Neural reactivation in parietal cortex enhances memory for episodically linked information

By Tanya R. Jonker, H. Dimsdale-Zucker, Maureen Ritchey, Alex Clarke, Charan Ranganath. 2018

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Significance Recalling information is useful for more than just accessing memories; it is also a powerful way to enhance long-term memory. Using brain imaging, we discovered that, when trying to remember, people reactivate the specific information they are searching for, along with other information from the same event. The results demonstrate that memories of the past are organized in terms of integrated events and the act of recalling even a small part of an event engages brain networks that have powerful effects on the ability to retain information from the entire event. Remembering is a complex process that involves recalling specific details, such as who you were with when you celebrated your last birthday, as well as contextual information, such as the place where you celebrated. It is well established that the act of remembering enhances long-term retention of the retrieved information, but the neural and cognitive mechanisms that drive memory enhancement are not yet understood. One possibility is that the process of remembering results in reactivation of the broader episodic context. Consistent with this idea, in two experiments, we found that multiple retrieval attempts enhanced long-term retention of both the retrieved object and the nontarget object that shared scene context, compared with a restudy control. Using representational similarity analysis of fMRI data in experiment 2, we found that retrieval resulted in greater neural reactivation of both the target objects and contextually linked objects compared with restudy. Furthermore, this reactivation occurred in a network of medial and lateral parietal lobe regions that have been linked to episodic recollection. The results demonstrate that retrieving a memory can enhance retention of information that is linked in the broader event context and the hippocampus and a posterior medial network of parietal cortical areas (also known as the Default Network) play complementary roles in supporting the reactivation of episodically linked information during retrieval.

Subfields: Cognitive Neuroscience