Targeting Language-specific and Executive-control Networks With Transcranial Direct Current Stimulation in Logopenic Variant PPA

"Device: Active HD-tDCS \& Repeat After Me (RAM) Treatment~Stimulation will be delivered by a battery-driven constant current stimulator. Electrical current will be administered to left supramarginal gyrus (L\_SMG). The stimulation will be delivered at an intensity of 2 milliamperes (mA) (estimated current density 0.04 mA/cm2; estimated total charge 0.048 Coulombs/cm2) in a ramp-like fashion for a maximum of 20 minutes.~Participants will receive RAM consisting of word span repetition span (increasing length, with/without response delay). Span tasks will be manipulated in terms of list length (single words, pair, triplets) and response delay (1 sec, 5 sec). Each list will consist of 10 spans. During each trial, participants will be asked to repeat words in the span after a response delay."

"Device: Sham Current will be administered in a ramp-like fashion but after the ramping phase the intensity will drop to 0 mA. Current under the Sham condition will last for a maximum of 30 seconds.~Participants will receive RAM consisting of word span repetition span (increasing length, with/without response delay). Span tasks will be manipulated in terms of list length (single words, pair, triplets) and response delay (1 sec, 5 sec). Each list will consist of 10 spans. During each trial, participants will be asked to repeat words in the span after a response delay."