High-definition transcranial direct current stimulation (HD-tDCS) seems to overcome a drawback of traditional bipolar tDCS: the wide-spread diffusion of the electric field. Nevertheless, most of the differences that characterise the two techniques are based on mathematical simulations and not on real, behavioural and neurophysiological, data. The study aims to compare a widespread tDCS montage (i.e., a Conventional bipolar montage with extracephalic return electrode) and HD-tDCS, investigating differences both at a behavioural level, in terms of dexterity performance, and a neurophysiological level, as modifications of alpha and beta power as measured with EEG. Thirty participants took part in three sessions, one for each montage: Conventional tDCS, HD-tDCS, and sham. In all the conditions, the anode was placed over C4, while the cathode/s placed according to the montage. At baseline, during, and after each stimulation condition, dexterity was assessed with a Finger Tapping Task. In addition, resting-state EEG was recorded at baseline and after the stimulation. Power spectrum density was calculated, selecting two frequency bands: alpha (8-12 Hz) and beta (18-22 Hz). Linear mixed effect models (LMMs) were used to analyse the modulation induced by tDCS. To evaluate differences among the montages and consider state-dependency phenomenon, the post-stimulation measurements were covariate-adjusted for baseline levels. We observed that HD-tDCS induced an alpha power reduction in participants with lower alpha at baseline. Conversely, Conventional tDCS induced a beta power reduction in participants with higher beta at baseline. Furthermore, data showed a trend towards a behavioural effect of HD-tDCS in participants with lower beta at baseline showing faster response times. Conventional and HD-tDCS distinctively modulated cortical activity. The study highlights the importance of considering state-dependency to determine the effects of tDCS on individuals.
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http://dx.doi.org/10.1038/s41598-021-87371-z | DOI Listing |
Brain Sci
November 2024
Department of Neurophysiology, National Institute of Mental Health & Neurosciences NIMHANS, Bengaluru 560029, India.
: Individualizing transcranial direct current stimulation (tDCS) parameters can improve precision in neuropsychiatric disorders. One important decision for the clinician is the selection of an appropriate montage-conventional or high-definition (HD)-to implement dose-controlled tDCS while maintaining the patient's safety. : The present study simulated tDCS administration using T1-weighted brain images of 50 dementia, 25 depression patients, and 25 healthy individuals for two conventional and HD montages, targeting the regions of interest (ROIs) in the dorsal and ventral pathways that support language processing.
View Article and Find Full Text PDFJ Women Aging
December 2024
School of Nursing and Midwifery, Faculty of Health, University of Technology Sydney, Ultimo, Australia.
J Neurol Sci
December 2024
Department of Neurology, Mayo Clinic, Jacksonville, FL, United States of America.
Objective: Rapid EEG devices (REDs) have demonstrated substantial benefit regarding reduced time to performance of study and diagnosis in cases where urgent EEG is needed to evaluate patients for potentially revealing nonconvulsive status epilepticus and seizures. However, urgent EEG is also important in identifying cases regarding the need for initiation of antiseizure medication as well as triaging the use of continuous EEG monitoring. Some forms of REDs have a reduced montage (RRME) with electrode derivations that are one-half of standard recordings.
View Article and Find Full Text PDFNeuromodulation
January 2025
Department of Computer Science and Engineering, Gyeongsang National University, Jinju, South Korea. Electronic address:
Objectives: Transcranial direct current stimulation (tDCS) is an emerging neuromodulation technique. The effect of tDCS can vary significantly depending on electrode position and current intensity, making it crucial to find an optimized tDCS montage. However, because of the high computational load, most tDCS optimization approaches have been performed with a limited number of candidates for electrode positions, such as 10-10 or 10-20 international channel configurations.
View Article and Find Full Text PDFFront Neurosci
September 2024
Laboratoire d'Imagerie Biomédicale (LIB), Inserm U1146, Sorbonne Université, CNRS UMR7371, 15 rue de l'Ecole de Médecine, Paris, France.
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