scholarly journals Fine multi-coil electronic control of transcranial magnetic stimulation: effects of stimulus orientation and intensity

2021 ◽  
Author(s):  
Victor H. Souza ◽  
Jaakko O. Nieminen ◽  
Sergei Tugin ◽  
Lari M. Koponen ◽  
Oswaldo Baffa ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Neurological Diseases ◽  
Brain Activity ◽  
Logistic Function ◽  
Stimulus Orientation ◽  
High Angular Resolution ◽  
Electronic Control ◽  
Fast Control ◽  
Electric Filed

Despite the evident benefit of transcranial magnetic stimulation (TMS) to probe human brain function and treat neurological diseases, current technology allows only a slow, mechanical adjustment of the electric filed orientation. Automated and fast control of the TMS orientation is critical to enable synchronizing the stimulation with the ongoing brain activity. We overcome these limitations with a two-coil electronically controlled TMS transducer to define precisely the pulse orientation (~1-degree steps) without mechanical movement. We validated the technology by determining the dependency of motor evoked responses on the stimulus orientation and intensity with high angular resolution. The motor response was found to follow a logistic function of the stimulus orientation, which helps to disentangle the TMS neuronal effects. The electronic control of the TMS electric field is a decisive step towards automated brain stimulation protocols with enhanced accuracy of stimulus targeting and timing for better diagnostics and improved clinical efficacy.

scholarly journals Effect of stimulus orientation and intensity on short-interval intracortical inhibition (SICI) and facilitation (SICF): A multi-channel transcranial magnetic stimulation study

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0257554
Author(s):  
Sergei Tugin ◽  
Victor H. Souza ◽  
Maria A. Nazarova ◽  
Pavel A. Novikov ◽  
Aino E. Tervo ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Short Interval ◽  
Intracortical Inhibition ◽  
Stimulus Orientation ◽  
Electronic Control ◽  
Field Orientation ◽  
Neuronal Populations ◽  
Resting Motor Threshold ◽  
Strongly Connected

Besides stimulus intensities and interstimulus intervals (ISI), the electric field (E-field) orientation is known to affect both short-interval intracortical inhibition (SICI) and facilitation (SICF) in paired-pulse transcranial magnetic stimulation (TMS). However, it has yet to be established how distinct orientations of the conditioning (CS) and test stimuli (TS) affect the SICI and SICF generation. With the use of a multi-channel TMS transducer that provides electronic control of the stimulus orientation and intensity, we aimed to investigate how changes in the CS and TS orientation affect the strength of SICI and SICF. We hypothesized that the CS orientation would play a major role for SICF than for SICI, whereas the CS intensity would be more critical for SICI than for SICF. In eight healthy subjects, we tested two ISIs (1.5 and 2.7 ms), two CS and TS orientations (anteromedial (AM) and posteromedial (PM)), and four CS intensities (50, 70, 90, and 110% of the resting motor threshold (RMT)). The TS intensity was fixed at 110% RMT. The intensities were adjusted to the corresponding RMT in the AM and PM orientations. SICI and SICF were observed in all tested CS and TS orientations. SICI depended on the CS intensity in a U-shaped manner in any combination of the CS and TS orientations. With 70% and 90% RMT CS intensities, stronger PM-oriented CS induced stronger inhibition than weaker AM-oriented CS. Similar SICF was observed for any CS orientation. Neither SICI nor SICF depended on the TS orientation. We demonstrated that SICI and SICF could be elicited by the CS perpendicular to the TS, which indicates that these stimuli affected either overlapping or strongly connected neuronal populations. We concluded that SICI is primarily sensitive to the CS intensity and that CS intensity adjustment resulted in similar SICF for different CS orientations.

scholarly journals Task-Modulated Brain Activity Predicts Antidepressant Responses of Prefrontal Repetitive Transcranial Magnetic Stimulation: A Randomized Sham-Control Study

2021 ◽  
Vol 5 ◽  
pp. 247054702110068
Author(s):  
Cheng-Ta Li ◽  
Chih-Ming Cheng ◽  
Chi-Hung Juan ◽  
Yi-Chun Tsai ◽  
Mu-Hong Chen ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Antidepressant Treatment ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Brain Activity ◽  
Characteristic Curve ◽  
Depression Score ◽  
Double Blind ◽  
Antidepressant Efficacy ◽  
Group B

Background Prolonged intermittent theta-burst stimulation (piTBS) and repetitive transcranial magnetic stimulation (rTMS) are effective antidepressant interventions for major depressive disorder (MDD). Cognition-modulated frontal theta (frontalθ) activity had been identified to predict the antidepressant response to 10-Hz left prefrontal rTMS. However, whether this marker also predicts that of piTBS needs further investigation. Methods The present double-blind randomized trial recruited 105 patients with MDD who showed no response to at least one adequate antidepressant treatment in the current episode. The recruited patients were randomly assigned to one of three groups: group A received piTBS monotherapy; group B received rTMS monotherapy; and group C received sham stimulation. Before a 2-week acute treatment period, electroencephalopgraphy (EEG) and cognition-modulated frontal theta changes (Δfrontalθ) were measured. Depression scores were evaluated at baseline, 1 week, and 2 weeks after the initiation of treatment. Results The Δfrontalθ at baseline was significantly correlated with depression score changes at week 1 (r = −0.383, p = 0.025) and at week 2 for rTMS group (r = −0.419, p = 0.014), but not for the piTBS and sham groups. The area under the receiver operating characteristic curve for Δfrontalθ was 0.800 for the rTMS group (p = 0.003) and was 0.549 for the piTBS group (p = 0.619). Conclusion The predictive value of higher baseline Δfrontalθ for antidepressant efficacy for rTMS not only replicates previous results but also implies that the antidepressant responses to rTMS could be predicted reliably at baseline and both piTBS and rTMS could be effective through different neurobiological mechanisms.

scholarly journals A Neurostimulator System for Real, Sham, and Multi-Target Transcranial Magnetic Stimulation

2021 ◽  
Author(s):  
Majid Memarian Sorkhabi ◽  
Timothy Denison
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Pulse Width Modulation ◽  
Pulse Generator ◽  
Control Method ◽  
Physical Distance ◽  
Magnetic Pulse ◽  
Electronic Control ◽  
Channel Modulation ◽  
Measured System

Background: Transcranial magnetic stimulation (TMS) is a clinically effective therapeutic instrument used to modulate neural activity. Despite three decades of research, two challenging issues remain, the possibility of changing the 1) stimulated spot and 2) stimulation type (real or sham) without physically moving the coil. Objective: In this study, a second-generation programmable TMS (pTMS2) device with advanced stimulus shaping is introduced that uses a 5-level cascaded H-bridge inverter and phase-shifted pulse-width modulation (PWM). The principal idea of this research is to obtain real, sham, and multi-locus stimulation with the same TMS system. Methods: We propose a two-channel modulation-based magnetic pulse generator and a novel coil arrangement, consisting of two circular coils with a physical distance of 20 mm between the coils and a control method for modifying the effective stimulus intensity, which leads to the live steerability of the location and type of stimulation. Results: Based on the measured system performance, the stimulation profile can be steered 20 mm along a line from the centroid of the coil locations by modifying the modulation index. Conclusion: The proposed system supports electronic control of the stimulation spot without physical coil movement, resulting in tunable modulation of targets, which is a crucial step towards automated TMS machines.

scholarly journals Alertness fluctuations during task performance modulate cortical evoked responses to transcranial magnetic stimulation

2017 ◽  
Author(s):  
Valdas Noreika ◽  
Marc R. Kamke ◽  
Andrés Canales-Johnson ◽  
Srivas Chennu ◽  
Tristan A. Bekinschtein ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Cognitive Neuroscience ◽  
Magnetic Stimulation ◽  
Motor Evoked Potentials ◽  
Brain Activity ◽  
Single Pulse ◽  
Neural Recording ◽  
Neural Responses ◽  
Spontaneous Fluctuations

ABSTRACTTranscranial magnetic stimulation (TMS) has been widely used in human cognitive neuroscience to examine the causal role of distinct cortical areas in perceptual, cognitive and motor functions. However, it is widely acknowledged that the effects of focal cortical stimulation on behaviour can vary substantially between participants and even from trial to trial within individuals. Here we asked whether spontaneous fluctuations in alertness can account for the variability in behavioural and neurophysiological responses to TMS. We combined single-pulse TMS with neural recording via electroencephalography (EEG) to quantify changes in motor and cortical reactivity with fluctuating levels of alertness defined objectively on the basis of ongoing brain activity. We observed rapid, non-linear changes in TMS-evoked neural responses – specifically, motor evoked potentials and TMS-evoked cortical potentials – as EEG activity indicated decreasing levels of alertness, even while participants remained awake and responsive in the behavioural task.IMPACT STATEMENTA substantial proportion of inter-trial variability in neurophysiological responses to TMS is due to spontaneous fluctuations in alertness, which should be controlled for during experimental and clinical applications of TMS.

scholarly journals Factors Influencing the Effects of Repetitive Transcranial Magnetic Stimulation in Parkinson's Disease

2016 ◽  
Vol 2 (4) ◽  
pp. 252-259
Author(s):  
Na Ye ◽  
Tao Feng
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Neurological Diseases ◽  
Future Research ◽  
Physical Factors ◽  
Motor Symptoms ◽  
Invasive Treatment

Barker first used transcranial magnetic stimulation in 1985 in human brain function research. Since then, it has gradually been developed into a secure and non-invasive treatment method for neurological diseases. In 1994, Pascual Leone first used it for the treatment of Parkinson's disease (PD) and observed an improvement in the motor symptoms of most of the patients. Recent studies have confirmed that both motor and non-motor symptoms of patients with PD could be improved through biochemical, electrophysiological, and functional magnetic resonance imaging analysis. Different therapeutic applications can be achieved by adjusting the stimulation parameters. Physical factors affecting the therapeutic effect include the shape and size of the coil, array orientation, materials and intensity, frequency of stimulus, etc.; the biological factors include stimulating targets, baseline, circadian rhythms, cerebral cortex thickness, and so on. This paper will review these factors and provide a reference for future research.

Effects of deep transcranial magnetic stimulation of the medial PFC and ACC on relapse to alcohol use and related brain activity

2017 ◽  
Vol 10 (4) ◽  
pp. e27
Author(s):  
Maayan Harel ◽  
Noam Barnea ◽  
Hadar Shalev ◽  
Itay Besser ◽  
Moti Salti ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Alcohol Use ◽  
Magnetic Stimulation ◽  
Brain Activity ◽  
Medial Pfc ◽  
Stimulation Of
Sign in / Sign up

Export Citation Format

Share Document