Cumulative sessions of repetitive transcranial magnetic stimulation (rTMS) build up facilitation to subsequent TMS-mediated behavioural disruptions

Effects of different modalities of transcranial magnetic stimulation on post-stroke cognitive impairment: a network meta-analysis

OBJECTIVE

The study aimed to evaluate, using a network meta-analysis, the effects of different transcranial magnetic stimulation (TMS) modalities on improving cognitive function after stroke.

METHODS

Computer searches of the Cochrane Library, PubMed, Web of Science, Embass, Google Scholar, CNKI, and Wanfang databases were conducted to collect randomized controlled clinical studies on the use of TMS to improve cognitive function in stroke patients, published from the time of database construction to November 2023.

RESULTS

A total of 29 studies and 2123 patients were included, comprising five interventions: high-frequency rTMS (HF-rTMS), low-frequency rTMS (LF-rTMS), intermittent theta rhythm stimulation (iTBS), sham stimulation (SS), and conventional rehabilitation therapy (CRT). A reticulated meta-analysis showed that the rankings of different TMS intervention modalities in terms of the Montreal Cognitive Assessment (MoCA) scores, Mini-Mental State Examination scores (MMSE), and Modified Barthel Index (MBI) scores were: HF-rTMS > LF-rTMS > iTBS > SS > CRT; the rankings of different TMS intervention modalities in terms of the event-related potential P300. amplitude scores were HF-rTMS > LF-rTMS > iTBS > CRT > SS; the rankings of different TMS intervention modalities in terms of the P300 latency scores were: iTBS > HF-rTMS > LF-rTMS > SS > CRT. Subgroup analyses of secondary outcome indicators showed that HF-rTMS significantly improved Rivermead Behavior Memory Test scores and Functional Independence Measurement-Cognitive scores.

CONCLUSIONS

High-frequency TMS stimulation has a better overall effect on improving cognitive functions and activities of daily living, such as attention and memory in stroke patients.

Use of transcranial magnetic stimulation (TMS) for studying cognitive control in depressed patients: A systematic review

Major depressive disorder (MDD) is a debilitating mental disorder and the leading cause of disease burden. Major depressive disorder is associated with emotional impairment and cognitive deficit. Cognitive control, which is the ability to use perceptions, knowledge, and information about goals and motivations to shape the selection of goal-directed actions or thoughts, is a primary function of the prefrontal cortex (PFC). Psychotropic medications are one of the main treatments for MDD, but they are not effective for all patients. An alternative treatment is transcranial magnetic stimulation (TMS). Previous studies have provided mixed results on the cognitive-enhancing effects of TMS treatment in patients with MDD. Some studies have found significant improvement, while others have not. There is a lack of understanding of the specific effects of different TMS protocols and stimulation parameters on cognitive control in MDD. Thus, this review aims to synthesize the effectiveness of the TMS methods and a qualitative assessment of their potential benefits in improving cognitive functioning in patients with MDD. We reviewed 21 studies in which participants underwent a treatment of any transcranial magnetic stimulation protocol, such as repetitive TMS or theta-burst stimulation. One of the primary outcome measures was any change in the cognitive control process. Overall, the findings indicate that transcranial magnetic stimulation (TMS) may enhance cognitive function in patients with MDD. Most of the reviewed studies supported the notion of cognitive improvement following TMS treatment. Notably, improvements were predominantly observed in inhibition, attention, set shifting/flexibility, and memory domains. However, fewer significant improvements were detected in evaluations of visuospatial function and recognition, executive function, phonemic fluency, and speed of information processing. This review found evidence supporting the use of TMS as a treatment for cognitive deficits in patients with MDD. The results are promising, but further research is needed to clarify the specific TMS protocol and stimulation locations that are most effective.

Causally Probing the Role of the Hippocampus in Fear Discrimination: A Precision Functional Mapping-Guided, Transcranial Magnetic Stimulation Study in Participants With Posttraumatic Stress Symptoms

Background

Fear overgeneralization is a promising pathogenic mechanism of clinical anxiety. A dominant model posits that hippocampal pattern separation failures drive overgeneralization. Hippocampal network-targeted transcranial magnetic stimulation (HNT-TMS) has been shown to strengthen hippocampal-dependent learning/memory processes. However, no study has examined whether HNT-TMS can alter fear learning/memory.

Methods

Continuous theta burst stimulation was delivered to individualized left posterior parietal stimulation sites derived via seed-based connectivity, precision functional mapping, and electric field modeling methods. A vertex control site was also stimulated in a within-participant, randomized controlled design. Continuous theta burst stimulation was delivered prior to 2 visual discrimination tasks (1 fear based, 1 neutral). Multilevel models were used to model and test data. Participants were undergraduates with posttraumatic stress symptoms (final n = 25).

Results

Main analyses did not indicate that HNT-TMS strengthened discrimination. However, multilevel interaction analyses revealed that HNT-TMS strengthened fear discrimination in participants with lower fear sensitization (indexed by responses to a control stimulus with no similarity to the conditioned fear cue) across multiple indices (anxiety ratings: β = 0.10, 95% CI, 0.04 to 0.17, p = .001; risk ratings: β = 0.07, 95% CI, 0.00 to 0.13, p = .037).

Conclusions

Overgeneralization is an associative process that reflects deficient discrimination of the fear cue from similar cues. In contrast, sensitization reflects nonassociative responding unrelated to fear cue similarity. Our results suggest that HNT-TMS may selectively sharpen fear discrimination when associative response patterns, which putatively implicate the hippocampus, are more strongly engaged.

Efficacy of repetitive transcranial magnetic stimulation with different application parameters for post-stroke cognitive impairment: a systematic review

Background

Cognitive impairment is a prevalent consequence of stroke, seriously affecting recovery and quality of life while imposing substantial burdens on both patients' families and society. Repetitive transcranial magnetic stimulation (rTMS) has emerged as an effective intervention for post-stroke cognitive impairment (PSCI). However, the a lack of standardized and explicit guidelines regarding rTMS application parameters. Therefore, this study systematically evaluated the efficacy of various parameters of rTMS in treating PSCI and explored its potential mechanism.

Methods

We conducted a comprehensive search across seven scientific databases, namely China National Knowledge Infrastructure (CNKI), Wanfang Data Knowledge Service Platform (Wanfang), China Science and Technology Journal Database (VIP), Web of Science, PubMed, Embase, and Cochrane Library, to identify randomized controlled trials (RCTs) investigating the efficacy of rTMS for PSCI. The search encompassed the period from database creation until July 28, 2023. To evaluate the risk of bias in included studies, we employed the Cochrane recommended risk of bias assessment tool. Furthermore, we extracted relevant clinical application parameters associated with rTMS and performed comparative analyses to assess their therapeutic effects under different parameter settings.

Results

The present study included 45 RCTs involving a total of 3,066 patients with PSCI. Both high-frequency repetitive transcranial magnetic stimulation (HF-rTMS) and low-frequency repetitive transcranial magnetic stimulation (LF-rTMS) demonstrated safety and efficacy, yet failed to exhibit significant differentiation in terms of cognitive improvement. Furthermore, intermittent theta burst stimulation (iTBS), although yielding positive results, did not surpass traditional rTMS in effectiveness. Combining HF-rTMS with LF-rTMS resulted in superior efficacy compared to single rTMS intervention. Moreover, the combination of rTMS with other cognitive therapies exhibited potential for enhanced benefits among patients.

Conclusion

rTMS can effectively and safely enhance cognitive function, improve quality of life, and enhance activities of daily living in patients with PSCI. Furthermore, the combination of rTMS with other conventional rehabilitation methods can yield additional positive effects. However, due to insufficient evidence, an optimal parameter protocol for rTMS can not be currently recommended. Future research should prioritize orthogonal experimental design methods that incorporate multiple parameters and levels to determine the optimal parameter protocol for rTMS in PSCI.

Effects of central-peripheral FMS on urinary retention after spinal cord injury: a pilot randomized controlled trial protocol

Background

Urinary retention is a common complication of spinal cord injury (SCI), which can seriously affect the quality of life of patients. Function magnetic stimulation (FMS) has been widely used in the recovery of neurological function in various diseases, but its application in urinary retention after SCI remains unclear. Therefore, we would like to conduct a pilot randomized controlled trial (RCT) to observe the feasible effect of FMS on urinary retention after SCI, to explore its mechanism of action.

Method/design

This is a single-center pilot RCT, which 60 patients with urinary retention after SCI will be selected, numbered in chronological order of hospitalization, and randomly divided into 4 groups using the random number table method, Groups A (control group), Group B, Group C, and Group D; Each group will receive the same conventional rehabilitation treatment. The whole intervention period 2 weeks and will be evaluated before and after treatment to collect data on residual bladder volume, functional near-infrared spectroscopy (fNIRS), changes in voiding condition, changes in surface electromyography (SEMG) values of pelvic floor muscle and quality of life scores (QoL).

Study hypothesis

We hypothesized that FMS for the treatment of urinary retention after SCI would have a significant clinical feasible effect;and that peripheral combined with central FMS would be more effective than single-site FMS for the treatment of urinary retention after SCI.

Objective

(1) To illustrate the clinical effectiveness of FMS in the treatment of urinary retention after SCI and to provide a new treatment modality for the patients; (2) Comparison of the differences in the efficacy of central and peripheral single FMS and combined central and peripheral FMS in the treatment of urinary retention after SCI; (3) To explore the central control mechanisms of bladder function recovery after SCI in conjunction with changes in fNIRS.

Trial registration

This study has been ethically approved by the Scientific and Ethics Committee of the First Affiliated Hospital of Gannan Medical university with approval number (LLSC-2022112401). It has been registered with the China Clinical Trials Registry with the registration number: ChiCTR2200067143.

Magnetic Stimulation as a Therapeutic Approach for Brain Modulation and Repair: Underlying Molecular and Cellular Mechanisms

Neurological and psychiatric diseases generally have no cure, so innovative non-pharmacological treatments, including non-invasive brain stimulation, are interesting therapeutic tools as they aim to trigger intrinsic neural repair mechanisms. A common brain stimulation technique involves the application of pulsed magnetic fields to affected brain regions. However, investigations of magnetic brain stimulation are complicated by the use of many different stimulation parameters. Magnetic brain stimulation is usually divided into two poorly connected approaches: (1) clinically used high-intensity stimulation (0.5-2 Tesla, T) and (2) experimental or epidemiologically studied low-intensity stimulation (μT-mT). Human tests of both approaches are reported to have beneficial outcomes, but the underlying biology is unclear, and thus optimal stimulation parameters remain ill defined. Here, we aim to bring together what is known about the biology of magnetic brain stimulation from human, animal, and in vitro studies. We identify the common effects of different stimulation protocols; show how different types of pulsed magnetic fields interact with nervous tissue; and describe cellular mechanisms underlying their effects-from intracellular signalling cascades, through synaptic plasticity and the modulation of network activity, to long-term structural changes in neural circuits. Recent advances in magneto-biology show clear mechanisms that may explain low-intensity stimulation effects in the brain. With its large breadth of stimulation parameters, not available to high-intensity stimulation, low-intensity focal magnetic stimulation becomes a potentially powerful treatment tool for human application.

Low intensity repetitive transcranial magnetic stimulation modulates brain-wide functional connectivity to promote anti-correlated c-Fos expression

Repetitive transcranial magnetic stimulation (rTMS) induces action potentials to induce plastic changes in the brain with increasing evidence for the therapeutic importance of brain-wide functional network effects of rTMS; however, the influence of sub-action potential threshold (low-intensity; LI-) rTMS on neuronal activity is largely unknown. We investigated whether LI-rTMS modulates neuronal activity and functional connectivity and also specifically assessed modulation of parvalbumin interneuron activity. We conducted a brain-wide analysis of c-Fos, a marker for neuronal activity, in mice that received LI-rTMS to visual cortex. Mice received single or multiple sessions of excitatory 10 Hz LI-rTMS with custom rodent coils or were sham controls. We assessed changes to c-Fos positive cell densities and c-Fos/parvalbumin co-expression. Peak c-Fos expression corresponded with activity during rTMS. We also assessed functional connectivity changes using brain-wide c-Fos-based network analysis. LI-rTMS modulated c-Fos expression in cortical and subcortical regions. c-Fos density changes were most prevalent with acute stimulation, however chronic stimulation decreased parvalbumin interneuron activity, most prominently in the amygdala and striatum. LI-rTMS also increased anti-correlated functional connectivity, with the most prominent effects also in the amygdala and striatum following chronic stimulation. LI-rTMS induces changes in c-Fos expression that suggest modulation of neuronal activity and functional connectivity throughout the brain. Our results suggest that LI-rTMS promotes anticorrelated functional connectivity, possibly due to decreased parvalbumin interneuron activation induced by chronic stimulation. These changes may underpin therapeutic rTMS effects, therefore modulation of subcortical activity supports rTMS for treatment of disorders involving subcortical dysregulation.

Gradual enhancement of corticomotor excitability during cortico-cortical paired associative stimulation

Cortico-cortical paired associative stimulation (ccPAS) is an effective transcranial magnetic stimulation (TMS) method for inducing associative plasticity between interconnected brain areas in humans. Prior ccPAS studies have focused on protocol’s aftereffects. Here, we investigated physiological changes induced “online” during ccPAS administration. We tested 109 participants receiving ccPAS over left ventral premotor cortex (PMv) and primary motor cortex (M1) using a standard procedure (90 paired-pulses with 8-ms interstimulus interval, repeated at 0.1 Hz frequency). On each paired-pulse, we recorded a motor-evoked potential (MEP) to continuously trace the emergence of corticomotor changes. Participant receiving forward-ccPAS (on each pair, a first TMS pulse was administered over PMv, second over M1, i.e., PMv-to-M1) showed a gradual and linear increase in MEP size that did not reach a plateau at the end of the protocol and was greater in participants with low motor threshold. Participants receiving reverse-ccPAS (i.e., M1-to-PMv) showed a trend toward inhibition. Our study highlights the facilitatory and inhibitory modulations that occur during ccPAS administration and suggest that online MEP monitoring could provide insights into the malleability of the motor system and protocol’s effectiveness. Our findings open interesting prospects about ccPAS potential optimization in experimental and clinical settings.

Things you wanted to know (but might have been afraid to ask) about how and why to explore and modulate brain plasticity with non-invasive neurostimulation technologies

Brain plasticity can be defined as the ability of local and extended neural systems to organize either the structure and/or the function of their connectivity patterns to better adapt to changes of our inner/outer environment and optimally respond to new challenging behavioral demands. Plasticity has been traditionally conceived as a spontaneous phenomenon naturally occurring during pre and postnatal development, tied to learning and memory processes, or enabled following neural damage and their rehabilitation. Such effects can be easily observed and measured but remain hard to harness or to tame 'at will'. Non-invasive brain stimulation (NIBS) technologies offer the possibility to engage plastic phenomena, and use this ability to characterize the relationship between brain regions, networks and their functional connectivity patterns with cognitive process or disease symptoms, to estimate cortical malleability, and ultimately contribute to neuropsychiatric therapy and rehabilitation. NIBS technologies are unique tools in the field of fundamental and clinical research in humans. Nonetheless, their abilities (and also limitations) remain rather unknown and in the hands of a small community of experts, compared to widely established methods such as functional neuroimaging (fMRI) or electrophysiology (EEG, MEG). In the current review, we first introduce the features, mechanisms of action and operational principles of the two most widely used NIBS methods, Transcranial Magnetic Stimulation (TMS) and Transcranial Current Stimulation (tCS), for exploratory or therapeutic purposes, emphasizing their bearings on neural plasticity mechanisms. In a second step, we walk the reader through two examples of recent domains explored by our team to further emphasize the potential and limitations of NIBS to either explore or improve brain function in healthy individuals and neuropsychiatric populations. A final outlook will identify a series of future topics of interest that can foster progress in the field and achieve more effective manipulation of brain plasticity and interventions to explore and improve cognition and treat the symptoms of neuropsychiatric diseases.

Non-invasive brain stimulation in rehabilitation

Non-invasive brain stimulation (NIBS) has been seen more common in rehabilitation settings. It can be used for the treatment of stroke, spinal cord injury, traumatic brain injury and multiple sclerosis, as well as for some diagnostic neurophysiological measurements. Two major modalities of NIBS are transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS). As an add-on therapy to conventional rehabilitative treatments, the main goal of NIBS is to create neuromodulation by inhibiting or activating neural activity in the targeted cortical region. Indications for therapeutic NIBS in neurorehabilitation are motor recovery, aphasia, neglect, dysphagia, cognitive disorders, spasticity, and central pain. The NIBS can be regarded a safe technique with appropriate patient selection and defined treatment parameters. This review provides an overview on NIBS modalities, specifically TMS and tDCS, the working mechanisms, the stimulation techniques, areas of use, neuronavigation systems and safety considerations.

Repetitive Transcranial Magnetic Stimulation (rTMS) as a Promising Treatment for Craving in Stimulant Drugs and Behavioral Addiction: A Meta-Analysis

Addiction is a mental disorder with limited available treatment options. The therapeutic potential of repetitive transcranial magnetic stimulation (rTMS) on it, by targeting craving in particular, has been explored with heterogenous results. This meta-analysis uses updated evidence to assess overall rTMS efficacy on craving, differential effects between addiction types clustered into three groups (depressant (alcohol, cannabis, opiate), stimulant (nicotine, cocaine, methamphetamine), and behavioral addiction (gambling, eating disorder)), and stimulation settings. Studies on substance use, gambling, and eating disorders are included, with unrestricted stimulation settings, by searching the PubMed, Embase, PsycINFO, and Cochrane databases up to 30 April 2020. A total of 34 eligible studies (42 units of analysis) were identified. Because of highly significant heterogeneity in primary results, a sensitivity analysis was performed on a remaining sample of 26 studies (30 units of analysis). Analyses performed using random effects model revealed a small effect size favoring active rTMS over shamTMS stimulation in the reduction in craving. We found a significant difference between addiction types, with a persistent small effect only for stimulant and behavioral groups. In these groups we found no difference between the different combinations of target and frequency of stimulation, but a significant correlation between number of sessions and craving reduction. In conclusion, efficacy of rTMS on craving in stimulant and behavioral addiction was highlighted, but recommendations on optimal stimulation settings and its clinical application await further research.

Psychiatric Applications of Repetitive Transcranial Magnetic Stimulation

Transcranial magnetic stimulation (TMS) is an increasingly popular noninvasive brain stimulation modality. In TMS, a pulsed magnetic field is used to noninvasively stimulate a targeted brain region. Repeated stimulation produces lasting changes in brain activity via mechanisms of synaptic plasticity similar to long-term potentiation. Local application of TMS alters activity in distant, functionally connected brain regions, indicating that TMS modulates activity of cortical networks. TMS has been approved by the U.S. Food and Drug Administration for the treatment of major depressive disorder, obsessive-compulsive disorder, and smoking cessation, and a growing evidence base supports its efficacy in the treatment of other neuropsychiatric conditions. TMS is rapidly becoming part of the standard of care for treatment-resistant depression, where it yields response rates of 40%-60%. TMS is generally safe and well tolerated; its most serious risk is seizure, which occurs very rarely. This review aims to familiarize practicing psychiatrists with basic principles of TMS, including target localization, commonly used treatment protocols and their outcomes, and safety and tolerability. Practical considerations, including evaluation and monitoring of patients undergoing TMS, device selection, treatment setting, and insurance reimbursement, are also reviewed.

Current perspectives on the benefits, risks, and limitations of noninvasive brain stimulation (NIBS) for post-stroke dysphagia

INTRODUCTION

Studies have shown that noninvasive brain stimulation (NIBS), including repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), can promote neuroplasticity, which is considered important for functional recovery of swallowing after stroke. Despite extensive studies on NIBS, there remains a gap between research and clinical practice.

AREAS COVERED

In this article, we update the current knowledge on the benefits and challenges of rTMS and tDCS for post-stroke dysphagia. We identify some key limitations of these techniques that hinder the translation from clinical trials to routine practice. Finally, we discuss the future of NIBS as a treatment for post-stroke dysphagia in real-world settings.

EXPERT OPINION

Current evidence suggests that rTMS and tDCS show promise as a treatment for post-stroke dysphagia. However, these techniques are limited by the response variability, uncertainty on the safety in patients with comorbidities and difficulties in clinical study designs. Such limitations call for further work to enhance their utility through individualized approaches. Despite this, the last decade has seen a growing acceptance toward these techniques among clinical personnel. As such, we advocate caution but support optimism that NIBS will gradually be recognized as a mainstream treatment approach for post-stroke dysphagia in the future.

Transcranial Direct Current Stimulation Targeting the Ventromedial Prefrontal Cortex Reduces Reactive Aggression and Modulates Electrophysiological Responses in a Forensic Population

BACKGROUND

Studies have shown that impairments in the ventromedial prefrontal cortex play a crucial role in violent behavior in forensic patients who also abuse cocaine and alcohol. Moreover, interventions that aimed to reduce violence risk in those patients are found not to be optimal. A promising intervention might be to modulate the ventromedial prefrontal cortex by high-definition (HD) transcranial direct current stimulation (tDCS). The current study aimed to examine HD-tDCS as an intervention to increase empathic abilities and reduce violent behavior in forensic substance dependent offenders. In addition, using electroencephalography, we examined the effects on the P3 and the late positive potential of the event-related potentials in reaction to situations that depict victims of aggression.

METHODS

Fifty male forensic patients with a substance dependence were tested in a double-blind, placebo-controlled randomized study. The patients received HD-tDCS 2 times a day for 20 minutes for 5 consecutive days. Before and after the intervention, the patients completed self-reports and performed the Point Subtraction Aggression Paradigm, and electroencephalography was recorded while patients performed an empathy task.

RESULTS

Results showed a decrease in aggressive responses on the Point Subtraction Aggression Paradigm and in self-reported reactive aggression in the active tDCS group. Additionally, we found a general increase in late positive potential amplitude after active tDCS. No effects on trait empathy and the P3 were found.

CONCLUSIONS

Current findings are the first to find positive effects of HD-tDCS in reducing aggression and modulating electrophysiological responses in forensic patients, showing the potential of using tDCS as an intervention to reduce aggression in forensic mental health care.

The role of repetitive transcranial magnetic stimulation in the treatment of cognitive impairment in stroke patients: A systematic review and meta-analysis

Stroke is a global health problem, and survivors of a stroke often suffer from cognitive impairment, which has an essential impact on the rehabilitation of various functions. Repetitive Transcranial Magnetic Stimulation (rTMS) has been widely used in the rehabilitation treatment of stroke patients. There are many investigations into how rTMS impacts motor dysfunction, speech dysfunction and swallowing dysfunction after stroke, but the analysis of rehabilitation effect on stroke patients with cognitive dysfunction is lacking. The purpose of this study was to analyze the effect of different rTMS related therapies on cognitive impairment and to evaluate its clinical effect on cognitive rehabilitation after stroke. Four databases including PubMed, EMBASE, MEDLINE and the Cochrane Library, were searched and a total of 2754 papers were collected. Two reviewers independently completed a review of all papers' titles and abstracts, screened out the documents that met the criteria, and carried out data extraction, quality assessment, and data analysis. A total of six studies with 197 patients were included. Three studies used the Mini-Mental Status Examination (MMSE) scale to evaluate the cognitive function with a mean effect size of 1.89 (95% CI = -3.08-6.86). Two studies used the Loewenstein Occupational Therapy of Cognitive Assessment (LOTCA) scale with the mean effect size of 1.64 (95% CI = -7.65-10.93). These studies were evaluated separately. Our article provides that rTMS has a positive effect on improving the cognitive ability of stroke patients, but the evidence is still limited, and further large-scale studies are needed to explore the optimal stimulus parameters.

Within-session repeated transcranial direct current stimulation of the posterior parietal cortex enhances spatial working memory

Spatial working memory (SWM) is an essential cognitive ability that supports complex tasks, but its capacity is limited. Studies using transcranial direct current stimulation (tDCS) have shown potential benefits for SWM performance. Recent studies have shown that repeated short applications of tDCS affected corticospinal excitability. Moreover, neuroimaging studies have indicated that the pattern of neural activity measured in the posterior parietal cortex (PPC) tracks SWM ability. It is unknown whether repeated tDCS can enhance SWM and whether varied tDCS protocols (single 10 min tDCS, 10 min tDCS-5 min break-10 min tDCS, 10 min tDCS-20 min break-10 min tDCS) over the right PPC have different effects on SWM. The current study investigated whether offline single-session and repeated tDCS over the right PPC affects SWM updating, as measured by spatial 2-back and 3-back tasks. The results showed that stimulating the right PPC with repeated 10 min anodal tDCS significantly improved the response speed of the spatial 2-back task relative to single-session tDCS. Repeated 10 min tDCS with a longer interval (i.e. inter-stimulation interval of 20 min) enhanced the response speed of the spatial 3-back task. Altogether these findings provide causal evidence that suggests that the right PPC plays an important role in SWM. Furthermore, repeated tDCS with longer intervals may be a promising intervention for improving SWM-related function.

Transcranial magnetic stimulation therapeutic applications on sleep and insomnia: a review

Repetitive transcranial magnetic stimulation (rTMS) is a neuromodulatory technique approved by the US Food and Drug Administration for use in treatment-resistant major depressive disorder. It works by generating localized magnetic fields that create depolarizing electrical currents in neurons a few centimeters below the scalp. This localized effect is believed to stimulate neural plasticity, activate compensatory processes, and influence cortical excitability. Additionally, rTMS has been used in a variety of clinical trials for neurological and psychiatric conditions such as anxiety, post-traumatic stress disorder and epilepsy. Beneficial effects in sleep parameters have been documented in these trials, as well as in major depressive disorder, and have led to an interest in using rTMS in the field of sleep medicine for specific disorders such as insomnia, hypersomnia, and restless legs syndrome. It is unknown whether rTMS has intrinsically beneficial properties when applied to primary sleep disorders, or if it only acts on sleep through mood disorders. This narrative review sought to examine available literature regarding the application of rTMS for sleep disorder to identify knowledge gaps and inform future study design. The literature in this area remains scarce, with few randomized clinical trials on rTMS and insomnia. Available studies have found mixed results, with some studies reporting subjective sleep improvement while objective improvement is less consistent. Due to the heterogeneity of results and the variations in rTMS protocols, no definitive conclusions have been reached, signaling the need for further research.

Cognitive effects and acceptability of non-invasive brain stimulation on Alzheimer's disease and mild cognitive impairment: a component network meta-analysis

OBJECTIVES

To compare cognitive effects and acceptability of repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) in patients with Alzheimer's disease (AD) or mild cognitive impairment (MCI), and to determine whether cognitive training (CT) during rTMS or tDCS provides additional benefits.

METHODS

Electronic search of PubMed, Medline, Embase, the Cochrane Library and PsycINFO up to 5 March 2020. We enrolled double-blind, randomised controlled trials (RCTs). The primary outcomes were acceptability and pre-post treatment changes in general cognition measured by Mini-Mental State Examination, and the secondary outcomes were memory function, verbal fluency, working memory and executive function. Durability of cognitive benefits (1, 2 and ≥3 months) after brain stimulation was examined.

RESULTS

We included 27 RCTs (n=1070), and the treatment components included high-frequency rTMS (HFrTMS) and low-frequency rTMS, anodal tDCS (atDCS) and cathodal tDCS (ctDCS), CT, sham CT and sham brain stimulation. Risk of bias of evidence in each domain was low (range: 0%-11.1%). HFrTMS (1.08, 9, 0.35-1.80) and atDCS (0.56, 0.03-1.09) had short-term positive effects on general cognition. CT might be associated with negative effects on general cognition (-0.79, -2.06 to 0.48) during rTMS or tDCS. At 1-month follow-up, HFrTMS (1.65, 0.77-2.54) and ctDCS (2.57, 0.20-4.95) exhibited larger therapeutic responses. Separate analysis of populations with pure AD and MCI revealed positive effects only in individuals with AD. rTMS and tDCS were well tolerated.

CONCLUSIONS

HFrTMS is more effective than atDCS for improving global cognition, and patients with AD may have better responses to rTMS and tDCS than MCI.

The effect of non-invasive brain stimulation on executive functioning in healthy controls: A systematic review and meta-analysis

In recent years, there has been a heightened interest in the effect of non-invasive brain stimulation on executive functioning. However, there is no comprehensive overview of its effects on different executive functioning domains in healthy individuals. Here, we assessed the state of the field by conducting a systematic review and meta-analysis on the effectiveness of non-invasive brain stimulation (i.e. repetitive transcranial magnetic stimulation and transcranial direct current stimulation) over prefrontal regions on tasks assessing working memory, inhibition, flexibility, planning and initiation performance. Our search yielded 63 studies (n = 1537), and the effectiveness of excitatory and inhibitory non-invasive brain stimulation were assessed per executive functioning task. Our analyses showed that excitatory non-invasive brain stimulation had a small but positive effect on Stop Signal Task and Go/No-Go Task performance, and that inhibitory stimulation had a small negative effect on Flanker Task performance. Non-invasive brain stimulation did not affect performance on working memory and flexibility tasks, and effects on planning tasks were inconclusive.

Past, Present, and Future of Non-invasive Brain Stimulation Approaches to Treat Cognitive Impairment in Neurodegenerative Diseases: Time for a Comprehensive Critical Review

Low birth rates and increasing life expectancy experienced by developed societies have placed an unprecedented pressure on governments and the health system to deal effectively with the human, social and financial burden associated to aging-related diseases. At present, ∼24 million people worldwide suffer from cognitive neurodegenerative diseases, a prevalence that doubles every five years. Pharmacological therapies and cognitive training/rehabilitation have generated temporary hope and, occasionally, proof of mild relief. Nonetheless, these approaches are yet to demonstrate a meaningful therapeutic impact and changes in prognosis. We here review evidence gathered for nearly a decade on non-invasive brain stimulation (NIBS), a less known therapeutic strategy aiming to limit cognitive decline associated with neurodegenerative conditions. Transcranial Magnetic Stimulation and Transcranial Direct Current Stimulation, two of the most popular NIBS technologies, use electrical fields generated non-invasively in the brain to long-lastingly enhance the excitability/activity of key brain regions contributing to relevant cognitive processes. The current comprehensive critical review presents proof-of-concept evidence and meaningful cognitive outcomes of NIBS in eight of the most prevalent neurodegenerative pathologies affecting cognition: Alzheimer's Disease, Parkinson's Disease, Dementia with Lewy Bodies, Primary Progressive Aphasias (PPA), behavioral variant of Frontotemporal Dementia, Corticobasal Syndrome, Progressive Supranuclear Palsy, and Posterior Cortical Atrophy. We analyzed a total of 70 internationally published studies: 33 focusing on Alzheimer's disease, 19 on PPA and 18 on the remaining neurodegenerative pathologies. The therapeutic benefit and clinical significance of NIBS remains inconclusive, in particular given the lack of a sufficient number of double-blind placebo-controlled randomized clinical trials using multiday stimulation regimes, the heterogeneity of the protocols, and adequate behavioral and neuroimaging response biomarkers, able to show lasting effects and an impact on prognosis. The field remains promising but, to make further progress, research efforts need to take in account the latest evidence of the anatomical and neurophysiological features underlying cognitive deficits in these patient populations. Moreover, as the development of in vivo biomarkers are ongoing, allowing for an early diagnosis of these neuro-cognitive conditions, one could consider a scenario in which NIBS treatment will be personalized and made part of a cognitive rehabilitation program, or useful as a potential adjunct to drug therapies since the earliest stages of suh diseases. Research should also integrate novel knowledge on the mechanisms and constraints guiding the impact of electrical and magnetic fields on cerebral tissues and brain activity, and incorporate the principles of information-based neurostimulation.

A Case of Psychogenic Myoclonus Responding to a Novel Transcranial Magnetic Stimulation Approach: Rationale, Feasibility, and Possible Neurophysiological Basis

Repetitive transcranial magnetic stimulation (rTMS) can relieve motor symptoms related to psychogenic movement disorders (PMDs), but the subtending neurophysiological basis is unclear. We report on a 50-year-old woman with a diagnosis of psychogenic myoclonus in the right lower limb, who was treated with a daily session (in the late morning/early afternoon) of 1 Hz rTMS over the left premotor cortex (PMC), five times a week for 6 weeks. Clinical data and EEG at rest were collected before and immediately and 2-month after the rTMS protocol completion. The patient reported a significant reduction of involuntary movement frequency and intensity and the related disability burden up to the follow-up. In parallel, any abnormality in terms of source current density within and connectivity between the frontal and parietal areas was reset. The short follow–up period, the lack of extensive neurophysiological measures, and the lack of control treatment represent the main limitation of the study. However, low-frequency rTMS over PMC seems a safe and promising approach for the management of psychogenic myoclonus owing to the combination of cortical neuromodulation and non-specific mechanisms suggesting cognitive-behavioral effects.

Contribution of transcranial magnetic stimulation in restless legs syndrome: pathophysiological insights and therapeutical approaches

Transcranial magnetic stimulation (TMS) may offer a reliable means to characterize significant pathophysiologic and neurochemical aspects of restless legs syndrome (RLS). Namely, TMS has revealed specific patterns of changes in cortical excitability and plasticity, in particular dysfunctional inhibitory mechanisms and sensorimotor integration, which are thought to be part of the pathophysiological mechanisms of RLS rather than reflect a non-specific consequence of sleep architecture alteration. If delivered repetitively, TMS is able to transiently modulate the neural activity of the stimulated and connected areas. Some studies have begun to therapeutically use repetitive TMS (rTMS) to improve sensory and motor disturbances in RLS. High-frequency rTMS applied over the primary motor cortex or the supplementary motor cortex, as well as low-frequency rTMS over the primary somatosensory cortex, seem to have transient beneficial effects. However, further studies with larger patient samples, repeated sessions, an optimized rTMS setup, and clinical follow-up are needed in order to corroborate preliminary results. Thus, we performed a systematic search of all the studies that have used TMS and rTMS techniques in patients with RLS.

Low frequency transcranial magnetic stimulation of right posterior parietal cortex reduces reaction time to perithreshold low spatial frequency visual stimuli

Research in humans and animal models suggests that visual responses in early visual cortical areas may be modulated by top-down influences from distant cortical areas, particularly in the frontal and parietal regions. The right posterior parietal cortex is part of a broad cortical network involved in aspects of visual search and attention, but its role in modulating activity in early visual cortical areas is less well understood. This study evaluated the influence of right posterior parietal cortex (PPC) on a direct measure of visual processing in humans. Contrast sensitivity (CS) and detection response times were recorded using a visual detection paradigm to two types of centrally-presented stimuli. Participants were tested on the detection task before, after, and 1 hour after low-frequency repetitive transcranial magnetic stimulation (rTMS) to the right PPC or to the scalp vertex. Low-frequency rTMS to the right PPC did not significantly change measures of contrast sensitivity, but increased the speed at which participants responded to visual stimuli of low spatial frequency. Response times returned to baseline 1-hour after rTMS. These data indicate that low frequency rTMS to the right PPC speeds up aspects of early visual processing, likely due to a disinhibition of the homotopic left posterior parietal cortex.

Effects of Ten Sessions of High Frequency Repetitive Transcranial Magnetic Stimulation (HF-rTMS) Add-on Treatment on Impulsivity in Alcohol Use Disorder

Introduction

Alcohol use disorder (AUD) is characterized by increased impulsivity, which is multifactorial and can be assessed by tests like the delay discounting, Go-Nogo, and stop signal task (SST). Impulsivity has been related to poor treatment outcomes in substance use disorders, including AUD. In order to decrease impulsivity or improve inhibitory control, high frequency transcranial magnetic stimulation (HF-rTMS) has gained interest. Studies applying HF-rTMS over the DLPFC of individuals suffering from AUD assessing its effects on impulsivity measures are scarce, and results are inconclusive.

Methods

The current study (registered in Netherlands Trial Register with trial number 5291: https://www.trialregister.nl/trial/5151) applied 10 sessions of HF-rTMS [sixty 10 Hz trains of 5 s at 110% motor threshold (MT)] over the right DLPFC of 80 alcohol dependent patients in clinical treatment on 10 consecutive workdays. At baseline, halfway and after the HF-rTMS treatment, the delay discounting, Go-NoGo, and SST were assessed.

Results

Ten sessions of HF-rTMS over the right DLPFC versus sham HF-rTMS did not affect performance on the delay discounting, Go-NoGo, and SSTs. A significant effect of age was found for the Go-NoGo task, with higher age associated with better performance. Furthermore, no significant correlations were found between difference scores of task performance and baseline impulsivity or severity of AUD.

Discussion

Results of this study, in combination with other studies using HF-rTMS studies in alcohol and substance use disorder, indicate mixed and inconclusive findings of HF-rTMS on impulsivity. Future studies within patient groups hospitalized at the same department are recommended to consider using a sham coil that mimics the sensations on the scalp of active HF-rTMS and to measure motivation across test sessions.

[Procognitive effects of transcranial magnetic stimulation in the light of neurocognitive deficit in schizophrenia]

Transcranial magnetic stimulation (TMS) is a relatively new method of non-invasive therapy of mental and neurological diseases that has great potential of therapeutic and diagnostic application. In schizophrenia, TMS may exert a positive effect on cognitive deficit. However this issue remains open. The authors analyze recent studies focused on the dynamics of neurocognitive deficit in TMS therapy and consider clinical effects of TMS in schizophrenia. The analysis has shown that TMS is successfully implemented in treatment of auditory positive symptoms and studies on its effect on negative symptoms of schizophrenia are perspective. Procognitive effect was found in working memory domain, and partially in perception domain within the perception of faces and facial expressions. The data on regulative functions, attention, speech, and nondeclarative memory remains controversial. It has been concluded that further research is needed to clarify the place of TMS in schizophrenia therapy.

Transcranial magnetic stimulation improves cognition over time in Parkinson's disease

INTRODUCTION

Cognitive impairment can occur in the early phase of Parkinson's disease and increases the risk of developing dementia. Cognitive deficits were shown to be associated with functional alterations in the dorsolateral prefrontal cortex (DLPFC) and caudate nucleus. Two previous transcranial magnetic stimulation studies over the left DLPFC showed short-term improvement in cognitive performance and focused on specific task.

METHODS

28 patients with idiopathic Parkinson's disease and mild cognitive impairment received intermittent "theta burst" stimulation (iTBS) (active, N = 14; or sham, N = 14) over the left DLPFC, twice a day for three days with 1-2 days in between. Detailed neuropsychological assessment of five cognitive domains was performed before iTBS and on days 1, 10, and 30 after the last iTBS session. Composite Z-scores were calculated for each domain and for overall cognition.

RESULTS

Our results showed an increase in overall cognition up to one month in both groups but this effect was only significant in the active group. Improvements were seen in the attention domain for both groups and in the visuospatial domain in the active group only. No significant differences were found between the groups.

CONCLUSION

These preliminary findings suggest that active iTBS might improve overall cognitive performance in patients with Parkinson's disease with mild cognitive impairment and that this effect can last up to one month. This cognitive improvement, is likely mediated by improvement on visuospatial abilities. Further studies are needed to explore the potential of iTBS as a therapeutical tool to slow cognitive decline in patients with Parkinson's disease.

Clinical Improvements in Comorbid Gambling/Cocaine Use Disorder (GD/CUD) Patients Undergoing Repetitive Transcranial Magnetic Stimulation (rTMS)

(1) Background: Pathological gambling behaviors may coexist with cocaine use disorder (CUD), underlying common pathogenic mechanisms. Repetitive transcranial magnetic stimulation (rTMS) has shown promise as a therapeutic intervention for CUD. In this case series, we evaluated the clinical effects of rTMS protocol stimulating the left dorsolateral prefrontal cortex (DLPFC) on the pattern of gambling and cocaine use. (2) Methods: Gambling severity, craving for cocaine, sleep, and other negative affect symptoms were recorded in seven patients with a diagnosis of gambling disorder (South Oaks Gambling Screen (SOGS) >5), in comorbidity with CUD, using the following scales: Gambling-Symptom Assessment Scale (G-SAS), Cocaine Craving Questionnaire (CCQ), Beck Depression Inventory-II (BDI-II), Self-rating Anxiety Scale (SAS), and Symptoms checklist-90 (SCL-90). The measures were assessed before the rTMS treatment and after 5, 30, and 60 days of treatment. Patterns of gambling and cocaine use were assessed by self-report and regular urine screens. (3) Results: Gambling severity at baseline ranged from mild to severe (mean ± Standard Error of the Mean (SEM), G-SAS score baseline: 24.42 ± 2.79). G-SAS scores significantly improved after treatment (G-SAS score Day 60: 2.66 ± 1.08). Compared to baseline, consistent improvements were significantly seen in craving for cocaine and in negative-affect symptoms. (4) Conclusions: The present findings provide unprecedent insights into the potential role of rTMS as a therapeutic intervention for reducing both gambling and cocaine use in patients with a dual diagnosis.

Test-Retest Reliability of the Effects of Continuous Theta-Burst Stimulation

OBJECTIVES

The utility of continuous theta-burst stimulation (cTBS) as index of cortical plasticity is limited by inadequate characterization of its test-retest reliability. We thus evaluated the reliability of cTBS aftereffects, and explored the roles of age and common single-nucleotide polymorphisms in the brain-derived neurotrophic factor (BDNF) and apolipoprotein E (APOE) genes.

METHODS

Twenty-eight healthy adults (age range 21-65) underwent two identical cTBS sessions (median interval = 9.5 days) targeting the motor cortex. Intraclass correlation coefficients (ICCs) of the log-transformed, baseline-corrected amplitude of motor evoked potentials (ΔMEP) at 5-60 min post-cTBS (T5-T60) were calculated. Adjusted effect sizes for cTBS aftereffects were then calculated by taking into account the reliability of each cTBS measure.

RESULTS

ΔMEP at T50 was the most-reliable cTBS measure in the whole sample (ICC = 0.53). Area under-the-curve (AUC) of ΔMEPs was most reliable when calculated over the full 60 min post-cTBS (ICC = 0.40). cTBS measures were substantially more reliable in younger participants (< 35 years) and in those with BDNF Val66Val and APOE ε4- genotypes.

CONCLUSION

cTBS aftereffects are most reliable when assessed 50 min post-cTBS, or when cumulative ΔMEP measures are calculated over 30-60 min post-cTBS. Reliability of cTBS aftereffects is influenced by age, and BDNF and APOE polymorphisms. Reliability coefficients are used to adjust effect-size calculations for interpretation and planning of cTBS studies.

The Effect of Noninvasive Brain Stimulation on Poststroke Cognitive Function: A Systematic Review

Introduction. Cognitive impairment after stroke has been associated with lower quality of life and independence in the long run, stressing the need for methods that target impairment for cognitive rehabilitation. The use of noninvasive brain stimulation (NIBS) on recovery of language functions is well documented, yet the effects of NIBS on other cognitive domains remain largely unknown. Therefore, we conducted a systematic review that evaluates the effects of different stimulation techniques on domain-specific (long-term) cognitive recovery after stroke. Methods. Three databases (PubMed, EMBASE, and PsycINFO) were searched for articles (in English) on the effects of NIBS on cognitive domains, published up to January 2018. Results. A total of 40 articles were included: randomized controlled trials (n = 21), studies with a crossover design (n = 9), case studies (n = 6), and studies with a mixed design (n = 4). Most studies tested effects on neglect (n = 25). The majority of the studies revealed treatment effects on at least 1 time point poststroke, in at least 1 cognitive domain. Studies varied highly on the factors time poststroke, number of treatment sessions, and stimulation protocols. Outcome measures were generally limited to a few cognitive tests. Conclusion. Our review suggests that NIBS is able to alleviate neglect after stroke. However, the results are still inconclusive and preliminary for the effect of NIBS on other cognitive domains. A standardized core set of outcome measures of cognition, also at the level of daily life activities and participation, and international agreement on treatment protocols, could lead to better evaluation of the efficacy of NIBS and comparisons between studies.

Perturbation-driven paradoxical facilitation of visuo-spatial function: Revisiting the 'Sprague effect'

The 'Sprague Effect' described in the seminal paper of James Sprague (Science 153:1544-1547, 1966a) is an unexpected paradoxical effect in which a second brain lesion reversed functional deficits induced by an earlier lesion. It was observed initially in the cat where severe and permanent contralateral visually guided attentional deficits generated by the ablation of large areas of the visual cortex were reversed by the subsequent removal of the superior colliculus (SC) opposite to the cortical lesion or by the splitting of the collicular commissure. Physiologically, this effect has been explained in several ways-most notably by the reduction of the functional inhibition of the ipsilateral SC by the contralateral SC, and the restoration of normal interactions between cortical and midbrain structures after ablation. In the present review, we aim at reappraising the 'Sprague Effect' by critically analyzing studies that have been conducted in the feline and human brain. Moreover, we assess applications of the 'Sprague Effect' in the rehabilitation of visually guided attentional impairments by using non-invasive therapeutic approaches such as transcranial magnetic stimulation (TMS) and transcranial direct-current stimulation (tDCS). We also review theoretical models of the effect that emphasize the inhibition and balancing between the two hemispheres and show implications for lesion inference approaches. Last, we critically review whether the resulting inter-hemispheric rivalry theories lead toward an efficient rehabilitation of stroke in humans. We conclude by emphasizing key challenges in the field of 'Sprague Effect' applications in order to design better therapies for brain-damaged patients.

Combining attentional bias modification with dorsolateral prefrontal rTMS does not attenuate maladaptive attentional processing

High frequency repetitive Transcranial Magnetic Stimulation (rTMS) over the left dorsolateral prefrontal cortex (DLPFC) has been shown to reduce depressive symptoms and improve cognitive biases such as attentional bias. One promising technique that may complement rTMS treatment is attentional bias modification (ABM) training, given the similarity in modulating attentional bias and affecting neuronal activity. We tested whether the combination of rTMS treatment and ABM training in a single session would attenuate maladaptive attentional processing and improve mood in participants with subclinical depressive symptoms. To this end, 122 healthy participants were randomly assigned to one of four groups, receiving either a single rTMS treatment, a single ABM treatment, a combination of rTMS and ABM or a sham treatment. Of these 122 participants, 72 showed a heightened BDI-II score (between 9 and 25) and were included in our main analyses. In our subclinical (≥9 and ≤25 BDI-II) sample, a single combination treatment of rTMS and ABM training induced no significant changes in attentional bias, attentional control or mood, nor did rTMS alone affect attentional bias systematically. We discuss these null findings in light of the task specifics and relate them to the ongoing discussion on ABM training in depression.

Effects of Non-invasive Neuromodulation on Executive and Other Cognitive Functions in Addictive Disorders: A Systematic Review

Background: In order to improve the current treatment of addictive disorders non-invasive neuromodulation over the dorsolateral prefrontal cortex (DLPFC) has gained attention. The DLPFC is crucially involved in executive functioning, functions which are related to the course of addictive disorders. Non-invasive stimulation of the DLPFC may lead to changes in executive functioning. Currently an overview of effects of neuromodulation on these functions is lacking. Therefore, this systematic review addresses the effects of non-invasive neuromodulation on executive functioning in addictive disorders. Methods: The current review is conducted and reported in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses for Protocols 2015 (PRISMA-P 2015) guidelines and has been registered in PROSPERO International Prospective Register of Systematic Reviews (https://www.crd.york.ac.uk/prospero/, registration number: CRD42018084157). Original articles were searched using the Ovid MEDLINE, Embase and PsycINFO database. Results: The systematic search resulted in 1,228 unique studies, of which sixteen were included in the current review. Some of these studies do not address the classic definition of executive functions, but another cognitive function. However, they were included in this review since the field is small and still under development and we aim to give an inclusive overview in its broadest sense. The following executive and other cognitive functioning domains were assessed: attention, cognitive flexibility, response inhibition, memory and learning, problem solving, social cognition, risk taking, cognitive bias modification and overall executive functioning. The executive function domain most positively affected was social cognition followed by memory & learning, response inhibition, cognitive flexibility and attention. Conclusions: The studies addressed in the current review used a large variability of stimulation protocols and study designs which complicates comparability of the results. Nevertheless, the results of these studies are promising in light of improvement of current treatment. Therefore, we recommend future studies that compare the effect of different types of stimulation, stimulation sides and number of stimulation sessions in larger clinical trials. This will significantly increase the comparability of the studies and thereby accelerate and clarify the conclusion on whether non-invasive neuromodulation is an effective add-on treatment for substance dependence.

Unilateral repetitive transcranial magnetic stimulation differentially affects younger and older adults completing a verbal working memory task

Functional neuroimaging studies have found that lateralization of activity in the dorsolateral prefrontal cortex (dlPFC) is reduced with aging. In the present study, repetitive transcranial magnetic stimulation (rTMS) was used to disrupt dlPFC activity in order to test the relationship of dlPFC laterality and age in verbal working memory (WM). Young (n=36) and older (n=35) subjects received 1Hz-rTMS (sham or active) to left or right dlPFC and WM performance was assessed pre- and post-stimulation via the n-back task. Significant increases in WM accuracy were observed following rTMS in the right dlPFC and sham conditions, but not with the left dlPFC stimulation. This was accompanied by a decrease in left P1 latency was also observed following left dlPFC stimulation. In contrast, older adults did not show a disruption in WM performance following rTMS in any of the stimulation conditions and exhibited increased left P3 amplitude following left stimulation. Our results show that changes in prefrontal laterality are evident with increasing age (left stimulation affects younger adults while older adults are not affected by stimulation) and this change is associated with specific neurophysiologic measures.

Rehabilitating the addicted brain with transcranial magnetic stimulation

Substance use disorders (SUDs) are one of the leading causes of morbidity and mortality worldwide. In spite of considerable advances in understanding the neural underpinnings of SUDs, therapeutic options remain limited. Recent studies have highlighted the potential of transcranial magnetic stimulation (TMS) as an innovative, safe and cost-effective treatment for some SUDs. Repetitive TMS (rTMS) influences neural activity in the short and long term by mechanisms involving neuroplasticity both locally, under the stimulating coil, and at the network level, throughout the brain. The long-term neurophysiological changes induced by rTMS have the potential to affect behaviours relating to drug craving, intake and relapse. Here, we review TMS mechanisms and evidence that rTMS is opening new avenues in addiction treatments.

Reproducibility of Single-Pulse, Paired-Pulse, and Intermittent Theta-Burst TMS Measures in Healthy Aging, Type-2 Diabetes, and Alzheimer's Disease

Background: Transcranial magnetic stimulation (TMS) can be used to assess neurophysiology and the mechanisms of cortical brain plasticity in humans in vivo. As the use of these measures in specific populations (e.g., Alzheimer’s disease; AD) increases, it is critical to understand their reproducibility (i.e., test–retest reliability) in the populations of interest.

Objective: Reproducibility of TMS measures was evaluated in older adults, including healthy, AD, and Type-2 diabetes mellitus (T2DM) groups.

Methods: Participants received two identical neurophysiological assessments within a year including motor thresholds, baseline motor evoked potentials (MEPs), short- and long-interval intracortical inhibition (SICI, LICI) and intracortical facilitation (ICF), and MEP changes following intermittent theta-burst stimulation (iTBS). Cronbach’s α coefficients were calculated to assess reproducibility. Multiple linear regression analyses were used to investigate factors related to intraindividual variability.

Results: Reproducibility was highest for motor thresholds, followed by baseline MEPs, SICI and LICI, and was lowest for ICF and iTBS aftereffects. The AD group tended to show higher reproducibility than T2DM or controls. Intraindividual variability of baseline MEPs was related to age and variability of RMT, while the intraindividual variability in post-iTBS measures was related to baseline MEP variability, intervisit duration, and Brain-derived neurotrophic factor (BDNF) polymorphism.

Conclusion: Increased reproducibility in AD may reflect pathophysiological declines in the efficacy of neuroplastic mechanisms. Reproducibility of iTBS aftereffects can be improved by keeping baseline MEPs consistent, controlling for BDNF genotype, and waiting at least a week between visits.

Significance: These findings provide the first direct assessment of reproducibility of TMS measures in older clinical populations. Reproducibility coefficients may be used to adjust effect- and sample size calculations for future studies.

Effectiveness of repetitive trancranial or peripheral magnetic stimulation in neuropathic pain

PURPOSE

Maladaptive plasticity in the sensorimotor system, following neurological lesions or diseases, plays a central role in the generation and maintenance of neuropathic pain. Repetitive magnetic stimulation of the central and peripheral nervous system has gained relevance as noninvasive approach for neuromodulation and pain relief. Systematic reviews that evaluate the effectiveness and specificity of different protocols of repetitive magnetic stimulation to control neuropathic pain in clinical populations have the potential to improve the therapeutic applicability of this technique.

METHODS

Studies whose primary goal was to evaluate the effectiveness of repetitive magnetic stimulation for the treatment of various types of neuropathic pain published in PubMed until August 2015 have been included in this systematic review.

RESULTS

A total of 39 articles fulfilling the inclusion criteria were analyzed of which 37 studies investigated pain modulation using repetitive magnetic stimulation over the motor or non-motor cortices and two studies evaluated pain modulation using repetitive peripheral magnetic stimulation protocols.

CONCLUSIONS

Repetitive transcranial magnetic stimulation of the primary motor cortex using high frequency stimulation protocols can effectively reduce neuropathic pain, particularly in individuals with pain related to non-cerebral lesions. The application of multiple sessions can lead to long-lasting pain modulation and cumulative effects. Implications for Rehabilitation Maladaptive plasticity plays a central role in sensitization of nociceptive pathways, generation and maintainance of neuropathic pain; Most neuropathic pain conditions are refractory to pharmacological therapies; Repetitive magnetic stimulation of the central and peripheral nervous system has gained relevance as noninvasive approach for neuromodulation and pain relief.

[Repetitive transcranial magnetic stimulation: A potential therapy for cognitive disorders?]

Considering the limited effectiveness of drugs treatments in cognitive disorders, the emergence of noninvasive techniques to modify brain function is very interesting. Among these techniques, repetitive transcranial magnetic stimulation (rTMS) can modulate cortical excitability and have potential therapeutic effects on cognition and behaviour. These effects are due to physiological modifications in the stimulated cortical tissue and their associated circuits, which depend on the parameters of stimulation. The objective of this article is to specify current knowledge and efficacy of rTMS in cognitive disorders. Previous studies found very encouraging results with significant improvement of higher brain functions. Nevertheless, these few studies have limits: a few patients were enrolled, the lack of control of the mechanisms of action by brain imaging, insufficiently formalized technique and variability of cognitive tests. It is therefore necessary to perform more studies, which identify statistical significant improvement and to specify underlying mechanisms of action and the parameters of use of the rTMS to offer rTMS as a routine therapy for cognitive dysfunction.

Impact of repetitive transcranial magnetic stimulation on post-stroke dysmnesia and the role of BDNF Val66Met SNP

Background

Little is known about the effects of low-frequency repetitive transcranial magnetic stimulation (rTMS) on dysmnesia and the impact of brain nucleotide neurotrophic factor (BDNF) Val66Met single-nucleotide polymorphism (SNP). This study investigated the impact of low-frequency rTMS on post-stroke dysmnesia and the impact of BDNF Val66Met SNP.

Material/Methods

Forty patients with post-stroke dysmnesia were prospectively randomized into the rTMS and sham groups. BDNF Val66Met SNP was determined using restriction fragment length polymorphism. Montreal Cognitive Assessment (MoCA), Loewenstein Occupational Therapy of Cognitive Assessment (LOTCA), and Rivermead Behavior Memory Test (RBMT) scores, as well as plasma BDNF concentrations, were measured at baseline and at 3 days and 2 months post-treatment.

Results

MoCA, LOTCA, and RBMT scores were higher after rTMS. Three days after treatment, BDNF decreased in the rTMS group but it increased in the sham group (P<0.05). Two months after treatment, RMBT scores in the rTMS group were higher than in the sham group, but not MoCA and LOTCA scores.

Conclusions

Low-frequency rTMS may improve after-stoke memory through various pathways, which may involve polymorphisms and several neural genes, but not through an increase in BDNF levels.

Long-term effects of continuous theta-burst stimulation in visuospatial neglect

Objective

To investigate whether the efficacy of continuous theta-burst stimulation (cTBS) for improving visuospatial neglect can be enhanced by providing more days of stimulation and more stimulation trains per day.

Methods

In a prospective study, right-handed patients with right hemisphere stroke and visuospatial neglect were randomized to cTBS or sham cTBS treatment for 2 weeks and were followed up for 4 weeks. The cTBS group received active cTBS over the posterior parietal cortex of the unaffected hemisphere, combined with conventional rehabilitation therapy. Changes in scores for two paper–pencil tests for visuospatial neglect (star cancellation and line bisection) were evaluated.

Results

In each group, 10 patients completed follow up. Compared with the sham group, star cancellation test scores in the cTBS group were improved by 37.03% at the end of treatment and by 47.21% after 4 weeks’ follow up, and the line bisection score improved by 21.37% at the end of treatment and by 35.99% after 4 weeks’ follow up.

Conclusions

These results suggest that the efficacy of cTBS in visuospatial neglect can be enhanced and prolonged by increasing the days of stimulation and the number of stimulation trains per day over the left posterior parietal cortex.

Low-intensity repetitive transcranial magnetic stimulation improves abnormal visual cortical circuit topography and upregulates BDNF in mice

Repetitive transcranial magnetic stimulation (rTMS) is increasingly used as a treatment for neurological and psychiatric disorders. Although the induced field is focused on a target region during rTMS, adjacent areas also receive stimulation at a lower intensity and the contribution of this perifocal stimulation to network-wide effects is poorly defined. Here, we examined low-intensity rTMS (LI-rTMS)-induced changes on a model neural network using the visual systems of normal (C57Bl/6J wild-type, n = 22) and ephrin-A2A5(-/-) (n = 22) mice, the latter possessing visuotopic anomalies. Mice were treated with LI-rTMS or sham (handling control) daily for 14 d, then fluorojade and fluororuby were injected into visual cortex. The distribution of dorsal LGN (dLGN) neurons and corticotectal terminal zones (TZs) was mapped and disorder defined by comparing their actual location with that predicted by injection sites. In the afferent geniculocortical projection, LI-rTMS decreased the abnormally high dispersion of retrogradely labeled neurons in the dLGN of ephrin-A2A5(-/-) mice, indicating geniculocortical map refinement. In the corticotectal efferents, LI-rTMS improved topography of the most abnormal TZs in ephrin-A2A5(-/-) mice without altering topographically normal TZs. To investigate a possible molecular mechanism for LI-rTMS-induced structural plasticity, we measured brain derived neurotrophic factor (BDNF) in the visual cortex and superior colliculus after single and multiple stimulations. BDNF was upregulated after a single stimulation for all groups, but only sustained in the superior colliculus of ephrin-A2A5(-/-) mice. Our results show that LI-rTMS upregulates BDNF, promoting a plastic environment conducive to beneficial reorganization of abnormal cortical circuits, information that has important implications for clinical rTMS.