tDCS effect on EEG profile in response to semantic motor anomaly detection

Introduction/Objectives: Cortical neuromodulation was explored in the present research by adopting a tDCS (transcranial direct current stimulation) brain stimulation to induce a temporary inhibition of the frontal area (Fz). The induced effect of brain modulation was tested on the EEG and ERP (event-related potentials) profile when subjects processed semantic anomalies. It was previously shown that an increased negative peak deflection (N400) is observable in case of anomalous linguistic meanings or incorrect objects uses. A significant reduction of this ERP deflections was attended when tDCS was applied to Fz area. Participants, Materials/Methods: Two subjects’ groups (experimental and control groups) were submitted to semantically correct or incorrect object use by using videotapes. During the detection task, participants were asked to evaluate the semantic correctness of some motor sequences that manipulated simple objects. EEG were registered during the tDCS (experimental groups) or no tDCS (control group) stimulation. Results: Behavioural (RTs and response correctness) EEG and ERP measures were analyzed and compared between-groups and within-condition (anomaly vs. no anomaly) (repeated measure ANOVAs). Significant differences were found between groups and conditions for EEG and behavioural variables. A standard N400 effect was revealed for control group in response to anomalous condition, whereas a reduction of the peak amplitude was observed in case of tDCS stimulation. Conclusions: Evidences for significant effect of brain inhibition induced by tDCS was suggested in case of motor sequence processing. This effect was tested for EEG and RTs. Significant applications might be provided by the present research to modulate EEG activity by tDCS for patients.