with non-invasive brain stimulation elucidate mechanisms of plasticity and reorganization in the language network. These approaches provide novel insights into general mechanisms of plasticity in the language network and might ultimately support recovery processes during speech and language therapy. Finally, the neurobiological correlates of therapy-induced plasticity are discussed. We argue that future studies should integrate individualized approaches that might vary the combination of language therapy with specific non-invasive brain stimulation protocols across the time course of recovery. The way forward will include the combination of such approaches with large data sets obtained from multicentre studies.

Optogenetically stimulating intact rat corticospinal tract post-stroke restores motor control through regionalized functional circuit formation

Current neuromodulatory strategies to enhance motor recovery after stroke often target large brain areas non-specifically and without sufficient understanding of their interaction with internal repair mechanisms. Here we developed a novel therapeutic approach by specifically activating corticospinal circuitry using optogenetics after large strokes in rats. Similar to a neuronal growth-promoting immunotherapy, optogenetic stimulation together with intense, scheduled rehabilitation leads to the restoration of lost movement patterns rather than induced compensatory actions, as revealed by a computer vision-based automatic behavior analysis. Optogenetically activated corticospinal neurons promote axonal sprouting from the intact to the denervated cervical hemi-cord. Conversely, optogenetically silencing subsets of corticospinal neurons in recovered animals, results in mistargeting of the restored grasping function, thus identifying the reestablishment of specific and anatomically localized cortical microcircuits. These results provide a conceptual framework to improve established clinical techniques such as transcranial magnetic or transcranial direct current stimulation in stroke patients.

Existing methods to improve motor function after stroke include non-specific neuromodulatory approaches. Here the authors use an automated method of analysis of reaching behaviour in rodents to show that optogenetic stimulation of intact corticospinal tract fibres leads to restoration of prior motor functions, rather than compensatory acquisition of new movements.

Low intensity transcranial electric stimulation: Safety, ethical, legal regulatory and application guidelines

Low intensity transcranial electrical stimulation (TES) in humans, encompassing transcranial direct current (tDCS), transcutaneous spinal Direct Current Stimulation (tsDCS), transcranial alternating current (tACS), and transcranial random noise (tRNS) stimulation or their combinations, appears to be safe. No serious adverse events (SAEs) have been reported so far in over 18,000 sessions administered to healthy subjects, neurological and psychiatric patients, as summarized here. Moderate adverse events (AEs), as defined by the necessity to intervene, are rare, and include skin burns with tDCS due to suboptimal electrode-skin contact. Very rarely mania or hypomania was induced in patients with depression (11 documented cases), yet a causal relationship is difficult to prove because of the low incidence rate and limited numbers of subjects in controlled trials. Mild AEs (MAEs) include headache and fatigue following stimulation as well as prickling and burning sensations occurring during tDCS at peak-to-baseline intensities of 1-2mA and during tACS at higher peak-to-peak intensities above 2mA. The prevalence of published AEs is different in studies specifically assessing AEs vs. those not assessing them, being higher in the former. AEs are frequently reported by individuals receiving placebo stimulation. The profile of AEs in terms of frequency, magnitude and type is comparable in healthy and clinical populations, and this is also the case for more vulnerable populations, such as children, elderly persons, or pregnant women. Combined interventions (e.g., co-application of drugs, electrophysiological measurements, neuroimaging) were not associated with further safety issues. Safety is established for low-intensity 'conventional' TES defined as <4mA, up to 60min duration per day. Animal studies and modeling evidence indicate that brain injury could occur at predicted current densities in the brain of 6.3-13A/m2 that are over an order of magnitude above those produced by tDCS in humans. Using AC stimulation fewer AEs were reported compared to DC. In specific paradigms with amplitudes of up to 10mA, frequencies in the kHz range appear to be safe. In this paper we provide structured interviews and recommend their use in future controlled studies, in particular when trying to extend the parameters applied. We also discuss recent regulatory issues, reporting practices and ethical issues. These recommendations achieved consensus in a meeting, which took place in Göttingen, Germany, on September 6-7, 2016 and were refined thereafter by email correspondence.

Towards the concept of disease-modifier in post-stroke or vascular cognitive impairment: a consensus report

BACKGROUND

Vascular cognitive impairment (VCI) is a complex spectrum encompassing post-stroke cognitive impairment (PSCI) and small vessel disease-related cognitive impairment. Despite the growing health, social, and economic burden of VCI, to date, no specific treatment is available, prompting the introduction of the concept of a disease modifier.

CONSENSUS AND SUGGESTIONS

Within this clinical spectrum, VCI and PSCI remain advancing conditions as neurodegenerative diseases with progression of both vascular and degenerative lesions accounting for cognitive decline. Disease-modifying strategies should integrate both pharmacological and non-pharmacological multimodal approaches, with pleiotropic effects targeting (1) endothelial and brain-blood barrier dysfunction; (2) neuronal death and axonal loss; (3) cerebral plasticity and compensatory mechanisms; and (4) degenerative-related protein misfolding. Moreover, pharmacological and non-pharmacological treatment in PSCI or VCI requires valid study designs clearly stating the definition of basic methodological issues, such as the instruments that should be used to measure eventual changes, the biomarker-based stratification of participants to be investigated, and statistical tests, as well as the inclusion and exclusion criteria that should be applied.

CONCLUSION

A consensus emerged to propose the development of a disease-modifying strategy in VCI and PSCI based on pleiotropic pharmacological and non-pharmacological approaches.

Buyang Huanwu decoction facilitates neurorehabilitation through an improvement of synaptic plasticity in cerebral ischemic rats

BACKGROUND

Loss of neural function is a critical but unsolved issue after cerebral ischemia insult. Neuronal plasticity and remodeling are crucial for recovery of neural functions after brain injury. Buyang Huanwu decoction, which is a classic formula in traditional Chinese medicine, can positively alter synaptic plasticity. This study assessed the effects of Buyang Huanwu decoction in combination with physical exercise on neuronal plasticity in cerebral ischemic rats.

METHODS

Cerebral ischemic rats were administered Buyang Huanwu decoction and participated in physical exercise after the induction of a permanent middle cerebral artery occlusion. The neurobehavioral functions and infarct volumes were evaluated. The presynaptic (SYN), postsynaptic (GAP-43) and cytoskeletal (MAP-2) proteins in the coronal brain samples were evaluated by immunohistochemistry and western blot analyses. The ultrastructure of the neuronal synaptic junctions in the same region were analyzed using transmission electron microscopy.

RESULTS

Combination treatment of Buyang Huanwu decoction and physical exercise ameliorated the neurobehavioral deficits (p < 0.05), significantly enhanced the expression levels of SYN, GAP-43 and MAP-2 (p < 0.05), and maintained the synaptic ultrastructure.

CONCLUSIONS

Buyang Huanwu decoction facilitated neurorehabilitation following a cerebral ischemia insult through an improvement in synaptic plasticity. Graphical abstract The Buyang Huanwu decoction (BYHWD) combined with physical exercise (PE) attenuates synaptic disruption and promotes synaptic plasticity following cerebral ischemia (stroke).

Activating Developmental Reserve Capacity Via Cognitive Training or Non-invasive Brain Stimulation: Potentials for Promoting Fronto-Parietal and Hippocampal-Striatal Network Functions in Old Age

Existing neurocomputational and empirical data link deficient neuromodulation of the fronto-parietal and hippocampal-striatal circuitries with aging-related increase in processing noise and declines in various cognitive functions. Specifically, the theory of aging neuronal gain control postulates that aging-related suboptimal neuromodulation may attenuate neuronal gain control, which yields computational consequences on reducing the signal-to-noise-ratio of synaptic signal transmission and hampering information processing within and between cortical networks. Intervention methods such as cognitive training and non-invasive brain stimulation, e.g., transcranial direct current stimulation (tDCS), have been considered as means to buffer cognitive functions or delay cognitive decline in old age. However, to date the reported effect sizes of immediate training gains and maintenance effects of a variety of cognitive trainings are small to moderate at best; moreover, training-related transfer effects to non-trained but closely related (i.e., near-transfer) or other (i.e., far-transfer) cognitive functions are inconsistent or lacking. Similarly, although applying different tDCS protocols to reduce aging-related cognitive impairments by inducing temporary changes in cortical excitability seem somewhat promising, evidence of effects on short- and long-term plasticity is still equivocal. In this article, we will review and critically discuss existing findings of cognitive training- and stimulation-related behavioral and neural plasticity effects in the context of cognitive aging, focusing specifically on working memory and episodic memory functions, which are subserved by the fronto-parietal and hippocampal-striatal networks, respectively. Furthermore, in line with the theory of aging neuronal gain control we will highlight that developing age-specific brain stimulation protocols and the concurrent applications of tDCS during cognitive training may potentially facilitate short- and long-term cognitive and brain plasticity in old age.

Granulocyte Colony Stimulating Factor and Physiotherapy after Stroke: Results of a Feasibility Randomised Controlled Trial: Stem Cell Trial of Recovery EnhanceMent after Stroke-3 (STEMS-3 ISRCTN16714730)

Background

Granulocyte-colony stimulating factor (G-CSF) mobilises endogenous haematopoietic stem cells and enhances recovery in experimental stroke. Recovery may also be dependent on an enriched environment and physical activity. G-CSF may have the potential to enhance recovery when used in combination with physiotherapy, in patients with disability late after stroke.

Methods

A pilot 2 x 2 factorial randomised (1:1) placebo-controlled trial of G-CSF (double-blind), and/or a 6 week course of physiotherapy, in 60 participants with disability (mRS >1), at least 3 months after stroke. Primary outcome was feasibility, acceptability and tolerability. Secondary outcomes included death, dependency, motor function and quality of life measured 90 and 365 days after enrolment.

Results

Recruitment to the trial was feasible and acceptable; of 118 screened patients, 92 were eligible and 32 declined to participate. 60 patients were recruited between November 2011 and July 2013. All participants received some allocated treatment. Although 29 out of 30 participants received all 5 G-CSF/placebo injections, only 7 of 30 participants received all 18 therapy sessions. G-CSF was well tolerated but associated with a tendency to more adverse events than placebo (16 vs 10 patients, p = 0.12) and serious adverse events (SAE) (9 vs 3, p = 0.10). On average, patients received 14 (out of 18 planned) therapy sessions, interquartile range [12, 17]. Only a minority (23%) of participants completed all physiotherapy sessions, a large proportion of sessions (114 of 540, 21%) were cancelled due to patient (94, 17%) and therapist factors (20, 4%). No significant differences in functional outcomes were detected in either the G-CSF or physiotherapy group at day 90 or 365.

Conclusions

Delivery of G-CSF is feasible in chronic stroke. However, the study failed to demonstrate feasibility for delivering additional physiotherapy sessions late after stroke therefore a definitive study using this trial design is not supported. Future work should occur earlier after stroke, alongside on-going clinical rehabilitation.

Trial Registration

ISRCTN.com ISRCTN16714730

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.

Anodal direct current stimulation in the healthy aged: Effects determined by the hemisphere stimulated

Purpose: Research popularity and scope for the application of transcranial direct current stimulation have been steadily increasing yet many fundamental questions remain unanswered. We sought to determine if anodal stimulation of either hemisphere leads to improved performance of the contralateral hand and/or altered function of the ipsilateral hand, or affects movement preparation, in older subjects.

Method: In this cross-over, double blind, sham controlled study, 34 healthy aged participants (age range 40– 86) were randomised to receive 20 minutes of stimulation to either the dominant or non-dominant motor cortex. The primary outcome was functional performance of both upper limbs measured by the Jebsen Taylor Test and hand grip strength. Additionally, we measured motor preparation using electrophysiological (EEG) recordings.

Results: Anodal stimulation resulted in statistically significantly improved performance of the non-dominant hand (p <  0.01) but did not produce significant changes in the dominant hand on any measure (p >  0.05). This effect occurred irrespective of the hemisphere stimulated. Stimulation did not produce significant effects on measures of gross function, grip strength, reaction times, or electrophysiological measures on the EEG data.

Conclusion: This study demonstrated that the hemispheres respond differently to anodal stimulation and the response appears to be task specific but not mediated by age.

Pharmacotherapy to Enhance Cognitive and Motor Recovery Following Stroke

Stroke is a leading cause of disability among older adults and more than half of stroke survivors have some residual neurological impairment. Traditionally, managing the aftermath of stroke has been by the implementation of several physical and language therapy modalities. The limitations of these rehabilitation efforts have sparked an interest in finding other ways to enhance neurological recovery. Some of these novel approaches have included pharmacological interventions, cell-derived treatments, and cortical magnetic stimulation. Mounting evidence over the last 2 decades suggests that pharmacological manipulations may have the potential to modulate practice-dependent neuroplasticity and potentially improve neurological recovery after stroke. Multiple pharmacological agents with different mechanisms of action have been evaluated, showing conflicting results. Some studies suggest some promise, yet the quality of the available studies is suboptimal overall, with most of the studies being underpowered. So far, the most promising agents include the antidepressants for motor recovery and acetylcholinesterase inhibitors and memantine for aphasia. However, large, well-designed clinical trials are needed to address the shortcomings of the available data and before any pharmacological agent can be recommended for routine use as part of the standard algorithm of stroke management.

Exploring Erythropoietin and G-CSF Combination Therapy in Chronic Stroke Patients

Erythropoietin (EPO) and granulocyte-colony stimulating factor (G-CSF) are known to have neuroprotective actions. Based on previous reports showing the synergistic effects of EPO+G-CSF combination therapy in experimental models, we investigated the safety of EPO+G-CSF combination therapy in patients with chronic stroke. In a pilot study, 3 patients were treated with EPO and G-CSF for 5 consecutive days, with follow-up on day 30. In an exploratory double-blind study, 6 patients were allocated to treatment with either EPO+G-CSF or placebo. Treatment was applied once a day for 5 days per month over 3 months. Participants were followed up for 6 months. To substantiate safety, vital signs, adverse events, and hematological values were measured on days 0, 5, and 30 in each cycle and on day 180. Functional outcomes were determined on day 0 and 180. In the laboratory measurements, EPO+G-CSF combination therapy significantly elevated erythropoietin, CD34⁺ hematopoietic stem cells, white blood cells, and neutrophils on day 5 of each cycle. There were no observations of serious adverse events. In the functional outcomes, the grip power of the dominant hand was increased in the EPO+G-CSF treatment group. In conclusion, this exploratory study suggests a novel strategy of EPO+G-CSF combination therapy for stroke patients.

Transcranial direct current stimulation (tDCS) for improving activities of daily living, and physical and cognitive functioning, in people after stroke

BACKGROUND

Stroke is one of the leading causes of disability worldwide. Functional impairment, resulting in poor performance in activities of daily living (ADLs) among stroke survivors is common. Current rehabilitation approaches have limited effectiveness in improving ADL performance, function, muscle strength and cognitive abilities (including spatial neglect) after stroke, but a possible adjunct to stroke rehabilitation might be non-invasive brain stimulation by transcranial direct current stimulation (tDCS) to modulate cortical excitability, and hence to improve ADL performance, arm and leg function, muscle strength and cognitive abilities (including spatial neglect), dropouts and adverse events in people after stroke.

OBJECTIVES

To assess the effects of tDCS on ADLs, arm and leg function, muscle strength and cognitive abilities (including spatial neglect), dropouts and adverse events in people after stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (February 2015), the Cochrane Central Register of Controlled Trials (CENTRAL; the Cochrane Library; 2015, Issue 2), MEDLINE (1948 to February 2015), EMBASE (1980 to February 2015), CINAHL (1982 to February 2015), AMED (1985 to February 2015), Science Citation Index (1899 to February 2015) and four additional databases. In an effort to identify further published, unpublished and ongoing trials, we searched trials registers and reference lists, handsearched conference proceedings and contacted authors and equipment manufacturers.

SELECTION CRITERIA

This is the update of an existing review. In the previous version of this review we focused on the effects of tDCS on ADLs and function. In this update, we broadened our inclusion criteria to compare any kind of active tDCS for improving ADLs, function, muscle strength and cognitive abilities (including spatial neglect) versus any kind of placebo or control intervention.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and risk of bias (JM and MP) and extracted data (BE and JM). If necessary, we contacted study authors to ask for additional information. We collected information on dropouts and adverse events from the trial reports.

MAIN RESULTS

We included 32 studies involving a total of 748 participants aged above 18 with acute, postacute or chronic ischaemic or haemorrhagic stroke. We also identified 55 ongoing studies. The risk of bias did not differ substantially for different comparisons and outcomes.We found nine studies with 396 participants examining the effects of tDCS versus sham tDCS (or any other passive intervention) on our primary outcome measure, ADLs after stroke. We found evidence of effect regarding ADL performance at the end of the intervention period (standardised mean difference (SMD) 0.24, 95% confidence interval (CI) 0.03 to 0.44; inverse variance method with random-effects model; moderate quality evidence). Six studies with 269 participants assessed the effects of tDCS on ADLs at the end of follow-up, and found improved ADL performance (SMD 0.31, 95% CI 0.01 to 0.62; inverse variance method with random-effects model; moderate quality evidence). However, the results did not persist in a sensitivity analysis including only trials of good methodological quality.One of our secondary outcome measures was upper extremity function: 12 trials with a total of 431 participants measured upper extremity function at the end of the intervention period, revealing no evidence of an effect in favour of tDCS (SMD 0.01, 95% CI -0.48 to 0.50 for studies presenting absolute values (low quality evidence) and SMD 0.32, 95% CI -0.51 to 1.15 (low quality evidence) for studies presenting change values; inverse variance method with random-effects model). Regarding the effects of tDCS on upper extremity function at the end of follow-up, we identified four studies with a total of 187 participants (absolute values) that showed no evidence of an effect (SMD 0.01, 95% CI -0.48 to 0.50; inverse variance method with random-effects model; low quality evidence). Ten studies with 313 participants reported outcome data for muscle strength at the end of the intervention period, but in the corresponding meta-analysis there was no evidence of an effect. Three studies with 156 participants reported outcome data on muscle strength at follow-up, but there was no evidence of an effect.In six of 23 studies (26%), dropouts, adverse events or deaths that occurred during the intervention period were reported, and the proportions of dropouts and adverse events were comparable between groups (risk difference (RD) 0.01, 95% CI -0.02 to 0.03; Mantel-Haenszel method with random-effects model; low quality evidence; analysis based only on studies that reported either on dropouts, or on adverse events, or on both). However, this effect may be underestimated due to reporting bias.

AUTHORS' CONCLUSIONS

At the moment, evidence of very low to moderate quality is available on the effectiveness of tDCS (anodal/cathodal/dual) versus control (sham/any other intervention) for improving ADL performance after stroke. However, there are many ongoing randomised trials that could change the quality of evidence in the future. Future studies should particularly engage those who may benefit most from tDCS after stroke and in the effects of tDCS on upper and lower limb function, muscle strength and cognitive abilities (including spatial neglect). Dropouts and adverse events should be routinely monitored and presented as secondary outcomes. They should also address methodological issues by adhering to the Consolidated Standards of Reporting Trials (CONSORT) statement.

Transcranial direct current stimulation accelerates recovery of function, induces neurogenesis and recruits oligodendrocyte precursors in a rat model of stroke

BACKGROUND

Clinical data suggest that transcranial direct current stimulation (tDCS) may be used to facilitate rehabilitation after stroke. However, data are inconsistent and the neurobiological mechanisms underlying tDCS remain poorly explored, impeding its implementation into clinical routine. In the healthy rat brain, tDCS affects neural stem cells (NSC) and microglia. We here investigated whether tDCS applied after stroke also beneficially affects these cells, which are known to be involved in regeneration and repair.

METHODS

Focal cerebral ischemia was induced in rats by transient occlusion of the middle cerebral artery. Twenty-eight animals with comparable infarcts, as judged by magnetic resonance imaging, were randomized to receive a multi-session paradigm of either cathodal, anodal, or sham tDCS. Behaviorally, recovery of motor function was assessed by Catwalk. Proliferation in the NSC niches was monitored by Positron-Emission-Tomography (PET) employing the radiotracer 3'-deoxy-3'-[(18)F]fluoro-l-thymidine ([(18)F]FLT). Microglia activation was depicted with [(11)C]PK11195-PET. In addition, immunohistochemical analyses were used to quantify neuroblasts, oligodendrocyte precursors, and activation and polarization of microglia.

RESULTS

Anodal and cathodal tDCS both accelerated functional recovery, though affecting different aspects of motor function. Likewise, tDCS induced neurogenesis independently of polarity, while only cathodal tDCS recruited oligodendrocyte precursors towards the lesion. Moreover, cathodal stimulation preferably supported M1-polarization of microglia.

CONCLUSIONS

TDCS acts through multifaceted mechanisms that far exceed its primary neurophysiological effects, encompassing proliferation and migration of stem cells, their neuronal differentiation, and modulation of microglia responses.

Challenges in Recruitment for the Study of Noninvasive Brain Stimulation in Stroke: Lessons from Deep Brain Stimulation

OBJECTIVE

Noninvasive brain stimulation (NIBS) can augment functional recovery following stroke; however, the technique lacks regulatory approval. Low enrollment in NIBS clinical trials is a key roadblock. Here, we pursued evidence to support the prevailing opinion that enrollment in trials of NIBS is even lower than enrollment in trials of invasive, deep brain stimulation (DBS).

METHODS

We compared 2 clinical trials in stroke conducted within a single urban hospital system, one employing NIBS and the other using DBS, (1) to identify specific criteria that generate low enrollment rates for NIBS and (2) to devise strategies to increase recruitment with guidance from DBS.

RESULTS

Notably, we found that enrollment in the NIBS case study was 5 times lower (2.8%) than the DBS trial (14.5%) (χ(2) = 20.815, P < .0001). Although the number of candidates who met the inclusion criteria was not different (χ(2) = .04, P < .841), exclusion rates differed significantly between the 2 studies (χ(2) = 21.354, P < .0001). Beyond lack of interest, higher exclusion rates in the NIBS study were largely due to exclusion criteria that were not present in the DBS study, including restrictions for recurrent strokes, seizures, and medications.

CONCLUSIONS

Based on our findings, we conclude and suggest that by (1) establishing criteria specific to each NIBS modality, (2) adjusting exclusion criteria based on guidance from DBS, and (3) including patients with common contraindications based on a probability of risk, we may increase enrollment and hence significantly impact the feasibility and generalizability of NIBS paradigms, particularly in stroke.

Potentials and limits to enhance cognitive functions in healthy and pathological aging by tDCS

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that is increasingly used in research and clinical settings to enhance the effects of cognitive training. In our present review, we will first summarize studies using tDCS alone and in combination with cognitive training in older adults and patients with Alzheimer’s dementia (AD). We will also review one study (Meinzer et al., 2014c) that showed an improvement in cognitive performance during anodal tDCS over the left inferior frontal cortex in patients with mild cognitive impairment (MCI) which is regarded as a prodromal stage of AD. Although promising short-term results have been reported, evidence from randomized controlled trials (RCTs) with sufficient sample sizes is scarce. In addition, stimulation protocols (in terms of intensity, duration, and repetition of stimulation) that lead to sustained improvements in outcome measures relevant for daily life still remain to be established. Following, we will discuss modulating factors such as technical parameters as well as the question whether there are specific cognitive functions (e.g., learning, memory consolidation, executive control) which are more amenable to tDCS enhancement than others. Finally, we will highlight future directions and limitations in this field and emphasize the need to conduct RCTs to establish efficacy of interventions for activities of daily life for a given patient population.

Transcranial direct current stimulation (tDCS) for improving aphasia in patients with aphasia after stroke

BACKGROUND

Stroke is one of the leading causes of disability worldwide and aphasia among survivors is common. Current speech and language therapy (SLT) strategies have only limited effectiveness in improving aphasia. A possible adjunct to SLT for improving SLT outcomes might be non-invasive brain stimulation by transcranial direct current stimulation (tDCS) to modulate cortical excitability and hence to improve aphasia.

OBJECTIVES

To assess the effects of tDCS for improving aphasia in people who have had a stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (November 2014), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, November 2014), MEDLINE (1948 to November 2014), EMBASE (1980 to November 2014), CINAHL (1982 to November 2014), AMED (1985 to November 2014), Science Citation Index (1899 to November 2014) and seven additional databases. We also searched trials registers and reference lists, handsearched conference proceedings and contacted authors and equipment manufacturers.

SELECTION CRITERIA

We included only randomised controlled trials (RCTs) and randomised controlled cross-over trials (from which we only analysed the first period as a parallel group design) comparing tDCS versus control in adults with aphasia due to stroke.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and risk of bias, and extracted data. If necessary, we contacted study authors for additional information. We collected information on dropouts and adverse events from the trials.

MAIN RESULTS

We included 12 trials involving 136 participants for qualitative assessment. None of the included studies used any formal outcome measure for our primary outcome measure of functional communication - that is, measuring aphasia in a real-life communicative setting. We did a meta-analysis of six trials with 66 participants of correct picture naming as our secondary outcome measure, which demonstrated that tDCS may not enhance SLT outcomes (standardised mean difference (SMD) 0.37, 95% CI -0.18 to 0.92; P = 0.19; I² = 0%; inverse variance method with random-effects model; with a higher SMD reflecting benefit from tDCS). We found no studies examining the effect of tDCS on cognition in stroke patients with aphasia. We did not find reported adverse events and the proportion of dropouts was comparable between groups.

AUTHORS' CONCLUSIONS

Currently there is no evidence of the effectiveness of tDCS (anodal tDCS, cathodal tDCS and bihemispheric tDCS) versus control (sham tDCS) for improving functional communication, language impairment and cognition in people with aphasia after stroke. Further RCTs are needed in this area to determine the effectiveness of this intervention. Authors of future research should adhere to the CONSORT Statement.

A combined therapeutic approach in stroke rehabilitation: A review on non-invasive brain stimulation plus pharmacotherapy

Stroke is a leading cause of disability in the United States. Available treatments for stroke have only a modest effect on motor rehabilitation and about 50-60% of stroke patients remain with some degree of motor impairment after standard treatment. Non-invasive brain stimulation (NIBS) techniques have been proposed as adjuvant treatments to physical therapy for motor recovery after stroke. High frequency rTMS and anodal tDCS can be delivered over the affected motor cortex in order to increase cortical excitability and induce brain plasticity with the intention to enhance motor learning and achieve functional goals in stroke patients. Similarly, low frequency rTMS and cathodal tDCS can be delivered to the unaffected motor cortex to reduce interhemispheric inhibition and hinder maladaptive plasticity. The use of several drugs such as amphetamines, selective serotonin reuptake inhibitors (SSRIs), levodopa and cholinergic agents have been also proposed to enhance the motor function. Given that both NIBS and pharmacotherapy might provide some treatment effect independently for motor rehabilitation in stroke and with the rationale that they could work in a synergistic fashion, we believe that a combined therapy- NIBS plus pharmacotherapy- canlead to better outcomes than one or the other alone. In this paper we review the literature that support the potential use of a combined approach in stroke recovery and present the studies that have already investigated this idea.

Optogenetic neuronal stimulation promotes functional recovery after stroke

Clinical and research efforts have focused on promoting functional recovery after stroke. Brain stimulation strategies are particularly promising because they allow direct manipulation of the target area's excitability. However, elucidating the cell type and mechanisms mediating recovery has been difficult because existing stimulation techniques nonspecifically target all cell types near the stimulated site. To circumvent these barriers, we used optogenetics to selectively activate neurons that express channelrhodopsin 2 and demonstrated that selective neuronal stimulations in the ipsilesional primary motor cortex (iM1) can promote functional recovery. Stroke mice that received repeated neuronal stimulations exhibited significant improvement in cerebral blood flow and the neurovascular coupling response, as well as increased expression of activity-dependent neurotrophins in the contralesional cortex, including brain-derived neurotrophic factor, nerve growth factor, and neurotrophin 3. Western analysis also indicated that stimulated mice exhibited a significant increase in the expression of a plasticity marker growth-associated protein 43. Moreover, iM1 neuronal stimulations promoted functional recovery, as stimulated stroke mice showed faster weight gain and performed significantly better in sensory-motor behavior tests. Interestingly, stimulations in normal nonstroke mice did not alter motor behavior or neurotrophin expression, suggesting that the prorecovery effect of selective neuronal stimulations is dependent on the poststroke environment. These results demonstrate that stimulation of neurons in the stroke hemisphere is sufficient to promote recovery.

Bilateral priming before wii-based movement therapy enhances upper limb rehabilitation and its retention after stroke: a case-controlled study

BACKGROUND

Motor deficits after a stroke are thought to be compounded by the development of asymmetric interhemispheric inhibition. Bilateral priming was developed to rebalance this asymmetry and thus improve therapy efficacy.

OBJECTIVE

This study investigated the effect of bilateral priming before Wii-based Movement Therapy to improve rehabilitation after stroke.

METHODS

Ten patients who had suffered a stroke (age, 23-77 years; 3-123 months after stroke) underwent a 14-day program of Wii-based Movement Therapy for upper limb rehabilitation. Formal Wii-based Movement Therapy sessions were immediately preceded by 15 minutes of bilateral priming, whereby active flexion-extension of the less affected wrist drove mirror-symmetric passive movements of the more affected wrist through a custom device. Functional movement was assessed at weeks 0 (before therapy), 3 (after therapy), and 28 (follow-up) using the Wolf Motor Function Test (WMFT), upper limb Fugl-Meyer Assessment (FMA), upper limb range of motion, and Motor Activity Log (MAL). Case-matched controls were patients who had suffered a stroke who received Wii-based Movement Therapy but not bilateral priming.

RESULTS

Upper limb functional ability improved for both groups on all measures tested. Posttherapy improvement on the FMA for primed patients was twice that of the unprimed patients (37.3% vs 14.6%, respectively) and was significantly better maintained at 28 weeks (P = .02). Improvements on the WMFT and MAL were similar for both groups, but the pattern of change in range of motion was strikingly different.

CONCLUSIONS

Bilateral priming before Wii-based Movement Therapy led to a greater magnitude and retention of improvement compared to control, especially measured with the FMA. These data suggest that bilateral priming can enhance the efficacy of Wii-based Movement Therapy, particularly for patients with low motor function after a stroke.