The Efficacy of Transcranial Direct Current Stimulation in Enhancing Surgical Skill Acquisition: A Preliminary Meta-Analysis of Randomized Controlled Trials

The Efficacy and Acceptability of Non-Invasive Brain Stimulation Interventions for Obsessive-Compulsive Disorder Management: A Network Meta-Analysis Based on 24 Stimulation Methods

INTRODUCTION

Despite the high lifetime prevalence and elevated disability rates, treatments for obsessive-compulsive disorder (OCD) have limited efficacy. Considering the abnormal connectivity in the cortical-striatal-thalamic-cortical loop circuits in OCD, several randomized controlled trials (RCTs) have addressed the efficacy of different non-invasive brain stimulation (NIBS) modalities for the management of OCD. However, these RCTs yielded inconclusive results.

METHODS

This network meta-analysis (NMA) included RCTs of NIBS interventions, such as transcranial direct current stimulation (tDCS) and various repetitive transcranial magnetic stimulation (rTMS), in OCD patients. The primary outcomes were changes in the overall severity of OCD and acceptability (i.e., dropout rates).

RESULTS

This NMA of 34 eligible RCTs (1089 participants) and 24 different NIBS interventions revealed that three NIBS interventions significantly improved overall OCD severity compared with sham controls, which were high-frequency rTMS over the dorsolateral prefrontal cortex (DLPFC) [mean difference (MD) = -10.81, 95% confidence intervals (95% CIs) = -20.80 to -0.82], high-frequency deep TMS over the dorsal medial prefrontal cortex/anterior cingulate cortex (dmPFC/ACC) (MD = -9.74, 95% CIs = -16.42 to -3.06), and low-frequency rTMS over the right DLPFC (MD = -4.70, 95% CIs = -8.84 to -0.57).

CONCLUSIONS

This study highlighted that excitatory stimulation over the dmPFC/ACC and bilateral DLPFC, or inhibitory stimulation over the right DLPFC, was associated with significant improvements in overall OCD severity. Further large-scale RCTs with longer follow-up periods are needed to investigate the true impact of NIBS-based intervention to manage OCD.

TRIAL REGISTRATION

PROSPERO: CRD42023394953.

Efficacy and acceptability of noninvasive brain stimulation for treating posttraumatic stress disorder symptoms: A network meta-analysis of randomized controlled trials

INTRODUCTION

Despite its high lifetime prevalence rate and the elevated disability caused by posttraumatic stress disorder (PTSD), treatments exhibit modest efficacy. In consideration of the abnormal connectivity between the dorsolateral prefrontal cortex (DLPFC) and amygdala in PTSD, several randomized controlled trials (RCTs) addressing the efficacy of different noninvasive brain stimulation (NIBS) modalities for PTSD management have been undertaken. However, previous RCTs have reported inconsistent results. The current network meta-analysis (NMA) aimed to compare the efficacy and acceptability of various NIBS protocols in PTSD management.

METHODS

We systematically searched ClinicalKey, Cochrane Central Register of Controlled Trials, Embase, ProQuest, PubMed, ScienceDirect, Web of Science, and ClinicalTrials.gov to identify relevant RCTs. The targeted RCTs was those comparing the efficacy of NIBS interventions, such as transcranial direct current stimulation (tDCS), repetitive transcranial magnetic stimulation (rTMS), and transcutaneous cervical vagal nerve stimulation, in patients with PTSD. The NMA was conducted using a frequentist model. The primary outcomes were changes in the overall severity of PTSD and acceptability (to be specific, rates of dropouts for any reason).

RESULTS

We identified 14 RCTs that enrolled 686 participants. The NMA demonstrated that among the investigated NIBS types, high-frequency rTMS over bilateral DLPFCs was associated with the greatest reduction in overall PTSD severity. Further, in comparison with the sham controls, excitatory stimulation over the right DLPFC with/without excitatory stimulation over left DLPFC were associated with significant reductions in PTSD-related symptoms, including depression and anxiety symptoms, and overall PTSD severity.

CONCLUSIONS

This NMA demonstrated that excitatory stimulation over the right DLPFC with or without excitatory stimulation over left DLPFC were associated with significant reductions in PTSD-related symptoms.

TRIAL REGISTRATION

PROSPERO CRD42023391562.

Anodal M1 tDCS enhances online learning of rhythmic timing videogame skill

Transcranial direct current stimulation (tDCS) has been shown to modify excitability of the primary motor cortex (M1) and influence online motor learning. However, research on the effects of tDCS on motor learning has focused predominantly on simplified motor tasks. The purpose of the present study was to investigate whether anodal stimulation of M1 over a single session of practice influences online learning of a relatively complex rhythmic timing video game. Fifty-eight healthy young adults were randomized to either a-tDCS or SHAM conditions and performed 2 familiarization blocks, a 20-minute 5 block practice period while receiving their assigned stimulation, and a post-test block with their non-dominant hand. To assess performance, a performance index was calculated that incorporated timing accuracy elements and incorrect key inputs. The results showed that M1 a-tDCS enhanced the learning of the video game based skill more than SHAM stimulation during practice, as well as overall learning at the post-test. These results provide evidence that M1 a-tDCS can enhance acquisition of skills where quality or success of performance depends on optimized timing between component motions of the skill, which could have implications for the application of tDCS in many real-world contexts.

Brain-behavior analysis of transcranial direct current stimulation effects on a complex surgical motor task

Transcranial Direct Current Stimulation (tDCS) has demonstrated its potential in enhancing surgical training and performance compared to sham tDCS. However, optimizing its efficacy requires the selection of appropriate brain targets informed by neuroimaging and mechanistic understanding. Previous studies have established the feasibility of using portable brain imaging, combining functional near-infrared spectroscopy (fNIRS) with tDCS during Fundamentals of Laparoscopic Surgery (FLS) tasks. This allows concurrent monitoring of cortical activations. Building on these foundations, our study aimed to explore the multi-modal imaging of the brain response using fNIRS and electroencephalogram (EEG) to tDCS targeting the right cerebellar (CER) and left ventrolateral prefrontal cortex (PFC) during a challenging FLS suturing with intracorporeal knot tying task. Involving twelve novices with a medical/premedical background (age: 22-28 years, two males, 10 females with one female with left-hand dominance), our investigation sought mechanistic insights into tDCS effects on brain areas related to error-based learning, a fundamental skill acquisition mechanism. The results revealed that right CER tDCS applied to the posterior lobe elicited a statistically significant (q < 0.05) brain response in bilateral prefrontal areas at the onset of the FLS task, surpassing the response seen with sham tDCS. Additionally, right CER tDCS led to a significant (p < 0.05) improvement in FLS scores compared to sham tDCS. Conversely, the left PFC tDCS did not yield a statistically significant brain response or improvement in FLS performance. In conclusion, right CER tDCS demonstrated the activation of bilateral prefrontal brain areas, providing valuable mechanistic insights into the effects of CER tDCS on FLS peformance. These insights motivate future investigations into the effects of CER tDCS on error-related perception-action coupling through directed functional connectivity studies.

Anodal cerebellar t-DCS impacts skill learning and transfer on a robotic surgery training task

The cerebellum has demonstrated a critical role during adaptation in motor learning. However, the extent to which it can contribute to the skill acquisition of complex real-world tasks remains unclear. One particularly challenging application in terms of motor activities is robotic surgery, which requires surgeons to complete complex multidimensional visuomotor tasks through a remotely operated robot. Given the need for high skill proficiency and the lack of haptic feedback, there is a pressing need for understanding and improving skill development. We investigated the effect of cerebellar transcranial direct current stimulation applied during the execution of a robotic surgery training task. Study participants received either real or sham stimulation while performing a needle driving task in a virtual (simulated) and a real-world (actual surgical robot) setting. We found that cerebellar stimulation significantly improved performance compared to sham stimulation at fast (more demanding) execution speeds in both virtual and real-world training settings. Furthermore, participants that received cerebellar stimulation more effectively transferred the skills they acquired during virtual training to the real world. Our findings underline the potential of non-invasive brain stimulation to enhance skill learning and transfer in real-world relevant tasks and, more broadly, its potential for improving complex motor learning.

M1 transcranial direct current stimulation augments laparoscopic surgical skill acquisition

The acquisition of basic surgical skills is a key component of medical education and trainees in laparoscopic surgery typically begin developing their skills using simulation box trainers. However, despite the advantages of simulation surgical training, access can be difficult for many trainees. One technique that has shown promise to enhance the deliberate practice of motor skills is transcranial electric stimulation (tES). The purpose of this study was to assess the impact of transcranial direct current stimulation (tDCS) on training induced improvements and retention of traditional time and kinematic based laparoscopic surgical skill metrics. Forty-nine medical students were randomly allocated to a neurostimulation or sham group and completed 5 training sessions of a bead transfer and threading laparoscopic task. Participants in both the sham and stimulation groups significantly improved their time and kinematic performance on both tasks following training. Although we did find that participants who received M1 tDCS saw greater performance benefits in response to training on a bead transfer task compared to those receiving sham stimulation no effect of neurostimulation was found for the threading task. This finding raises new questions regarding the effect that motor task complexity has on the efficacy of neurostimulation to augment training induced improvement and contributes to a growing body of research investigating the effects of neurostimulation on the sensory-motor performance of laparoscopic surgical skill.

Optical neuroimaging and neurostimulation in surgical training and assessment: A state-of-the-art review

Introduction

Functional near-infrared spectroscopy (fNIRS) is a non-invasive optical neuroimaging technique used to assess surgeons' brain function. The aim of this narrative review is to outline the effect of expertise, stress, surgical technology, and neurostimulation on surgeons' neural activation patterns, and highlight key progress areas required in surgical neuroergonomics to modulate training and performance.

Methods

A literature search of PubMed and Embase was conducted to identify neuroimaging studies using fNIRS and neurostimulation in surgeons performing simulated tasks.

Results

Novice surgeons exhibit greater haemodynamic responses across the pre-frontal cortex than experts during simple surgical tasks, whilst expert surgical performance is characterized by relative prefrontal attenuation and upregulation of activation foci across other regions such as the supplementary motor area. The association between PFC activation and mental workload follows an inverted-U shaped curve, activation increasing then attenuating past a critical inflection point at which demands outstrip cognitive capacity Neuroimages are sensitive to the impact of laparoscopic and robotic tools on cognitive workload, helping inform the development of training programs which target neural learning curves. FNIRS differs in comparison to current tools to assess proficiency by depicting a cognitive state during surgery, enabling the development of cognitive benchmarks of expertise. Finally, neurostimulation using transcranial direct-current-stimulation may accelerate skill acquisition and enhance technical performance.

Conclusion

FNIRS can inform the development of surgical training programs which modulate stress responses, cognitive learning curves, and motor skill performance. Improved data processing with machine learning offers the possibility of live feedback regarding surgeons' cognitive states during operative procedures.

Multiple comparison of different noninvasive brain stimulation and pharmacologic interventions in patients with methamphetamine use disorders: A network meta-analysis of randomized controlled trials

AIM

In recent decades, the prevalence of amphetamine and methamphetamine use disorders has at least doubled in some regions/countries, with accompanying high risks of drug overdose-associated mortality. Noninvasive brain stimulation (NIBS) methods may be effective treatments. However, the comparative efficacy of the NIBS protocol for amphetamine/methamphetamine use disorder (AUD/MUD) remains unknown to date. The aim of this network meta-analysis (NMA) was to compare the efficacy and acceptability of various NIBS methods/protocols for AUD/MUD management.

METHODS

A frequentist model-based NMA was conducted. We included randomized controlled trials (RCTs) that investigated the efficacy of NIBS and guideline-recommended pharmacologic treatments to reduce craving severity in patients with either AUD or MUD.

RESULTS

Twenty-two RCTs including 1888 participants met the eligibility criteria. Compared with the sham/placebo group (study = 19, subjects = 891), a combination of intermittent theta burst stimulation over the left dorsolateral prefrontal cortex (DLPFC) and continuous TBS over the left ventromedial prefrontal cortex (study = 1, subjects = 19) was associated with the largest decreases in craving severity [standardized mean difference (SMD) = -1.50; 95% confidence intervals (95%CIs) = -2.70 to -0.31]. High-frequency repetitive transcranial magnetic stimulation over the left DLPFC was associated with the largest improvements in depression and quality of sleep (study = 3, subjects = 86) (SMD = -2.48; 95%CIs = -3.25 to -1.71 and SMD = -2.43; 95%CIs = -3.38 to -1.48, respectively). The drop-out rate of most investigated treatments did not significantly differ between groups.

CONCLUSION

The combined TBS protocol over the prefrontal cortex was associated with the greatest improvement in craving severity. Since few studies were available for inclusion, additional large-scale randomized controlled trials are warranted.

Non-invasive brain stimulation for smoking cessation: a systematic review and meta-analysis

BACKGROUND AND AIMS

Non-invasive brain stimulation (NIBS) methods have showed promising results for the treatment of tobacco use disorder, but little is known about the efficacy of NIBS on sustained tobacco abstinence. We aimed to assess its effectiveness for long-term smoking cessation.

METHODS

Systematic review and meta-analysis of randomized controlled trials (RCT). PubMed, Cochrane library, Embase, PsycINFO and clinical trials registries were systematically searched for relevant studies up to May 2021. Relevant studies included adult smokers seeking smoking cessation, included in an RCT using NIBS [specifically repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS)], and with follow-up of more than 4 weeks. There were no restrictions on location. Abstinence rates in the active NIBS groups were compared with abstinence rates in sham NIBS or in usual treatment groups, from 4 weeks to 12 months following the quit attempt. Smoking abstinence was measured on an intention-to-treat basis and we used risk ratios (RRs) as measures of effect size.

RESULTS

Seven studies were included (n = 699 patients). In all included studies, the control groups were receiving sham NIBS and only data from 3 to 6 months were analysable. By pooling the seven included studies, the RR of sustained abstinence of any form of NIBS relative to sham NIBS was 2.39 [95% confidence interval (CI) = 1.26-4.55; I²  = 40%]. Subgroup analyses found that the RR was even higher when excitatory rTMS was used on the left dorsolateral prefrontal cortex (RR = 4.34; 95% CI = 1.69-11.18; I²  = 0%) or when using deep rTMS targeting the lateral prefrontal cortex and insula bilaterally (RR = 4.64; 95% CI = 1.61-13.39; I²  = 0%). A high risk of bias was found in four included studies. We also determined, using grades of recommendation, assessment, development and evaluation, that overall there was a low level of confidence in the results.

CONCLUSION

Non-invasive brain stimulation (NIBS) may improve smoking abstinence rates from 3 to 6 months after quitting smoking, compared with sham NIBS or usual treatment.

Assessment of Noninvasive Brain Stimulation Interventions for Negative Symptoms of Schizophrenia: A Systematic Review and Network Meta-analysis

IMPORTANCE

Negative symptoms have a detrimental impact on functional outcomes and quality of life in people with schizophrenia, and few therapeutic options are considered effective for this symptomatic dimension. Studies have suggested that noninvasive brain stimulation (NIBS) interventions may be effective in treating negative symptoms. However, the comparative efficacy of different NIBS protocols for relieving negative symptoms remains unclear.

OBJECTIVE

To compare the efficacy and acceptability of different NIBS interventions for treating negative symptoms.

DATA SOURCES

The ClinicalKey, Cochrane CENTRAL, Embase, ProQuest, PubMed, ScienceDirect, ClinicalTrials.gov, and Web of Science electronic databases were systematically searched from inception through December 7, 2021.

STUDY SELECTION

A frequentist model network meta-analysis was conducted to assess the pooled findings of trials that evaluated the efficacy of repetitive transcranial magnetic stimulation (rTMS), theta-burst stimulation, transcranial random noise stimulation, transcutaneous vagus nerve stimulation, and transcranial direct current stimulation on negative symptoms in schizophrenia. Randomized clinical trials (RCTs) examining NIBS interventions for participants with schizophrenia were included.

DATA EXTRACTION AND SYNTHESIS

The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline was followed. Data were independently extracted by multiple observers. The pair-wise meta-analytic procedures were conducted using a random-effects model.

MAIN OUTCOMES AND MEASURES

The coprimary outcomes were changes in the severity of negative symptoms and acceptability (ie, dropout rates owing to any reason). Secondary outcomes were changes in positive and depressive symptoms.

RESULTS

Forty-eight RCTs involving 2211 participants (mean [range] age, 38.7 [24.0-57.0] years; mean [range] proportion of female patients, 30.6% [0%-70.0%]) were included. Compared with sham control interventions, excitatory NIBS strategies (standardized mean difference [SMD]: high-definition transcranial random noise stimulation, -2.19 [95% CI, -3.36 to -1.02]; intermittent theta-burst stimulation, -1.32 [95% CI, -1.88 to -0.76]; anodal transcranial direct current stimulation, -1.28 [95% CI, -2.55 to -0.02]; high-frequency rTMS, -0.43 [95% CI, -0.68 to -0.18]; extreme high-frequency rTMS, -0.45 [95% CI, -0.79 to -0.12]) over the left dorsolateral prefrontal cortex with or without other inhibitory stimulation protocols in the contralateral regions of the brain were associated with significantly larger reductions in negative symptoms. Acceptability did not significantly differ between the groups.

CONCLUSIONS AND RELEVANCE

In this network meta-analysis, excitatory NIBS protocols over the left dorsolateral prefrontal cortex were associated with significantly large improvements in the severity of negative symptoms. Because relatively few studies were available for inclusion, additional well-designed, large-scale RCTs are warranted.

Effectiveness and acceptability of noninvasive brain and nerve stimulation techniques for migraine prophylaxis: a network meta-analysis of randomized controlled trials

BACKGROUND

Current pharmacologic prophylactic strategies for migraine have exhibited limited efficacy, with response rates as low as 40%-50%. In addition to the limited efficacy, the acceptability of those pharmacologic prophylactic strategies were unacceptable. Although noninvasive brain/nerve stimulation strategies may be effective, the evidence has been inconsistent. The aim of this network meta-analysis (NMA) was to compare strategies of noninvasive brain/nerve stimulation for migraine prophylaxis with respect to their effectiveness and acceptability.

METHODS

The PubMed, Embase, ScienceDirect, ProQuest, ClinicalTrials.gov , ClinicalKey, Cochrane CENTRAL, Web of Science, and ClinicalTrials.gov databases were systematically searched to date of June 4th, 2021 for randomized controlled trials (RCTs). Patients with diagnosis of migraine, either episodic migraine or chronic migraine, were included. All NMA procedures were conducted under the frequentist model.

RESULTS

Nineteen RCTs were included (N = 1493; mean age = 38.2 years; 82.0% women). We determined that the high frequency repetitive transcranial magnetic stimulation (rTMS) over C3 yielded the most decreased monthly migraine days among all the interventions [mean difference = - 8.70 days, 95% confidence intervals (95%CIs): - 14.45 to - 2.95 compared to sham/control groups]. Only alternating frequency (2/100 Hz) transcutaneous occipital nerve stimulation (tONS) over the Oz (RR = 0.36, 95%CIs: 0.16 to 0.82) yielded a significantly lower drop-out rate than the sham/control groups did.

CONCLUSIONS

The current study provided a new direction for the design of more methodologically robust and larger RCTs based on the findings of the potentially beneficial effect on migraine prophylaxis in participants with migraine by different noninvasive brain/nerve stimulation, especially the application of rTMS and tONS.

TRIAL REGISTRATION

CRD42021252638. The current study had been approval by the Institutional Review Board of the Tri-Service General Hospital, National Defense Medical Center (TSGHIRB No. B-109-29).

Neural correlates of working memory function in euthymic people with bipolar disorder compared to healthy controls: A systematic review and meta-analysis

BACKGROUND

Bipolar disorders (BD) are serious mental health disorders that impacts on cognitive and social functioning. We aimed to systematically review and conduct a meta-analysis of fMRI correlates of working memory in euthymic people with BD compared to healthy participants.

METHOD

Web of Science, Embase and PubMed databases were systematically searched to identify studies which examined the fMRI correlates of working memory function in euthymic people with BD and healthy participants. Relevant demographic, behavioral and functional MRI (fMRI) data was qualitatively and quantitatively assessed, and the quality of the included studies evaluated. Comparable studies which used the same working memory task were included in a meta-analysis using Seed-Based D Mapping software (SDM).

RESULTS

Twenty-four studies were included in this systematic review. Consistent brain fMRI activity differences were found in key brain areas of the working memory network in euthymic people with BD compared to healthy participants including the ventromedial and dorsolateral prefrontal cortices. Cognitive performance was not significantly different between the two groups. Six studies were suitable to be included in the meta-analysis. There was no significant overlap in areas of brain activation after family-wise correction for multiple comparisons.

LIMITATIONS

Heterogeneity of task paradigms, small sample sizes and inherent difficulty in the interpretation of functional brain activity due to variations between studies were all limitations.

CONCLUSION

The differences in working memory related fMRI activity identified by this study between people with BD and healthy participants are consistent with existing literature reporting impaired working memory performance in BD. This was not accompanied by significant differences in cognitive performance in the reviewed studies, likely due to small sample sizes. Further studies are needed to investigate the relationship between differential brain activity and working memory performance in people with BD.

Neuroimaging Guided Transcranial Electrical Stimulation in Enhancing Surgical Skill Acquisition. Comment on Hung et al. The Efficacy of Transcranial Direct Current Stimulation in Enhancing Surgical Skill Acquisition: A Preliminary Meta-Analysis of Randomized Controlled Trials. Brain Sci. 2021, 11, 707

Surgical skill acquisition may be facilitated with a safe application of transcranial direct current stimulation (tDCS). A preliminary meta-analysis of randomized control trials showed that tDCS was associated with significantly better improvement in surgical performance than the sham control; however, meta-analysis does not address the mechanistic understanding. It is known from skill learning studies that the hierarchy of cognitive control shows a rostrocaudal axis in the frontal lobe where a shift from posterior to anterior is postulated to mediate progressively abstract, higher-order control. Therefore, optimizing the transcranial electrical stimulation to target surgical task-related brain activation at different stages of motor learning may provide the causal link to the learning behavior. This comment paper presents the computational approach for neuroimaging guided tDCS based on open-source software pipelines and an open-data of functional near-infrared spectroscopy (fNIRS) for complex motor tasks. We performed an fNIRS-based cortical activation analysis using AtlasViewer software that was used as the target for tDCS of the motor complexity-related brain regions using ROAST software. For future studies on surgical skill training, it is postulated that the higher complexity laparoscopic suturing with intracorporeal knot tying task may result in more robust activation of the motor complexity-related brain areas when compared to the lower complexity laparoscopic tasks.