Journal articles: 'EEG-TMS'

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Ilmoniemi, R. J. "TMS–EEG: Methodology." Clinical Neurophysiology 127, no. 3 (March 2016): e21. http://dx.doi.org/10.1016/j.clinph.2015.11.057.

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Peters, Judith C., Joel Reithler, Teresa Schuhmann, Tom de Graaf, Kâmil Uludağ, Rainer Goebel, and Alexander T. Sack. "On the feasibility of concurrent human TMS-EEG-fMRI measurements." Journal of Neurophysiology 109, no. 4 (February 15, 2013): 1214–27. http://dx.doi.org/10.1152/jn.00071.2012.

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Simultaneously combining the complementary assets of EEG, functional MRI (fMRI), and transcranial magnetic stimulation (TMS) within one experimental session provides synergetic results, offering insights into brain function that go beyond the scope of each method when used in isolation. The steady increase of concurrent EEG-fMRI, TMS-EEG, and TMS-fMRI studies further underlines the added value of such multimodal imaging approaches. Whereas concurrent EEG-fMRI enables monitoring of brain-wide network dynamics with high temporal and spatial resolution, the combination with TMS provides insights in causal interactions within these networks. Thus the simultaneous use of all three methods would allow studying fast, spatially accurate, and distributed causal interactions in the perturbed system and its functional relevance for intact behavior. Concurrent EEG-fMRI, TMS-EEG, and TMS-fMRI experiments are already technically challenging, and the three-way combination of TMS-EEG-fMRI might yield additional difficulties in terms of hardware strain or signal quality. The present study explored the feasibility of concurrent TMS-EEG-fMRI studies by performing safety and quality assurance tests based on phantom and human data combining existing commercially available hardware. Results revealed that combined TMS-EEG-fMRI measurements were technically feasible, safe in terms of induced temperature changes, allowed functional MRI acquisition with comparable image quality as during concurrent EEG-fMRI or TMS-fMRI, and provided artifact-free EEG before and from 300 ms after TMS pulse application. Based on these empirical findings, we discuss the conceptual benefits of this novel complementary approach to investigate the working human brain and list a number of precautions and caveats to be heeded when setting up such multimodal imaging facilities with current hardware.

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Varone, Giuseppe, Zain Hussain, Zakariya Sheikh, Adam Howard, Wadii Boulila, Mufti Mahmud, Newton Howard, Francesco Carlo Morabito, and Amir Hussain. "Real-Time Artifacts Reduction during TMS-EEG Co-Registration: A Comprehensive Review on Technologies and Procedures." Sensors 21, no. 2 (January 18, 2021): 637. http://dx.doi.org/10.3390/s21020637.

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Transcranial magnetic stimulation (TMS) excites neurons in the cortex, and neural activity can be simultaneously recorded using electroencephalography (EEG). However, TMS-evoked EEG potentials (TEPs) do not only reflect transcranial neural stimulation as they can be contaminated by artifacts. Over the last two decades, significant developments in EEG amplifiers, TMS-compatible technology, customized hardware and open source software have enabled researchers to develop approaches which can substantially reduce TMS-induced artifacts. In TMS-EEG experiments, various physiological and external occurrences have been identified and attempts have been made to minimize or remove them using online techniques. Despite these advances, technological issues and methodological constraints prevent straightforward recordings of early TEPs components. To the best of our knowledge, there is no review on both TMS-EEG artifacts and EEG technologies in the literature to-date. Our survey aims to provide an overview of research studies in this field over the last 40 years. We review TMS-EEG artifacts, their sources and their waveforms and present the state-of-the-art in EEG technologies and front-end characteristics. We also propose a synchronization toolbox for TMS-EEG laboratories. We then review subject preparation frameworks and online artifacts reduction maneuvers for improving data acquisition and conclude by outlining open challenges and future research directions in the field.

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Nardone, Raffaele, Luca Sebastianelli, Viviana Versace, Davide Ferrazzoli, Leopold Saltuari, and Eugen Trinka. "TMS–EEG Co-Registration in Patients with Mild Cognitive Impairment, Alzheimer’s Disease and Other Dementias: A Systematic Review." Brain Sciences 11, no. 3 (February 27, 2021): 303. http://dx.doi.org/10.3390/brainsci11030303.

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An established method to assess effective brain connectivity is the combined use of transcranial magnetic stimulation with simultaneous electroencephalography (TMS–EEG) because TMS-induced cortical responses propagate to distant anatomically connected brain areas. Alzheimer’s disease (AD) and other dementias are associated with changes in brain networks and connectivity, but the underlying pathophysiology of these processes is poorly defined. We performed here a systematic review of the studies employing TMS–EEG co-registration in patients with dementias. TMS–EEG studies targeting the motor cortex have revealed a significantly reduced TMS-evoked P30 in AD patients in the temporo-parietal cortex ipsilateral to stimulation side as well as in the contralateral fronto-central area, and we have demonstrated a deep rearrangement of the sensorimotor system even in mild AD patients. TMS–EEG studies targeting other cortical areas showed alterations of effective dorsolateral prefrontal cortex connectivity as well as an inverse correlation between prefrontal-to-parietal connectivity and cognitive impairment. Moreover, TMS–EEG analysis showed a selective increase in precuneus neural activity. TMS–EEG co-registrations can also been used to investigate whether different drugs may affect cognitive functions in patients with dementias.

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Fong, P. Y., D. Spampinato, L. Rocchi, J. Ibáñez, K. Brown, A. Latorre, A. Di Santo, K. Bhatia, and J. Rothwell. "P63 Cerebellar TMS-EEG." Clinical Neurophysiology 131, no. 4 (April 2020): e47. http://dx.doi.org/10.1016/j.clinph.2019.12.174.

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Noda, Yoshihiro. "Potential Neurophysiological Mechanisms of 1Hz-TMS to the Right Prefrontal Cortex for Depression: An Exploratory TMS-EEG Study in Healthy Participants." Journal of Personalized Medicine 11, no. 2 (January 24, 2021): 68. http://dx.doi.org/10.3390/jpm11020068.

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Background: The present study aimed to examine the acute neurophysiological effects of 1Hz transcranial magnetic stimulation (TMS) administered to the right dorsolateral prefrontal cortex (DLPFC) in healthy participants. Methods: TMS combined with simultaneous electroencephalography (EEG) recording was conducted for 21 healthy participants. For the right DLPFC, 1Hz-TMS (100 pulses/block × 17 sessions) was applied in the resting-state, while for the left DLPFC, 1Hz-TMS (100 pulses/block × 2 sessions) was administered during the verbal fluency tasks (VFTs). For TMS-EEG data, independent component analysis (ICA) was applied to extract TMS-evoked EEG potentials to calculate TMS-related power as well as TMS-related coherence from the F4 and F3 electrode sites during the resting-state and VFTs. Results: TMS-related power was significantly increased in alpha, beta, and gamma bands by 1Hz-TMS at the stimulation site during the resting-state, while TMS-related power was significantly increased in alpha and beta bands but not in the gamma band during the VFTs. On the other hand, TMS-related coherence in alpha and beta bands significantly increased but not in gamma band by 1Hz-TMS that was administered to the right DLPFC in resting-state, whereas there were no significant changes in coherence for all frequency bands by 1Hz-TMS that applied to the left DLPFC during the VFTs. Conclusions: Collectively, 1Hz-repetitive TMS (rTMS) to the right DLPFC may rapidly neuromodulate EEG activity, which might be associated with a therapeutic mechanism for depression.

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Veniero, Domenica, Marta Bortoletto, and Carlo Miniussi. "TMS-EEG co-registration: On TMS-induced artifact." Clinical Neurophysiology 120, no. 7 (July 2009): 1392–99. http://dx.doi.org/10.1016/j.clinph.2009.04.023.

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Pastiadis, Konstantinos, Ioannis Vlachos, Evangelia Chatzikyriakou, Yiftach Roth, Samuel Zibman, Abraham Zangen, Dimitris Kugiumtzis, and Vasilios K. Kimiskidis. "Auditory Fine-Tuned Suppressor of TMS-Clicks (TMS-Click AFTS): A Novel, Perceptually Driven/Tuned Approach for the Reduction in AEP Artifacts in TMS-EEG Studies." Applied Sciences 13, no. 2 (January 12, 2023): 1047. http://dx.doi.org/10.3390/app13021047.

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TMS contaminates concurrent EEG recordings with Auditory Evoked Potentials (AEPs), which are caused by the perceived impulsive acoustic noise of the TMS coils. We hereby introduce a novel and perceptually motivated/tuned method for the suppression of auditory evoked EEG artifacts of rTMS under the name of “Auditory Fine-Tuned Suppressor of TMS-Clicks” (TMS-click AFTS). The proposed method is based on the deployment of a psychophysically-matched wide-band noise (WBN) masking stimulus, whose parametric synthesis and presentation are based upon adaptive psychophysical optimization. The masking stimulus is constructed individually for each patient/subject, thus facilitating aspects of precision medicine. A specially designed automation software is used for the realization of an adaptive procedure for optimal parameterization of masking noise level, optimizing both the subject’s comfort and the degree of AEP reduction. The proposed adaptive procedure also takes into account the combined effect of TMS intensity level and can as well account for any possibly available subject’s hearing acuity data. To assess the efficacy of the proposed method in reducing the acoustic effects of TMS, we performed TMS-EEG recordings with a 60 channel TMS-compatible EEG system in a cohort of healthy subjects (n = 10) and patients with epilepsy (n = 10) under four conditions (i.e., resting EEG with and without acoustic mask and sham TMS-EEG with and without acoustic mask at various stimulus intensity levels). The proposed approach shows promising results in terms of efficiency of AEP suppression and subject’s comfort and warrants further investigation in research and clinical settings.

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Takano, Mayuko, Masataka Wada, Reza Zomorrodi, Keita Taniguchi, Xuemei Li, Shiori Honda, Yui Tobari, et al. "Investigation of Spatiotemporal Profiles of Single-Pulse TMS-Evoked Potentials with Active Stimulation Compared with a Novel Sham Condition." Biosensors 12, no. 10 (October 1, 2022): 814. http://dx.doi.org/10.3390/bios12100814.

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Identifying genuine cortical stimulation-elicited electroencephalography (EEG) is crucial for improving the validity and reliability of neurophysiology using transcranial magnetic stimulation (TMS) combined with EEG. In this study, we evaluated the spatiotemporal profiles of single-pulse TMS-elicited EEG response administered to the left dorsal prefrontal cortex (DLPFC) in 28 healthy participants, employing active and sham stimulation conditions. We hypothesized that the early component of TEP would be activated in active stimulation compared with sham stimulation. We specifically analyzed the (1) stimulus response, (2) frequency modulation, and (3) phase synchronization of TMS–EEG data at the sensor level and the source level. Compared with the sham condition, the active condition induced a significant increase in TMS-elicited EEG power in the 30–60 ms time interval in the stimulation area at the sensor level. Furthermore, in the source-based analysis, the active condition induced significant increases in TMS-elicited response in the 30–60 ms compared with the sham condition. Collectively, we found that the active condition could specifically activate the early component of TEP compared with the sham condition. Thus, the TMS–EEG method that was applied to the DLPFC could detect the genuine neurophysiological cortical responses by properly handling potential confounding factors such as indirect response noises.

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Tscherpel, Caroline, Sebastian Dern, Lukas Hensel, Ulf Ziemann, Gereon R. Fink, and Christian Grefkes. "Brain responsivity provides an individual readout for motor recovery after stroke." Brain 143, no. 6 (May 6, 2020): 1873–88. http://dx.doi.org/10.1093/brain/awaa127.

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Abstract Promoting the recovery of motor function and optimizing rehabilitation strategies for stroke patients is closely associated with the challenge of individual prediction. To date, stroke research has identified critical pathophysiological neural underpinnings at the cellular level as well as with regard to network reorganization. However, in order to generate reliable readouts at the level of individual patients and thereby realize translation from bench to bedside, we are still in a need for innovative methods. The combined use of transcranial magnetic stimulation (TMS) and EEG has proven powerful to record both local and network responses at an individual’s level. To elucidate the potential of TMS-EEG to assess motor recovery after stroke, we used neuronavigated TMS-EEG over ipsilesional primary motor cortex (M1) in 28 stroke patients in the first days after stroke. Twenty-five of these patients were reassessed after >3 months post-stroke. In the early post-stroke phase (6.7 ± 2.5 days), the TMS-evoked EEG responses featured two markedly different response morphologies upon TMS to ipsilesional M1. In the first group of patients, TMS elicited a differentiated and sustained EEG response with a series of deflections sequentially involving both hemispheres. This response type resembled the patterns of bilateral activation as observed in the healthy comparison group. By contrast, in a subgroup of severely affected patients, TMS evoked a slow and simplified local response. Quantifying the TMS-EEG responses in the time and time-frequency domain revealed that stroke patients exhibited slower and simple responses with higher amplitudes compared to healthy controls. Importantly, these patterns of activity changes after stroke were not only linked to the initial motor deficit, but also to motor recovery after >3 months post-stroke. Thus, the data revealed a substantial impairment of local effects as well as causal interactions within the motor network early after stroke. Additionally, for severely affected patients with absent motor evoked potentials and identical clinical phenotype, TMS-EEG provided differential response patterns indicative of the individual potential for recovery of function. Thereby, TMS-EEG extends the methodological repertoire in stroke research by allowing the assessment of individual response profiles.

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Mancuso, Marco, Valerio Sveva, Alessandro Cruciani, Katlyn Brown, Jaime Ibáñez, Vishal Rawji, Elias Casula, et al. "Transcranial Evoked Potentials Can Be Reliably Recorded with Active Electrodes." Brain Sciences 11, no. 2 (January 22, 2021): 145. http://dx.doi.org/10.3390/brainsci11020145.

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Electroencephalographic (EEG) signals evoked by transcranial magnetic stimulation (TMS) are usually recorded with passive electrodes (PE). Active electrode (AE) systems have recently become widely available; compared to PE, they allow for easier electrode preparation and a higher-quality signal, due to the preamplification at the electrode stage, which reduces electrical line noise. The performance between the AE and PE can differ, especially with fast EEG voltage changes, which can easily occur with TMS-EEG; however, a systematic comparison in the TMS-EEG setting has not been made. Therefore, we recorded TMS-evoked EEG potentials (TEPs) in a group of healthy subjects in two sessions, one using PE and the other using AE. We stimulated the left primary motor cortex and right medial prefrontal cortex and used two different approaches to remove early TMS artefacts, Independent Component Analysis and Signal Space Projection—Source Informed Recovery. We assessed statistical differences in amplitude and topography of TEPs, and their similarity, by means of the concordance correlation coefficient (CCC). We also tested the capability of each system to approximate the final TEP waveform with a reduced number of trials. The results showed that TEPs recorded with AE and PE do not differ in amplitude and topography, and only few electrodes showed a lower-than-expected CCC between the two methods of amplification. We conclude that AE are a viable solution for TMS-EEG recording.

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Ilmoniemi, R. J., H. Mäki, J. C. Hernandez Pavon, R. Korhonen, J. Metsomaa, and J. Sarvas. "S48-4 TMS and EEG." Clinical Neurophysiology 121 (October 2010): S68. http://dx.doi.org/10.1016/s1388-2457(10)60290-8.

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Paus, T., P. K. Sipila, and A. P. Strafella. "Synchronization of Neuronal Activity in the Human Primary Motor Cortex by Transcranial Magnetic Stimulation: An EEG Study." Journal of Neurophysiology 86, no. 4 (October 1, 2001): 1983–90. http://dx.doi.org/10.1152/jn.2001.86.4.1983.

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Using multichannel electroencephalography (EEG), we investigated temporal dynamics of the cortical response to transcranial magnetic stimulation (TMS). TMS was applied over the left primary motor cortex (M1) of healthy volunteers, intermixing single suprathreshold pulses with pairs of sub- and suprathreshold pulses and simultaneously recording EEG from 60 scalp electrodes. Averaging of EEG data time locked to the onset of TMS pulses yielded a waveform consisting of a positive peak (30 ms after the pulse P30), followed by two negative peaks [at 45 (N45) and 100 ms]. Peak-to-peak amplitude of the P30–N45 waveform was high, ranging from 12 to 70 μV; in most subjects, the N45 potential could be identified in single EEG traces. Spectral analysis revealed that single-pulse TMS induced a brief period of synchronized activity in the beta range (15–30 Hz) in the vicinity of the stimulation site; again, this oscillatory response was apparent not only in the EEG averages but also in single traces. Both the N45 and the oscillatory response were lower in amplitude in the 12-ms (but not 3-ms) paired-pulse trials, compared with the single-pulse trials. These findings are consistent with the possibility that TMS applied to M1 induces transient synchronization of spontaneous activity of cortical neurons within the 15- to 30-Hz frequency range. As such, they corroborate previous studies of cortical oscillations in the motor cortex and point to the potential of the combined TMS/EEG approach for further investigations of cortical rhythms in the human brain.

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Ferreri, Florinda, David Ponzo, Taina Hukkanen, Esa Mervaala, Mervi Könönen, Patrizio Pasqualetti, Fabrizio Vecchio, Paolo Maria Rossini, and Sara Määttä. "Human brain cortical correlates of short-latency afferent inhibition: a combined EEG–TMS study." Journal of Neurophysiology 108, no. 1 (July 1, 2012): 314–23. http://dx.doi.org/10.1152/jn.00796.2011.

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When linking in time electrical stimulation of the peripheral nerve with transcranial magnetic stimulation (TMS), the excitability of the motor cortex can be modulated to evoke clear inhibition, as reflected by the amplitude decrement in the motor-evoked potentials (MEPs). This specific property, designated short-latency afferent inhibition (SAI), occurs when the nerve–TMS interstimulus interval (ISI) is approximately 25 ms and is considered to be a corticothalamic phenomenon. The aim of the present study was to use the electroencephalographic (EEG) responses to navigated-TMS coregistration to better characterize the neuronal circuits underlying SAI. The present experimental set included magnetic resonance imaging (MRI)–navigated TMS and 60-channel TMS-compatible EEG devices. TMS-evoked EEG responses and MEPs were analyzed in eight healthy volunteers; ISIs between median nerve and cortical stimulation were determined relative to the latency of the individual N20 component of the somatosensory-evoked potential (SEP) obtained after stimulation of the median nerve. ISIs from the latency of the N20 plus 3 ms and N20 plus 10 ms were investigated. In all experimental conditions, TMS-evoked EEG responses were characterized by a sequence of negative deflections peaking at approximately 7, 44, and 100 ms alternating with positive peaks at approximately 30, 60, and 180 ms post-TMS. Moreover, ISI N20+3 ms modulated both EEG-evoked activity and MEPs. In particular, it inhibited MEP amplitudes, attenuated cortical P60 and N100 responses, and induced motor cortex beta rhythm selective decrement of phase locking. The findings of the present experiment suggest the cortical origin of SAI that could result from the cortico–cortical activation of GABAergic-mediated inhibition onto the corticospinal neurons modulated by cholinergic activation able to reducing intralaminar inhibition and promoting intracolumnar inhibition.

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Julkunen, Petro, Anne M. Jauhiainen, Mervi Könönen, Ari Pääkkönen, Jari Karhu, and Hilkka Soininen. "Combining Transcranial Magnetic Stimulation and Electroencephalography May Contribute to Assess the Severity of Alzheimer's Disease." International Journal of Alzheimer's Disease 2011 (2011): 1–9. http://dx.doi.org/10.4061/2011/654794.

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Alzheimer's disease (AD) is the most common form of old age dementia, and mild cognitive impairment (MCI) often precedes AD. In our previous study (Julkunen et al. 2008), we found that the combination of transcranial magnetic stimulation (TMS) and electroencephalography (EEG) was able to find distinct differences in AD and MCI patients as compared to controls. Here, we reanalyzed the small sample data from our previous study with the aim to test the sensitivity of the TMS-EEG characteristics to discriminate control subjects (n=4) from MCI (n=5) and AD (n=5) subjects. Furthermore, we investigated how the TMS-EEG response characteristics related to the scores of the dementia rating scales used to evaluate the severity of cognitive decline in these subjects. We found that the TMS-EEG response P30 amplitude correlated with cognitive decline and showed good specificity and sensitivity in identifying healthy subjects from those with MCI or AD. Given the small sample size, further studies may be needed to confirm the results.

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Keil, Julian, Jana Timm, Iria SanMiguel, Hannah Schulz, Jonas Obleser, and Marc Schönwiesner. "Cortical brain states and corticospinal synchronization influence TMS-evoked motor potentials." Journal of Neurophysiology 111, no. 3 (February 1, 2014): 513–19. http://dx.doi.org/10.1152/jn.00387.2013.

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Transcranial magnetic stimulation (TMS) influences cortical processes. Recent findings indicate, however, that, in turn, the efficacy of TMS depends on the state of ongoing cortical oscillations. Whereas power and phase of electromyographic (EMG) activity recorded from the hand muscles as well as neural synchrony between cortex and hand muscles are known to influence the effect of TMS, to date, no study has shown an influence of the phase of cortical oscillations during wakefulness. We applied single-pulse TMS over the motor cortex and recorded motor-evoked potentials along with the electroencephalogram (EEG) and EMG. We correlated phase and power of ongoing EEG and EMG signals with the motor-evoked potential (MEP) amplitude. We also investigated the functional connectivity between cortical and hand muscle activity (corticomuscular coherence) with the MEP amplitude. EEG and EMG power and phase in a frequency band around 18 Hz correlated with the MEP amplitude. High beta-band (∼34 Hz) corticomuscular coherence exhibited a positive linear relationship with the MEP amplitude, indicating that strong synchrony between cortex and hand muscles at the moment when TMS is applied entails large MEPs. Improving upon previous studies, we demonstrate a clear dependence of TMS-induced motor effects on the state of ongoing EEG phase and power fluctuations. We conclude that not only the sampling of incoming information but also the susceptibility of cortical communication flow depends cyclically on neural phase.

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Ozdemir, Recep A., Ehsan Tadayon, Pierre Boucher, Davide Momi, Kelly A. Karakhanyan, Michael D. Fox, Mark A. Halko, Alvaro Pascual-Leone, Mouhsin M. Shafi, and Emiliano Santarnecchi. "Individualized perturbation of the human connectome reveals reproducible biomarkers of network dynamics relevant to cognition." Proceedings of the National Academy of Sciences 117, no. 14 (March 19, 2020): 8115–25. http://dx.doi.org/10.1073/pnas.1911240117.

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Large-scale brain networks are often described using resting-state functional magnetic resonance imaging (fMRI). However, the blood oxygenation level-dependent (BOLD) signal provides an indirect measure of neuronal firing and reflects slow-evolving hemodynamic activity that fails to capture the faster timescale of normal physiological function. Here we used fMRI-guided transcranial magnetic stimulation (TMS) and simultaneous electroencephalography (EEG) to characterize individual brain dynamics within discrete brain networks at high temporal resolution. TMS was used to induce controlled perturbations to individually defined nodes of the default mode network (DMN) and the dorsal attention network (DAN). Source-level EEG propagation patterns were network-specific and highly reproducible across sessions 1 month apart. Additionally, individual differences in high-order cognitive abilities were significantly correlated with the specificity of TMS propagation patterns across DAN and DMN, but not with resting-state EEG dynamics. Findings illustrate the potential of TMS-EEG perturbation-based biomarkers to characterize network-level individual brain dynamics at high temporal resolution, and potentially provide further insight on their behavioral significance.

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Farzan, Faranak, Mera S. Barr, Andrea J. Levinson, Robert Chen, Willy Wong, Paul B. Fitzgerald, and Zafiris J. Daskalakis. "Reliability of Long-Interval Cortical Inhibition in Healthy Human Subjects: A TMS–EEG Study." Journal of Neurophysiology 104, no. 3 (September 2010): 1339–46. http://dx.doi.org/10.1152/jn.00279.2010.

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Cortical inhibition (CI) is measured by transcranial magnetic stimulation (TMS) combined with electromyography (EMG) through long-interval CI (LICI) and cortical silent period (CSP) paradigms. Recently, we illustrated that LICI can be measured from the dorsolateral prefrontal cortex (DLPFC) through combined TMS with electroencephalography (EEG). We further demonstrated that LICI had different effects on cortical oscillations in the DLPFC compared with motor cortex. The purpose of this study was to establish the validity and reliability of TMS–EEG indices of CI and to replicate our previous findings in an extended sample. The validity of TMS–EEG was examined by evaluating its relationship to standard EMG measures of LICI and the CSP in the left motor cortex in 36 and 16 subjects, respectively. Test–retest reliability was examined in 14 subjects who returned for a repeat session within 7 days of the first session. LICI was applied to the left DLPFC in 30 subjects to compare LICI in the DLPFC with that in the motor cortex. In the motor cortex, EEG measures of LICI correlated with EMG measures of LICI and CSP. All indices of LICI showed high test–retest reliability in motor cortex and DLPFC. Gamma and beta oscillations were significantly inhibited in the DLPFC but not in the motor cortex, confirming previous findings in an extended sample. These findings demonstrate that indexing LICI through TMS combined with EEG is a valid and reliable method to evaluate inhibition from motor and prefrontal regions.

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Li, Xuemei, Shiori Honda, Shinichiro Nakajima, Masataka Wada, Kazunari Yoshida, Zafiris J. Daskalakis, Masaru Mimura, and Yoshihiro Noda. "TMS-EEG Research to Elucidate the Pathophysiological Neural Bases in Patients with Schizophrenia: A Systematic Review." Journal of Personalized Medicine 11, no. 5 (May 10, 2021): 388. http://dx.doi.org/10.3390/jpm11050388.

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Schizophrenia (SCZ) is a serious mental disorder, and its pathogenesis is complex. Recently, the glutamate hypothesis and the excitatory/inhibitory (E/I) imbalance hypothesis have been proposed as new pathological hypotheses for SCZ. Combined transcranial magnetic stimulation (TMS) and electroencephalography (EEG) is a non-invasive novel method that enables us to investigate the cortical activity in humans, and this modality is a suitable approach to evaluate these hypotheses. In this study, we systematically reviewed TMS-EEG studies that investigated the cortical dysfunction of SCZ to examine the emerging hypotheses for SCZ. The following search terms were set in this systematic review: (TMS or ‘transcranial magnetic stimulation’) and (EEG or electroencephalog*) and (schizophrenia). We inspected the articles written in English that examined humans and were published by March 2020 via MEDLINE, Embase, PsycINFO, and PubMed. The initial search generated 379 studies, and 14 articles were finally identified. The current review noted that patients with SCZ demonstrated the E/I deficits in the prefrontal cortex, whose dysfunctions were also associated with cognitive impairment and clinical severity. Moreover, TMS-induced gamma activity in the prefrontal cortex was related to positive symptoms, while theta/delta band activities were associated with negative symptoms in SCZ. Thus, this systematic review discusses aspects of the pathophysiological neural basis of SCZ that are not explained by the traditional dopamine hypothesis exclusively, based on the findings of previous TMS-EEG research, mainly in terms of the E/I imbalance hypothesis. In conclusion, TMS-EEG neurophysiology can be applied to establish objective biomarkers for better diagnosis as well as to develop new therapeutic strategies for patients with SCZ.

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Manganotti, Paolo, Emanuela Formaggio, Silvia Francesca Storti, Daniele De Massari, Alessandro Zamboni, Alessandra Bertoldo, Antonio Fiaschi, and Gianna Maria Toffolo. "Time-frequency analysis of short-lasting modulation of EEG induced by intracortical and transcallosal paired TMS over motor areas." Journal of Neurophysiology 107, no. 9 (May 1, 2012): 2475–84. http://dx.doi.org/10.1152/jn.00543.2011.

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Dynamic changes in spontaneous electroencephalogram (EEG) rhythms can be seen to occur with a high rate of variability. An innovative method to study brain function is by triggering oscillatory brain activity with transcranial magnetic stimulation (TMS). EEG-TMS coregistration was performed on five healthy subjects during a 1-day experimental session that involved four steps: baseline acquisition, unconditioned single-pulse TMS, intracortical inhibition (ICI, 3 ms) paired-pulse TMS, and transcallosal stimulation over left and right primary motor cortex (M1). A time-frequency analysis based on the wavelet method was used to characterize rapid modifications of oscillatory EEG rhythms induced by TMS. Single, paired, and transcallosal TMS applied on the sensorimotor areas induced rapid desynchronization over the frontal and central-parietal electrodes mainly in the alpha and beta bands, followed by a rebound of synchronization, and rapid synchronization of delta and theta activity. Wavelet analysis after a perturbation approach is a novel way to investigate modulation of oscillatory brain activity. The main findings are consistent with the concept that the human motor system may be based on networklike oscillatory cortical activity and might be modulated by single, paired, and transcallosal magnetic pulses applied to M1, suggesting a phenomenon of fast brain activity resetting and triggering of slow activity.

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Ilmoniemi, Risto J., and Dubravko Kičić. "Methodology for Combined TMS and EEG." Brain Topography 22, no. 4 (December 10, 2009): 233–48. http://dx.doi.org/10.1007/s10548-009-0123-4.

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Jin, Yi, Aaron S. Kemp, Yueqin Huang, Trung Minh Thai, Zhaorui Liu, Wanjiao Xu, Hua He, and Steven G. Potkin. "Alpha EEG guided TMS in schizophrenia." Brain Stimulation 5, no. 4 (October 2012): 560–68. http://dx.doi.org/10.1016/j.brs.2011.09.005.

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Lioumis, Pantelis, Dubravko Kičić, Petri Savolainen, Jyrki P. Mäkelä, and Seppo Kähkönen. "Reproducibility of TMS-Evoked EEG responses." Human Brain Mapping 30, no. 4 (April 2009): 1387–96. http://dx.doi.org/10.1002/hbm.20608.

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KIMISKIDIS, VASILIOS K., DIMITRIS KUGIUMTZIS, SOTIRIOS PAPAGIANNOPOULOS, and NIKOLAOS VLAIKIDIS. "TRANSCRANIAL MAGNETIC STIMULATION (TMS) MODULATES EPILEPTIFORM DISCHARGES IN PATIENTS WITH FRONTAL LOBE EPILEPSY: A PRELIMINARY EEG-TMS STUDY." International Journal of Neural Systems 23, no. 01 (December 30, 2012): 1250035. http://dx.doi.org/10.1142/s0129065712500359.

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Background: TMS is being increasingly used as a noninvasive brain stimulation technique for the therapeutic management of partial epilepsies. However, the acute effects of TMS on epileptiform discharges (EDs, i.e. interictal epileptiform activity and subclinical electrographic seizure patterns) remain unexplored. Objective: To investigate whether TMS can modulate EDs in partial epilepsy. Methods: In Experiment Set 1, the safety of the TMS protocol was investigated in 10 well-controlled by anti-epileptic drugs (AEDs) epileptic patients. In Experiment Set 2, the effects of TMS on EDs were studied in three subjects with intractable frontal lobe epilepsies, characterized by particularly frequent EDs. TMS was applied over the electrographic focus with a circular and a figure of eight coil while recording EEG with a 60-channel TMS-compatible EEG system. The effectiveness of TMS in aborting EDs was investigated using survival analysis and brain connectivity analysis. Results: The TMS protocol was well-tolerated. TMS was an effective method to abort EDs even when adjusting for its latency with respect to ED onset (CMH test, p < 0.0001). While the effective brain connectivity around the epileptic focus increased significantly during EDs (p < 0.01), with TMS administration the increase was not statistically significant. Conclusion: TMS can modulate EDs in patients with epileptogenic foci in the cortical convexity and is associated with reversal of ED-induced changes in brain connectivity.

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Poorganji, Mohsen, Reza Zomorrodi, Christoph Zrenner, Aiyush Bansal, Colin Hawco, Aron T. Hill, Itay Hadas, et al. "Pre-Stimulus Power but Not Phase Predicts Prefrontal Cortical Excitability in TMS-EEG." Biosensors 13, no. 2 (February 3, 2023): 220. http://dx.doi.org/10.3390/bios13020220.

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The cortical response to transcranial magnetic stimulation (TMS) has notable inter-trial variability. One source of this variability can be the influence of the phase and power of pre-stimulus neuronal oscillations on single-trial TMS responses. Here, we investigate the effect of brain oscillatory activity on TMS response in 49 distinct healthy participants (64 datasets) who had received single-pulse TMS over the left dorsolateral prefrontal cortex. Across all frequency bands of theta (4–7 Hz), alpha (8–13 Hz), and beta (14–30 Hz), there was no significant effect of pre-TMS phase on single-trial cortical evoked activity. After high-powered oscillations, whether followed by a TMS pulse or not, the subsequent activity was larger than after low-powered oscillations. We further defined a measure, corrected_effect, to enable us to investigate brain responses to the TMS pulse disentangled from the power of ongoing (spontaneous) oscillations. The corrected_effect was significantly different from zero (meaningful added effect of TMS) only in theta and beta bands. Our results suggest that brain state prior to stimulation might play some role in shaping the subsequent TMS-EEG response. Specifically, our findings indicate that the power of ongoing oscillatory activity, but not phase, can influence brain responses to TMS. Aligning the TMS pulse with specific power thresholds of an EEG signal might therefore reduce variability in neurophysiological measurements and also has the potential to facilitate more robust therapeutic effects of stimulation.

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Shergill, Sukhwinder S., Viviana Santoro, Lorenzo Rocchi, Meng Di Hou, and Isabella Premoli. "TMS-EEG indexes abnormal GABAergic signalling in patients with schizophrenia." BJPsych Open 7, S1 (June 2021): S52. http://dx.doi.org/10.1192/bjo.2021.185.

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AimsTranscranial magnetic stimulation (TMS) is a non-invasive brain stimulation tool designed to probe the strength of inhibitory and excitatory neurotransmission in the cortex. Combined with electromyography, paired-pulse TMS paradigms have revealed a deficit in inhibition mediated by GABA-A receptors in patients with schizophrenia. Combined TMS-electroencephalography (TMS-EEG) provides a more detailed examination of cortical excitability and may shed more light into the pathophysiology of schizophrenia. Of the various peaks of the TMS-evoked EEG signal, responses at 45 (N45) and 100 ms (N100) likely reflect GABA-A and GABA-B receptor-mediated inhibition, respectively. Responses at 25 ms (P25) are affected by voltage-gated channel ligands, whereas glutamatergic processes may be related to the P70 component. We here aim to systematically investigate the role of these neural processes in patients with schizophrenia by using TMS-EEG.MethodTMS-evoked EEG potentials (TEPs) were recorded in patients with schizophrenia (n = 19) and in age-matched healthy controls (n = 17). 150 TMS pulses at 90% of resting motor threshold were applied over the left primary motor cortex during EEG recording. Differences in TEPs between the two groups were analysed for all electrodes and for time windows corresponding to each TEP (P25: 0.015-0.035 ms; N45: 0.035-0.06 ms; P70: 0.035-0.06 ms; N100: 0.09-0.14ms) by applying multiple independent sample t-tests. Further, a cluster-based permutation analysis approach was implemented to correct for multiple comparisons.ResultCompared to controls, patients showed amplitude reduction for the P25 (negative and positive cluster; p < 0.001 and p = 0.04, respectively), N45 (negative and positive cluster; p < 0.001 and p = 0.001, respectively) and P70 component (negative and positive cluster; p = 0.04 and p = 0.004, respectively).ConclusionThere results extend on previous literature about impairment of GABA-A receptor mediated inhibition in schizophrenia, as demonstrated by the N45 amplitude reduction, whereas no significant differences in GABA-B index (i.e., N100) were revealed. Our results also showed that, although specific mechanisms underlying P25 and P70 have not been fully elucidated yet, excitatory neurotransmission is altered in this clinical population. To conclude, TMS-EEG may provide a more comprehensive view of the inhibitory and excitatory mechanisms involved in the pathophysiology of schizophrenia.

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Sasaki, Keisuke, Yuki Fujishige, and Masato Odagaki. "EEG Coherence Analysis for Suppression of MEP Amplitude Variability in TMS." International Journal of Online and Biomedical Engineering (iJOE) 17, no. 06 (June 25, 2021): 87. http://dx.doi.org/10.3991/ijoe.v17i06.22553.

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Transcranial magnetic stimulation (TMS) is a non-invasive stimulation method for cortical neurons. When TMS is delivered to the primary motor cortex (M1), motor evoked potentials can be measured in electromyograms for the peripheral muscle. However, the motor-evoked potential (MEP) amplitudes measured by stimulations for M1 fluctuated from trial to trial. MEP fluctuations are caused by changes in cortical excitability. We hypothesized that MEP variability could be suppressed with application of TMS when cortical excitability was stable. Thus, we developed a TMS system to suppress MEP amplitude variabilities. We used electroencephalographic (EEG) online measurements with coherence analysis to obtain the similarity of cortical excitabilities. The system enables us to trigger TMS if the EEGs measured from the two channels have a high similarity in the frequency domain. In this study, we found that the suppression of MEP fluctuation was dependent on the state of cortical excitability obtained by EEG coherence analysis.

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de Goede, A. A., and M. J. A. M. van Putten. "ID 152 – Paired pulse TMS-EMG and TMS-EEG in epilepsy." Clinical Neurophysiology 127, no. 3 (March 2016): e81. http://dx.doi.org/10.1016/j.clinph.2015.11.269.

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Lioumis, Pantelis, Elena Ukharova, Sabin Sathyan, Victor Souza, Baran Aydogan, Mia Liljeström, Hanna Renvall, Mario Rosanova, and Risto Ilmoniemi. "Advanced approaches for cortical mapping with navigated TMS and TMS–EEG." Brain Stimulation 16, no. 1 (January 2023): 215. http://dx.doi.org/10.1016/j.brs.2023.01.298.

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Canali, P., S. Casarotto, M. Rosanova, G. Sferrazza-Papa, A. G. Casali, O. Gosseries, M. Massimini, E. Smeraldi, C. Colombo, and F. Benedetti. "Abnormal brain oscillations persist after recovery from bipolar depression." European Psychiatry 41, no. 1 (2017): 10–15. http://dx.doi.org/10.1016/j.eurpsy.2016.10.005.

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AbstractWhen directly perturbed in healthy subjects, premotor cortical areas generate electrical oscillations in the beta range (20–40 Hz). In schizophrenia, major depressive disorder and bipolar disorder (BD), these oscillations are markedly reduced, in terms of amplitude and frequency. However, it still remains unclear whether these abnormalities can be modulated over time, or if they can be still observed after treatment. Here, we employed transcranial magnetic stimulation (TMS) combined with EEG to assess the frontal oscillatory activity in eighteen BD patients before/after antidepressant treatments (sleep deprivation and light therapy), relative to nine healthy controls. In order to detect dominant frequencies, event related spectral perturbations (ERSP) were computed for each TMS/EEG session in all participants, using wavelet decomposition. The natural frequency at which the cortical circuit oscillates was calculated as the frequency value with the largest power across 300 ms post-stimulus time interval. Severity of depression markedly decreased after treatment with 12 patients achieving response and nine patients achieving remission. TMS/EEG resulted in a significant activation of the beta/gamma band response (21–50 Hz) in healthy controls. In patients, the main frequencies of premotor EEG responses to TMS did not significantly change before/after treatment and were always significantly lower than those of controls (11–27 Hz) and comparable in patients achieving remission and in those not responding to treatment. These results suggest that the reduction of natural frequencies is a trait marker of BD, independent from the clinical status of the patients. The present findings shed light on the neurobiological underpinning of severe psychiatric disorders and demonstrate that TMS/EEG represents a unique tool to develop biomarkers in psychiatry.

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Veniero, Domenica, Claudio Maioli, and Carlo Miniussi. "Potentiation of Short-Latency Cortical Responses by High-Frequency Repetitive Transcranial Magnetic Stimulation." Journal of Neurophysiology 104, no. 3 (September 2010): 1578–88. http://dx.doi.org/10.1152/jn.00172.2010.

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It is generally accepted that low- and high-frequency repetitive transcranial magnetic stimulation (rTMS) induces changes in cortical excitability, but there is only indirect evidence of its effects despite a large number of studies employing different stimulation parameters. Typically the cortical modulations are inferred through indirect measurements, such as recording the change in electromyographic responses. Recently it has become possible to directly evaluate rTMS-induced changes at the cortical level using electronencephalography (EEG). The present study investigates the modulation induced by high-frequency rTMS via EEG by evaluating changes in the latency and amplitude of TMS-evoked responses. In this study, rTMS was applied to the left primary motor cortex (MI) in 16 participants while an EEG was simultaneously acquired from 29 scalp electrodes. The rTMS consisted of 40 trains at 20 Hz with 10 stimuli each (a total of 400 stimuli) that were delivered at the individual resting motor threshold. The on-line modulation induced by the high-frequency TMS was characterized by a sequence of EEG responses. Two of the rTMS-induced responses, P5 and N8, were specifically modulated according to the protocol. Their latency decreased from the first to the last TMS stimuli, while the amplitude values increased. These results provide the first direct, on-line evaluation of the effects of high-frequency TMS on EEG activity. In addition, the results provide a direct demonstration of cortical potentiation induced by rTMS in humans.

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Voineskos, Daphne, Reza Zomorrodi, and Zafiris Daskalakis. "M11. ALTERED TRANSCRANIAL MAGNETIC STIMULATION ELECTROENCEPHALOGRAPHIC MARKERS IN SCHIZOPHRENIA." Schizophrenia Bulletin 46, Supplement_1 (April 2020): S137. http://dx.doi.org/10.1093/schbul/sbaa030.323.

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Abstract Background Cortical inhibition is a neurophysiological process in which cortical gamma-aminobutyric acid (GABA) inhibitory interneurons modulate the activity of pyramidal neurons in the cerebral cortex. Multiple lines of evidence, including neurophysiological and neuropathological, report that individuals with schizophrenia have deficits in cortical inhibition. Combining transcranial magnetic stimulation (TMS) with electroencephalography is a reliable approach to measure inhibitory processes in the cortex. The overall waveform produced by TMS-EEG may index cortical reactivity as a whole and previous investigations have linked the N45 component peak and the N100 component peak with GABA-A and GABA-B inhibitory neurotransmission, respectively. The aim of this study was to stimulate the DLPFC with TMS and examine resultant differences in the TMS-EEG waveform peaks between patients with schizophrenia and healthy subjects. We hypothesized that individuals with schizophrenia will have smaller TMS-evoked potentials, specifically the amplitudes of the N100 and N45 components, those previously related to GABA-ergic inhibition. Methods We applied TMS over the left DLPFC and recorded EEG activity in 48 healthy subjects (mean age: 33.8±5.3) and 46 patients with schizophrenia (mean age: 43.3±6.4). Monophasic TMS pulses were administered using a 7-cm figure-of-8 coil, and two Magstim 200 stimulators connected via a Bistim module. Single pulse TMS was administered over the left DLPFC with 100 total pulses, which were delivered every 5s. Resultant waveforms were extracted and analyzed through custom MATLAB scripts. The TMS-evoked potential waveform was examined through Global Mean Field Amplitude (GMFA) analysis of waveform peaks in each the two groups. Normality of the distribution of each variable was assessed and a Mann Whitney U test was then performed for each variable of interest to assess differences between groups. Results Individuals in the schizophrenia group demonstrated smaller measures of cortical inhibition in the DLPFC. Specifically, smaller amplitudes of the N45 (U=724.00, p=0.004) and N100 peaks (U=831.00, p=0.039), although the overall AUC of the waveform did not differ between groups (U=969.00, p=0.307). Further analysis is underway to examine medication and symptom cluster effects. Discussion These results demonstrate novel findings of deficits in both GABA-A and GABA-B associated measures of cortical inhibition as indexed by single pulse TMS-EEG. This reinforces previous evidence from different research modalities demonstrating overall GABAergic inhibitory deficits in schizophrenia, and specifically provides new support which confirms recent findings of aberrant GABA-Aergic inhibitory neurotransmission in schizophrenia.

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Kugiumtzis, Dimitris, and Vasilios K. Kimiskidis. "Direct Causal Networks for the Study of Transcranial Magnetic Stimulation Effects on Focal Epileptiform Discharges." International Journal of Neural Systems 25, no. 05 (June 17, 2015): 1550006. http://dx.doi.org/10.1142/s0129065715500069.

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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.

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Huang, G., and A. Mouraux. "P1090: Neuronal dynamic of TMS induced MEPs: a combined TMS-EEG study." Clinical Neurophysiology 125 (June 2014): S339. http://dx.doi.org/10.1016/s1388-2457(14)51118-2.

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Van Doren, J., B. Langguth, and M. Schecklmann. "TMS-related potentials and artifacts in combined TMS-EEG measurements: Comparison of three different TMS devices." Neurophysiologie Clinique/Clinical Neurophysiology 45, no. 2 (May 2015): 159–66. http://dx.doi.org/10.1016/j.neucli.2015.02.002.

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Ilmoniemi, R. "S23.04 Monitoring TMS with EEG and MEG." European Psychiatry 15, S2 (October 2000): 259s. http://dx.doi.org/10.1016/s0924-9338(00)94116-6.

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Tremblay, Sara, Nigel C. Rogasch, Isabella Premoli, Daniel M. Blumberger, Silvia Casarotto, Robert Chen, Vincenzo Di Lazzaro, et al. "Clinical utility and prospective of TMS–EEG." Clinical Neurophysiology 130, no. 5 (May 2019): 802–44. http://dx.doi.org/10.1016/j.clinph.2019.01.001.

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van de Laar, Bram, Daniela de Bonis, and Frank Zanow. "Simultaneous TMS & EEG: Methodology and pitfalls." Neurophysiologie Clinique/Clinical Neurophysiology 46, no. 3 (June 2016): 232. http://dx.doi.org/10.1016/j.neucli.2016.06.039.

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Premoli, I., N. Perales Castellanos, D. Rivolta, P. Belardinelli, R. Bajo, C. Zipser, S. Espenhahn, T. Heidegger, F. Mueller-Dahlhaus, and U. Ziemann. "P1088: TMS-EEG signatures of GABAergic neurotransmission." Clinical Neurophysiology 125 (June 2014): S338. http://dx.doi.org/10.1016/s1388-2457(14)51116-9.

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Rogasch, Nigel C., and Paul B. Fitzgerald. "Assessing cortical network properties using TMS-EEG." Human Brain Mapping 34, no. 7 (February 29, 2012): 1652–69. http://dx.doi.org/10.1002/hbm.22016.

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Rogasch, Nigel C., Zafiris J. Daskalakis, and Paul B. Fitzgerald. "Mechanisms underlying long-interval cortical inhibition in the human motor cortex: a TMS-EEG study." Journal of Neurophysiology 109, no. 1 (January 1, 2013): 89–98. http://dx.doi.org/10.1152/jn.00762.2012.

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Long-interval cortical inhibition (LICI) refers to suppression of neuronal activity following paired-pulse transcranial magnetic stimulation (TMS) with interstimulus intervals (ISIs) between 50 and 200 ms. LICI can be measured either from motor-evoked potentials (MEPs) in small hand muscles or directly from the cortex using concurrent electroencephalography (EEG). However, it remains unclear whether EEG inhibition reflects similar mechanisms to MEP inhibition. Eight healthy participants received single- and paired-pulse TMS (ISI = 100 ms) over the motor cortex. MEPs were measured from a small hand muscle (first dorsal interosseus), whereas early (P30, P60) and late (N100) TMS-evoked cortical potentials (TEPs) were measured over the motor cortex using EEG. Conditioning and test TMS intensities were altered, and modulation of LICI strength was measured using both methods. LICI of MEPs and both P30 and P60 TEPs increased in strength with increasing conditioning intensities and decreased with increasing test intensities. LICI of N100 TEPs remained unchanged across all conditions. In addition, MEP and P30 LICI strength correlated with the slope of the N100 evoked by the conditioning pulse. LICI of early and late TEP components was differentially modulated with altered TMS intensities, suggesting independent underlying mechanisms. LICI of P30 is consistent with inhibition of cortical excitation similar to MEPs, whereas LICI of N100 may reflect presynaptic autoinhibition of inhibitory interneurons. The N100 evoked by the conditioning pulse is consistent with the mechanism responsible for LICI, most likely GABAB-mediated inhibition of cortical activity.

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Kugiumtzis, Dimitris, Christos Koutlis, Alkiviadis Tsimpiris, and Vasilios K. Kimiskidis. "Dynamics of Epileptiform Discharges Induced by Transcranial Magnetic Stimulation in Genetic Generalized Epilepsy." International Journal of Neural Systems 27, no. 07 (August 28, 2017): 1750037. http://dx.doi.org/10.1142/s012906571750037x.

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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.

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Lambooij, E., H. Anil, SR Butler, H. Reimert, L. Workel, and V. Hindle. "Transcranial magnetic stunning of broilers: a preliminary trial to induce unconsciousness." Animal Welfare 20, no. 3 (August 2011): 407–12. http://dx.doi.org/10.1017/s0962728600002967.

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AbstractThis study was performed to identify whether non-focal transcranial magnetic stimulation (TMS) with an adapted coil for broilers has the potential for use as a non-invasive stunning method for broilers. Application of the TMS probe resulted in dominance of theta and delta waves and appearance of spikes in the electroencephalogram (EEG) after stimulation. Correlation dimension (CD) analyses of the EEG signals recorded prior to and following the application of TMS suggested that the birds might be unconscious for approximately 15 to 20 s assuming that a reduction in CD to 60% of the baseline value indicates unconsciousness. Other observations included loss of behavioural arousal or muscle tone (muscle flaccidity), and irregular heart rate after TMS. It can be suggested that TMS has the potential to be developed as a stunning method in the future. The technique, evaluated using small number of broilers in this study, requires further improvement and the use of a power supply optimised in future research. Transcranial magnetic stimulation of the brain has potential for application as a non-invasive stunning method for broilers, which could be acceptable to some religious groups opposed to the use of established or conventional stunning methods.

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Sinitsyn, Dmitry O., Alexandra G. Poydasheva, Ilya S. Bakulin, Liudmila A. Legostaeva, Elizaveta G. Iazeva, Dmitry V. Sergeev, Anastasia N. Sergeeva, et al. "Detecting the Potential for Consciousness in Unresponsive Patients Using the Perturbational Complexity Index." Brain Sciences 10, no. 12 (November 27, 2020): 917. http://dx.doi.org/10.3390/brainsci10120917.

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The difficulties of behavioral evaluation of prolonged disorders of consciousness (DOC) motivate the development of brain-based diagnostic approaches. The perturbational complexity index (PCI), which measures the complexity of electroencephalographic (EEG) responses to transcranial magnetic stimulation (TMS), showed a remarkable sensitivity in detecting minimal signs of consciousness in previous studies. Here, we tested the reliability of PCI in an independently collected sample of 24 severely brain-injured patients, including 11 unresponsive wakefulness syndrome (UWS), 12 minimally conscious state (MCS) patients, and 1 emergence from MCS patient. We found that the individual maximum PCI value across stimulation sites fell within the consciousness range (i.e., was higher than PCI*, which is an empirical cutoff previously validated on a benchmark population) in 11 MCS patients, yielding a sensitivity of 92% that surpassed qualitative evaluation of resting EEG. Most UWS patients (n = 7, 64%) showed a slow and stereotypical TMS-EEG response, associated with low-complexity PCI values (i.e., ≤PCI*). Four UWS patients (36%) provided high-complexity PCI values, which might suggest a covert capacity for consciousness. In conclusion, this study successfully replicated the performance of PCI in discriminating between UWS and MCS patients, further motivating the application of TMS-EEG in the workflow of DOC evaluation.

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Sasaki, Keisuke, Yuki Fujishige, Yutaka Kikuchi, and Masato Odagaki. "A Transcranial Magnetic Stimulation Trigger System for Suppressing Motor-Evoked Potential Fluctuation Using Electroencephalogram Coherence Analysis: Algorithm Development and Validation Study." JMIR Biomedical Engineering 6, no. 2 (June 7, 2021): e28902. http://dx.doi.org/10.2196/28902.

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Background Transcranial magnetic stimulation (TMS), when applied over the primary motor cortex, elicits a motor-evoked potential (MEP) in electromyograms measured from peripheral muscles. MEP amplitude has often been observed to fluctuate trial to trial, even with a constant stimulus. Many factors cause MEP fluctuations in TMS. One of the primary factors is the weak stationarity and instability of cortical activity in the brain, from which we assumed MEP fluctuations originate. We hypothesized that MEP fluctuations are suppressed when TMS is delivered to the primary motor cortex at a time when several electroencephalogram (EEG) channels measured on the scalp are highly similar in the frequency domain. Objective We developed a TMS triggering system to suppress MEP fluctuations using EEG coherence analysis, which was performed to detect the EEG signal similarity between the 2 channels in the frequency domain. Methods Seven healthy adults participated in the experiment to confirm whether the TMS trigger system works adequately, and the mean amplitude and coefficient of the MEP variation were recorded and compared with the values obtained during the control task. We also determined the experimental time under each condition and verified whether it was within the predicted time. Results The coefficient of variation of MEP amplitude decreased in 5 of the 7 participants, and significant differences (P=.02) were confirmed in 2 of the participants according to an F test. The coefficient of variation of the experimental time required for each stimulus after threshold modification was less than that without threshold modification, and a significant difference (P<.001) was confirmed by performing an F test. Conclusions We found that MEP could be suppressed using the system developed in this study and that the TMS trigger system could also stabilize the experimental time by changing the triggering threshold automatically.

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Rostami, M., R. Rostami, and G. A. Hossein-Zadeh. "P20 Dissociating TMS-evoked potentials from peripheral effects in sham-controlled TMS-EEG." Clinical Neurophysiology 131, no. 4 (April 2020): e22. http://dx.doi.org/10.1016/j.clinph.2019.12.131.

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Biabani, M., A. Fornito, T. Mutanen, J. Morrow, and N. Rogasch. "Sensory contamination in TMS-EEG recordings: Can we isolate TMS-evoked neural activity?" Brain Stimulation 12, no. 2 (March 2019): 473. http://dx.doi.org/10.1016/j.brs.2018.12.543.

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Bai, Zhongfei, Jiaqi Zhang, and Kenneth N. K. Fong. "Intermittent Theta Burst Stimulation to the Primary Motor Cortex Reduces Cortical Inhibition: A TMS-EEG Study." Brain Sciences 11, no. 9 (August 24, 2021): 1114. http://dx.doi.org/10.3390/brainsci11091114.

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Introduction: The aim of this study was to reveal the effects of intermittent theta burst stimulation (iTBS) in modulating cortical networks using transcranial magnetic stimulation and electroencephalography (TMS-EEG) recording. Methods: Eighteen young adults participated in our study and received iTBS to the primary motor cortex (M1), supplementary motor area, and the primary visual cortex in three separate sessions. A finger tapping task and ipsilateral single-pulse TMS-EEG recording for the M1 were administrated before and after iTBS in each session. The effects of iTBS in motor performance and TMS-evoked potentials (TEPs) were investigated. Results: The results showed that iTBS to the M1, but not supplementary motor area or the primary visual cortex, significantly reduced the N100 amplitude of M1 TEPs in bilateral hemispheres (p = 0.019), with a more prominent effect in the contralateral hemisphere than in the stimulated hemisphere. Moreover, only iTBS to the M1 decreased global mean field power (corrected ps < 0.05), interhemispheric signal propagation (t = 2.53, p = 0.030), and TMS-induced early α-band synchronization (p = 0.020). Conclusion: Our study confirmed the local and remote after-effects of iTBS in reducing cortical inhibition in the M1. TMS-induced oscillations after iTBS for changed cortical excitability in patients with various neurological and psychiatric conditions are worth further exploration.

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Dugué, Laura, Philippe Marque, and Rufin VanRullen. "Theta Oscillations Modulate Attentional Search Performance Periodically." Journal of Cognitive Neuroscience 27, no. 5 (May 2015): 945–58. http://dx.doi.org/10.1162/jocn_a_00755.

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Visual search—finding a target element among similar-looking distractors—is one of the prevailing experimental methods to study attention. Current theories of visual search postulate an early stage of feature extraction interacting with an attentional process that selects candidate targets for further analysis; in difficult search situations, this selection is iterated until the target is found. Although such theories predict an intrinsic periodicity in the neuronal substrates of attentional search, this prediction has not been extensively tested in human electrophysiology. Here, using EEG and TMS, we study attentional periodicities in visual search. EEG measurements indicated that successful and unsuccessful search trials were associated with different amounts of poststimulus oscillatory amplitude and phase-locking at ∼6 Hz and opposite prestimulus oscillatory phase at ∼6 Hz. A trial-by-trial comparison of pre- and poststimulus ∼6 Hz EEG phases revealed that the functional interplay between prestimulus brain states, poststimulus oscillations, and successful search performance was mediated by a partial phase reset of ongoing oscillations. Independently, TMS applied over occipital cortex at various intervals after search onset demonstrated a periodic pattern of interference at ∼6 Hz. The converging evidence from independent TMS and EEG measurements demonstrates that attentional search is modulated periodically by brain oscillations. This periodicity is naturally compatible with a sequential exploration by attention, although a parallel but rhythmically modulated attention spotlight cannot be entirely ruled out.

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Garcia, Javier O., Emily D. Grossman, and Ramesh Srinivasan. "Evoked potentials in large-scale cortical networks elicited by TMS of the visual cortex." Journal of Neurophysiology 106, no. 4 (October 2011): 1734–46. http://dx.doi.org/10.1152/jn.00739.2010.

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Single pulses of transcranial magnetic stimulation (TMS) result in distal and long-lasting oscillations, a finding directly challenging the virtual lesion hypothesis. Previous research supporting this finding has primarily come from stimulation of the motor cortex. We have used single-pulse TMS with simultaneous EEG to target seven brain regions, six of which belong to the visual system [left and right primary visual area V1, motion-sensitive human middle temporal cortex, and a ventral temporal region], as determined with functional MRI-guided neuronavigation, and a vertex “control” site to measure the network effects of the TMS pulse. We found the TMS-evoked potential (TMS-EP) over visual cortex consists mostly of site-dependent theta- and alphaband oscillations. These site-dependent oscillations extended beyond the stimulation site to functionally connected cortical regions and correspond to time windows where the EEG responses maximally diverge (40, 200, and 385 ms). Correlations revealed two site-independent oscillations ∼350 ms after the TMS pulse: a theta-band oscillation carried by the frontal cortex, and an alpha-band oscillation over parietal and frontal cortical regions. A manipulation of stimulation intensity at one stimulation site (right hemisphere V1-V3) revealed sensitivity to the stimulation intensity at different regions of cortex, evidence of intensity tuning in regions distal to the site of stimulation. Together these results suggest that a TMS pulse applied to the visual cortex has a complex effect on brain function, engaging multiple brain networks functionally connected to the visual system with both invariant and site-specific spatiotemporal dynamics. With this characterization of TMS, we propose an alternative to the virtual lesion hypothesis. Rather than a technique that simulates lesions, we propose TMS generates natural brain signals and engages functional networks.

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Journal articles on the topic 'EEG-TMS'

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