Multielectrode Transcranial Electrical Stimulation of the Left and Right Prefrontal Cortices Differentially Impacts Verbal Working Memory Neural Circuitry

Abstract

Recent studies have examined the effects of conventional transcranial direct current stimulation (tDCS) on working memory (WM) performance, but this method has relatively low spatial precision and generally involves a reference electrode that complicates interpretation. Herein, we report a repeated-measures crossover study of 25 healthy adults who underwent multielectrode tDCS of the left dorsolateral prefrontal cortex (DLPFC), right DLPFC, or sham in 3 separate visits. Shortly after each stimulation session, participants performed a verbal WM (VWM) task during magnetoencephalography, and the resulting data were examined in the time–frequency domain and imaged using a beamformer. We found that after left DLPFC stimulation, participants exhibited stronger responses across a network of left-lateralized cortical areas, including the supramarginal gyrus, prefrontal cortex, inferior frontal gyrus, and cuneus, as well as the right hemispheric homologues of these regions. Importantly, these effects were specific to the alpha-band, which has been previously implicated in VWM processing. Although stimulation condition did not significantly affect performance, stepwise regression revealed a relationship between reaction time and response amplitude in the left precuneus and supramarginal gyrus. These findings suggest that multielectrode tDCS targeting the left DLPFC affects the neural dynamics underlying offline VWM processing, including utilization of a more extensive bilateral cortical network.

Transcutaneous Auricular Vagus Nerve Stimulation Improves Spatial Working Memory in Healthy Young Adults

“…At present, non-invasive brain stimulation techniques, such as transcranial direct current stimulation (tDCS; Andrews et al, 2011 ; Arkan, 2019 ; Živanović et al, 2021 ), transcranial alternating current stimulation (tACS; Ermolova et al, 2019 ; Benussi et al, 2021 ), and transcranial magnetic stimulation (TMS; Chen et al, 2015 ; Hulst et al, 2017 ), have become one of the mainstream clinical treatment approaches to moderate the WM because of their potential, convenience, and safety. Although some of previous studies have demonstrated the availability of transcranial current stimulation on modulating WM by altering the activity of neurons through changing the resting membrane potential of neurons ( Bindman et al, 1962 ; Nitsche and Paulus, 2000 ), some recent studies found limited positive effects of tDCS on WM accuracy with a minor reaction time enhancement in healthy cohorts (e.g., Koshy et al, 2020 ; Shires et al, 2020 ; for meta-analysis, see Hill et al, 2016 ; Medina and Cason, 2017 ). Indeed, the effect of tDCS on WM heavily relies on the stimulation form (online/offline), stimulation duration, current density, and stimulation area (right or left dorsolateral/ventral lateral prefrontal cortex, posterior parietal cortex, or premotor cortex, etc.…”

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

“…By comparison, so-called high-definition tDCS (HD-tDCS) uses metal electrodes and when applied using the 4 × 1 ring montage is thought to provide more focal and longer-lasting effects (Datta et al 2008(Datta et al , 2009Edwards et al 2013;Kuo et al 2013). Our laboratory has leveraged this attribute of HD-tDCS in several recent studies and demonstrated specific effects on multiple cognitive domains, including visuospatial attention (Arif et al 2020), verbal working memory (Koshy et al 2020), and selective attention (Spooner et al 2020). Herein, we investigate the effects of such stimulation on the dynamic functional connectivity that serves Gƒ.…”

Disrupted Regional Cerebral Blood Flow and Functional Connectivity in Pontine Infarction: A Longitudinal MRI Study

“…These FC changes showed a similar trend, gradually decreasing to a minimum at 3 months and then increasing thereafter. Several previous studies have investigated the neural bases of verbal memory and have demonstrated that the left-lateralized frontoparietal network, superior temporal and occipital lobe cortices, and cerebellum are involved in the verbal memory process and that the left SMG is one of the key regions (Emch et al, 2019;Koshy et al, 2019). Impaired verbal memory after disease may lead to functional and structural changes in the homologous brain regions to maintain processing.…”