d-cycloserine facilitates procedural learning but not declarative learning in healthy humans: A randomized controlled trial of the effect of d-cycloserine and valproic acid on overnight properties in the performance of non-emotional memory tasks

► d-cycloserine (DCS) and valproic acid (VPA) facilitate fear conditioned learning. ► We examined their effects on non-emotional (declarative and procedural) learning. ► A randomized, blind, 4-arm (placebo, DCS, VPA, combination) trial was performed. ► DCS administered once alone facilitated procedural learning. ► VPA suppressed DCS facilitation of procedural learning.