Query: econnectome  tdcs      rest    EEG

title: 45 Anodal tDCS Decreases Total EEG Power at Rest and Alters Brain Signaling during Fatigue in High Performance Athletes

title: EEG dataset of individuals with intellectual and developmental disorder and healthy controls under rest and music stimuli
abstract: This article presents a collection of electroencephalographic (EEG) data recorded from 14 participants, that includes 7 participants with Intellectual and Developmental Disorder (IDD) and 7 Typically Developing Controls (TDC) under resting state and under music stimuli. The EEG data were acquired using the EMOTIV EPOC+ device that is a 14 channel dry electrode device. The article provides two types of data: (1) Raw EEG data under resting state and with music stimuli (i.e. task based data) and (2) pre processed EEG data under resting state and with music stimuli. Alongside this data, we provide a robust and fully automated pre processing pipeline for EEG data. The pipeline performs filtering, line noise removal, data selection, ICA, and automatic artefact removal.

title: The role of physiological complexity changes in resting state EEG in clinical effectiveness of rTMS and tDCS in treatments of resistant depression
abstract: The present literature about possible mechanisms behind the effectivity of noninvasive electromagnetic stimulation in major depressive disorder (MDD) is not very rich. Despite extensive research in applications for clinical practice, the exact effects are yet not clear. We are comparing our previous results about the complexity changes induced by repetitive Transcranial Magnetic Stimulation (rTMS) and transcranial direct current stimulation (tDCS) which are known to modulate neural dynamics. Also, we are reviewing different biomarkers of complexity changes connected to depression, and how they change with the stimulation. TDCS is low intensity TES, known to have polarity specific effects (neuromodulatory effects) and rTMS is inducing an electric field in the tissue circumstantially via Faraday's law. Both nonlinear modalities of electromagnetic stimulation may affect the levels of physiological complexity in the brain. We also compare the changes of complexity in electroencephalogram (EEG) and electrocardiogram (ECG) as potential future predictors of therapy outcome.

title: Effect of tDCS stimulation of motor cortex and cerebellum on EEG classification of motor imagery and sensorimotor band power
abstract: BackgroundTranscranial direct current stimulation (tDCS) is a technique for brain modulation that has potential to be used in motor neurorehabilitation. Considering that the cerebellum and motor cortex exert influence on the motor network, their stimulation could enhance motor functions, such as motor imagery, and be utilized for brain computer interfaces (BCIs) during motor neurorehabilitation. new tDCS montage that influences cerebellum and either right hand or feet motor area is proposed and validated with a simulation of electric field. The effect of current density (0, 0.02, 0.04 or 0.06 mA/cm2) on electroencephalographic (EEG) classification into rest or right hand/feet motor imagery was evaluated on 5 healthy volunteers for different stimulation modalities: 1) 10 minutes anodal tDCS before EEG acquisition over right hand or 2) feet motor cortical area, and 3) 4 seconds anodal tDCS during EEG acquisition either on right hand or feet cortical areas before each time right hand or feet motor imagery is performed. For each subject and tDCS modality, analysis of variance and Tukey Kramer multiple comparisons tests (p <0.001) are used to detect significant differences between classification accuracies that are obtained with different current densities. For tDCS modalities that improved accuracy, t tests (p <0.05) are used to compare m and b band power when a specific current density is provided against the case of supplying no stimulation.ResultsThe proposed montage improved the classification of right hand motor imagery for 4 out of 5 subjects when the highest current was applied for 10 minutes over the right hand motor area. Although EEG band power changes could not be related directly to classification improvement, tDCS appears to affect variably different motor areas on m and/or b band.ConclusionsThe proposed montage seems capable of enhancing right hand motor imagery detection when the right hand motor area is stimulated. Future research should be focused on applying higher currents over the feet motor cortex, which is deeper in the brain compared to the hand motor cortex, since it may allow observation of effects due to tDCS. Also, strategies for improving analysis of EEG respect to accuracy changes should be implemented.

title: Single session tDCS over the dominant hemisphere affects contralateral spectral EEG power, but does not enhance neurofeedback guided event related desynchronization of the non dominant hemisphere's sensorimotor rhythm
abstract: Transcranial direct current stimulation (tDCS) and neurofeedback guided motor imagery (MI) have attracted considerable interest in neurorehabilitation, given their ability to influence neuroplasticity. As tDCS has been shown to modulate event related desynchronization (ERD) the neural signature of motor imagery detected for neurofeedback, a combination of the techniques was recently proposed. One limitation of this approach is that the area targeted for stimulation is the same from which the signal for neurofeedback is acquired. As tDCS may interfere with proximal electroencephalographic (EEG) electrodes, in this study our aim was to test whether contralateral tDCS could have interhemispheric effects on the spectral power of the unstimulated hemisphere, possibly mediated by transcallosal connection, and whether such effects could be used to enhance ERD magnitudes. A contralateral stimulation approach would indeed facilitate co registration, as the stimulation electrode would be far from the recording sites.  Twenty right handed healthy volunteers (aged 21 to 32) participated in the study: ten assigned to cathodal, ten to anodal versus sham stimulation. We applied stimulation over the dominant (left) hemisphere, and assessed ERD and spectral power over the non dominant (right) hemisphere. The effect of tDCS was evaluated over time. Spectral power was assessed in theta, alpha and beta bands, under both rest and MI conditions, while ERD was evaluated in alpha and beta bands.  Two main findings emerged: (1) contralateral alpha ERD was reduced after anodal (p 0.0147) but not enhanced after cathodal tDCS; (2) both stimulations had remote effects on the spectral power of the contralateral hemisphere, particularly in theta and alpha (significant differences in the topographical t value maps)  The absence of contralateral cathodal ERD enhancement suggests that the protocol is not applicable in the context of MI training. Nevertheless, ERD results of anodal and spectral power results of both stimulations complement recent findings on the distant tDCS effects between functionally related areas.

title: Individual Baseline Performance and Electrode Montage Impact on the Effects of Anodal tDCS Over the Left Dorsolateral Prefrontal Cortex
abstract: Anodal transcranial direct current stimulation (tDCS) applied over the left dorsolateral prefrontal cortex (lDLPFC) can produce significant effects on working memory (WM) performance and associated neurophysiological activity. However, results from previous studies are inconsistent and occasionally contradictory. This inconsistency may be attributed to methodological and individual differences during experiments. This study therefore investigated two hypotheses: (1) A multichannel optimized montage was expected to be more effective than a classical bipolar montage, because of increased focality. (2) The subjects were expected to benefit differently from the stimulation depending on their initial task performance. In a sham controlled crossover study, 24 healthy participants received bipolar, multichannel, and sham stimulation for 20 min in randomized order, targeting the lDLPFC while performing a 2 back WM task. After stimulation, electroencephalography (EEG) was recorded at rest and during 2 back and nontarget continuous performance task (CPT) performance. Bipolar and multichannel stimulations were both well tolerated and effectively blinded. We found no effect of stimulation on behavioral performance or neuronal oscillations comparing the classical bipolar or multichannel montage with sham stimulation. We did, however, find an interaction between stimulation and initial task performance. For multichannel stimulation, initially low performing participants tended to improve their WM performance while initially high performing participants tended to worsen their performance compared to sham stimulation. Both tDCS montages induced changes in neural oscillatory power, which correlated with baseline performance. The worse the participants' initial WM performance was, the more task related theta power was induced by multichannel and bipolar stimulation. The same effect was observed for alpha power in the nontarget task following multichannel stimulation. Notably, we were not able to show a superiority of multichannel stimulation compared to bipolar stimulation. Still, comparing both montages with sham stimulation, multichannel stimulation led to stronger effects than bipolar stimulation. The current study highlights the importance of investigating different parameters with potential influence on tDCS effects in combination. Our results demonstrate how individual differences in cognitive performance and electrode montages influence effects of tDCS on neuropsychological performance. These findings support the idea of an individualized and optimized stimulation setting, potentially leading to increased tDCS effects.

title: Null effects of tDCS over the Left Prefrontal Cortex on Self paced Exercise and EEG
abstract: to test the hypothesis that transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (DLPFC) influences performance in a 20aEUR(tm) self paced exercise and electroencephalographic (EEG) oscillatory brain activity in a group of trained male cyclists.  We conducted a pre registered (https:/osf.io/rf95j/ randomised, sham controlled, within subject design experiment. 36 trained males cyclists, age 27 (6.8) years, VO2max: 54 (6.13) ml/min/kg, completed a 20aEUR(tm) self paced exercise in three separate sessions, under three stimulation conditions: anodal, cathodal and sham. TDCS was delivered for 20' before each test at a current intensity of 2.0 mA. The anode electrode was placed over the DLPFC and the cathode over the shoulder. We measured the power output, heart rate, RPE and EGG (at baseline and during exercise)  The were not difference in power output (F 0.031 0.31, p 0.05) during the self paced exercise between conditions: Anodal (235 W [95%CI 222 249 W] Cathodal (235 W [95%CI 222 248 W] and Sham (234 W [95%CI 220 248 W] Neither the heart rate, RPE nor EEG activity were affected by the tDCS (all Ps 0.05) Conclusions tDCS over the left DLFC did not affect self paced exercise performance in trained cyclists. Moreover, tDCS did not elicit any change on EEG activity either at baseline or during exercise. Our data suggest that the significant effects of tDCS on endurance performance (and at rest) reported by recent studies should be taken with caution.  This project was supported by grants from from the Spanish Ministerio de EconomAa, Industria y Competitividad PSI2016 75956 P to Daniel Sanabria and Mikel Zabala, a predoc toral grant from the Spanish Ministerio de EconomAa, Industria y Competitividad (BES 2014 069050) to Luis Ciria, and a Spanish aEURoeMinisterio de EducaciA3n, Cultura y DeporteaEUR predoctoral grant (FPU14/06229) to DarAas Holgado.

title: tDCS over posterior parietal cortex increases cortical excitability but decreases learning: An ERPs and TMS EEG study
abstract: The application of anodal transcranial direct current stimulation (AtDCS) is generally associated with increased neuronal excitability and enhanced cognitive functioning. Nevertheless, previous work showed that applying this straight reasoning does not always lead to the desired results at behavioural level. Here, we investigated electrophysiological markers of AtDCS mediated effects on visuo spatial contextual learning (VSCL) In order to assess cortical excitability changes after 3 mA AtDCS applied over posterior parietal cortex, event related potentials (ERPs) were collected during task performance. Additionally, AtDCS induced effects on cortical excitability were explored by measuring TMS evoked potentials (TEPs) collected before AtDCS, after AtDCS and after AtDCS and VSCL interaction. Behavioural results revealed that the application of AtDCS induced a reduction of VSCL. At the electrophysiological level, ERPs showed enhanced cortical response (P2 component) in the group receiving Real AtDCS as compared to Sham AtDCS. Cortical responsiveness at rest as measured by TEP, did not indicate any significant difference between Real and Sham tDCS groups, albeit a trend was present. Overall, our results suggest that AtDCS increases cortical response to incoming visuo spatial stimuli, but with no concurrent increase in learning. Detrimental effects on behaviour could result from the interaction between AtDCS and task mediated cortical activation. This interaction might enhance cortical excitability and hinder normal task related neuroplastic phenomena subtending learning.

title: Comparison and Affecting Factors of Three tDCS Montages in Motor Recovery of Chronic Stroke Patients: A Resting State EEG Study
abstract: We aimed at exploring the modulation of tDCS on spontaneous cortical activity through the changing of EEG rhythms to different tDCS montages and the interaction between cortical responses and variability factors of stroke individuals. 19 stroke subjects underwent 4 tDCS sessions with 3 different tDCS montages (anodal (atDCS) cathodal (ctDCS) and bilateral (bi tDCS) and sham stimulation in a single blind, randomized, controlled crossover design. We acquired resting state (eyes closing and opening alternately) EEG data before and after tDCS, and calculated the spectral power of each frequency band. Paired samples T test was applied to examine the difference of spectral power between pre and post stimulation of each montage. Three way repeated measures analysis of variance with lesion hemispheres, stimulation montages and locations were carried out to investigate tDCS effects of different lesion, montages, and channel locations, and the interaction. Further, the effects of tDCS over time were analyzed applying three way repeated ANOVAs as well with post trials, lesion hemispheres and channel locations separately to each montage. Finally, linear and quadratic regression model were used separately to describe the association between clinical factors of stroke patients and change of spectral power. We found that induced effect of tDCS was limited to the alpha rhythm of opening state. atDCS increased the alpha power especially alpha1 (8 10 Hz) in local and distant areas of mainly frontal and partial. bi tDCS affected the alpha power as well, but in a smaller area which mainly focused on alpha2 (10 13 Hz) ctDCS and sham had no effect on alpha rhythm. No significant difference of alpha band was found over the observed time range after the stimulation over. Results further showed that the quadratic model can better characterize the relationship between clinical factors and the tDCS effects of alpha rhythm than linear model. The changing of alpha especially alpha2 in contralateral hemisphere induced by atDCS was related to time since stroke, and alpha2 in ipsilateral hemisphere induced by bi tDCS to motor impairment level. Our results provide electrophysiological evidence that different tDCS montages in stroke subjects modulate rhythmic cortical activity of alpha band in different ways, and the effects maintained for at least 30 minutes. The tDCS modulation effect was related to clinical factors, especially the time since stroke and the level of motor impairment. These findings are of great significance for the knowledge on modulation effect to stroke patients and for therapeutic application of motor recovery following stroke.

title: Predicting tDCS treatment outcomes of patients with major depressive disorder using automated EEG classification.
abstract: Transcranial direct current stimulation (tDCS) is a promising treatment for major depressive disorder (MDD) Standard tDCS treatment involves numerous sessions running over a few weeks. However, not all participants respond to this type of treatment. This study aims to investigate the feasibility of identifying MDD patients that respond to tDCS treatment based on resting state electroencephalography (EEG) recorded prior to treatment commencing.  We used machine learning to predict improvement in mood and cognition during tDCS treatment from baseline EEG power spectra. Ten participants with a current diagnosis of MDD were included. Power spectral density was assessed in five frequency bands: delta (0.5 4Hz) theta (4 8Hz) alpha (8 12Hz) beta (13 30Hz) and gamma (30 100Hz) Improvements in mood and cognition were assessed using the Montgomery Asberg Depression Rating Scale and Symbol Digit Modalities Test, respectively. We trained the classifiers using three algorithms (support vector machine, extreme learning machine and linear discriminant analysis) and a leave one out cross validation approach.  Mood labels were accurately predicted in 8 out of 10 participants using EEG channels FC4 AF8 (accuracy=76% p=0.034) Cognition labels were accurately predicted in 10 out of 10 participants using channels pair CPz CP2 (accuracy=92% p=0.004) LIMITATIONS Due to the limited number of participants (n=10) the presented results mainly aim to serve as a proof of concept.  These finding demonstrate the feasibility of using machine learning to identify patients that will respond to tDCS treatment. These promising results warrant a larger study to determine the clinical utility of this approach.