Patterns of brain oscillations across different electrode montages in transcranial pulsed current stimulation

Abstract

Transcranial pulsed current stimulation (tPCS) is a neuromodulatory technique that has been studied in the last decade. Several parameters have been assessed independently to optimize the effects. Our aim was to explore the effects of tPCS using different montages on cortical brain oscillations indexed by power spectrum and interhemispheric coherence in different electroencephalography frequency bands. Twenty healthy individuals were randomized to receive either active tPCS or sham intervention using the following bilateral montages: ear clip (conventional), ear hook, or mastoid placement. Electroencephalography was recorded before and after the electroencephalography intervention to assess tPCS-induced after effects. Our results showed that active tPCS with bimastoid montage increased significantly alpha absolute power (P =0.0166) and low alpha (P =0.0014) in the frontal region, as well as in the low alpha power spectrum in the central (P =0.0001) and parieto-occipital regions (P =0.0068) compared with the other montages. For interhemispheric coherence analysis, the Kruskal–Wallis test showed a significant main effect of group for theta (P =0.0012) in the frontal region, mainly for ear-clip montage. Our findings evidenced that tPCS delivered through different electrode montages exert different effects on cortical brain oscillations and thus have a different neural signature. We discuss the implications of these findings as well as potential clinical explorations of this technique.

Effects of Transcranial Direct Current Stimulation, Transcranial Pulsed Current Stimulation, and Their Combination on Brain Oscillations in Patients with Chronic Visceral Pain: A Pilot Crossover Randomized Controlled Study

“…With respect to tES techniques, our preliminary data suggest that the combination of tDCS with tPCS, applied simultaneously, does not lead to improvements in cortical oscillations, similarly to what has been observed in healthy population ( 26 ). We also highlighted that tDCS and tPCS influence brain activity differently, and therefore may be underlined by different neural mechanisms as previously shown ( 26 , 40 ). While there are a limited amount of data on the neurophysiological reorganization in patients with CVP, our results could help designing future trials using tES as an intervention and neurophysiological assessment to evaluate its effects.…”

“…While no changes were observed clinically, neurophysiologically, the combination of tDCS with tPCS did not lead to any changes in brain activity, while the application of the two techniques separately induced different cortical modifications, as already demonstrated ( 23 , 24 , 38 , 39 ). Therefore, it is becoming increasingly apparent that the effects of tDCS and tPCS are not mediated by the same neurophysiological mechanisms ( 40 ). By reaching deeper structures, it seems feasible that tPCS could stimulate bottom–up connectivity trough thalamo-cortical circuits ( 40 ).…”

“…Therefore, it is becoming increasingly apparent that the effects of tDCS and tPCS are not mediated by the same neurophysiological mechanisms ( 40 ). By reaching deeper structures, it seems feasible that tPCS could stimulate bottom–up connectivity trough thalamo-cortical circuits ( 40 ). On the other hand, tDCS seems to target a top–down cortico-thalamic pathway ( 41 ) and increases cortical excitability under the stimulating electrodes and associated cortical networks ( 38 ).…”

“…Considering each technique individually, tPCS has shown promising and reproducible results as a neuromodulatory tool given the reported effects on coherence and power ( 22 , 23 , 40 ). In particular, in healthy volunteers, 6–10 Hz tPCS seems to modulate brain oscillation within the spectrum contained in these frequencies (i.e., high theta and low alpha).…”

Median nerve stimulation induced motor learning in healthy adults: A study of timing of stimulation and type of learning

“…Recent studies show the effects of varying intensity and random frequency ranges of stimulation on neural effects (Chen, Lin, Chen, & Fregni, ; Chen et al., ; Morales‐Quezada, Saavedra, Rozisky, Hadlington, & Fregni, ; Morales‐Quezada et al., ). In the sham procedure, the device setup remained unchanged, and excepted active stimulation was only applied for the first and last 30 s. We have successfully used this method in our other studies using pulsed peripheral stimulation with similar intensities (Thibaut et al., ; Vasquez, Thibaut, Morales‐Quezada, Leite, & Fregni, ; Vasquez et al., ). Labuschagne Foundation (Luzerne, Switzerland) provided the MNS stimulation devices.…”