Direct Causal Networks for the Study of Transcranial Magnetic Stimulation Effects on Focal Epileptiform Discharges

2015 ◽  
Vol 25 (05) ◽  
pp. 1550006 ◽  
Author(s):  
Dimitris Kugiumtzis ◽  
Vasilios K. Kimiskidis
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Network Structure ◽  
Magnetic Stimulation ◽  
Brain Connectivity ◽  
Effective Connectivity ◽  
Epileptic Focus ◽  
Sham Stimulation ◽  
Focal Seizures ◽  
Epileptiform Discharges ◽  
The Brain

Background: Transcranial magnetic stimulation (TMS) can have inhibitory effects on epileptiform discharges (EDs) of patients with focal seizures. However, the brain connectivity before, during and after EDs, with or without the administration of TMS, has not been extensively explored. Objective: To investigate the brain network of effective connectivity during ED with and without TMS in patients with focal seizures. Methods: For the effective connectivity a direct causality measure is applied termed partial mutual information from mixed embedding (PMIME). TMS-EEG data from two patients with focal seizures were analyzed. Each EEG record contained a number of EDs in the majority of which TMS was administered over the epileptic focus. As a control condition, sham stimulation over the epileptogenic zone or real TMS at a distance from the epileptic focus was also performed. The change in brain connectivity structure was investigated from the causal networks formed at each sliding window. Conclusion: The PMIME could detect distinct changes in the network structure before, within, and after ED. The administration of real TMS over the epileptic focus, in contrast to sham stimulation, terminated the ED prematurely in a node-specific manner and regained the network structure as if it would have terminated spontaneously.

Dynamics of Epileptiform Discharges Induced by Transcranial Magnetic Stimulation in Genetic Generalized Epilepsy

2017 ◽  
Vol 27 (07) ◽  
pp. 1750037 ◽  
Author(s):  
Dimitris Kugiumtzis ◽  
Christos Koutlis ◽  
Alkiviadis Tsimpiris ◽  
Vasilios K. Kimiskidis
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Brain Connectivity ◽  
Effective Connectivity ◽  
Brain Network ◽  
Brain State ◽  
Epileptiform Discharges ◽  
Eeg Recordings ◽  
Generalized Epilepsy ◽  
The Brain

Objective: In patients with Genetic Generalized Epilepsy (GGE), transcranial magnetic stimulation (TMS) can induce epileptiform discharges (EDs) of varying duration. We hypothesized that (a) the ED duration is determined by the dynamic states of critical network nodes (brain areas) at the early post-TMS period, and (b) brain connectivity changes before, during and after the ED, as well as within the ED. Methods: EEG recordings from two GGE patients were analyzed. For hypothesis (a), the characteristics of the brain dynamics at the early ED stage are measured with univariate and multivariate EEG measures and the dependence of the ED duration on these measures is evaluated. For hypothesis (b), effective connectivity measures are combined with network indices so as to quantify the brain network characteristics and identify changes in brain connectivity. Results: A number of measures combined with specific channels computed on the first EEG segment post-TMS correlate with the ED duration. In addition, brain connectivity is altered from pre-ED to ED and post-ED and statistically significant changes were also detected across stages within the ED. Conclusion: ED duration is not purely stochastic, but depends on the dynamics of the post-TMS brain state. The brain network dynamics is significantly altered in the course of EDs.

scholarly journals Transcranial magnetic stimulation: studying the brain--behaviour relationship by induction of ‘virtual lesions’

1999 ◽  
Vol 354 (1387) ◽  
pp. 1229-1238 ◽  
Author(s):  
Alvaro Pascual-Leone
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Brain Connectivity ◽  
Brain Activity ◽  
Causal Link ◽  
Non Invasive ◽  
Invasive Method ◽  
Normal Humans ◽  
The Brain ◽  
Neuroimaging Techniques

Transcranial magnetic stimulation (TMS) provides a non-invasive method of induction of a focal current in the brain and transient modulation of the function of the targeted cortex. Despite limited understanding about focality and mechanisms of action, TMS provides a unique opportunity of studying brain-behaviour relations in normal humans. TMS can enhance the results of other neuroimaging techniques by establishing the causal link between brain activity and task performance, and by exploring functional brain connectivity.

Connectivity Guided Theta Burst Transcranial Magnetic Stimulation Versus Repetitive Transcranial Magnetic Stimulation for Treatment Resistant Moderate to Severe Depression: Magnetic Resonance Imaging Protocol and SARS COVID-19 induced changes for a Randomised Double-blind Controlled Trial (BRIGhTMIND) (Preprint)

2021 ◽  
Author(s):  
Stefan Pszczolkowski ◽  
William J. Cottam ◽  
Paul M. Briley ◽  
Sarina J. Iwabuchi ◽  
Catherine Kaylor-Hughes ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Resonance ◽  
Magnetic Stimulation ◽  
Brain Connectivity ◽  
Controlled Trial ◽  
Treatment Resistant ◽  
Double Blind ◽  
Mri Guidance ◽  
Dorsolateral Prefrontal ◽  
The Brain

BACKGROUND Depression is a significant health and economic burden. In approximately one third of patients, depression is resistant to first line treatments and therefore it is essential that alternative treatments are found. Transcranial magnetic stimulation (TMS) is a neuromodulatory treatment involving the application of magnetic pulses to the brain that is approved in the UK and the US in treatment resistant depression. This trial aims to compare the clinical effectiveness, cost-effectiveness and mechanism of action between standard treatment repetitive TMS (rTMS) targeted at the F3 EEG site, with a newer treatment – a type of TMS called theta-burst stimulation (TBS) targeted based on measures of functional brain connectivity. This protocol outlines the brain imaging acquisition and analysis for the BRIGhTMIND trial that is used to create personalised TMS targets and answer the proposed mechanistic hypotheses. OBJECTIVE The objectives of the imaging arm of the BRIGhTMIND study are to identify functional and neurochemical brain signatures indexing the treatment mechanisms of rTMS and cgiTBS and to identify imaging-based markers predicting response to treatment. METHODS The study is a randomised double-blind controlled trial with 1:1 allocation to either 20 sessions of a) TBS or b) standard rTMS. Multimodal magnetic resonance imaging (MRI) is acquired per participant at baseline (prior to TMS treatment) with T1-weighted and task-free functional MRI during rest (rsfMRI) utilised to estimate TMS targets. For participants enrolled in the mechanistic substudy additional diffusion-weighted, sequences are acquired at baseline and at post-treatment follow-up 16 weeks after treatment randomisation. Core datasets of T1-weighted and task-free functional MRI during rest (rsfMRI) are acquired for all participants and utilised to estimate TMS targets. Additional sequences of arterial spin labelling, magnetic resonance spectroscopy and diffusion-weighted images are acquired dependent on recruitment site for mechanistic evaluation. Standard rTMS treatment is targeted at the F3 electrode site over the left dorsolateral prefrontal cortex whilst TBS treatment is guided using the coordinate of peak effective connectivity from the right anterior insula to the left dorsolateral prefrontal cortex. Both treatment targets benefit from a level of MRI-guidance but only TBS is provided with precision targeting based on functional brain connectivity. RESULTS Recruitment began January 2019 and is ongoing. Data collection is expected to continue until January 2023. CONCLUSIONS This trial will determine the impact of precision MRI guidance on rTMS treatment, and furthermore, assess the neural mechanisms underlying this treatment in treatment resistant depressed patients. CLINICALTRIAL International Standard Randomized Controlled Trial Number (ISRCTN) 19674644; https://www.isrctn.com/ISRCTN19674644. Registered 2nd October 2018.

Stereotactic Brain Biopsy in Eloquent Areas Assisted by Navigated Transcranial Magnetic Stimulation: a Technical Case Report

2018 ◽  
Vol 17 (3) ◽  
pp. E124-E129 ◽  
Author(s):  
Jiri Bartek ◽  
Gerald Cooray ◽  
Mominul Islam ◽  
Margret Jensdottir
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Stereotactic Biopsy ◽  
Brain Biopsy ◽  
Awake Surgery ◽  
Histopathological Diagnosis ◽  
Navigated Transcranial Magnetic Stimulation ◽  
Stereotactic Brain Biopsy ◽  
Eloquent Areas ◽  
The Brain

Abstract BACKGROUND AND IMPORTANCE Stereotactic brain biopsy (SB) is an important part of the neurosurgical armamentarium, with the possibility of achieving histopathological diagnosis in otherwise inaccessible lesions of the brain. Nevertheless, the procedure is not without the risk of morbidity, which is especially true for lesions in eloquent parts of the brain, where even a minor adverse event can result in significant deficits. Navigated transcranial magnetic stimulation (nTMS) is widely used to chart lesions in eloquent areas, successfully guiding maximal safe resection, while its potential role in aiding with the planning of a stereotactic biopsy is so far unexplored. CLINICAL PRESENTATION Magnetic resonance imaging of a 67-yr-old woman presenting with dysphasia revealed a noncontrast enhancing left-sided lesion in the frontal and parietal pars opercularis. Due to the location of the lesion, nTMS was used to chart both primary motor and language cortex, utilizing this information to plan a safe SB trajectory and sampling area according to the initial work-up recommendations from the multidisciplinary neuro-oncology board. The SB was uneventful, with histology revealing a ganglioglioma, WHO I. The patient was discharged the following day, having declined to proceed with tumor resection (awake surgery) due to the non-negligible risk of morbidity. Upon 1- and 3-mo follow-up, she showed no signs of any procedure-related deficits. CONCLUSION nTMS can be implemented to aid with the planning of a stereotactic biopsy procedure in eloquent areas of the brain, and should be considered part of the neurosurgical armamentarium.

scholarly journals Predictive Role of Executive Function in the Efficacy of Intermittent Theta Burst Transcranial Magnetic Stimulation Modalities for Treating Methamphetamine Use Disorder—A Randomized Clinical Trial

2021 ◽  
Vol 12 ◽  
Author(s):  
Li-Jin Wang ◽  
Lin-Lin Mu ◽  
Zi-Xuan Ren ◽  
Hua-Jun Tang ◽  
Ya-Dong Wei ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Working Memory ◽  
Executive Function ◽  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Therapeutic Effects ◽  
Sham Stimulation ◽  
Theta Burst ◽  
Stimulation Group

Background: Repetitive transcranial magnetic stimulation (rTMS) has therapeutic effects on craving in methamphetamine (METH) use disorder (MUD). The chronic abuse of METH causes impairments in executive function, and improving executive function reduces relapse and improves treatment outcomes for drug use disorder. The purpose of this study was to determine whether executive function helped predict patients' responses to rTMS treatment.Methods: This study employed intermittent theta burst stimulation (iTBS) rTMS modalities and observed their therapeutic effects on executive function and craving in MUD patients. MUD patients from an isolated Drug Rehabilitation Institute in China were chosen and randomly allocated to the iTBS group and sham-stimulation group. All participants underwent the Behavior Rating Inventory of Executive Function - Adult Version Scale (BRIEF-A) and Visual Analog Scales (VAS) measurements. Sixty-five healthy adults matched to the general condition of MUD patients were also recruited as healthy controls.Findings: Patients with MUD had significantly worse executive function. iTBS groups had better treatment effects on the MUD group than the sham-stimulation group. Further Spearman rank correlation and stepwise multivariate regression analysis revealed that reduction rates of the total score of the BRIEF-A and subscale scores of the inhibition factor and working memory factor in the iTBS group positively correlated with improvements in craving. ROC curve analysis showed that working memory (AUC = 87.4%; 95% CI = 0.220, 0.631) and GEC (AUC = 0.761%; 95% CI = 0.209, 0.659) had predictive power to iTBS therapeutic efficacy. The cutoff values are 13.393 and 59.804, respectively.Conclusions: The iTBS rTMS had a better therapeutic effect on the executive function of patients with MUD, and the improved executive function had the potential to become a predictor for the efficacy of iTBS modality for MUD treatment.Clinical Trial Registration:ClinicalTrials.gov, identifier: ChiCTR2100046954.

scholarly journals Determination of Dynamic Brain Connectivity via Spectral Analysis

2021 ◽  
Vol 15 ◽  
Author(s):  
Peter A. Robinson ◽  
James A. Henderson ◽  
Natasha C. Gabay ◽  
Kevin M. Aquino ◽  
Tara Babaie-Janvier ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Brain Structure ◽  
Brain Connectivity ◽  
Spatial Scales ◽  
Effective Connectivity ◽  
Physical Nature ◽  
Building Blocks ◽  
Brain Dynamics ◽  
Compact Representation ◽  
The Brain

Spectral analysis based on neural field theory is used to analyze dynamic connectivity via methods based on the physical eigenmodes that are the building blocks of brain dynamics. These approaches integrate over space instead of averaging over time and thereby greatly reduce or remove the temporal averaging effects, windowing artifacts, and noise at fine spatial scales that have bedeviled the analysis of dynamical functional connectivity (FC). The dependences of FC on dynamics at various timescales, and on windowing, are clarified and the results are demonstrated on simple test cases, demonstrating how modes provide directly interpretable insights that can be related to brain structure and function. It is shown that FC is dynamic even when the brain structure and effective connectivity are fixed, and that the observed patterns of FC are dominated by relatively few eigenmodes. Common artifacts introduced by statistical analyses that do not incorporate the physical nature of the brain are discussed and it is shown that these are avoided by spectral analysis using eigenmodes. Unlike most published artificially discretized “resting state networks” and other statistically-derived patterns, eigenmodes overlap, with every mode extending across the whole brain and every region participating in every mode—just like the vibrations that give rise to notes of a musical instrument. Despite this, modes are independent and do not interact in the linear limit. It is argued that for many purposes the intrinsic limitations of covariance-based FC instead favor the alternative of tracking eigenmode coefficients vs. time, which provide a compact representation that is directly related to biophysical brain dynamics.

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