Using fMRI To Examine Brain Activity In Forgetting Memories Through Suppression And Substitution

Two neurologists used functional magnetic resonance imaging (fMRI) to examine the brain activity when volunteers attempt to forget memories by either blocking them out or recalling substitute memories.

Roland Benoit and Michael Anderson of the MRC Cognition and Brain Sciences Unit at the University of Cambridge found that these two mechanisms, substitution and suppression, are how the brain voluntary forget specific memories. This finding can lead to the development of treatments to improve disorders of memory control.

Functional Magnetic Resonance Imaging or functional MRI (fMRI) measures brain activity by detecting associated changes in blood flow. It is an imaging process that utilizes MRI technology used to study the brain and its process.

"This study is the first demonstration of two distinct mechanisms that cause such forgetting: one by shutting down the remembering system, and the other by facilitating the remembering system to occupy awareness with a substitute memory," says lead study author Benoit.

It has been known that individuals can voluntary block memories from awareness and that the brain systems involved in the process are identified. What is not revealed are the cognitive tactics that people use or the precise neural underpinnings which has its own distinct neural pathways that are opposite each other.

Video: Repression vs. Suppression

During memory suppression, a brain structure called dorsolateral prefrontal cortex inhibited activity in the hippocampus, a region critical for recalling past events. On the other hand, memory substitution was supported by caudal prefrontal cortex and midventrolateral prefrontal cortex—two regions involved in bringing specific memories into awareness in the presence of distracting memories.

"A better understanding of these mechanisms and how they break down may ultimately help understanding disorders that are characterized by a deficient regulation of memories, such as posttraumatic stress disorder," Benoit says. "Knowing that distinct processes contribute to forgetting may be helpful, because people may naturally be better at one approach or the other."

The study is published by Cell Press October 17 in the journal Neuron