Figure 1.

(A) Serial reaction time task (SRTT)–Presentation of the eight-digit SRTT in four target locations on the screen requiring participants to react with the first four fingers of the right hand on the response button box. From left to right: blank, thumb, middle, ring, index finger. (B) The SRTT was divided into identical trials prior to and immediately after 10 min tACS/tDCS at rest. Each trial was subdivided into a random (R) and sequential (S) condition. Selected sequences for data analysis are highlighted: baseline (T1; pre S₂, R₂), end of acquisition (T2; pre S₁₀, R₁₀), retrieval (T3; post S₂, R₂), reacquisition (T4; post S₁₀, R₁₀).