Modulating Cortico-cortical Networks with Transcranial Alternating Current Stimulation: A Minireview

Advancements in brain imaging and analytical methods have demonstrated that behavior arises from the coordinated activity of multiple brain regions within cortico-cortical networks. Transcranial alternating current stimulation (tACS), a noninvasive brain stimulation (NIBS) technique, applies weak sinusoidal alternating currents to specific brain regions using scalp-mounted electrodes. Traditionally, tACS has been used to target single brain regions to enhance functions such as motor, sensory, and cognitive abilities. However, recent findings indicate its potential for simultaneously stimulating 2 brain regions, thereby modulating cortico-cortical network strength through neural entrainment-where brain oscillations synchronize with external rhythmic stimuli. Despite this potential, tACS applications remain primarily focused on individual brain regions. Given that behavior stems from dynamic interactions within cortico-cortical networks rather than isolated regions, this minireview explores the role of these networks in shaping behavior through functional connectivity as identified by neuroimaging. It also provides an in-depth analysis of tACS as a tool for modifying cortico-cortical networks via neural entrainment, offering promising applications in neurorehabilitation for brain disorders linked to network dysfunction. This highlights tACS as a novel approach for targeted modulation of cortico-cortical networks, distinguishing it from traditional NIBS techniques.