Memory extinction, defined as a decrease of a conditioned response as a function of a non-reinforced conditioned stimulus presentation, has high biological and clinical relevance. Extinction is not a passive reversing or erasing of the plasticity associated with acquisition, but a novel, active learning process. Nifedipine blocks L-type voltage…

Extinction of classically conditioned fear, like its acquisition, is active learning, but little is known about its molecular mechanisms. We recently reported that temporal massing of conditional stimulus (CS) presentations improves extinction memory acquisition, and suggested that temporal spacing was less effective because individual CS…