DOI: 10.5061/dryad.3m8j0
title: Data from: 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

description: Background and objective: 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. Methods:
 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. Results: 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).
 Conclusion: 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.
description: EEG data from the right
 motor cortex during left-hand motor imagery, collected before, during and
 after contralateral tDCSThe present dataset
 includes the EEG data from twenty healthy volunteers, from the study
 described in our manuscript. The EEG data were acquired from 12 electrodes
 (Fcz, Fc2, Fc4, Fc6, Cz, C2, C4, C6, Cpz, Cp2, Cp4, Cp6) placed on the
 right motor cortex, during a left hand motor imagery task, and visually
 guided by neurofeedback. As the aim of the study was testing the effect of
 contralateral transcranial direct current stimulation (tDCS), the present
 dataset includes EEG recordings before, during and after stimulation. The
 EEG data were acquired by the LABVIEW-based neurofeedback software
 specifically implemented for this study, and stored in TAB-delimited .txt
 files. A "Readme.pdf" file is added to describe the organization
 of the dataset in detail.raw_data_contralateral_tDCS.rar