scholarly journals Decoding individualized motor cortical excitability states from whole-brain electroencephalography

2021 ◽  
Author(s):  
Sara J Hussain ◽  
Romain Quentin
Keyword(s):  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Brain State ◽  
Individual Subject ◽  
Whole Brain ◽  
State Dependent ◽  
Subject Specific ◽  
The Individual ◽  
Real Time Identification ◽  
The Right

OBJECTIVE: Brain state-dependent transcranial magnetic stimulation (TMS) requires real-time identification of cortical excitability states. Here, we aimed to identify individualized, subject-specific motor cortex (M1) excitability states from whole-scalp electroencephalography (EEG) signals. METHODS: We analyzed a pre-existing dataset that delivered 600 single TMS pulses to the right M1 during EEG and electromyography (EMG) recordings. Subject-specific multivariate pattern classification was used to discriminate between brain states during which TMS elicited small or large motor-evoked potentials (MEPs). RESULTS: Classifiers trained at the individual subject level successfully discriminated between low and high M1 excitability states. MEPs elicited during classifier-predicted high excitability states were significantly larger than those elicited during classifier-predicted low excitability states. Classifiers trained on subject-specific data obtained immediately before TMS delivery performed better than classifiers trained on data from earlier time points, and subject-specific classifiers generalized weakly but significantly across subjects. CONCLUSION: Decoding individualized M1 excitability states from whole-brain EEG activity is feasible and robust. SIGNIFICANCE: Deploying subject-specific classifiers during brain state-dependent TMS may enable effective, fully individualized neuromodulation in the future.

scholarly journals Neural activity related to volitional regulation of cortical excitability

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Kathy Ruddy ◽  
Joshua Balsters ◽  
Dante Mantini ◽  
Quanying Liu ◽  
Pegah Kassraian-Fard ◽  
...  
Keyword(s):  
Magnetic Stimulation ◽  
Dynamic Range ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Recovery Of Function ◽  
Brain State ◽  
Large Dynamic Range ◽  
Conditioning Paradigm ◽  
Alpha Oscillations ◽  
Human Motor

To date there exists no reliable method to non-invasively upregulate or downregulate the state of the resting human motor system over a large dynamic range. Here we show that an operant conditioning paradigm which provides neurofeedback of the size of motor evoked potentials (MEPs) in response to transcranial magnetic stimulation (TMS), enables participants to self-modulate their own brain state. Following training, participants were able to robustly increase (by 83.8%) and decrease (by 30.6%) their MEP amplitudes. This volitional up-versus down-regulation of corticomotor excitability caused an increase of late-cortical disinhibition (LCD), a TMS derived read-out of presynaptic GABAB disinhibition, which was accompanied by an increase of gamma and a decrease of alpha oscillations in the trained hemisphere. This approach paves the way for future investigations into how altered brain state influences motor neurophysiology and recovery of function in a neurorehabilitation context.

scholarly journals Stability and similarity of the pediatric connectome as developmental measures

2019 ◽  
Author(s):  
Tamara Vanderwal ◽  
Jeffrey Eilbott ◽  
Clare Kelly ◽  
Simon R. Frew ◽  
Todd S. Woodward ◽  
...  
Keyword(s):  
Social Skills ◽  
Functional Connectivity ◽  
Principal Component ◽  
List Type ◽  
Individual Subject ◽  
Whole Brain ◽  
Functional Connectome ◽  
Brain Connectome ◽  
The Social ◽  
The Individual

AbstractPatterns of functional connectivity are unique at the individual level, enabling test-retest matching algorithms to identify a subject from among a group using only their functional connectome. Recent findings show that accuracies of these algorithms in children increase with age. Relatedly, the persistence of functional connectivity (FC) patterns across tasks and rest also increases with age. This study investigated the hypothesis that within-subject stability and between-subject similarity of the whole-brain pediatric connectome are developmentally relevant outcomes. Using data from 210 help-seeking children and adolescents, ages 6-21 years (Healthy Brain Network Biobank), we computed whole-brain FC matrices for each participant during two different movies (MovieDM and MovieTP) and two runs of task-free rest (all from a single scan session) and fed these matrices to a test-retest matching algorithm. We replicated the finding that matching accuracies for children and youth (ages 6-21 years) are low (18-44%), and that cross-state and cross-movie accuracies were the lowest. Results also showed that parcellation resolution and the number of volumes used in each matrix affect fingerprinting accuracies. Next, we calculated three measures of whole-connectome stability for each subject: cross-rest (Rest1-Rest2), crossstate (MovieDM-Rest1), and cross-movie (MovieDM-MovieTP), and three measures of within-state between-subject connectome similarity for Rest1, MovieDM, and MovieTP. We show that stability and similarity were correlated, but that these measures were not related to age. A principal component analysis of these measures yielded two components that we used to test for brain-behavior correlations with IQ, general psychopathology, and social skills measures (n=119). The first component was significantly correlated with the social skills measure (r=-0.26, p=0.005). Post hoc correlations showed that the social skills measure correlated with both cross-rest stability (r=-0.29, p=0.001) and with connectome similarity during MovieDM (r=-0.28, p=0.002). These findings suggest that the stability and similarity of the whole-brain connectome relate to overall brain development, and in particular, to those regions that support social skills. We infer that the development of the functional connectome simultaneously achieves patterns of FC that are distinct at the individual subject level, that are shared across individuals, and that are persistent across states and across runs—features which presumably combine to optimize neural processing during development. Future longitudinal work could reveal the developmental trajectories of stability and similarity of the connectome.Highlights- Identification algorithms yielded low accuracies in this developmental sample.- Individual differences in FC were not as persistent across states or movies.- Connectome within-subject stability and between-subject similarity were interrelated.- Stability during rest and similarity during a movie correlate with social skills scores.

Brain State-dependent Gain Modulation of Corticospinal Output in the Active Motor System

2019 ◽  
Vol 30 (1) ◽  
pp. 371-381 ◽  
Author(s):  
Georgios Naros ◽  
Tobias Lehnertz ◽  
Maria Teresa Leão ◽  
Ulf Ziemann ◽  
Alireza Gharabaghi
Keyword(s):  
Muscle Activation ◽  
Motor Evoked Potentials ◽  
Brain State ◽  
Robotic Hand ◽  
Response Modulation ◽  
Beta Band ◽  
State Dependent ◽  
Communication Through Coherence ◽  
Oscillatory Cycle ◽  
Hand Opening

Abstract The communication through coherence hypothesis suggests that only coherently oscillating neuronal groups can interact effectively and predicts an intrinsic response modulation along the oscillatory rhythm. For the motor cortex (MC) at rest, the oscillatory cycle has been shown to determine the brain’s responsiveness to external stimuli. For the active MC, however, the demonstration of such a phase-specific modulation of corticospinal excitability (CSE) along the rhythm cycle is still missing. Motor evoked potentials in response to transcranial magnetic stimulation (TMS) over the MC were used to probe the effect of cortical oscillations on CSE during several motor conditions. A brain–machine interface (BMI) with a robotic hand orthosis allowed investigating effects of cortical activity on CSE without the confounding effects of voluntary muscle activation. Only this BMI approach (and not active or passive hand opening alone) revealed a frequency- and phase-specific cortical modulation of CSE by sensorimotor beta-band activity that peaked once per oscillatory cycle and was independent of muscle activity. The active MC follows an intrinsic response modulation in accordance with the communication through coherence hypothesis. Furthermore, the BMI approach may facilitate and strengthen effective corticospinal communication in a therapeutic context, for example, when voluntary hand opening is no longer possible after stroke.

scholarly journals EEG-triggered TMS reveals stronger brain state-dependent modulation of motor evoked potentials at weaker stimulation intensities

2019 ◽  
Vol 12 (1) ◽  
pp. 110-118 ◽  
Author(s):  
Natalie Schaworonkow ◽  
Jochen Triesch ◽  
Ulf Ziemann ◽  
Christoph Zrenner
Keyword(s):  
Evoked Potentials ◽  
Motor Evoked Potentials ◽  
Brain State ◽  
State Dependent

scholarly journals Transcranial static magnetic stimulation over the motor cortex can facilitate the contralateral cortical excitability in human

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yasuyuki Takamatsu ◽  
Satoko Koganemaru ◽  
Tatsunori Watanabe ◽  
Sumiya Shibata ◽  
Yoshihiro Yukawa ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Single Pulse ◽  
Brain Network ◽  
Corticospinal Excitability ◽  
Double Blind ◽  
The Right

AbstractTranscranial static magnetic stimulation (tSMS) has been focused as a new non-invasive brain stimulation, which can suppress the human cortical excitability just below the magnet. However, the non-regional effects of tSMS via brain network have been rarely studied so far. We investigated whether tSMS over the left primary motor cortex (M1) can facilitate the right M1 in healthy subjects, based on the hypothesis that the functional suppression of M1 can cause the paradoxical functional facilitation of the contralateral M1 via the reduction of interhemispheric inhibition (IHI) between the bilateral M1. This study was double-blind crossover trial. We measured the corticospinal excitability in both M1 and IHI from the left to right M1 by recording motor evoked potentials from first dorsal interosseous muscles using single-pulse and paired-pulse transcranial magnetic stimulation before and after the tSMS intervention for 30 min. We found that the corticospinal excitability of the left M1 decreased, while that of the right M1 increased after tSMS. Moreover, the evaluation of IHI revealed the reduced inhibition from the left to the right M1. Our findings provide new insights on the mechanistic understanding of neuromodulatory effects of tSMS in human.

Interpreting Release from Proactive Interference for the Individual Subject

1980 ◽  
Vol 46 (3_suppl) ◽  
pp. 1044-1046 ◽  
Author(s):  
Barrie Gunter
Keyword(s):  
Proactive Interference ◽  
Individual Subject ◽  
Shift Trial ◽  
Subject Specific ◽  
Release From Proactive Interference ◽  
The Individual ◽  
Trial Performance

Re-analysis of data from three Brown-Peterson experiments in terms of individual subject shift-trial performance showed that large proportions of subjects failed to exhibit release from proactive interference, indicating that this effect may often be subject-specific.

scholarly journals Investigating the interaction between white matter and brain state on tDCS-induced changes in brain network activity

2020 ◽  
Author(s):  
Danielle L. Kurtin ◽  
Ines R. Violante ◽  
Karl Zimmerman ◽  
Robert Leech ◽  
Adam Hampshire ◽  
...  
Keyword(s):  
White Matter ◽  
Brain Activity ◽  
Inferior Frontal Gyrus ◽  
Brain Networks ◽  
Brain Network ◽  
Network Activity ◽  
Brain State ◽  
State Dependent ◽  
Cathodal Tdcs ◽  
The Right

AbstractBackgroundTranscranial direct current stimulation (tDCS) is a form of noninvasive brain stimulation whose potential as a cognitive therapy is hindered by our limited understanding of how participant and experimental factors influence its effects. Using functional MRI to study brain networks, we have previously shown in healthy controls that the physiological effects of tDCS are strongly influenced by brain state. We have additionally shown, in both healthy and traumatic brain injury (TBI) populations, that the behavioral effects of tDCS are positively correlated with white matter (WM) structure.ObjectivesIn this study we investigate how these two factors, WM structure and brain state, interact to shape the effect of tDCS on brain network activity.MethodsWe applied anodal, cathodal and sham tDCS to the right inferior frontal gyrus (rIFG) of healthy (n=22) and TBI participants (n=34). We used the Choice Reaction Task (CRT) performance to manipulate brain state during tDCS. We acquired simultaneous fMRI to assess activity of cognitive brain networks and used Fractional Anisotropy (FA) as a measure of WM structure.ResultsWe find that the effects of tDCS on brain network activity in TBI participants are highly dependent on brain state, replicating findings from our previous healthy control study in a separate, patient cohort. We then show that WM structure further modulates the brain-state dependent effects of tDCS on brain network activity. These effects are not unidirectional – in the absence of task with anodal and cathodal tDCS, FA is positively correlated with brain activity in several regions of the default mode network. Conversely, with cathodal tDCS during CRT performance, FA is negatively correlated with brain activity in a salience network region.ConclusionsOur results show that experimental and participant factors interact to have unexpected effects on brain network activity, and that these effects are not fully predictable by studying the factors in isolation.

scholarly journals Efficient high-resolution TMS mapping of the human motor cortex by nonlinear regression

2021 ◽  
Author(s):  
Ole Numssen ◽  
Anna-Leah Zier ◽  
Axel Thielscher ◽  
Gesa Hartwigsen ◽  
Thomas R. Knösche ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Motor Evoked Potentials ◽  
Random Coil ◽  
Individual Response ◽  
Precentral Gyrus ◽  
Individual Subject ◽  
Human Motor Cortex ◽  
Preoperative Mapping ◽  
The Individual

AbstractBackgroundThe precise cortical origins of the electrophysiological and behavioral effects of transcranial magnetic stimulation (TMS) remain largely unclear. Addressing this question is further impeded by substantial inter-individual response variability to TMS.ObjectiveWe present a novel method to reliably and user-independently determine the effectively stimulated cortical site at the individual subject level. This generic approach combines physiological measurements with electric field simulations and leverages information from random coil positions, electric field estimations, and electromyography.MethodsWe applied ~1000 single biphasic TMS pulses with standard TMS hardware to 13 subjects with random coil positions & orientations over the primary motor hand area. Motor evoked potentials (MEPs) of three finger muscles were recorded concurrently. We calculated the corresponding electric fields for all TMS pulses and regressed them against the elicited MEPs in each cortical element. This yields a cortical map of congruency between induced field strength and generated response.ResultsWe observed high congruence between the electric fields and the elicited MEPs in hotspots located primarily on the crowns and rims of the precentral gyrus. The three cortical digit representations could be distinguished at the individual subject level with a high spatial resolution. A post-hoc convergence analysis revealed a possible lower bound of only 180 pulses to obtain qualitatively identical results.ConclusionsLeveraging information from many different TMS pulses significantly reduces the number of necessary stimulations and mapping time. The protocol is easy to implement due to the realization of arbitrary coil positions & orientations and is suitable for practical and clinical use such as preoperative mapping.

scholarly journals Spontaneous Fluctuations in Oscillatory Brain State Cause Differences in Transcranial Magnetic Stimulation Effects Within and Between Individuals

2021 ◽  
Vol 15 ◽  
Author(s):  
Shanice E. W. Janssens ◽  
Alexander T. Sack
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Signal Propagation ◽  
Individual Variability ◽  
Brain State ◽  
State Dependent ◽  
Oscillatory State ◽  
Transcranial Alternating Current Stimulation ◽  
The Individual ◽  
Spontaneous Fluctuations

Transcranial magnetic stimulation (TMS) can cause measurable effects on neural activity and behavioral performance in healthy volunteers. In addition, TMS is increasingly used in clinical practice for treating various neuropsychiatric disorders. Unfortunately, TMS-induced effects show large intra- and inter-subject variability, hindering its reliability, and efficacy. One possible source of this variability may be the spontaneous fluctuations of neuronal oscillations. We present recent studies using multimodal TMS including TMS-EMG (electromyography), TMS-tACS (transcranial alternating current stimulation), and concurrent TMS-EEG-fMRI (electroencephalography, functional magnetic resonance imaging), to evaluate how individual oscillatory brain state affects TMS signal propagation within targeted networks. We demonstrate how the spontaneous oscillatory state at the time of TMS influences both immediate and longer-lasting TMS effects. These findings indicate that at least part of the variability in TMS efficacy may be attributable to the current practice of ignoring (spontaneous) oscillatory fluctuations during TMS. Ignoring this state-dependent spread of activity may cause great individual variability which so far is poorly understood and has proven impossible to control. We therefore also compare two technical solutions to directly account for oscillatory state during TMS, namely, to use (a) tACS to externally control these oscillatory states and then apply TMS at the optimal (controlled) brain state, or (b) oscillatory state-triggered TMS (closed-loop TMS). The described multimodal TMS approaches are paramount for establishing more robust TMS effects, and to allow enhanced control over the individual outcome of TMS interventions aimed at modulating information flow in the brain to achieve desirable changes in cognition, mood, and behavior.

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