Frequency-specific and state-dependent neural responses to brain stimulation.

Non-invasive brain stimulation is promising for treating many neuropsychiatric and neurological conditions. It could be optimized by understanding its intracranial responses in different brain regions. We implanted multi-site intracranial electrodes and systematically assessed the acute responses in these regions to transcranial alternating current stimulation (tACS) at different frequencies. We observed robust neural oscillation changes in the hippocampus and amygdala in response to non-invasive tACS procedures, and these effects were frequency-specific and state-dependent. Notably, the hippocampus responded most strongly and stably to 10 Hz stimulation, with pronounced changes across a wide frequency range, suggesting the potential of 10 Hz oscillatory stimulation to modulate a broad range of neural activity related to cognitive functions. Future work with increased sample sizes is required to determine the clinical implications of these findings for therapeutic efficiency.