Cortical thickness is related to working memory performance after non-invasive brain stimulation

Non-invasive brain stimulation (NIBS) probing the dorsolateral prefrontal cortex (DLPFC) has been shown to have little effect on working memory. The variability of NIBS responses might be explained by inter-subject brain anatomical variability. We investigated whether baseline cortical brain thickness of regions of interest was associated with working memory performance after NIBS by performing a secondary analysis of previously published research. Structural magnetic resonance imaging data were analyzed from healthy subjects who received transcranial direct current stimulation (tDCS), intermittent theta-burst stimulation (iTBS), and placebo. Twenty-two participants were randomly assigned to receive all the interventions in a random order. The working memory task was conducted after the end of each NIBS session. Regions of interest were the bilateral DLPFC, medial prefrontal cortex, and posterior cingulate cortex. Overall, 66 NIBS sessions were performed. Findings revealed a negative significant association between cortical thickness of the bilateral dorsolateral prefrontal cortex and reaction time for both tDCS (left: P=0.045, right: P=0.037) and iTBS (left: P=0.007, right: P=0.007) compared to placebo. A significant positive association was found for iTBS and posterior cingulate cortex (P=0.03). No association was found for accuracy. Our findings provide the first evidence that individual cortical thickness of healthy subjects might be associated with working memory performance following different NIBS interventions. Therefore, cortical thickness could explain - to some extent - the heterogeneous effects of NIBS probing the DLPFC.

Ethical Discussion on Clinical Application of Non-invasive Brain Stimulation Technology / 中国医学伦理学

With the rapid development of non-invasive brain stimulation (NIBS) technology, NIBS has shown good therapeutic prospect for mental disorders and neurological diseases in clinical research, and the medical ethical issues related to NIBS have received increasingly attention. This paper analyzed the medical ethical issues of informed consent, safety, and privacy protection faced in the clinical application of NIBS technology by combining the technical characteristics of NIBS, and proposed targeted response strategies, with a view to promoting the healthy development of NIBS technology based on the full protection of patients’ rights.

Association of BDNF, HTR2A, TPH1, SLC6A4, and COMT polymorphisms with tDCS and escitalopram efficacy: ancillary analysis of a double-blind, placebo-controlled trial

Objective: We investigated whether single nucleotide polymorphisms (SNPs) associated with neuroplasticity and activity of monoamine neurotransmitters, such as the brain-derived neurotrophic factor (BDNF, rs6265), the serotonin transporter (SLC6A4, rs25531), the tryptophan hydroxylase 1 (TPH1, rs1800532), the 5-hydroxytryptamine receptor 2A (HTR2A, rs6311, rs6313, rs7997012), and the catechol-O-methyltransferase (COMT, rs4680) genes, are associated with efficacy of transcranial direct current stimulation (tDCS) in major depression. Methods: Data from the Escitalopram vs. Electrical Current Therapy for Treating Depression Clinical Study (ELECT-TDCS) were used. Participants were antidepressant-free at baseline and presented with an acute, moderate-to-severe unipolar depressive episode. They were randomized to receive escitalopram/tDCS-sham (n=75), tDCS/placebo-pill (n=75), or placebo-pill/sham-tDCS (n=45). General linear models assessed the interaction between treatment group and allele-wise carriers. Additional analyses were performed for each group and each genotype separately. Results: Pairwise group comparisons (tDCS vs. placebo, tDCS vs. escitalopram, and escitalopram vs. placebo) did not identify alleles associated with depression improvement. In addition, exploratory analyses also did not identify any SNP unequivocally associated with improvement of depression in any treatment group. Conclusion: Larger, combined datasets are necessary to identify candidate genes for tDCS response.

Frontiers and Progress in Neuro-Biomechanical Ergogenic Technology / 医用生物力学

In recent years, the effects of the neuro-biomechanical ergogenic technology on improving and enhancing human function and physical movement performance have widely attracted certain attentions. This review summarized the recent achievements in the effects of non-invasive brain stimulation (NIBS) and biomechanical ergogenic technology based on sports equipment on human physical performance, and further explored the possible mechanisms for improving and promoting human physical performance. The obtained preliminary evidence based on animal experiments and biomechanical researches on neuromotor control under multi-joint movement were also summarized, so as to explain the coordinated development of human function enhancement at cerebral cortex regulation and neuromuscular coordinated control levels, and interpret its integration with sports equipment. This review ultimately provided certain references for the future frontier development and research position of neuro-biomechanics and human sports biomechanics.

Transcranial Direct Current Stimulation in ADHD: A Systematic Review of Efficacy, Safety, and Protocol-induced Electrical Field Modeling Results / 神经科学通报·英文版

Transcranial direct current stimulation (tDCS) is a promising method for altering cortical excitability with clinical implications. It has been increasingly used in neurodevelopmental disorders, especially attention-deficit hyperactivity disorder (ADHD), but its efficacy (based on effect size calculations), safety, and stimulation parameters have not been systematically examined. In this systematic review, we aimed to (1) explore the effectiveness of tDCS on the clinical symptoms and neuropsychological deficits of ADHD patients, (2) evaluate the safety of tDCS application, especially in children with ADHD, (3) model the electrical field intensity in the target regions based on the commonly-applied and effective versus less-effective protocols, and (4) discuss and propose advanced tDCS parameters. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses approach, a literature search identified 14 empirical experiments investigating tDCS effects in ADHD. Partial improving effects of tDCS on cognitive deficits (response inhibition, working memory, attention, and cognitive flexibility) or clinical symptoms (e.g., impulsivity and inattention) are reported in 10 studies. No serious adverse effects are reported in 747 sessions of tDCS. The left and right dorsolateral prefrontal cortex are the regions most often targeted, and anodal tDCS the protocol most often applied. An intensity of 2 mA induced stronger electrical fields than 1 mA in adults with ADHD and was associated with significant behavioral changes. In ADHD children, however, the electrical field induced by 1 mA, which is likely larger than the electrical field induced by 1 mA in adults due to the smaller head size of children, was sufficient to result in significant behavioral change. Overall, tDCS seems to be a promising method for improving ADHD deficits. However, the clinical utility of tDCS in ADHD cannot yet be concluded and requires further systematic investigation in larger sample sizes. Cortical regions involved in ADHD pathophysiology, stimulation parameters (e.g. intensity, duration, polarity, and electrode size), and types of symptom/deficit are potential determinants of tDCS efficacy in ADHD. Developmental aspects of tDCS in childhood ADHD should be considered as well.

Transcranial Direct Current Stimulation in ADHD: A Systematic Review of Efficacy, Safety, and Protocol-induced Electrical Field Modeling Results / 神经科学通报·英文版

Transcranial direct current stimulation (tDCS) is a promising method for altering cortical excitability with clinical implications. It has been increasingly used in neurodevelopmental disorders, especially attention-deficit hyperactivity disorder (ADHD), but its efficacy (based on effect size calculations), safety, and stimulation parameters have not been systematically examined. In this systematic review, we aimed to (1) explore the effectiveness of tDCS on the clinical symptoms and neuropsychological deficits of ADHD patients, (2) evaluate the safety of tDCS application, especially in children with ADHD, (3) model the electrical field intensity in the target regions based on the commonly-applied and effective versus less-effective protocols, and (4) discuss and propose advanced tDCS parameters. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses approach, a literature search identified 14 empirical experiments investigating tDCS effects in ADHD. Partial improving effects of tDCS on cognitive deficits (response inhibition, working memory, attention, and cognitive flexibility) or clinical symptoms (e.g., impulsivity and inattention) are reported in 10 studies. No serious adverse effects are reported in 747 sessions of tDCS. The left and right dorsolateral prefrontal cortex are the regions most often targeted, and anodal tDCS the protocol most often applied. An intensity of 2 mA induced stronger electrical fields than 1 mA in adults with ADHD and was associated with significant behavioral changes. In ADHD children, however, the electrical field induced by 1 mA, which is likely larger than the electrical field induced by 1 mA in adults due to the smaller head size of children, was sufficient to result in significant behavioral change. Overall, tDCS seems to be a promising method for improving ADHD deficits. However, the clinical utility of tDCS in ADHD cannot yet be concluded and requires further systematic investigation in larger sample sizes. Cortical regions involved in ADHD pathophysiology, stimulation parameters (e.g. intensity, duration, polarity, and electrode size), and types of symptom/deficit are potential determinants of tDCS efficacy in ADHD. Developmental aspects of tDCS in childhood ADHD should be considered as well.

Transcranial direct current stimulation (tDCS) effects on traumatic brain injury (TBI) recovery: A systematic review / Efeitos da estimulação transcraniana por corrente contínua (ETCC) na recuperação do traumatismo cranioencefálico (TCE): uma revisão sistemática

ABSTRACT. Traumatic brain injury (TBI) is a major cause of chronic disability. Less than a quarter of moderate and severe TBI patients improved in their cognition within 5 years. Non-invasive brain stimulation, including transcranial direct current stimulation (tDCS), may help neurorehabilitation by boosting adaptive neuroplasticity and reducing pathological sequelae following TBI. Methods: we searched MEDLINE/PubMed and Web of Science databases. We used Jadad scale to assess methodological assumptions. Results: the 14 papers included reported different study designs; 2 studies were open-label, 9 were crossover randomized clinical trials (RCTs), and 3 were parallel group RCTs. Most studies used anodal tDCS of the left dorsolateral prefrontal cortex, but montages and stimulation parameters varied. Multiple studies showed improved coma recovery scales in disorders of consciousness, and improved cognition on neuropsychological assessments. Some studies showed changes in neurophysiologic measures (electroencephalography (EEG) and transcranial magnetic stimulation (TMS), correlating with clinical findings. The main methodological biases were lack of blinding and randomization reports. Conclusion: tDCS is a safe, non-invasive neuromodulatory technique that can be given as monotherapy but may be best combined with other therapeutic strategies (such as cognitive rehabilitation and physical therapy) to further improve clinical cognitive and motor outcomes. EEG and TMS may help guide research due to their roles as biomarkers for neuroplasticity.

RESUMO. A lesão cerebral traumática (TCE) é uma das principais causas de incapacidade crônica. Menos de um quarto dos pacientes com TCE moderada e grave melhoraram sua cognição dentro de cinco anos. A estimulação cerebral não invasiva, incluindo a estimulação transcraniana por corrente contínua (ETCC), pode ajudar na reabilitação neurológica, aumentando a neuroplasticidade adaptativa e reduzindo as sequelas patológicas após o TCE. Métodos: pesquisamos os bancos de dados MEDLINE / PubMed e Web of Science. Usamos a escala de Jadad para avaliar os métodos utilizados nos ensaios clínicos. Resultados: os 14 artigos incluídos relataram diferentes desenhos de estudo; 2 estudos foram abertos, 9 foram ensaios clínicos randomizados (ECRs) cruzados e 3 foram ECR de grupos paralelos. A maioria dos estudos utilizou a ETCC anódica do córtex pré-frontal dorsolateral esquerdo, mas os parâmetros de montagem e estimulação variaram. Múltiplos estudos mostraram melhoras nas escalas de recuperação de coma em pacientes com distúrbios da consciência e melhora da cognição. Alguns estudos mostraram alterações nas medidas neurofisiológicas (eletroencefalografia (EEG) e estimulação magnética transcraniana (EMT)), correlacionando com os achados clínicos. Os principais vieses metodológicos foram a falta de relatos de cegamento e randomização. Conclusão: a ETCC é uma técnica neuromodulatória segura e não invasiva que pode ser administrada em monoterapia, mas a utilização da ETCC parece impulsionar os resultados clínicos quando combinada com outras estratégias terapêuticas (como reabilitação cognitiva e fisioterapia). O EEG e o EMT podem ajudar a orientar a pesquisa e tambem mensurar os ganhos clínicos por serem potenciais biomarcadores da neuroplasticidade.

Application of non-invasive brain stimulation techniques in decision-making behavior / 中华行为医学与脑科学杂志

Non-invasive brain stimulation techniques,including transcranial direct current stimula-tion (TDCS) and transcranial magnetic stimulation (TMS),are safe and non-invasive techniques,which can change the local excitability of the brain. The application of these techniques in the field of psychology,espe-cially decision making,has developed rapidly. These techniques provide the researchers a new perspective to study how people make decisions and to explore the neural mechanisms behind decision-making behaviors. This paper reviews the studies of non-invasive brain stimulation techniques in the field of different decision-making behaviors (risky choice,intertemporal choice and social decision-making) and the problems existing in the current studies,and puts forward some possible solutions.

Effect of Anodal Transcranial Direct Current Stimulation over the Motor Cortex for Cognition

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that modulates cortical excitability and influences cognition. The role of the primary motor cortex (M1) in cognition is controversial. Here, we investigated the offline effects of anodal and sham tDCS over M1 on cognitive tasks that require comparable motor skills, but different levels of working memory and attention. Twenty healthy young female adults received anodal tDCS and sham tDCS to the M1 on two separate testing days in a counter balanced order. The cognitive functions outcome variables were the response time from the Attention Switching Task (AST) and Motor Screening Task (MST) tests using the Cambridge Neuropsychological Test Automated Battery before and after the anodal/sham tDCS. Anodal tDCS significantly improved AST response times from baseline in congruent and incongruent condition and MST mean correct latency (all p < 0.05). There was a significant difference for AST tasks variable include AST Switching cost (mean, correct), AST Mean correct latency, in congruent, incongruent, blocks 3, 5 (non-switching blocks), block 7 (switching block) (p < 0.01) and MST mean latency (p < 0.05) between anodal and sham conditions. These results indicate that tDCS is a promising tool to an improvement in response time in task related attention and motor speed. However, this study warrants further research to determine the long-term effect on other cognitive functions and in different age and gender groups.

Progress of transcranial direct current stimulation for treatment of obsessive-compulsive disorder / 上海交通大学学报（医学版）

Obsessive-compulsive disorder is a disabling disease with symptoms of repeated and persistent unwanted intrusive thoughts and compulsive behaviors. The current first-line treatment methods mainly include psychopharmacology, psychotherapy, and the combination of both, but nearly 40% patients still show no response to conventional treatment. Among the recently developed treatments, non-invasive brain stimulation techniques, such as transcranial direct current stimulation (tDCS), are expected to alleviate the symptoms of various psychiatric disorders and improve cognitive function. tDCS has been applied to the treatment of depression, schizophrenia, generalized anxiety disorder and other mental diseases, and has achieved definite clinical effect. However, there are few studies about tDCS applying to the obsessive-compulsive disorder, especially in the number of randomized controlled trials. Most of the studies are open trials and case reports, and the results are inconsistent. By reviewing the effect of tDCS in treating obsessive-compulsive disorder patients in existing reports, the possibility of applying tDCS widely to treating obsessive-compulsive disorder in the future is analyzed.

Estimulação transcraniana por corrente contínua no autismo: uma revisão sistemática / Transcranial direct current stimulation in autism: a systematic review / Estimulación transcraneal de corriente directa en el autismo: una revisión sistemática

O transtorno do espectro autista (TEA) é caracterizado por apresentar prejuízos nas interações sociais, limitações nos comportamentos de comunicação, além de alterações comportamentais de interesses. Devido a sua complexa fisiopatologia, é imprescindível a existência de biomarcadores válidos e confiáveis para um diagnóstico e tratamento eficaz, objetivando a melhora da sintomática. A estimulação transcraniana por corrente contínua (ETCC), uma das formas de estimulação não-invasiva mais utilizadas, apresenta-se como uma técnica promissora com potenciais diagnóstico e terapêutico. Usando a metodologia PRISMA, realizamos uma revisão da contribuição e evidência científica para o uso da ETCC no TEA. Entre 43 artigos, foram identificados seis estudos relevantes. Os dados preliminares sugerem melhora nos sintomas comportamentais e cognitivos do TEA. Todavia, apesar da eficácia da ETCC, algumas divergências metodológicas foram observadas entre os artigos, trazendo a necessidade da realização de mais estudos bem desenhados e controlados para confirmar potencialidade real da ETCC no TEA.

Autism spectrum disorder (ASD) is characterized by deficits in social interactions, language and communication impairment, and highly restrictive behavioral interests. Due to its complex physiopathology, it is essential to have valid and reliable biomarkers for an effective diagnosis and treatment, aiming at the improvement of the symptomatic. Transcranial Direct Current Stimulation (tDCS), one of the most widely used forms of non-invasive stimulation, may represent a promising technique with both diagnostic and therapeutic potential. Using the PRISMA methodology, we conducted a review of the contribution and scientific evidence for the use of tDCS in ASD. Out of 43 references, we identified six relevant studies. Preliminary data suggest an improvement in the behavioral and cognitive symptoms of ASD. However, despite the efficacy of tDCS, some methodological divergences were observed among the studies, leading to the need for well-designed and controlled studies to confirm the true potential of tDCS in ASD.

El trastorno del espectro autista (TEA) es caracterizado por déficits persistentes en comunicación social, deterioro en el lenguaje y la comunicación, y patrones de comportamiento repetitivos. Debido su carácter complejo, es importante conocer los marcadores válidos para el diagnóstico y tratamiento eficaz, mejorando los síntomas. La estimulación transcraneal con corriente directa (tDCS en inglés) es una nova técnica que es una herramienta terapéutica y diagnóstica muy prometedora. Utilizando las directrices PRISMA, se realizó una revisión para ver la evidencia científica para el uso de tDCS en TEA. De los 43 artículos, se identificaron seis estudios potenciales. Los datos preliminares sugieren una mejora en los síntomas conductuales y cognitivos del TEA. Sin embargo, a pesar de la eficacia de tDCS, algunas divergencias metodológicas se observaron entre los estudios, lo que lleva a la necesidad de estudios bien diseñados y controlados para confirmar el verdadero potencial de tDCS en TEA.

Non-Invasive Brain Stimulation for Treatment of Focal Hand Dystonia: Update and Future Direction

Focal hand dystonia (FHD) is characterized by excessive and unwanted muscle activation in both the hand and arm resulting in impaired performance in particular tasks. Understanding the pathophysiology of FHD has progressed significantly for several decades and this has led to consideration of other potential therapies such as non-invasive brain stimulation (NIBS). A number of studies have been conducted to develop new therapy for FHD using transcranial magnetic stimulation and transcranial direct current stimulation. In this paper, we review previous studies and describe the potential therapeutic use of NIBS for FHD. We also discuss the future direction of NIBS to treat FHD.

Application of Transcranial Direct Current Stimulation in Psychiatry / 신경정신의학

Transcranial cranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that consists of applying a weak current over the scalp to modulate cortical excitability by facilitating or inhibiting ongoing neuronal processes. tDCS is attracting much attention among researchers and clinicians because it has a low risk and low cost, and it is simple to operate, being portable. In this review, the authors provide a summary of developmental history, technical aspects and mechanism of action of tDCS and review the current literature regarding the use of tDCS in psychiatry. Depression was the most extensively researched condition, followed by schizophrenia, substance use disorders, and obsessive-compulsive disorder. Other topics explored were child and adolescent psychiatry. This review suggested that tDCS interventions comprising multiple sessions can alleviate symptoms of several major psychiatric disorders, both acutely and in the long-term and are well tolerated and safe for patients including child and adolescent. Nevertheless, the number of publications regarding tDCS is low and randomized controlled trials are very few. Evidence from large-scale, multi-center randomized controlled trials is required to transition this technique from the laboratory to the clinic. In addition, tDCS parameters such as electrode size, dosage, and location of electrode should be investigated.

Research Progress of Melodic Intonation Therapy and Non-invasive Brain Stimulation in Aphasia after Stroke (review) / 中国康复理论与实践

@#The neuromechanism of language function recovery in patients with aphasia after stroke is still unclear. It is supported that the language function of aphasia after extensive damage of left hemisphere mainly recovered through activating the right hemisphere of ho-mologous regions to improve the function of speech. Melodic intonation therapy (MIT) can be achieved by melody tone and left hand clap to activate the right hemisphere of the frontal temporal lobe, which is particularly applicable to improve language function of non-fluent aphasia patients with large left hemisphere lesion. Non-invasive brain stimulation techniques (NBS) changes brain activity through stimulat-ing affected or contralateral side, which has been used to facilitate language functional recovery after stroke. Excitatory transcranial stimula-tion on the right hemisphere homology combined with melodic intonation therapy can promote language recovery of patients with extensive damage of left hemisphere after stroke. It is valuable to combine traditional speech training with MIT and NBS to activate related language functional areas to maximum improvement of language recovery after stroke.