High‐definition transcranial direct current stimulation dissociates fronto‐visual theta lateralization during visual selective attention

Abstract

Key points Visual attention involves discrete multispectral oscillatory responses in visual and ‘higher‐order’ prefrontal cortices. Prefrontal cortex laterality effects during visual selective attention are poorly characterized. High‐definition transcranial direct current stimulation dynamically modulated right‐lateralized fronto‐visual theta oscillations compared to those observed in left fronto‐visual pathways. Increased connectivity in right fronto‐visual networks after stimulation of the left dorsolateral prefrontal cortex resulted in faster task performance in the context of distractors. Our findings show clear laterality effects in theta oscillatory activity along prefrontal–visual cortical pathways during visual selective attention. Abstract Studies of visual attention have implicated oscillatory activity in the recognition, protection and temporal organization of attended representations in visual cortices. These studies have also shown that higher‐order regions such as the prefrontal cortex are critical to attentional processing, but far less is understood regarding prefrontal laterality differences in attention processing. To examine this, we selectively applied high‐definition transcranial direct current stimulation (HD‐tDCS) to the left or right dorsolateral prefrontal cortex (DLPFC). We predicted that HD‐tDCS of the left versus right prefrontal cortex would differentially modulate performance on a visual selective attention task, and alter the underlying oscillatory network dynamics. Our randomized crossover design included 27 healthy adults that underwent three separate sessions of HD‐tDCS (sham, left DLPFC and right DLPFC) for 20 min. Following stimulation, participants completed an attention protocol during magnetoencephalography. The resulting oscillatory dynamics were imaged using beamforming, and peak task‐related neural activity was subjected to dynamic functional connectivity analyses to evaluate the impact of stimulation site (i.e. left and right DLPFC) on neural interactions. Our results indicated that HD‐tDCS over the left DLPFC differentially modulated right fronto‐visual functional connectivity within the theta band compared to HD‐tDCS of the right DLPFC and further, specifically modulated the oscillatory response for detecting targets among an array of distractors. Importantly, these findings provide network‐specific insight into the complex oscillatory mechanisms serving visual selective attention.

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“…While the left DLPFC works in an impulsive short-term mode, the right DLPFC seems to have a slower and less impulsive timing of its activity (Seikel, 2018). Transcranial direct current stimulation (TDCS) studies considering attention aspects suggest that left DLPFC controls selective (visual) attention by modulating frontooccipital connectivity in the theta band (Spooner et al, 2020) whereas right DLPFC seems to be involved in the management of error awareness (Harty et al, 2014). In line with the findings that the left DLPFC serves attentional focusing, asymmetrical tDCS stimulation over the DLPFC showed that craving for chocolate, after left anodal/right cathodal stimulation (enhancing left and dampening right hemisphere activity), was increased, in contrast to sham stimulation or the opposite polarity pattern (Carvalho et al, 2019).…”

High‐definition transcranial direct current stimulation modulates performance and alpha/beta parieto‐frontal connectivity serving fluid intelligence

“…2020), and selective attention (Spooner et al . 2020). Herein, we investigate the effects of such stimulation on the dynamic functional connectivity that serves Gƒ.…”

“…2000; Spooner et al . 2020), we hypothesized that right DLPFC stimulation would have a greater impact on the neural networks underlying logical reasoning.…”

Individual differences in amygdala volumes predict changes in functional connectivity between subcortical and cognitive control networks throughout adolescence

“…Despite being assessed at rest, many of the identified networks are implicated in cognitive, emotional, and sensorimotor functioning during tasks ( Dwyer et al, 2014 ; Marek et al, 2015 ; Rosazza and Minati, 2011 ). For example, a commonly identified “cognitive control” network is comprised of structures spanning mainly frontal and parietal regions, which are commonly active during tasks requiring attentional control, emotional control, and high-level reasoning ( Agcaoglu et al, 2019 ; Heller et al, 2016 ; Jung and Haier, 2007 ; Petersen and Posner, 2012 ; Spooner et al, 2019 ; Taylor et al, 2021 , 2020 ). Likewise, the “subcortical” network, although somewhat more ambiguously named with respect to function, is commonly implicated in a wide array of abilities like emotional control and reward processing ( Agcaoglu et al, 2019 ; Cerliani et al, 2015 ; Gabard-Durnam et al, 2014 ; Heller et al, 2016 ).…”