Neural NoiseTranscranial alternating current stimulation (tACS) applies sinusoidal electrical currents to the scalp at specific frequencies, with the goal of entraining endogenous brain oscillations. By delivering stimulation at frequencies matching intrinsic neural rhythms — such as alpha (8-12 Hz), beta (13-30 Hz), or gamma (30-100 Hz) — tACS aims to enhance or modulate the amplitude and phase of oscillatory brain activity.
The theoretical basis for tACS rests on the role of neural oscillations in coordinating information processing across brain networks. Research has explored tACS effects on perception, attention, memory, and motor control, with frequency-specific modulation of cognitive functions. For example, gamma-frequency tACS has been investigated as a potential intervention for Alzheimer’s disease, while alpha-frequency stimulation has been studied in the context of pain and visual perception.
Key methodological challenges include the difficulty of measuring oscillatory entrainment during stimulation due to electrical artifacts, individual variability in skull and cortical anatomy affecting current distribution, and the need for better understanding of dose-response relationships. Advances in multi-electrode tACS montages and closed-loop designs that adapt stimulation parameters to the brain’s ongoing oscillatory state represent the frontier of this stimulation-and-neuromodulation approach.