Effects Of Non-invasive Brain Stimulation Research Articles

Non-invasive Brain Stimulation for Central Neuropathic Pain.

The research and clinical application of the noninvasive brain stimulation (NIBS) technique in the treatment of neuropathic pain (NP) are increasing. In this review article, we outline the effectiveness and limitations of the NIBS approach in treating common central neuropathic pain (CNP). This article summarizes the research progress of NIBS in the treatment of different CNPs and describes the effects and mechanisms of these methods on different CNPs. Repetitive transcranial magnetic stimulation (rTMS) analgesic research has been relatively mature and applied to a variety of CNP treatments. But the optimal stimulation targets, stimulation intensity, and stimulation time of transcranial direct current stimulation (tDCS) for each type of CNP are still difficult to identify. The analgesic mechanism of rTMS is similar to that of tDCS, both of which change cortical excitability and synaptic plasticity, regulate the release of related neurotransmitters and affect the structural and functional connections of brain regions associated with pain processing and regulation. Some deficiencies are found in current NIBS relevant studies, such as small sample size, difficulty to avoid placebo effect, and insufficient research on analgesia mechanism. Future research should gradually carry out large-scale, multicenter studies to test the stability and reliability of the analgesic effects of NIBS.

The effects of noninvasive brain stimulation on heart rate and heart rate variability: A systematic review and meta-analysis.

Noninvasive brain stimulation (NIBS) techniques such as transcranial magnetic stimulation and transcranial direct current stimulation are widely used to test the involvement of specific cortical regions in various domains such as cognition and emotion. Despite the capability of stimulation techniques to test causal directions, this approach has been only sparsely used to examine the cortical regulation of autonomic nervous system (ANS) functions such as heart rate (HR) and heart rate variability (HRV) and to test current models in this regard. In this preregistered (PROSPERO) systematic review and meta-analysis, we aimed to investigate, based on meta-regression, whether NIBS represents an effective method for modulating HR and HRV measures, and to evaluate whether the ANS is modulated by cortical mechanisms affected by NIBS. Here we have adhered to the PRISMA guidelines. In a series of four meta-analyses, a total of 131 effect sizes from 35 sham-controlled trials were analyzed using robust variance estimation random-effects meta-regression technique. NIBS was found to effectively modulate HR and HRV with small to medium effect sizes. Moderator analyses yielded significant differences in effects between stimulation of distinct cortical areas. Our results show that NIBS is a promising tool to investigate the cortical regulation of ANS, which may add to the existing brain imaging and animal study literature. Future research is needed to identify further factors modulating the size of effects. As many of the studies reviewed were found to be at high risk of bias, we recommend that methods to reduce potential risk of bias be used in the design and conduct of future studies.

Can we rewire criminal mind via non-invasive brain stimulation of prefrontal cortex? Insights from clinical, forensic and social cognition studies.

Non-compliance with social and legal norms and regulations represents a high burden for society. Social cognition deficits are frequently called into question to explain criminal violence and rule violations in individuals diagnosed with antisocial personality disorder (APD), borderline personality disorder (BPD), and psychopathy. In this article, we proposed to consider the potential benefits of non-invasive brain stimulation (NIBS) to rehabilitate forensic population. We focused on the effects of NIBS of the prefrontal cortex, which is central in social cognition, in modulating aggression and impulsivity in clinical disorders, as well as in forensic population. We also addressed the effect of NIBS on empathy, and theory of mind in non-clinical and/or prison population. The reviewed data provide promising evidence on the beneficial effect of NIBS on aggression/impulsivity dyscontrol and social cognitive functions, suggesting its relevance in promoting reintegration of criminals into society.

Non-invasive brain stimulation interventions for treating Clinical and Sub-clinical eating disorders: A meta-analysis of randomized controlled trials and nonrandomized studies

This meta-analysis examined the effects of noninvasive brain stimulation (NIBS) for treating eating disorders (EDs), evaluating the difference between repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS). We identified 15 studies on EDs, including 9 RCTs (266 participants) and 6 one-arm trials (59 participants). The pooled effect sizes indicated that NIBS plays a positive role in improving the eating symptoms of ED patients. Although its long-term effects need to be further explored, this treatment has the potential to be an important supplement to conventional ED therapy.

The Predictive Value of Individual Electric Field Modeling for Transcranial Alternating Current Stimulation Induced Brain Modulation.

There is considerable individual variability in the reported effectiveness of non-invasive brain stimulation. This variability has often been ascribed to differences in the neuroanatomy and resulting differences in the induced electric field inside the brain. In this study, we addressed the question whether individual differences in the induced electric field can predict the neurophysiological and behavioral consequences of gamma band tACS. In a within-subject experiment, bi-hemispheric gamma band tACS and sham stimulation was applied in alternating blocks to the participants’ superior temporal lobe, while task-evoked auditory brain activity was measured with concurrent functional magnetic resonance imaging (fMRI) and a dichotic listening task. Gamma tACS was applied with different interhemispheric phase lags. In a recent study, we could show that anti-phase tACS (180° interhemispheric phase lag), but not in-phase tACS (0° interhemispheric phase lag), selectively modulates interhemispheric brain connectivity. Using a T1 structural image of each participant’s brain, an individual simulation of the induced electric field was computed. From these simulations, we derived two predictor variables: maximal strength (average of the 10,000 voxels with largest electric field values) and precision of the electric field (spatial correlation between the electric field and the task evoked brain activity during sham stimulation). We found considerable variability in the individual strength and precision of the electric fields. Importantly, the strength of the electric field over the right hemisphere predicted individual differences of tACS induced brain connectivity changes. Moreover, we found in both hemispheres a statistical trend for the effect of electric field strength on tACS induced BOLD signal changes. In contrast, the precision of the electric field did not predict any neurophysiological measure. Further, neither strength, nor precision predicted interhemispheric integration. In conclusion, we found evidence for the dose-response relationship between individual differences in electric fields and tACS induced activity and connectivity changes in concurrent fMRI. However, the fact that this relationship was stronger in the right hemisphere suggests that the relationship between the electric field parameters, neurophysiology, and behavior may be more complex for bi-hemispheric tACS.

Repetitive Transcranial Magnetic Stimulation and Transcranial Direct Current Stimulation as Treatment of Poststroke Depression: A Systematic Review and Meta-Analysis.

Previous studies showed that the application of repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) during stroke rehabilitation improve the depression symptoms in poststroke depression (PSD). However, some studies showed inconsistent results. The study was designed to make a meta-analysis to evaluate the effect of noninvasive brain stimulation (tDCS and rTMS) on PSD. Articles published before July 2021 were searched in databases: PubMed, Web of Science, and Google Scholar. STATA 12.0 software was utilized to make meta-analysis. We extracted or calculated mean values and SD of reduction or increase rate of depression-related scales. Standardized mean difference (SMD) and 95% confidence intervals (CIs) were calculated as effect size. The study showed increased immediate and long-term improvement in depression in rTMS group compared with sham rTMS group after treatment with random-effects models (immediate: SMD=4.92, 95% CI=2.69-7.15, I2 =95.2%, P -value for Q test <0.001; long term: SMD=7.21, 95% CI=3.50-10.92, I2 =93.9%, P -value for Q test <0.001). Meta-analysis showed increased substantially immediate improvement in depression in tDCS group compared with sham tDCS group with a random effect model (SMD=5.30, 95% CI=1.30-9.30, I2 =97.3%, P- value for Q test <0.001). rTMS and tDCS were demonstrated to be effective and safe treatment techniques for PSD. More large-scale studies were essential to explore the effect of rTMS with different frequencies and tDCS on PSD.

Effects of Non-Invasive Brain Stimulation on Alzheimer's Disease.

Previous meta-analyses did not explore the immediate and long-term effect of non-invasive brain stimulation (NIBS) on different cognitive domains in Alzheimer's disease (AD). The meta-analysis aimed to assess the therapy effect of repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) on different cognitive domains in AD in randomized controlled trials (RCTs). Studies published before December 2021 and exploring therapy effect of rTMS, tDCS on different cognitive domains in AD were searched in the following databases: PubMed and Web of Science. We used STATA 12.0 software to compute the standard mean difference (SMD) and a 95% confidence interval (CI). The present study included 16 articles (including 372 AD patients treated with rTMS and 310 treated with sham rTMS) for rTMS and 11 articles (including 152 AD patients treated with tDCS and 134 treated with sham tDCS) for tDCS. The present study showed better immediate and long-term general cognitive function increase effects in AD given rTMS, compared to those given sham rTMS with random effects models (immediate effect: SMD = 2.07, 95% CI = 0.37 to 3.77, I2 = 97.8%, p < 0.001; long-term effect: SMD = 5.04, 95% CI = 2.25 to 7.84, I2 = 97.8%, p < 0.001). The present study showed no significant immediate and long-term effects of rTMS on attention, executive, language and memory functions. In addition, the present study showed no significant difference in immediate or long-term effects of tDCS on general cognitive function, attention, language or memory functions between tDCS group and sham tDCS group. RTMS was an effective treatment technique for general cognitive function in AD, whereas tDCS showed no significant therapy effect on cognitive function in AD. More large-scale studies were essential to explore the effect of NIBS on various cognitive function in AD.

Effects of non-invasive brain stimulation in multiple sclerosis: systematic review and meta-analysis.

Objective:The objective of this meta-analysis was to summarize evidence on the therapeutic effects of non-invasive brain stimulation (NIBS) on core symptoms of multiple sclerosis (MS). Specifically, findings from studies deploying transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS) protocols were summarized in this review.Methods:We systematically searched articles published in four databases, until 31 May 2021, which compared the effects of active tDCS or rTMS with sham intervention in MS patients. We used a random-effects model for this meta-analysis. Meta-regression and subgroup meta-analysis were used to examine the effects of stimulation dose and different stimulation protocols, respectively.Results:Twenty-five randomized controlled trials (RCTs) were included in this review, consisting of 19 tDCS and 6 rTMS studies. tDCS led to a significant and immediate reduction of fatigue with a large effect size (Hedges’s g = −0.870, 95% confidence intervals (CI) = [−1.225 to −0.458], number needed to treat (NNT) = 2). Particularly, a subgroup analysis showed that applying tDCS over the left DLPFC and bilateral S1 led to fatigue reductions compared to sham stimulation. Furthermore, tDCS had favorable effects on fatigue in MS patients with low physical disability but not those with high physical disability, and additionally improved cognitive function. Finally, whereas rTMS was observed to reduce muscle spasticity, these NIBS protocols showed no further effect on MS-associated pain and mood symptoms.Conclusion:tDCS in MS alleviates fatigue and improves cognitive function whereas rTMS reduces muscle spasticity. More high-quality studies are needed to substantiate the therapeutic effects of different NIBS protocols in MS.

Effects of non-invasive brain stimulation in dystonia: a systematic review and meta-analysis.

Deep brain stimulation is a highly effective treatment of dystonia but is invasive and associated with risks, such as intraoperative bleeding and infections. Previous research has used non-invasive brain stimulation (NIBS) in an attempt to alleviate symptoms of dystonia. The results of these studies, however, have been variable, leaving efficacy unclear. This study aimed to evaluate the effects of NIBS on symptoms of dystonia and determine whether methodological characteristics are associated with variability in effect size. Web of Science, Embase, and MEDLINE Complete databases were searched for articles using any type of NIBS as an intervention in dystonia patients, with changes in dystonia symptoms the primary outcome of interest. Meta-analysis of 27 studies demonstrated a small effect size for NIBS in reducing symptoms of dystonia (random-effects Hedges' g = 0.21, p = .002). Differences in the type of NIBS, type of dystonia, and brain region stimulated had a significant effect on dystonia symptoms. Meta-regression revealed that 10 sessions of active stimulation and the application of concurrent motor training programs resulted in significantly larger mean effect sizes. NIBS has yielded small improvements to dystonic symptoms, but effect sizes depended on methodological characteristics, with more sessions of stimulation producing a larger response. Future research should further investigate the application of NIBS parallel to motor training, in addition to providing a greater quantity of sessions, to help define optimal parameters for NIBS protocols in dystonia. PROSPERO 2020, CRD42020175944.

The effect of non-invasive brain stimulation on neuroplasticity in the early recovery period after ischemic stroke

Studying the different variants of NIBS influence on synaptic neuroplasticity in the early recovery period after ischemic stroke. The rehabilitation of 62 patients with PSCI syndrome after ischemic stroke outcomes were studied. The patients were assigned to 5 groups. Patients from the control group underwent standardized nootropic therapy and course sessions with a neuropsychologist. The rest of the patients were divided into 4 groups, in which, in addition to the basic program of cognitive rehabilitation, different options for the course use of NIBS were used: photochromotherapy (PCT) with narrow-band optical radiation (NOR) with a wavelength of 530 nm (green light); rhythmic transcranial magnetic stimulation (rTMS) with a low-intensity high-frequency running pulsed magnetic field; infrared radiation with a wavelength of 1-56 microns, modulated by terahertz frequencies (IRMT); bioacoustic correction (BAC). We analyzed the dynamics of changes in scores of MMSE scales, FAB, Roshchina. In order to assess the effect of NIBS on neuroplasticity, the concentrations of BDNF and antibodies to the NR2 fragment of the NMDA receptor were evaluated before and after the completion of the rehabilitation course. Concentration values of antibodies to the NR2 subunit of the NMDA receptor in all groups remained consistently above the norm (more than 2 ng/ml) throughout the entire course of rehabilitation. Differences between groups in the dynamics of BDNF concentration in the peripheral blood were revealed. There was a significant (p<0.05) decrease in its concentration by almost 2 times by the end of rehabilitation course in control group. In the rTMS and IRMT groups, a decrease in the BDNF concentration was also recorded in dynamics, which, however, did not reach a significant level. There was no decrease in BDNF levels in the BAC group. There was an increase of this level in the PCT group. The use of different types of NIBS in the program of cognitive rehabilitation of patients with PSCI syndrome contributes to an increase in the rehabilitation potential due to the activation of neurotrophin-mediated synaptic neuroplasticity. Green light PCT and BAC have the greatest effect on increasing neuroplasticity after ischemic stroke.

Chapter 15 - Noninvasive brain stimulation to augment language therapy for poststroke aphasia

Behavioral language treatment approaches represent the standard of care for persons with aphasia (PWA), but the benefits of these treatments are variable. Moreover, due to the logistic and financial limitations on the amount of behavioral therapy available to patients, it is often infeasible for PWA to receive behavioral interventions with the level of frequency, intensity, or duration that would provide significant and lasting benefit, underscoring the need for novel, effective treatment approaches. Noninvasive brain stimulation (NIBS) techniques, such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), have emerged as promising neurally-based tools to enhance language abilities for PWA following stroke. This chapter first provides an overview of the methods and physiologic basis motivating the use of NIBS to enhance aphasia recovery followed by a selective review of the growing evidence of its potential as a novel therapeutic tool. Subsequent sections discuss some of the principles that may prove most useful in guiding and optimizing the effects of NIBS on aphasia recovery, focusing on how the functional state of the brain at the time of stimulation interacts with the behavioral aftereffects of neuromodulation. We conclude with a discussion of current challenges and future directions for NIBS in aphasia treatment.

Improvement of Insight with Non-Invasive Brain Stimulation in Patients with Schizophrenia: A Systematic Review.

Patients with schizophrenia are often unaware of their condition and the consequences of their illness. This lack of insight results in impaired functioning, treatment non-adherence and poor prognosis. Here, we aimed to investigate the effects of non-invasive brain stimulation (NIBS) on two forms of insight, clinical and cognitive, in patients with schizophrenia. We conducted a systematic review of the literature registered in the PROSPERO database (CRD42020220323) according to PRISMA guidelines. The literature search was conducted in Medline and Web of Science databases based on studies published up until October 2020 that included pre-NIBS and post-NIBS measurements of clinical and/or cognitive insight in adults with schizophrenia. A total of 14 studies were finally included, and their methodological quality was assessed by using the QualSyst tool. Despite the lack of well-conducted large randomized-controlled studies using insight as the primary outcome, the available findings provide preliminary evidence that NIBS can improve clinical insight in patients with schizophrenia, with a majority of studies using transcranial direct current stimulation with a left frontotemporal montage. Further studies should investigate the effect of NIBS on insight as a primary outcome and how these effects on insight could translate into clinical and functional benefits in patients with schizophrenia.

The Role of Expectation and Beliefs on the Effects of Non-Invasive Brain Stimulation.

Non-invasive brain stimulation (NIBS) techniques are used in clinical and cognitive neuroscience to induce a mild magnetic or electric field in the brain to modulate behavior and cortical activation. Despite the great body of literature demonstrating promising results, unexpected or even paradoxical outcomes are sometimes observed. This might be due either to technical and methodological issues (e.g., stimulation parameters, stimulated brain area), or to participants’ expectations and beliefs before and during the stimulation sessions. In this narrative review, we present some studies showing that placebo and nocebo effects, associated with positive and negative expectations, respectively, could be present in NIBS trials, both in experimental and in clinical settings. The lack of systematic evaluation of subjective expectations and beliefs before and after stimulation could represent a caveat that overshadows the potential contribution of placebo and nocebo effects in the outcome of NIBS trials.

Effectiveness of noninvasive brain stimulation in the treatment of anxiety disorders: a meta-analysis of sham or behaviour-controlled studies.

Background:The possibility of using noninvasive brain stimulation to treat mental disorders has received considerable attention recently. Repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) are considered to be effective treatments for depressive symptoms. However, no treatment recommendation is currently available for anxiety disorders, suggesting that evidence is still limited. We conducted a systematic review of the literature and a quantitative analysis of the effectiveness of rTMS and tDCS in the treatment of anxiety disorders.Methods:Following PRISMA guidelines, we screened 3 electronic databases up to the end of February 2020 for English-language, peer-reviewed articles that included the following: a clinical sample of patients with an anxiety disorder, the use of a noninvasive brain stimulation technique, the inclusion of a control condition, and pre/post scores on a validated questionnaire that measured symptoms of anxiety.Results:Eleven papers met the inclusion criteria, comprising 154 participants assigned to a stimulation condition and 164 to a sham or control group. We calculated Hedge’s g for scores on disorder-specific and general anxiety questionnaires before and after treatment to determine effect size, and we conducted 2 independent random-effects meta-analyses. Considering the well-known comorbidity between anxiety and depression, we ran a third meta-analysis analyzing outcomes for depression scores. Results showed a significant effect of noninvasive brain stimulation in reducing scores on disorder-specific and general anxiety questionnaires, as well as depressive symptoms, in the real stimulation compared to the control condition.Limitations:Few studies met the inclusion criteria; more evidence is needed to strengthen conclusions about the effectiveness of noninvasive brain stimulation in the treatment of anxiety disorders.Conclusion:Our findings showed that noninvasive brain stimulation reduced anxiety and depression scores compared to control conditions, suggesting that it can alleviate clinical symptoms in patients with anxiety disorders.

Systematic Review and Network Meta-Analysis of Noninvasive Brain Stimulation on Dysphagia after Stroke.

Background Dysphagia is a common sequelae after stroke. Noninvasive brain stimulation (NIBS) is a tool that has been used in the rehabilitation process to modify cortical excitability and improve dysphagia. Objective To systematically evaluate the effect of NIBS on dysphagia after stroke and compare the effects of two different NIBS. Methods Randomized controlled trials about the effect of NIBS on dysphagia after stroke were retrieved from databases of PubMed, Embase, Cochrane Library, Web of Science, CNKI, Wanfang Data, VIP, and CBM, from inception to June 2021. The quality of the trials was assessed, and the data were extracted according to the Cochrane Handbook for Systematic Reviews of Interventions. A statistical analysis was carried out using RevMan 5.3 and ADDIS 1.16.8. The effect size was evaluated by using the standardized mean difference (SMD) and a 95% confidence interval (CI). Results Ultimately, 18 studies involving 738 patients were included. Meta-analysis showed that NIBS could improve the dysphagia outcome and severity scale (DOSS) score (standard mean difference (SMD) = 1.44, 95% CI 0.80 to 2.08, P < 0.05) and the water swallow test score (SMD = 6.23, 95% CI 5.44 to 7.03, P < 0.05). NIBS could reduce the standardized swallowing assessment (SSA) score (SMD = −1.04, 95% CI -1.50 to -0.58, P < 0.05), the penetration-aspiration scale (PAS) score (SMD = −0.85, 95% CI -1.33 to -0.36, P < 0.05), and the functional dysphagia scale score (SMD = −1.05, 95% CI -1.48 to -0.62, P < 0.05). Network meta-analysis showed that the best probabilistic ranking of the effects of two different NIBS on the DOSS score is rTMS (P = 0.52) > tDCS (P = 0.48), the best probabilistic ranking of the SSA score is rTMS (P = 0.72) > tDCS (P = 0.28), and the best probabilistic ranking of the PAS score is rTMS (P = 0.68) > tDCS (P = 0.32). Conclusion Existing evidence showed that NIBS could improve swallowing dysfunction and reduce the occurrence of aspiration after stroke, and that rTMS is better than tDCS. Limited by the number of included studies, more large-sample, multicenter, double-blind, high-quality clinical randomized controlled trials are still needed in the future to further confirm the results of this research.

The Effect of Non-Invasive Brain Stimulation (NIBS) on Executive Functioning, Attention and Memory in Rehabilitation Patients with Traumatic Brain Injury: a Systematic Review and Meta-analysis

The Effect of Non-Invasive Brain Stimulation (NIBS) on Executive Functioning, Attention and Memory in Rehabilitation Patients with Traumatic Brain Injury: a Systematic Review and Meta-analysis

Effect of non-invasive brain stimulation on lower limb function in patients after stroke: A PRISMA-compliant systematic review and meta-analysis

Background: In recent years, it is reported that non-invasive brain stimulation [including transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS)] could improve lower limb function in patients after stroke. However, some studies showed no effect. In the present study, we aimed to make a meta-analysis to assess effect of non-invasive brain stimulation on lower limb function in patients after stroke. Methods: Studies exploring the effect of tDCS or rTMS on lower limb function in patients after stroke were searched on the PubMed, Web of Science, EMBASE, Medline, Google Scholar before March 2021. Meta-analysis was made to summarize results of these studies. Results: The present study showed significantly better walking speed, mobility and muscle strength increase effect in tDCS group compared to sham tDCS group [walking speed: standard mean difference (SMD) = 1.14, 95% CI = 0.48 to 1.80, I2 = 74.0%, p value for Q test &lt; 0.001; mobility: SMD = 0.79, 95% CI = 0.21 to 1.36, I2 = 53.8%, p value for Q test = 0.043; muscle strength: SMD = 2.79, 95% CI = 0.61 to 4.98, I2 = 93.9%, p value for Q test &lt; 0.001]. In addition, meta-analysis showed significantly better walking speed, balance and motor function increase effect in rTMS group compared to sham rTMS group [walking speed: SMD = 3.31, 95% CI = 1.38 to 5.24, I2 = 92.1%, p value for Q test &lt; 0.001; balance: SMD = 3.54, 95% CI = 1.45 to 5.63, I2 = 95.4%, p value for Q test &lt; 0.001; motor function: SMD = 1.65, 95% CI = 0.53 to 2.76, I2 = 90.3%, p value for Q test &lt; 0.001]. Conclusions: This meta-analysis suggested that non-invasive brain stimulation improved lower limb function in patients after stroke. More large scale, blinded RCTs were necessary to confirm the effect of rTMS and tDCS on lower limb function in patients after stroke.

Effects of non-invasive brain stimulation on visual perspective taking: A meta-analytic study

Visual perspective taking (VPT) is a critical ability required by complex social interaction. Non-invasive brain stimulation (NIBS) has been increasingly used to examine the causal relationship between brain activity and VPT, yet with heterogeneous results. In the current study, we conducted two meta-analyses to examine the effects of NIBS of the right temporoparietal junction (rTPJ) or dorsomedial prefrontal cortex (dmPFC) on VPT, respectively. We performed a comprehensive literature search to identify qualified studies and computed the standardized effect size (ES) for each combination of VPT level (Level-1: visibility judgment; Level-2: mental rotation) and perspective (self and other). Thirteen studies (rTPJ: 12 studies, 23 ESs; dmPFC: 4 studies, 14 ESs) were included in the meta-analyses. Random-effects models were used to generate the overall effects. Subgroup analyses for distinct VPT conditions were also performed. We found that rTPJ stimulation significantly improved participants' visibility judgment from the allocentric perspective, whereas its effects on other VPT conditions are negligible. Stimulation of dmPFC appeared to influence Level-1 performance from the egocentric perspective, although this finding was only based on a small number of studies. Notably, contrary to some theoretical models, we did not find strong evidence that these regions are involved in Level-2 VPT with a higher requirement of mental rotation. These findings not only advance our understanding of the causal roles of the rTPJ and dmPFC in VPT, but also reveal that the efficacy of NIBS on VPT is relatively small. Additionally, researchers should also be cautious about the potential publication bias and selective reporting.

Symposium (SY) Symposium 1: Non-invasive brain stimulation SY1.1. The effects of non-invasive brain stimulation and neuroplasticity

The recent development of non-invasive brain stimulation (NIBS) techniques, e.g. repetitive transcranial magnetic stimulation (rTMS) and transcranial direct/alternating current stimulation, are capable of suppress or enhance the brain excitability outlasting the period of stimulation for up to one hour or more. These protocols mimic the repetitive or constant electrical stimulation that is commonly used to change the synaptic efficiency forming the basic concept of synaptic plasticity mechanism in animal brain slices. Neuroplasticity or plasticity is generally believed as the fundamental mechanism of many aspects of brain function, e.g. learning, memory and recovery. Several lines of evidence based on pharmacological physiological and behavioural studies in humans and protein analysis in animals have confirmed that the after effects of NIBS are induced through a plasticity-like mechanisms. In this talk, the basic concept of plasticity will be introduced and how the effects of NIBS are linked to the mechanisms of plasticity will be explained. The audience will understand how NIBS works on the brain and how to design their applications of NIBS based on the knowledge.

P 18. Transcranial direct current stimulation reverses stroke-induced network alterations in mice

Introduction. Transcranial direct current stimulation (tDCS) non-invasively modulates cortical function. We and others reported that tDCS could promote recovery after stroke ( Braun et al., Exp. Neurol., 2016; Hummel et al., Brain, 2005 ). As a stroke affects entire networks, an aspect long neglected in translational research, we recently established a resting-state functional magnetic resonance imaging (rs-fMRI) protocol to detect similar network alterations in both rodent and human stroke ( Blaschke et al., under review ). We here investigated whether rs-fMRI can validate the efficacy of tDCS in altering functional connectivity after experimental stroke. Methods. Focal cortical stroke was induced via photothrombosis in male C57Bl/6J mice. Three days thereafter, cathodal tDCS over the lesioned sensory-motor cortex was applied for 15 minutes each day for ten days (charge density of 39600 C/m 2 ). Longitudinal assessment of functional connectivity as measured by rs-fMRI was performed for up to 28 days post-stroke using a 9.4 T Bruker small animal scanner. Images were registered to the Allen Mouse Brain Atlas to derive seed regions for graph-based analysis and global graph parameters of network integration (characteristic path length, CPL) and segregation (clustering coefficient, CC) were computed over a sparse density range (10 – 30 % density), mimicking the brains“ functional structure. Additionally, a multiple linear regression was fitted to predict motor recovery based on initial network alteration, initial motor deficit, and tDCS treatment on motor recovery. Results. Ischemia induced an increase in connectivity. Already detectable three days after stroke, effects peaked at day 14, and spontaneously declined by day 28. Moreover, there was a significant reduction in characteristic path length (CPL) 14 days after stroke (p < 0.01). Intriguingly, ten days of cathodal tDCS treatment reversed the ischemia-induced hyperconnectivity, with reversal of ischemia-induced reduction in CPL ( p < 0.05). Networks effect correlated to tDCS accelerated motor recovery within the observation period. On the individual level, multiple linear regression model (F (3,22) = 11.1, p < 0.001, adjusted R 2 = .54) revealed, that - besides the initial motor deficit ( p < 0.01) - functional network alteration ( p < 0.01) and the treatment with tDCS ( p < 0.01) significantly improved prediction of motor recovery after stroke. Conclusion. Stroke induces characteristic network changes that can be detected by rs-fMRI. Importantly, these network changes can, at least in part, be reversed by tDCS. Besides, the data suggest that early markers of network impairment improve the prediction of motor recovery. Overall, the data suggest that the characterization of functional connectivity by rs-fMRI is a powerful tool to analyze global changes after experimental stroke and to assess the therapeutic effects of non-invasive brain stimulation in preclinical studies.