Midfrontal theta transcranial alternating current stimulation modulates behavioural adjustment after error execution

Abstract

Cognitive control during conflict monitoring, error processing, and post‐error adjustment appear to be associated with the occurrence of midfrontal theta (MFϴ). While this association is supported by correlational EEG studies, much less is known about the possible causal link between MFϴ and error and conflict processing. In the present study, we aimed to explore the role of band‐specific effects in modulating the error system during a conflict resolution. In turn, we delivered transcranial alternating current stimulation (tACS) at different frequency bands (delta δ, theta θ, alpha α, beta β, gamma γ) and sham stimulation over the medial frontal cortex (MFC) in 36 healthy participants performing a modified version of the Flanker task. Task performance and reports about the sensations (e.g. visual flickering, cutaneous burning) induced by the different frequency bands, were also recorded. We found that online θ‐tACS increased the response speed to congruent stimuli after error execution with respect to sham stimulation. Importantly, the accuracy following the errors did not decrease because of speed‐accuracy trade off. Moreover, tACS evoked visual and somatosensory sensations were significantly stronger at α‐tACS and β‐tACS compared to other frequencies. Our findings suggest that theta activity plays a causative role in modulating behavioural adjustments during perceptual choices in a stimulus‐response conflict task.

The Modulation of Cognitive Performance with Transcranial Alternating Current Stimulation: A Systematic Review of Frequency-Specific Effects

“…For executive functions, most studies applied online stimulation with the goal of entrainment. Faster responseswere induced by theta-tACS during response inhibition [55,57,60] and by alpha-or beta-tACS during time estimation [59]. Additionally, individual alpha-peak-tACS increased mental rotation performance [58].…”

“…Further, Laczó and colleagues [38] applied another spatial attention task. They tested the facilitatory or inhibitory effects of attention on contrast detection thresholds, while stimulating at different gamma frequencies (40,60,80 Hz). Only gamma-tACS at 60 Hz improved the participants' contrast detection performance compared with sham.…”

“…Fusco et al [60] stimulated during a response inhibition task (i.e., flanker task) where participants had to respond to target letters embedded in a string of distractor letters. Six different blocks of stimulation were applied in randomized order (delta, theta, alpha, beta, gamma, or sham).…”

Frontal and occipito-temporal Theta activity as marker of error monitoring in Human-Avatar joint performance

“…Alpha (8-13Hz) synchronizations over fronto-central electrodes as markers of the performance monitoring system activity (Luu et al, 2004;Trujillo & Allen, 2007;Cavanagh et al, 2009;Cohen, 2011). A recent study showed that inducing Theta over FCz by means of transcranial alternating current stimulation (tACS) resulted in modulation in behavioural adjustment after error execution (Fusco et al, 2018). More recently, Theta and Alpha synchronizations have also been detected during the observation of motor errors performed by an embodied avatar seen from a first-person perspective Spinelli et al, 2017;Pezzetta et al, 2018).…”

Modifications of cognitive performance in the stroop task following deep rTMS treatment course in OCD patients

“…PES is associated with increased theta activity over the medial prefrontal cortex (mPFC) [3], and PES of OCD patients was shown to be mainly driven by abnormally slow PC RTs rather than a failure to slow down after errors [1]. Notably, a recent study [4] has demonstrated that acute theta transcranial alternating current stimulation over the mPFC of healthy volunteers induced short-term reductions of PES without compromising post-error accuracy (PEA) in the Flanker task. Given the notion that the effects of stimulation may accumulate over repeated sessions [5], it is plausible that multiple stimulation sessions of the mPFC may induce long-term modifications to cognitive functions associated with error monitoring [5].…”