Hard real-time closed-loop electrophysiology with the Real-Time eXperiment Interface (RTXI)
Fig 8
Optimization of therapeutic benefit of tACS via closed-loop EEG feedback-controlled tACS.
(A) Hard real-time closed-loop protocol used for feedback-controlled delivery of tACS. EEG are measured and amplified prior to sampling with RTXI while the subject opens and closes their eyes every 30 seconds. EEG data from international 10–20 system sites O2, A1, and A2 are processed in hard RT using a custom module written to measure the alpha band power within a one second window. The computed power is validated against a threshold criteria, which determines the tACS amplitude to be delivered. The output from RTXI is connected to an external current-controlled stimulation and isolation unit. Sample alpha-filtered EEG traces with and without feedback-controlled tACS are shown in (B). Feedback-controlled tACS (C) almost completely suppressed alpha band power in a targeted way (Ratio ECα to EOα = 1.03, p = 0.041). Dose-matched random tACS (D) also suppressed alpha band power (normalized random-No Stim = −0.31, p = 0.0183), but was less effective than feedback-controlled tACS (normalized feedbackα—randomα = −0.10, p = 0.0145). All figures obtained and modified with permission from [14].