Voluntary Suppression and Involuntary Repression: Brain Mechanisms for Forgetting Unpleasant Memories

Abstract

The present chapter reviews the current accomplishments regarding investigations of the brain mechanisms that underlie active inhibitory control processes in mnemonic processing. We focus on both voluntary and involuntary inhibitory processes, namely, the suppression and repression of memory. The results from studies on voluntary memory suppression in healthy participants indicate that individuals may deteriorate or disrupt the encoding and retrieval of an unwanted memory by voluntary suppression. The neural basis of memory suppression comprises the activated dorsolateral prefrontal cortex, which operates as an inhibitor of the medial temporal lobe (MTL), and the deactivated MTL memory system, which enables motivated forgetting. The results from studies of involuntary memory repression in patients with dissociative amnesia indicate two potential brain mechanisms: “hyper-suppression” and “hypo-retrieval.” The former appears to share a similar neural basis with voluntary suppression, in which interactions between prefrontal cortex activation and MTL deactivation are closely linked to memory impairment. In the latter, baseline activity in the regions responsible for the initiation of memory retrieval is decreased. A recently proposed model attempts to reconcile these two ideas. These lines of investigation have significant implications for understanding how our memory system may be controlled by active forgetting processes through interactions between specific brain areas.