Targeting the neurophysiology of cognitive systems with transcranial alternating current stimulation

Abstract

Cognitive impairment represents one of the most debilitating and most difficult symptom to treat of many psychiatric illnesses. Human neurophysiology studies have suggested that specific pathologies of cortical network activity correlate with cognitive impairment. However, we lack demonstration of causal relationships between specific network activity patterns and cognitive capabilities and treatment modalities that directly target impaired network dynamics of cognition. Transcranial alternating current stimulation (tACS), a novel non-invasive brain stimulation approach, may provide a crucial tool to tackle these challenges. Here, we propose that tACS can be used to elucidate the causal role of cortical synchronization in cognition and, eventually, to enhance pathologically weakened synchrony that may underlie cognitive deficits. To accelerate such development of tACS as a treatment for cognitive deficits, we discuss studies on tACS and cognition performed in healthy participants, according to the Research Domain Criteria of the National Institute of Mental Health.

Keywords: RDoC; Research Domain Criteria project; cognitive symptoms; cortex; non-invasive brain stimulation; non-pharmacological treatments; oscillations; psychiatric illness; tACS; transcranial alternating current stimulation.

Figure 1

Transcranial alternating current stimulation (tACS) applies a weak sine-wave electric field to the scalp. (A) As demonstrated in vitro, weak sine-waves with different periods (T) entrain action potential firing. Top: no EF applied, middle: T = 13.3 seconds, bottom: T = 10.0 seconds. Adapted from [3], reprinted with permission. (B) TACS delivers sine-wave electrical current of differing frequencies and phase-alignment (phase denoted on the far left).

Figure 2

The Research Domain Criteria project (RDoC) is an initiative by the NIMH to classify psychopathology based on dimensions of observable behavior and neurobiological measures. The project includes five domains (shown in bolded black boxes), each of which contains constructs. In this review, we focus on the six constructs of the Cognitive Systems domain [41].