Described is a system for weakening an undesirable memory. The system initiates application of a first pattern of spatiotemporally distributed transcranial stimulation via a set of electrodes to a subject who is in a calm mental state, causing association of the first pattern of spatiotemporally distributed transcranial stimulation with the calm mental state. The system then initiates application of the first pattern of spatiotemporally distributed transcranial stimulation via the set of electrodes when the undesirable memory is recalled by the subject, causing recall of the calm mental state and reconsolidation of the undesirable memory with the calm mental state.