Transcranial Direct Current Stimulation as a Tool to Induce Language Recovery in Patients with Post-Stroke Aphasia
In recent years, possible therapeutic effects of transcranial direct current stimulation (tDCS) have been widely investigated in studies dealing with different types of neural pathologies. Initially, tDCS was applied for treatment of patients with motor stroke; later on, it was introduced into studies of patients with Alzheimer’s disease, multiple sclerosis, Parkinson’s disease, schizophrenia, and post-stroke aphasia. Recent reviews of tDCS application in patients with post-stroke aphasia did not provide coherent evidence on the tDCS efficiency. There were no uniform protocols of stimulation used, patients’ selection criteria were highly divergent, and the reports of treatment outcomes varied dramatically. In this review, we will focus on the reported heterogeneity of tDCS effects, trying to disentangle its putative underpinnings rooted in the diversity of lesion types, aphasia severity, and recovery stages. Given the current theoretical models suggesting the qualitatively different patterns of brain activity to accompany post-stroke aphasia recovery, a number of physiological factors should be taken into account to choose optimal tDCS parameters. With this in mind, we assess results of ten studies applying tDCS in post-stroke aphasia treatment, and, based on this analysis, suggest directions for further research in this rapidly developing field.
Background: Accurate information on stroke burden in men and women are important for evidence-based healthcare planning and resource allocation. Previously, limited research suggested that the absolute number of deaths from stroke in women was greater than in men, but the incidence and mortality rates were greater in men. However, sex differences in various metrics of stroke burden on a global scale have not been a subject of comprehensive and comparable assessment for most regions of the world, nor have sex differences in stroke burden been examined for trends over time. Methods: Stroke incidence, prevalence, mortality, disability-adjusted life years (DALYs) and healthy years lost due to disability were estimated as part of the Global Burden of Disease (GBD) 2013 Study. Data inputs included all available information on stroke incidence, prevalence and death and case fatality rates. Analysis was performed separately by sex and 5-year age categories for 188 countries. Statistical models were employed to produce globally comprehensive results over time. All rates were age-standardized to a global population and 95% uncertainty intervals (UIs) were computed. Findings: In 2013, global ischemic stroke (IS) and hemorrhagic stroke (HS) incidence (per 100,000) in men (IS 132.77 (95% UI 125.34-142.77); HS 64.89 (95% UI 59.82-68.85)) exceeded those of women (IS 98.85 (95% UI 92.11-106.62); HS 45.48 (95% UI 42.43-48.53)). IS incidence rates were lower in 2013 compared with 1990 rates for both sexes (1990 male IS incidence 147.40 (95% UI 137.87-157.66); 1990 female IS incidence 113.31 (95% UI 103.52-123.40)), but the only significant change in IS incidence was among women. Changes in global HS incidence were not statistically significant for males (1990 = 65.31 (95% UI 61.63-69.0), 2013 = 64.89 (95% UI 59.82-68.85)), but was significant for females (1990 = 64.892 (95% UI 59.82-68.85), 2013 = 45.48 (95% UI 42.427-48.53)). The number of DALYs related to IS rose from 1990 (male = 16.62 (95% UI 13.27-19.62), female = 17.53 (95% UI 14.08-20.33)) to 2013 (male = 25.22 (95% UI 20.57-29.13), female = 22.21 (95% UI 17.71-25.50)). The number of DALYs associated with HS also rose steadily and was higher than DALYs for IS at each time point (male 1990 = 29.91 (95% UI 25.66-34.54), male 2013 = 37.27 (95% UI 32.29-45.12); female 1990 = 26.05 (95% UI 21.70-30.90), female 2013 = 28.18 (95% UI 23.68-33.80)). Interpretation: Globally, men continue to have a higher incidence of IS than women while significant sex differences in the incidence of HS were not observed. The total health loss due to stroke as measured by DALYs was similar for men and women for both stroke subtypes in 2013, with HS higher than IS. Both IS and HS DALYs show an increasing trend for both men and women since 1990, which is statistically significant only for IS among men. Ongoing monitoring of sex differences in the burden of stroke will be needed to determine if disease rates among men and women continue to diverge. Sex disparities related to stroke will have important clinical and policy implications that can guide funding and resource allocation for national, regional and global health programs.
The present work is dedicated to the role of gestures in overcoming lexical access problems in patients with motor aphasia. The study is based on a corpus of narratives by brain-damaged individuals – «Russian CliPS» (Clinical Pear Stories), the videos from which were annotated in the linguistic annotator «ELAN», with the gestural layout included in the analysis. The results suggest that most often the difficulties with lexical access were related to the search for nouns and verbs, and gestures (deictic and rhythmic gestures, beats) facilitated lexical access in patients.
Currently there is a need for standardized language assessment test in Russian. Our group has developed Russian Aphasia Test (RAT) based on modern psycholinguistic models and psychometric principles, taking into account existing standardized tests in other languages. RAT allows to separately assess each level of linguistic processing: from phonemic perception to discourse. Here we present the design of the test and the first results of its approbation in groups of neurologically healthy participants and individuals with aphasia. Preliminary results demonstrated that the test is sensitive to language deficits and their severity. Thus, RAT is a practical instrument for language assessment in aphasia which can be used both in clinical practice and for research purposes. At present test standardization in a large group of participants with and without aphasia is on-going with the goal of developing appropriate clinical and age norms.
Human societies crucially depend on social norms that specify appropriate actions in various situation. The effect of norms on collective behavior can break down if norm violations are not sanctioned. Social punishment is a form of behavior to enforce social norm compliance that relies on two key brain region: the “mentalizing network” (right temporo-parietal junction – rTPJ) evaluating individual responsibility and the “central-executive network” (right dorsolateral prefrontal cortex – rDLPFC) determining the final decision to punish norm violators. Here we further investigate the role of the brain network – rDLPFC-rTPJ – in third-party punishment. We used transcranial direct-current stimulation (tDCS) to disrupt the rDLPFC-rTPJ network of healthy subjects while they performed the Dictator Game. Our results suggests that the frequency of third-party punishment increased after the tDCS of the rDLPFC-rTPJ. To the best of our knowledge, this is the first study demonstrating the effect of simultaneous tDCS of the rDLPFC and rTPJ on the third-party punishment. We also show that personality traits modulate the effect of tDCS on the third-party punishment.
The theory of cognitive dissonance suggests that individuals prefer new incoming information to be consistent with already existing knowledge. Conflicting or inconsistent information results in an emotionally uncomfortable state called cognitive dissonance. Cognitive dissonance theory suggests that a choice between two similarly valued alternatives creates psychological tension (cognitive dissonance) that is reduced by a post-decision re-evaluation of the alternatives. According to the action-based model of cognitive dissonance, activity in the posterior medial prefrontal cortex (pMFC) underlies the detection of cognitive conflicts and the reduction of the dissonance. Nevertheless, the neurocomputational foundation of cognitive dissonance remains unclear. In this study, for the first time we show that cathodal transcranial direct current stimulation (tDCS) of the pMFC significantly reduced post-decision re-evaluation of the alternatives. An ongoing follow-up study that applied anodal tDCS to the pMFC preliminarily showed a tendency to increase choice-induced preference changes. Our results suggest that cognitive dissonance, underlined by the activity of the prefrontal cortex, is a part of the performance-monitoring circuitry
RaPID-3 aims to be an interdisciplinary forum for researchers to share information, findings, methods, models and experience on the collection and processing of data produced by people with various forms of mental, cognitive, neuropsychiatric, or neurodegenerative impairments, such as aphasia, dementia, autism, bipolar disorder, Parkinson's disease or schizophrenia. Particularly, the workshop's focus is on creation, processing and application of data resources from individuals at various stages of these impairments and with varying degrees of severity. Creation of resources includes e.g. annotation, description, analysis and interpretation of linguistic, paralinguistc and extra-linguistic data (such as spontaneous spoken language, transcripts, eyetracking measurements, wearable and sensor data, etc). Processing is done to identify, extract, correlate, evaluate and disseminate various linguistic or multimodal phenotypes and measurements, which then can be applied to aid diagnosis, monitor the progression or predict individuals at risk.
Cervical artery dissection (CeAD), a mural hematoma in a carotid or vertebral artery, is a major cause of ischemic stroke in young adults although relatively uncommon in the general population (incidence of 2.6/100,000 per year)1. Minor cervical traumas, infection, migraine and hypertension are putative risk factors1, 2, 3, and inverse associations with obesity and hypercholesterolemia are described3, 4. No confirmed genetic susceptibility factors have been identified using candidate gene approaches5. We performed genome-wide association studies (GWAS) in 1,393 CeAD cases and 14,416 controls. The rs9349379[G] allele (PHACTR1) was associated with lower CeAD risk (odds ratio (OR) = 0.75, 95% confidence interval (CI) = 0.69–0.82; P = 4.46 × 10−10), with confirmation in independent follow-up samples (659 CeAD cases and 2,648 controls; P = 3.91 × 10−3; combined P = 1.00 × 10−11). The rs9349379[G] allele was previously shown to be associated with lower risk of migraine and increased risk of myocardial infarction6, 7, 8, 9. Deciphering the mechanisms underlying this pleiotropy might provide important information on the biological underpinnings of these disabling conditions.