In order to prevent the mind becoming flooded with unwanted memories, a brain region determines when a person is about to think of an unwanted memory and then signals other regions to suppress it. The discovery was recently published in JNeurosci.
Preventing unwanted memories from coming to mind is an adaptive ability of humans. This ability relies on inhibitory control processes in the prefrontal cortex to modulate hippocampal retrieval processes. How and when reminders to unwelcome memories come to trigger prefrontal control mechanisms remains unknown.
Crespo García et al. measured participants’ brain activity with both EEG and fMRI while they completed a memory task. The participants memorised sets of words (ie, gate and train) and were asked to either recall a cue word’s pair (see gate, think about train) or only focus on the cue word (see gate, only think about gate). During proactive memory suppression, activity increased in the anterior cingulate cortex (ACC), a brain region involved in cognitive control, within the first 500 milliseconds of the task. The ACC relayed information to the dorsolateral prefrontal cortex (DLPFC), which then inhibited activity in the hippocampus, a key region for memory recall. The activity levels in the ACC and DLPFC remained low for the rest of the trial, a sign of success — the memory was stopped early enough so no more suppression was needed. If the memory was not suppressed in time, the ACC generated a reactive alarm, increasing its activity to signal to the DLPFC to stop the intrusion.
Source: EurekAlert!
