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Transcranial magnetic stimulation (TMS) perturbs specific brain regions and, combined with electroencephalography (EEG), enables the assessment of activity within their connected networks. We present a resting-state TMS-EEG protocol, combined with a controlled experimental design, to assess changes in brain network activity during offline processing, following a behavioral task. We describe steps for experimental design planning, setup preparation, data collection, and analysis. This approach minimizes biases inherent to TMS-EEG, ensuring an accurate assessment of changes within the network. For complete details of the use and execution of this protocol, please refer to Bracco et al. 1 ., Competing Interests: Declaration of interests T.P.M. has received consultation fees from Nexstim Plc (Helsinki, Finland) and is currently employed at Bittium Ltd (Oulu, Finland)., (Copyright © 2025 The Authors. Published by Elsevier Inc. All rights reserved.)

Objective: Cortico-cortical paired associative stimulation (ccPAS) is a form of dual-site transcranial magnetic stimulation (TMS) entailing a series of single-TMS pulses paired at specific interstimulus intervals (ISI) delivered to distant cortical areas. The goal of this article is to systematically review its efficacy in inducing plasticity in humans focusing on stimulation parameters and hypotheses of underlying neurophysiology., Methods: A systematic review of the literature from 2009-2023 was undertaken to identify all articles utilizing ccPAS to study brain plasticity and connectivity. Six electronic databases were searched and included., Results: 32 studies were identified. The studies targeted connections within the same hemisphere or between hemispheres. 28 ccPAS studies were in healthy participants, 1 study in schizophrenia, and 1 in Alzheimer's disease (AD) patients. 2 additional studies used cortico-cortical repetitive paired associative stimulation (cc-rPAS) in generalized anxiety disorder (GAD) patients. Outcome measures include electromyography (EMG), behavioral measures, electroencephalography (EEG), and functional magnetic resonance imaging (fMRI). ccPAS seems to be able to modulate brain connectivity depending on the ISI., Conclusions: ccPAS can be used to modulate corticospinal excitability, brain activity, and behavior. Although the stimulation parameters used across studies reviewed in this paper are varied, ccPAS is a promising approach for basic research and potential clinical applications., Significance: Recent advances in neuroscience have caused a shift of interest from the study of single areas to a more complex approach focusing on networks of areas that orchestrate brain activity. Consequently, the TMS community is also witnessing a change, with a growing interest in targeting multiple brain areas rather than a single locus, as evidenced by an increasing number of papers using ccPAS. In light of this new enthusiasm for brain connectivity, this review summarizes existing literature and stimulation parameters that have proven effective in changing electrophysiological, behavioral, or neuroimaging-derived measures., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.)

Statistical power in cognitive neuroimaging experiments is often very low. Low sample size can reduce the likelihood of detecting real effects (false negatives) and increase the risk of detecting non-existing effects by chance (false positives). Here, we document our experience of leveraging a relatively unexplored method of collecting a large sample size for simple electroencephalography (EEG) studies: by recording EEG in the community during public engagement and outreach events. We collected data from 346 participants (189 females, age range 6-76 years) over 6 days, totalling 29 hours, at local science festivals. Alpha activity (6-15 Hz) was filtered from 30 seconds of signal, recorded from a single electrode placed between the occipital midline (Oz) and inion (Iz) while the participants rested with their eyes closed. A total of 289 good-quality datasets were obtained. Using this community-based approach, we were able to replicate controlled, lab-based findings: individual alpha frequency (IAF) increased during childhood, reaching a peak frequency of 10.28 Hz at 28.1 years old, and slowed again in middle and older age. Total alpha power decreased linearly, but the aperiodic-adjusted alpha power did not change over the lifespan. Aperiodic slopes and intercepts were highest in the youngest participants. There were no associations between these EEG indexes and self-reported fatigue, measured by the Multidimensional Fatigue Inventory. Finally, we present a set of important considerations for researchers who wish to collect EEG data within public engagement and outreach environments., Competing Interests: The authors declare no competing interests., (© 2023 Massachusetts Institute of Technology. Published under a Creative Commons CC BY-NC 4.0 license.)

Once formed, the fate of memory is uncertain. Subsequent offline interactions between even different memory types (actions versus words) modify retention. 1 , 2 , 3 , 4 , 5 , 6 These interactions may occur due to different oscillations functionally linking together different memory types within a circuit. 7 , 8 , 9 , 10 , 11 , 12 , 13 With memory processing driving the circuit, it may become less susceptible to external influences. 14 We tested this prediction by perturbing the human brain with single pulses of transcranial magnetic stimulation (TMS) and simultaneously measuring the brain activity changes with electroencephalography (EEG 15 , 16 , 17 ). Stimulation was applied over brain areas that contribute to memory processing (dorsolateral prefrontal cortex, DLPFC; primary motor cortex, M1) at baseline and offline, after memory formation, when memory interactions are known to occur. 1 , 4 , 6 , 10 , 18 The EEG response decreased offline (compared with baseline) within the alpha/beta frequency bands when stimulation was applied to the DLPFC, but not to M1. This decrease exclusively followed memory tasks that interact, revealing that it was due specifically to the interaction, not task performance. It remained even when the order of the memory tasks was changed and so was present, regardless of how the memory interaction was produced. Finally, the decrease within alpha power (but not beta) was correlated with impairment in motor memory, whereas the decrease in beta power (but not alpha) was correlated with impairment in word-list memory. Thus, different memory types are linked to different frequency bands within a DLPFC circuit, and the power of these bands shapes the balance between interaction and segregation between these memories., Competing Interests: Declaration of interests T.P.M. has received research funding from Bittium Biosignals Oy (Kuopio, Finland)., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Transcranial magnetic stimulation (TMS) evokes neuronal activity in the targeted cortex and connected brain regions. The evoked brain response can be measured with electroencephalography (EEG). TMS combined with simultaneous EEG (TMS-EEG) is widely used for studying cortical reactivity and connectivity at high spatiotemporal resolution. Methodologically, the combination of TMS with EEG is challenging, and there are many open questions in the field. Different TMS-EEG equipment and approaches for data collection and analysis are used. The lack of standardization may affect reproducibility and limit the comparability of results produced in different research laboratories. In addition, there is controversy about the extent to which auditory and somatosensory inputs contribute to transcranially evoked EEG. This review provides a guide for researchers who wish to use TMS-EEG to study the reactivity of the human cortex. A worldwide panel of experts working on TMS-EEG covered all aspects that should be considered in TMS-EEG experiments, providing methodological recommendations (when possible) for effective TMS-EEG recordings and analysis. The panel identified and discussed the challenges of the technique, particularly regarding recording procedures, artifact correction, analysis, and interpretation of the transcranial evoked potentials (TEPs). Therefore, this work offers an extensive overview of TMS-EEG methodology and thus may promote standardization of experimental and computational procedures across groups., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: PJ has received consulting fees and shares a patent with Nexstim Oyj. PL has received consulting fees from Nexstim Oyj. HRS has received honoraria as speaker from Sanofi Genzyme, Denmark, Lundbeck AS, Denmark, and Novartis, Denmark, as consultant from Sanofi Genzyme, Denmark, Lophora, Denmark, and Lundbeck AS, Denmark, and as editor-in-chief (Neuroimage Clinical) and senior editor (NeuroImage) from Elsevier Publishers, Amsterdam, The Netherlands. He has received royalties as book editor from Springer Publishers, Stuttgart, Germany and from Gyldendal Publishers, Copenhagen, Denmark. TPM has successfully applied for funding for a collaborative research project (project not started at the time of the submission) with Bittium Biosignals Oy (Kuopio, Finland). SC is advisor and share-holder of Intrinsic Power, a spinf-off of the University of Milan., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Most people are often tempted by their impulses to "indulge" in high-calorie food, even if this behaviour is not consistent with their goal to control weight in the long term and might not be healthy. The outcome of this conflict is strongly dependent on inhibitory control. It has already been reported that individuals with weaker inhibitory control consume more high-calorie food, are more often unsuccessful dieters, overweight or obese compared to people with more effective inhibitory control. In the present study, we aimed at investigating inhibitory control in the context of human eating behaviour. A sample of 20 healthy normal-weight adults performed a 50% probability visual affective Go/NoGo task involving food (high- and low-calorie) and non-food images as stimuli. Single-pulse transcranial magnetic stimulation (TMS) was administered over the right primary motor cortex (M1) either 300 ms after image presentation to measure corticospinal excitability during the different stimulus categories or 300 ms after the appearance of a fixation point, as a control stimulation condition. The experimental session consisted of a food target and a non-food target block. Behavioural outcomes showed a natural implicit inclination towards high-calorie food in that participants were faster and more accurate compared to the other categories. This advantage was selectively deleted by TMS, which slowed down reaction times. MEPs did not differ according to the stimulus category, but, as expected, were bigger for Go compared to NoGo trials. Participants judged high-calorie food also as more appetising than low-calorie food images. Overall, our results point to a differential modulation when targeting inhibitory control, in favour of the more palatable food category (high-calorie). Present data suggest that the activity of the motor system is modulated by food nutritional value, being more engaged by appetising food. Future work should explore to what extent these processes are affected in patients with eating disorders and should aim to better characterise the related dynamics of cortical connectivity within the motor network., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Bianco, Veniero, D’Acunto, Koch and Picazio.)

Alpha-band oscillatory activity over occipito-parietal areas is involved in shaping perceptual and cognitive processes, with a growing body of electroencephalographic (EEG) evidence indicating that pre-stimulus alpha-band amplitude relates to the subjective perceptual experience, but not to objective measures of visual task performance (discrimination accuracy). The primary aim of the present transcranial magnetic stimulation (TMS) study was to investigate whether causality can be established for this relationship, using rhythmic (alpha-band) TMS entrainment protocols. It was anticipated that pre-stimulus 10 Hz-TMS would induce changes in subjective awareness ratings but not accuracy, in the visual hemifield contralateral to TMS. To test this, we administered 10 Hz-TMS over the right intraparietal sulcus prior to visual stimulus presentation in 17 participants, while measuring their objective performance and subjective awareness in a visual discrimination task. Arrhythmic and 10 Hz sham-TMS served as control conditions (within-participant design). Resting EEG was used to record individual alpha frequency (IAF). A study conducted in parallel to ours with a similar design but reported after we completed data collection informed further, secondary analyses for a causal relationship between pre-stimulus alpha-frequency and discrimination accuracy. This was explored through a regression analysis between rhythmic-TMS alpha-pace relative to IAF and performance measures. Our results revealed that contrary to our primary expectation, pre-stimulus 10 Hz-TMS did not affect subjective measures of performance, nor accuracy, relative to control-TMS. This null result is in accord with a recent finding showing that for influencing subjective measures of performance, alpha-TMS needs to be applied post-stimulus. In addition, our secondary analysis showed that IAF was positively correlated with task accuracy across participants, and that 10 Hz-TMS effects on accuracy-but not awareness ratings-depended on IAF: The slower (or faster) the IAF, relative to the fixed 10 Hz TMS frequency, the stronger the TMS-induced performance improvement (or worsening), indicating that 10 Hz-TMS produced a gain (or a loss) in individual performance, directly depending on TMS-pace relative to IAF. In support of recent reports, this is evidence for alpha-frequency playing a causal role in perceptual sensitivity likely through regulating the speed of sensory sampling., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The reviewer CT declared a past collaboration with one of the authors, GT to the handling editor., (Copyright © 2022 Coldea, Veniero, Morand, Trajkovic, Romei, Harvey and Thut.)

Transcranial alternating current stimulation (tACS) is a popular technique that has been used for manipulating brain oscillations and inferring causality regarding the brain-behaviour relationship. Although it is a promising tool, the variability of tACS results has raised questions regarding the robustness and reproducibility of its effects. Building on recent research using tACS to modulate visuospatial attention, we here attempted to replicate findings of lateralized parietal tACS at alpha frequency to induce a change in attention bias away from the contra- towards the ipsilateral visual hemifield. 40 healthy participants underwent tACS in two separate sessions where either 10 Hz tACS or sham was applied via a high-density montage over the left parietal cortex at 1.5 mA for 20 min, while performance was assessed in an endogenous attention task. Task and tACS parameters were chosen to match those of previous studies reporting positive effects. Unlike these studies, we did not observe lateralized parietal alpha tACS to affect attention deployment or visual processing across the hemifields as compared to sham. Likewise, additional resting electroencephalography immediately offline to tACS did not reveal any notable effects on individual alpha power or frequency. Our study emphasizes the need for more replication studies and systematic investigations of the factors that drive tACS effects., Competing Interests: The authors have declared that no competing interests exist.

Voluntary allocation of visual attention is controlled by top-down signals generated within the Frontal Eye Fields (FEFs) that can change the excitability of lower-level visual areas. However, the mechanism through which this control is achieved remains elusive. Here, we emulated the generation of an attentional signal using single-pulse transcranial magnetic stimulation to activate the FEFs and tracked its consequences over the visual cortex. First, we documented changes to brain oscillations using electroencephalography and found evidence for a phase reset over occipital sites at beta frequency. We then probed for perceptual consequences of this top-down triggered phase reset and assessed its anatomical specificity. We show that FEF activation leads to cyclic modulation of visual perception and extrastriate but not primary visual cortex excitability, again at beta frequency. We conclude that top-down signals originating in FEF causally shape visual cortex activity and perception through mechanisms of oscillatory realignment.

Fluid intelligence (gf) represents a crucial component of human cognition, as it correlates with academic achievement, successful aging, and longevity. However, it has strong resilience against enhancement interventions, making the identification of gf enhancement approaches a key unmet goal of cognitive neuroscience. Here, we applied a spike-timing-dependent plasticity (STDP)-inducing brain stimulation protocol, named cortico-cortical paired associative stimulation (cc-PAS), to modulate gf in 29 healthy young subjects (13 females-mean ± standard deviation, 25.43 years ± 3.69), based on dual-coil transcranial magnetic stimulation (TMS). Pairs of neuronavigated TMS pulses (10-ms interval) were delivered over two frontoparietal nodes of the gf network, based on individual functional magnetic resonance imaging data and in accordance with cognitive models of information processing across the prefrontal and parietal lobe. cc-PAS enhanced accuracy at gf tasks, with parieto-frontal and fronto-parietal stimulation significantly increasing logical and relational reasoning, respectively. Results suggest the possibility of using SPTD-inducing TMS protocols to causally validate cognitive models by selectively engaging relevant networks and manipulating inter-regional temporal dynamics supporting specific cognitive functions., (© The Author(s) 2019. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Existing literature on sensory deprivation suggests that short-lasting periods of dark adaptation (DA) can cause changes in visual cortex excitability. DA cortical effects have previously been assessed through phosphene perception, i.e., the ability to report visual sensations when a transcranial magnetic stimulation (TMS) pulse is delivered over the visual cortex. However, phosphenes represent an indirect measure of visual cortical excitability which relies on a subjective report. Here, we aimed at overcoming this limitation by assessing visual cortical excitability by combining subjective (i.e., TMS-induced phosphenes) and objective (i.e., TMS-evoked potentials - TEPs) measurements in a TMS-EEG protocol after 30 min of DA. DA effects were compared to a control condition, entailing 30 min of controlled light exposure. TMS was applied at 11 intensities in order to estimate the psychometric function of phosphene report and explore the relationship between TEPs and TMS intensity. Compared to light adaptation, after DA the slope of the psychometric function was significantly steeper, and the amplitude of a TEP component (P60) was lower, only for high TMS intensities. The perceptual threshold was not affected by DA. These results support the idea that DA leads to a change in the excitability of the visual cortex, accompanied by a behavioral modification of visual perception. Furthermore, this study provides a first valuable description of the relationship between TMS intensity and visual TEPs.

Neuroimaging and transcranial magnetic stimulation (TMS) studies have implicated a dorsal fronto-parietal network in endogenous attention control and a more ventral set of areas in exogenous attention shifts. However, the extent and circumstances under which these cortical networks overlap and/or interact remain unclear. Crucially, whereas previous studies employed experimental designs that tend to confound exogenous with endogenous attentional engagement, we used a cued target discrimination paradigm that behaviourally dissociates exogenous from endogenous attention processes. Participants engaged with endogenous attention cues, while simultaneous apparent motion cues were driving exogenous attention along the motion path towards or away from the target position. To interfere with dorsal or ventral attention networks, we delivered neuronavigated double-pulse TMS over either right intraparietal sulcus (rIPS) or right temporo-parietal junction (rTPJ) towards the end of the cue target interval, and compared the effects to a sham-TMS condition. For sham-TMS, endogenous and exogenous cueing both benefitted discrimination accuracy. Target discrimination was enhanced at validly versus invalidly cued locations (endogenous cueing benefit) as well as when targets appeared in versus out of the motion path (exogenous cueing benefit), despite motion being uninformative and task-irrelevant, replicating previous findings. Interestingly, both rIPS- and rTPJ-TMS abolished attention benefits from exogenous cueing, while endogenous cueing benefits were unaffected. Our findings provide evidence against independent involvement of the dorsal and ventral attention network nodes in exogenous attention processes., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Oscillatory neural activity is a fundamental characteristic of the mammalian brain spanning multiple levels of spatial and temporal scale. Current theories of neural oscillations and analysis techniques employed to investigate their functional significance are based on an often implicit assumption: In the absence of experimental manipulation, the spectral content of any given EEG- or MEG-recorded neural oscillator remains approximately stationary over the course of a typical experimental session (∼1 h), spontaneously fluctuating only around its dominant frequency. Here, we examined this assumption for ongoing neural oscillations in the alpha-band (8-13 Hz). We found that alpha peak frequency systematically decreased over time, while alpha-power increased. Intriguingly, these systematic changes showed partial independence of each other: Statistical source separation (independent component analysis) revealed that while some alpha components displayed concomitant power increases and peak frequency decreases, other components showed either unique power increases or frequency decreases. Interestingly, we also found these components to differ in frequency. Components that showed mixed frequency/power changes oscillated primarily in the lower alpha-band (∼8-10 Hz), while components with unique changes oscillated primarily in the higher alpha-band (∼9-13 Hz). Our findings provide novel clues on the time-varying intrinsic properties of large-scale neural networks as measured by M/EEG, with implications for the analysis and interpretation of studies that aim at identifying functionally relevant oscillatory networks or at driving them through external stimulation., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

How neural representations of low-level visual information are accessed by higher-order processes to inform decisions and give rise to conscious experience is a longstanding question. Research on perceptual decision making has revealed a late event-related EEG potential (the Centro-Parietal Positivity, CPP) to be a correlate of the accumulation of sensory evidence. We tested how this evidence accumulation signal relates to externally presented (physical) and internally experienced (subjective) sensory evidence. Our results show that the known relationship between the physical strength of the external evidence and the evidence accumulation signal (reflected in the CPP amplitude) is mediated by the level of subjective experience of stimulus strength. This shows that the CPP closely tracks the subjective perceptual evidence, over and above the physically presented evidence. We conclude that a remarkably close relationship exists between the evidence accumulation process (i.e. CPP) and subjective perceptual experience, suggesting that neural decision processes and components of conscious experience are tightly linked.

Prismatic adaption (PA) has been proposed as a tool to induce neural plasticity and is used to help neglect rehabilitation. It leads to a recalibration of visuomotor coordination during pointing as well as to aftereffects on a number of sensorimotor and attention tasks, but whether these effects originate at a motor or attentional level remains a matter of debate. Our aim was to further characterize PA aftereffects by using an approach that allows distinguishing between effects on attentional and motor processes. We recorded EEG in healthy human participants (9 females and 7 males) while performing a new double step, anticipatory attention/motor preparation paradigm before and after adaptation to rightward-shifting prisms, with neutral lenses as a control. We then examined PA aftereffects through changes in known oscillatory EEG signatures of spatial attention orienting and motor preparation in the alpha and beta frequency bands. Our results were twofold. First, we found PA to rightward-shifting prisms to selectively affect EEG signatures of motor but not attentional processes. More specifically, PA modulated preparatory motor EEG activity over central electrodes in the right hemisphere, contralateral to the PA-induced, compensatory leftward shift in pointing movements. No effects were found on EEG signatures of spatial attention orienting over occipitoparietal sites. Second, we found the PA effect on preparatory motor EEG activity to dominate in the beta frequency band. We conclude that changes to intentional visuomotor, rather than attentional visuospatial, processes underlie the PA aftereffect of rightward-deviating prisms in healthy participants. SIGNIFICANCE STATEMENT Prismatic adaptation (PA) has been proposed as a tool to induce neural plasticity in both healthy participants and patients, due to its aftereffect impacting on a number of visuospatial and visuomotor functions. However, the neural mechanisms underlying PA aftereffects are poorly understood as only little neuroimaging evidence is available. Here, we examined, for the first time, the origin of PA aftereffects studying oscillatory brain activity. Our results show a selective modulation of preparatory motor activity following PA in healthy participants but no effect on attention-related activity. This provides novel insight into the PA aftereffect in the healthy brain and may help to inform interventions in neglect patients., (Copyright © 2018 Bracco, Veniero et al.)

Prestimulus oscillatory neural activity has been linked to perceptual outcomes during performance of psychophysical detection and discrimination tasks. Specifically, the power and phase of low frequency oscillations have been found to predict whether an upcoming weak visual target will be detected or not. However, the mechanisms by which baseline oscillatory activity influences perception remain unclear. Recent studies suggest that the frequently reported negative relationship between α power and stimulus detection may be explained by changes in detection criterion (i.e., increased target present responses regardless of whether the target was present/absent) driven by the state of neural excitability, rather than changes in visual sensitivity (i.e., more veridical percepts). Here, we recorded EEG while human participants performed a luminance discrimination task on perithreshold stimuli in combination with single-trial ratings of perceptual awareness. Our aim was to investigate whether the power and/or phase of prestimulus oscillatory activity predict discrimination accuracy and/or perceptual awareness on a trial-by-trial basis. Prestimulus power (3-28 Hz) was inversely related to perceptual awareness ratings (i.e., higher ratings in states of low prestimulus power/high excitability) but did not predict discrimination accuracy. In contrast, prestimulus oscillatory phase did not predict awareness ratings or accuracy in any frequency band. These results provide evidence that prestimulus α power influences the level of subjective awareness of threshold visual stimuli but does not influence visual sensitivity when a decision has to be made regarding stimulus features. Hence, we find a clear dissociation between the influence of ongoing neural activity on conscious awareness and objective performance.

Actions are typically associated with sensory consequences. For example, knocking at a door results in predictable sounds. These self-initiated sensory stimuli are known to elicit smaller cortical responses compared to passively presented stimuli, e.g., early auditory evoked magnetic fields known as M100 and M200 components are attenuated. Current models implicate the cerebellum in the prediction of the sensory consequences of our actions. However, causal evidence is largely missing. In this study, we introduced a constant delay (of 100 ms) between actions and action-associated sounds, and we recorded magnetoencephalography (MEG) data as participants adapted to the delay. We found an increase in the attenuation of the M100 component over time for self-generated sounds, which indicates cortical adaptation to the introduced delay. In contrast, no change in M200 attenuation was found. Interestingly, disrupting cerebellar activity via transcranial magnetic stimulation (TMS) abolished the adaptation of M100 attenuation, while the M200 attenuation reverses to an M200 enhancement. Our results provide causal evidence for the involvement of the cerebellum in adapting to delayed action effects, and thus in the prediction of the sensory consequences of our actions., (Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Transcranial electrical stimulation (tES) is being investigated as an experimental and clinical interventional technique in human participants. While promising, important limitations have been identified, including weak effect sizes and high inter- and intra-individual variability of outcomes. Here, we compared two "inhibitory" tES-techniques with supposedly different mechanisms of action as to their effects on performance in a visuospatial attention task, and report on a direct replication attempt. In two experiments, 2 × 20 healthy participants underwent tES in three separate sessions testing different protocols (10 min stimulation each) with a montage targeting right parietal cortex (right parietal-left frontal, electrode-sizes: 3cm × 3cm-7 cm × 5 cm), while performing a perceptual line bisection (landmark) task. The tES-protocols were compared as to their ability to modulate pseudoneglect (thought to be under right hemispheric control). In experiment 1, sham-tES was compared to transcranial alternating current stimulation at alpha frequency (10 Hz; α-tACS) (expected to entrain "inhibitory" alpha oscillations) and to cathodal transcranial direct current stimulation (c-tDCS) (shown to suppress neuronal spiking activity). In experiment 2, we attempted to replicate the findings of experiment 1, and establish frequency-specificity by adding a 45 Hz-tACS condition to α-tACS and sham. In experiment 1, right parietal α-tACS led to the expected changes in spatial attention bias, namely a rightward shift in subjective midpoint estimation (relative to sham). However, this was not confirmed in experiment 2 and in the complete sample. Right parietal c-tDCS and 45 Hz-tACS had no effect. These results highlight the importance of replication studies, adequate statistical power and optimizing tES-interventions for establishing the robustness and reliability of electrical stimulation effects, and best practice.

Background: The effects of deep brain stimulation of the subthalamic nucleus (DBS-STN) and L-dopa (LD) on cortical activity in Parkinson's disease (PD) are poorly understood., Objectives: By combining transcranial magnetic stimulation (TMS) and electroencephalography (EEG) we explored the effects of STN-DBS, either alone or in combination with L-Dopa (LD), on TMS-evoked cortical activity in a sample of implanted PD patients., Methods: PD patients were tested in three clinical conditions: i) LD therapy with STN-DBS turned on (ON/ON condition); ii) without LD therapy with STN-DBS turned on (OFF/ON condition); iii) without LD therapy with STN-DBS turned off (OFF/OFF condition). TMS pulses were delivered over left M1 while simultaneously acquiring EEG. Eight age-matched healthy volunteers (HC) were tested as a control group., Results: STN-DBS enhanced early global TMS-evoked activity (∼45-80ms) and high-alpha TMS-evoked oscillations (11-13 Hz) as compared to OFF/OFF condition, independently from concomitant LD therapy. LD intake (ON/ON condition) produced a further increase of late TMS-evoked activity (∼80-130ms) and beta TMS-evoked oscillations (13-30 Hz), as compared to OFF/OFF and OFF/ON conditions, that normalized reactivity as compared to HC range of values., Conclusions: Our data reveal that bilateral STN-DBS and LD therapy induce a modulation of specific cortical components and specific ranges of frequency. These findings demonstrate that STN-DBS and LD therapy may have synergistic effects on motor cortical activity., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Voluntary movement control and execution are regulated by the influence of the cerebellar output over different interconnected cortical areas, through dentato-thalamo connections. In the present study we applied transcranial magnetic stimulation (TMS) and electroencephalography (EEG) to directly assess the effects of cerebellar theta-burst stimulation (TBS) over the controlateral primary motor cortex (M1) and posterior parietal cortex (PPC) in a group of healthy volunteers. We found a TBS-dependent bidirectional modulation over TMS-evoked activity; specifically, cTBS increased whereas iTBS decreased activity between 100 and 200 ms after TMS, in a similar manner over both M1 and PPC areas. On the oscillatory domain, TBS induced specific changes over M1 natural frequencies of oscillation: TMS-evoked alpha activity was decreased by cTBS whereas beta activity was enhanced by iTBS. No effects were observed after sham stimulation. Our data provide novel evidence showing that the cerebellum exerts its control on the cortex likely by impinging on specific set of interneurons dependent on GABA-ergic activity. We show that cerebellar TBS modulates cortical excitability of distant interconnected cortical areas by acting through common temporal, spatial and frequency domains.

A number of rhythmic protocols have emerged for non-invasive brain stimulation (NIBS) in humans, including transcranial alternating current stimulation (tACS), oscillatory transcranial direct current stimulation (otDCS), and repetitive (also called rhythmic) transcranial magnetic stimulation (rTMS). With these techniques, it is possible to match the frequency of the externally applied electromagnetic fields to the intrinsic frequency of oscillatory neural population activity ("frequency-tuning"). Mounting evidence suggests that by this means tACS, otDCS, and rTMS can entrain brain oscillations and promote associated functions in a frequency-specific manner, in particular during (i.e., online to) stimulation. Here, we focus instead on the changes in oscillatory brain activity that persist after the end of stimulation. Understanding such aftereffects in healthy participants is an important step for developing these techniques into potentially useful clinical tools for the treatment of specific patient groups. Reviewing the electrophysiological evidence in healthy participants, we find aftereffects on brain oscillations to be a common outcome following tACS/otDCS and rTMS. However, we did not find a consistent, predictable pattern of aftereffects across studies, which is in contrast to the relative homogeneity of reported online effects. This indicates that aftereffects are partially dissociated from online, frequency-specific (entrainment) effects during tACS/otDCS and rTMS. We outline possible accounts and future directions for a better understanding of the link between online entrainment and offline aftereffects, which will be key for developing more targeted interventions into oscillatory brain activity.

Many behaviourally relevant sensory events such as motion stimuli and speech have an intrinsic spatio-temporal structure. This will engage intentional and most likely unintentional (automatic) prediction mechanisms enhancing the perception of upcoming stimuli in the event stream. Here we sought to probe the anticipatory processes that are automatically driven by rhythmic input streams in terms of their spatial and temporal components. To this end, we employed an apparent visual motion paradigm testing the effects of pre-target motion on lateralized visual target discrimination. The motion stimuli either moved towards or away from peripheral target positions (valid vs. invalid spatial motion cueing) at a rhythmic or arrhythmic pace (valid vs. invalid temporal motion cueing). Crucially, we emphasized automatic motion-induced anticipatory processes by rendering the motion stimuli non-predictive of upcoming target position (by design) and task-irrelevant (by instruction), and by creating instead endogenous (orthogonal) expectations using symbolic cueing. Our data revealed that the apparent motion cues automatically engaged both spatial and temporal anticipatory processes, but that these processes were dissociated. We further found evidence for lateralisation of anticipatory temporal but not spatial processes. This indicates that distinct mechanisms may drive automatic spatial and temporal extrapolation of upcoming events from rhythmic event streams. This contrasts with previous findings that instead suggest an interaction between spatial and temporal attention processes when endogenously driven. Our results further highlight the need for isolating intentional from unintentional processes for better understanding the various anticipatory mechanisms engaged in processing behaviourally relevant stimuli with predictable spatio-temporal structure such as motion and speech.

The posteromedial cortex including the precuneus (PC) is thought to be involved in episodic memory retrieval. Here we used continuous theta burst stimulation (cTBS) to disentangle the role of the precuneus in the recognition memory process in a sample of healthy subjects. During the encoding phase, subjects were presented with a series of colored pictures. Afterwards, during the retrieval phase, all previously presented items and a sample of new pictures were presented in black, and subjects were asked to indicate whether each item was new or old, and in the latter case to indicate the associated color. cTBS was delivered over PC, posterior parietal cortex (PPC) and vertex before the retrieval phase. The data were analyzed in terms of hits, false alarms, source errors and omissions. cTBS over the precuneus, but not over the PPC or the vertex, induced a selective decrease in source memory errors, indicating an improvement in context retrieval. All the other accuracy measurements were unchanged. These findings suggest a direct implication of the precuneus in successful context-dependent retrieval., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Recent developments in neuroscience have emphasised the importance of integrated distributed networks of brain areas for successful cognitive functioning. Our current understanding is that the brain has a modular organisation in which segregated networks supporting specialised processing are linked through a few long-range connections, ensuring processing integration. Although such architecture is structurally stable, it appears to be flexible in its functioning, enabling long-range connections to regulate the information flow and facilitate communication among the relevant modules, depending on the contingent cognitive demands. Here we show how insights brought by the coregistration of transcranial magnetic stimulation and electroencephalography (TMS-EEG) integrate and support recent models of functional brain architecture. Moreover, we will highlight the types of data that can be obtained through TMS-EEG, such as the timing of signal propagation, the excitatory/inhibitory nature of connections and causality. Last, we will discuss recent emerging applications of TMS-EEG in the study of brain disorders., (Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Despite the fact that different studies have been performed using transcranial direct current stimulation (tDCS) in aphasia, so far, to what extent the stimulation of a cerebral region may affect the activity of anatomically connected regions remains unclear. The authors used a combination of transcranial magnetic stimulation (TMS) and electroencephalography (EEG) to explore brain areas' excitability modulation before and after active and sham tDCS. Six chronic aphasics underwent 3 weeks of language training coupled with tDCS over the right inferior frontal gyrus. To measure the changes induced by tDCS, TMS-EEG closed to the area stimulated with tDCS were calculated. A significant improvement after tDCS stimulation was found which was accompained by a modification of the EEG over the stimulated region.

A fully adapted behavior requires maximum efficiency to inhibit processes in the motor domain. Although a number of cortical and subcortical brain regions have been implicated, converging evidence suggests that activation of right inferior frontal gyrus (r-IFG) and right presupplementary motor area (r-preSMA) is crucial for successful response inhibition. However, it is still unknown how these prefrontal areas convey the necessary signal to the primary motor cortex (M1), the cortical site where the final motor plan eventually has to be inhibited or executed. On the basis of the widely accepted view that brain oscillations are fundamental for communication between neuronal network elements, one would predict that the transmission of these inhibitory signals within the prefrontal-central networks (i.e., r-IFG/M1 and/or r-preSMA/M1) is realized in rapid, periodic bursts coinciding with oscillatory brain activity at a distinct frequency. However, the dynamics of corticocortical effective connectivity has never been directly tested on such timescales. By using double-coil transcranial magnetic stimulation (TMS) and electroencephalography (EEG), we assessed instantaneous prefrontal-to-motor cortex connectivity in a Go/NoGo paradigm as a function of delay from (Go/NoGo) cue onset. In NoGo trials only, the effects of a conditioning prefrontal TMS pulse on motor cortex excitability cycled at beta frequency, coinciding with a frontocentral beta signature in EEG. This establishes, for the first time, a tight link between effective cortical connectivity and related cortical oscillatory activity, leading to the conclusion that endogenous (top-down) inhibitory motor signals are transmitted in beta bursts in large-scale cortical networks for inhibitory motor control., (Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.)

Paired associative stimulation (PAS) protocols induce forms of spike-timing-dependent-plasticity (STDP) when paired pulses are repeatedly applied with different timing over interconnected cortical areas such as the posterior parietal cortex (PPC) and the primary motor cortex (M1). However, the assessment of PAS effects is usually limited to M1 through recording of motor-evoked potential (MEP) amplitude. Here, by combining transcranial magnetic stimulation (TMS) with EEG we aimed at investigating PAS effects over both areas (PPC, M1) and the modulation induced on their connectivity in humans. In different PAS conditions, PPC preceded or followed M1 TMS by 5 ms. We found that TMS-evoked potentials (TEPs) changed differently according to the long-term depression (LTD) or potentiation (LTP) after-effect assessed by MEPs, but did not vary at PPC level. Moreover, there was no change in local oscillatory power. However, there was a remarkable increase of coherence between the PPC and the M1 areas. When the PAS protocol induced LTD as revealed by MEPs, there was a specific increase of the coherence between PPC and M1 within the beta band. On the contrary, when PAS induced LTP, the coherence crucially increased in the alpha band. The same LTP results were confirmed when rotating the stimulating coil in M1 during the PAS protocol. In conclusion, we report new evidence that opposite STDP-like effects induced by corticocortical PAS are associated with increased communication between involved brain areas and that antithetic forms of STDP-like after-effects result in distinct cortical rhythms connectivity changes.

Learning of new skills may occur through Hebbian associative changes in the synaptic strength of cortical connections [spike-timing-dependent plasticity (STDP)], but how the precise temporal relationship of the presynaptic and postsynaptic inputs determines the STDP effects in humans is poorly understood. We used a novel paired associative stimulation protocol to repeatedly activate the short-latency connection between the posterior parietal cortex and the primary motor cortex (M1) of the left-dominant hemisphere. In different experiments, we systematically varied the temporal relationships between the stimuli and the preferential activation of different M1 neuronal populations by applying transcranial magnetic stimulation over M1 with different coil orientations and in different states of cortical excitability (rest vs muscular contraction). We found evidence for the existence of both Hebbian and anti-Hebbian STDP in human long-range connections. The induction of bidirectional long-term potentiation or depression in M1 depended not only on the relative timing between the stimuli but, crucially, on the stimulation of specific neuronal populations and the activity state of the cortex. Our findings demonstrate that these mechanisms are not fixed but susceptible to rapid adaptations. This sudden transition from anti-Hebbian to Hebbian plasticity likely involves local dynamics of interaction with different populations of postsynaptic neurons.

The human brain is characterized by the lateralization of cognitive functions. Multiple lines of evidence suggest the deployment of visuospatial attention is controlled by a frontoparietal network, with a right hemisphere dominance. Among cortical areas included in the network, the right posterior parietal cortex (PPC) has been proposed to be a crucial node and has also been implicated on clinical grounds. Here, the authors provide an overview of the existent literature giving evidence to a functional asymmetry of the parietal cortices in directing visuospatial attention, focusing on those studies seeking to characterize the causal role of PPC, applying transcranial magnetic stimulation and its combination with imaging techniques, such as electroencephalography and fMRI. First, the role of PPC and how this region exerts its control over remote areas of both hemispheres is discussed. The second part discusses studies involving neglect patients shedding light on the complex interplay between left and right PPC, strongly supporting the hemispheric rivalry theory. Finally, studies demonstrating changes of neglect disorders following the manipulation of the unaffected hemisphere activation will be discussed.

Transcranial magnetic stimulation-electroencephalogram (TMS-EEG) co-registration offers the opportunity to test reactivity of brain areas across distinct conditions through TMS-evoked potentials (TEPs). Several TEPs have been described, their functional meaning being largely unknown. In particular, short-latency potentials peaking at 5 (P5) and 8 (N8) ms after the TMS pulse have been recently described, but because of their large amplitude, the problem of whether their origin is cortical or not has been opened. To gain information about these components, we employed a protocol that modulates primary motor cortex excitability (MI): low frequency stimulation of premotor area (PMC). TMS was applied simultaneously with EEG recording from 70 electrodes. Amplitude of TEPs evoked by 200 single-pulses TMS delivered over MI at 110% of resting motor threshold (rMT) was measured before and after applying 900 TMS conditioning stimuli to left PMC with 1 Hz repetition rate. Single subject analyses showed reduction in TEPs amplitude after PMC conditioning in a sample of participants and increase in TEPs amplitude in two subjects. No effects were found on corticospinal excitability as recorded by motor-evoked potentials (MEPs). Furthermore, correlation analysis showed an inverse relation between the effects of the conditioning protocol on P5-N8 complex amplitude and MEPs amplitude. Because the effects of the used protocol have been ascribed to a cortical interaction between premotor area and MI, we suggest that despite the sign of P5-N8 amplitude modulation is not consistent across participant; this modulation could indicate, at least in part, their cortical origin. We conclude that with an accurate experimental procedure early latency components can be used to evaluate the reactivity of the stimulated cortex.

Differential diagnoses between vegetative and minimally conscious states (VS and MCS, respectively) are frequently incorrect. Hence, further research is necessary to improve the diagnostic accuracy at the bedside. The main neuropathological feature of VS is the diffuse damage of cortical and subcortical connections. Starting with this premise, we used electroencephalography (EEG) recordings to evaluate the cortical reactivity and effective connectivity during transcranial magnetic stimulation (TMS) in chronic VS or MCS patients. Moreover, the TMS-EEG data were compared with the results from standard somatosensory-evoked potentials (SEPs) and event-related potentials (ERPs). Thirteen patients with chronic consciousness disorders were examined at their bedsides. A group of healthy volunteers served as the control group. The amplitudes (reactivity) and scalp distributions (connectivity) of the cortical potentials evoked by TMS (TEPs) of the primary motor cortex were measured. Short-latency median nerve SEPs and auditory ERPs were also recorded. Reproducible TEPs were present in all control subjects in both the ipsilateral and the contralateral hemispheres relative to the site of the TMS. The amplitudes of the ipsilateral and contralateral TEPs were reduced in four of the five MCS patients, and the TEPs were bilaterally absent in one MCS patient. Among the VS patients, five did not manifest ipsilateral or contralateral TEPs, and three of the patients exhibited only ipsilateral TEPs with reduced amplitudes. The SEPs were altered in five VS and two MCS patients but did not correlate with the clinical diagnosis. The ERPs were impaired in all patients and did not correlate with the clinical diagnosis. These TEP results suggest that cortical reactivity and connectivity are severely impaired in all VS patients, whereas in most MCS patients, the TEPs are preserved but with abnormal features. Therefore, TEPs may add valuable information to the current clinical and neurophysiological assessment of chronic consciousness disorders.

The effects of repetitive transcranial magnetic stimulation (rTMS) on cortical excitability are usually inferred from indirect indexes, such as EMG responses. It has now become possible to directly evaluate rTMS impact by means of concurrent EEG recording. The aim of this study was to examine the modulation induced by high frequency rTMS (20 Hz) over left primary motor cortex on the ongoing oscillatory activity. Thirteen subjects underwent two sham and a real rTMS session while acquiring EEG. Event-related desynchronization/synchronization was calculated for the α and β bands. rTMS induced a dose-dependent increase in synchronization in both bands over central and parietal sites. The strongest effect found for the α band outlasted the end of the stimulation. Considering previous studies, our data suggest that α generation may represent an intrinsic induced response and a basic response signature to TMS targeting the human resting motor cortex., (Copyright © 2011 Society for Psychophysiological Research.)

Background: Neuronal elements underlying perception, cognition, and action exhibit distinct oscillatory phenomena, measured in humans by electro- or magnetoencephalography (EEG/MEG). So far, the correlative or causal nature of the link between brain oscillations and functions has remained elusive. A compelling demonstration of causality would primarily generate oscillatory signatures that are known to correlate with particular cognitive functions and then assess the behavioral consequences. Here, we provide the first direct evidence for causal entrainment of brain oscillations by transcranial magnetic stimulation (TMS) using concurrent EEG., Results: We used rhythmic TMS bursts to directly interact with an MEG-identified parietal α-oscillator, activated by attention and linked to perception. With TMS bursts tuned to its preferred α-frequency (α-TMS), we confirmed the three main predictions of entrainment of a natural oscillator: (1) that α-oscillations are induced during α-TMS (reproducing an oscillatory signature of the stimulated parietal cortex), (2) that there is progressive enhancement of this α-activity (synchronizing the targeted, α-generator to the α-TMS train), and (3) that this depends on the pre-TMS phase of the background α-rhythm (entrainment of natural, ongoing α-oscillations). Control conditions testing different TMS burst profiles and TMS-EEG in a phantom head confirmed specificity of α-boosting to the case of synchronization between TMS train and neural oscillator., Conclusions: The periodic electromagnetic force that is generated during rhythmic TMS can cause local entrainment of natural brain oscillations, emulating oscillatory signatures activated by cognitive tasks. This reveals a new mechanism of online TMS action on brain activity and can account for frequency-specific behavioral TMS effects at the level of biologically relevant rhythms., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

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.

The present twin study investigates heritability of motor cortex excitability, measured by the paired pulse transcranial magnetic stimulation technique. Specifically, intracortical facilitation (ICF) and inhibition (ICI) and corticospinal excitability were tested in monozygotic (MZ), dizygotic (DZ), and unrelated pairs (UP). Robust ICF and ICI effects were found, with a higher similarity of MZ than DZ and UP pairs. Heritability estimates (h(2)) were 0.80 for ICI and 0.92 for ICF. However, corticospinal excitability did not show significant differences between MZ and DZ pairs, whereas both significantly differed from UP. Hence, the study provides--for the first time--a clear evidence of heritable individual differences in motor cortex excitability.

Objective: The combination of brain stimulation by transcranial magnetic stimulation (TMS) and simultaneous electroencephalographic (EEG) recording has the potential to be of great value for understanding human brain functions. Recording EEG during TMS can be technically challenging because TMS induces a very strong electrical field that can saturate recording amplifiers for a long duration. Advances in amplifier technology, however, have led to the development of TMS-compatible EEG equipment that can work in very high, time-varying magnetic fields without saturation. The aim of the present study was to identify stimulus-related artifacts, and to provide experimental data containing the length of the artifact induced by the magnetic field and its variations with respect to the experimental setting., Methods: A phantom head was stimulated to record the artifact while excluding cortical responses. We tested different types of electrodes, coils, models of stimulator, and frequencies and intensities of stimulation to see how these parameters influence the duration of the artifact., Results: The electrical artifact produced by the magnetic pulse lasted approximately 5 ms following TMS onset. Its length was invariant irrespective of different experimental conditions., Conclusions: These data suggest that it is possible to analyze the cortical evoked response induced by TMS 5 ms after TMS onset., Significance: The possibility to study the early physiological responses to TMS stimulation may have valuable implications for both clinical and experimental purposes, providing information about the early direct cortical response of the stimulated areas.

Changes of cortical and corticospinal excitability as a function of sleep deprivation have been studied, using EEG power maps and several TMS measures in 33 normal subjects before and after a 40-h sleep deprivation (SD). The effects of SD were independently assessed by subjective and EEG measures of sleepiness, the latter being represented in terms of cortical maps for different frequency bands. Short intracortical facilitation (SICF) and inhibition (SICI) were measured by the paired-pulse TMS technique with different inter-stimulus intervals. Besides standardized motor threshold (MT), lower threshold (LT) and upper threshold (UT) were also determined. Subjective sleepiness severely increased as a consequence of SD, paralleled by a drastic decrease of alertness. EEG topography showed large increases in delta and theta activity, mainly evident at fronto-central areas. Standard MTs, as well as LTs and UTs, all increased as a consequence of SD. SICF also showed a significant increase as compared to pre-deprivation values, but only in females. The increase of theta activity was strongly associated in the left frontal and prefrontal cortex to a smaller decrease of corticospinal excitability, expressed by MTs, and a larger increase of intracortical facilitation, expressed by SICF. TMS and EEG measures converge in indicating that SD has severe effects on both cortical and corticospinal excitability, as shown respectively by the increases of slow-frequency EEG power and MTs. The SICF enhancement in females and the results of the combined topographical analysis of EEG and TMS changes are coherent with the hypothesis that cortical TMS-evoked responses are higher as a consequence of a longer wakefulness. However, the lack of an increase in cortical excitability after prolonged wakefulness in males suggests some caution in the generalization of these effects, that deserve further investigation.

Objective: Electrical stimulation of the median nerve followed by a magnetic pulse on the primary motor cortex (M1) is effective to cause an increase in the amplitude of motor evoked potential (MEP) registered in the target muscle with the interstimulus interval (ISI) at 25ms (paired associative stimulation, PAS). The aim of this study is to evaluate the reproducibility of PAS with ISI 25 (PAS25), assessed in two separate sessions. Intraindividual reliability of TMS measures was also evaluated., Methods: Motor threshold of abductor pollicis brevis (APB), assessed at rest, and MEP amplitude of APB and abductor digiti minimi (ADM) were assessed before and after PAS25 in 18 healthy volunteers (nine males and nine females)., Results: Data showed a significant increase of MEP amplitude in the target muscle (APB) after PAS25 and a reproducibility of group effect in the two sessions, as assessed by ANOVA, but a lack of intraindividual reliability, as assessed by intraclass correlation coefficients (ICC)., Conclusions: The results underline the reproducibility of mean effects and the need to be careful when comparing the same subject on different days., Significance: Electrical stimulation of the median nerve followed by a magnetic pulse delivered on M1 after 25ms causes a reproducible increase in MEP amplitude, without showing an acceptable intraindividual reliability.