Bifocal Transcranial Alternating Current Stimulation Targeting the Frontoparietal Network in Stroke Patients

21 minutes and 30 seconds of bifocal stimulation at 3 mA peak-to-peak per field, targeting the aIPS and PMv of the lesioned hemisphere. The stimulation is delivered at 24 Hz with the waveforms of both fields aligned in phase. A 10-second ramp-up at the beginning and a 10-second ramp-down at the end are included to ensure participant comfort. The protocol is administered using the Starstim® device with gel-based electrodes, each with a π cm² surface area.

21 minutes and 30 seconds of bifocal stimulation at 3 mA peak-to-peak per field over the aIPS and PMv of the lesioned hemisphere at 24 Hz. In this condition, the waveforms of the two fields are shifted by 180°, creating an out-of-phase stimulation pattern. A 10-second ramp-up and ramp-down are included, and the protocol is administered using the Starstim® device with gel-based electrodes, each with a π cm² surface area.

21 minutes and 30 seconds of stimulation mimicking the setup of active tACS, with an initial 10-second ramp-up followed by a 10-second ramp-down. The remainder of the session is stimulation-free. This protocol is administered using the Starstim® device and gel-based electrodes with a π cm² surface area, maintaining the same setup as the active conditions to ensure comparability.