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Transcranial stimulation of alpha oscillations up-regulates the default mode network

K. Clancy, Jeremy A. Andrzejewski, Yuqi You, J. Rosenberg, M. Ding, Wen Li

Proceedings of the National Academy of Sciences June 11, 2021 DOI: 10.1073/pnas.2110868119 (opens in new tab)

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Study at a glance

AI-extracted from the abstract
Characteristics Randomized controlled trial Peer reviewed
Population Healthy adults
Intervention high-definition alpha-frequency transcranial alternating current stimulation (α-tACS)
Topics Default mode network
Key findings α-tACS augmented EEG alpha oscillations and strengthened fMRI and source-level alpha connectivity within the core of the DMN, with alpha increase mediating DMN connectivity enhancement.

Abstract

Significance In the brain’s functional organization, the default mode network (DMN) represents a key architecture, whose dysregulation is involved in a host of major neuropsychiatric disorders. However, insights into the regulation of the DMN remain scarce. Through neural synchrony, the alpha-frequency oscillation represents another key underpinning of the brain’s organization and is thought to share an inherent interdependence with the DMN. Here, we demonstrated that transcranial alternating current stimulation of alpha oscillations (α-tACS) not only augmented alpha activity but also strengthened connectivity of the DMN, with the former serving as a mediator of the latter. These findings reveal that alpha oscillations can support DMN functioning. In addition, they identify an effective noninvasive approach to regulate the DMN via α-tACS. The default mode network (DMN) is the most-prominent intrinsic connectivity network, serving as a key architecture of the brain’s functional organization. Conversely, dysregulated DMN is characteristic of major neuropsychiatric disorders. However, the field still lacks mechanistic insights into the regulation of the DMN and effective interventions for DMN dysregulation. The current study approached this problem by manipulating neural synchrony, particularly alpha (8 to 12 Hz) oscillations, a dominant intrinsic oscillatory activity that has been increasingly associated with the DMN in both function and physiology. Using high-definition alpha-frequency transcranial alternating current stimulation (α-tACS) to stimulate the cortical source of alpha oscillations, in combination with simultaneous electroencephalography and functional MRI (EEG-fMRI), we demonstrated that α-tACS (versus Sham control) not only augmented EEG alpha oscillations but also strengthened fMRI and (source-level) alpha connectivity within the core of the DMN. Importantly, increase in alpha oscillations mediated the DMN connectivity enhancement. These findings thus identify a mechanistic link between alpha oscillations and DMN functioning. That transcranial alpha modulation can up-regulate the DMN further highlights an effective noninvasive intervention to normalize DMN functioning in various disorders.

Comparable studies

Other randomized controlled trials on default mode network, most cited first.

Study Year Design Participants
Neural correlates of the psychedelic state as determined by fMRI studies with psilocybin Healthy volunteers 2012 Within-subjects, placebo-controlled, task-free fMRI study n = 30
The effects of psilocybin and MDMA on between-network resting state functional connectivity in healthy volunteers 2014 Placebo-controlled study
Ketamine Decreases Resting State Functional Network Connectivity in Healthy Subjects: Implications for Antidepressant Drug Action Healthy subjects 2012 Randomized, placebo-controlled, double-blind, crossover rsfMRI challenge
Antidepressants Normalize the Default Mode Network in Patients With Dysthymia Subjects with dysthymic disorder and healthy control participants aged 18 to 53 years 2013 Randomized controlled trial n = 41
Functional Connectivity Measures After Psilocybin Inform a Novel Hypothesis of Early Psychosis Healthy volunteers 2012 Within-subject, placebo-controlled experimental study n = 15

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