Phase timing between acoustic and electric stimulation was the core experimental variable

Evidence

The critical parameter was the relative timing of acoustic and electric stimulation (Fig. 1a ). This phase lag was manipulated across six conditions by varying the onset of the target in steps of 41.7 ms (30°) across the 4-Hz tACS cycles. — Dijk, Pim van, Physiology, Psychoacoustics and…, 4785

Categorization

• QUESTION: What physiological mechanism makes the relative phase between a 4-Hz current and a 4-Hz click train matter? TACS phase effects likely ride on neural oscillation entrainment but the causal chain is unclear.