Insight Reconfigures Hippocampal-Prefrontal Memories

Abstract

Our memories are remarkably dynamic and allow us to reinterpret the past once new information comes to light. Gaining novel insights can lead to mental reorganization of previously unrelated events, thus linking them into narratives. The hippocampus and medial prefrontal cortex (mPFC) support integration of partially overlapping events, but the neural mechanisms underlying the reorganization of memories for the formation of coherent narratives remain elusive. Here, we combine fMRI with The Sims 3 videos of life-like animated events, which could either be integrated into narratives or not. We show that insight triggers the emergence of de novo mnemonic representations of the narratives and is associated with increased neural similarity between linked event representations in the posterior hippocampus, mPFC, and autobiographical-memory network. Simultaneously, events irrelevant to the newly established memory of the narrative were pruned out. This process was accompanied by increased neural dissimilarity between non-linked event representations in the posterior hippocampus and mPFC and was additionally signaled by a mismatch response in the anterior hippocampus. Our results demonstrate that insight leads to neural reconfiguration of representational networks within a memory space and have implications for knowledge acquisition in educational settings.

Still searching for the engram

“…Consistent with these findings on rodents, several fMRI studies have shown that the hippocampus is engaged as related memories are assimilated and integrated to support novel transitive inferences in humans (Heckers et al, 2004; Preston et al, 2004; Zalesak & Heckers, 2009; Kumaran et al, 2009; Zeithmova & Preston, 2010, 2012; Milivojevic et al, 2015). Notably, these roles in organizing memories extend to a range of non-spatial tasks including learning a hierarchical organization (Piaget’s transitive inference task) and associative organizations (the associative inference task and acquired equivalence; Shohamy & Wagner, 2008; Wimmer & Shohamy, 2012; see Zeithamova et al, 2012; Milivojevic et al, 2015). …”

Grid-cell representations in mental simulation

“…Even though this appears unlikely due to the sampling of each direction from multiple locations (Figure 1—figure supplement 2) we compared the visual similarity of the scenes to be imagined based on a set of visual features (Milivojevic et al, 2015). For each trial, the view from the start position facing the direction of the target building was captured at a resolution of 1024 × 768 pixels.…”

What Learning Systems do Intelligent Agents Need? Complementary Learning Systems Theory Updated

“…The paired associate inference (PAI) task [91,[96][97][98] provides an example of a task that involves the hippocampus and captures the essence of requiring cross-item inferences required in other relevant tasks (such as the transitive inference task reviewed in [4]). In the study phase of the PAI task, subjects view pairs of objects (e.g., AB, BC) that are derived from triplets (i.e., ABC) or larger object sets (e.g., sextets: A, B, C, D, E, F; Box 6).…”

“…In the crucial test trials, subjects are tested on their ability to appreciate the indirect relationships between items that were never presented together (e.g., A and F in the sextet version). Evidence for a role of the hippocampus in supporting inference in such settings [91,92,[96][97][98] naturally raises the question of the neural mechanisms underlying this function, and has been seen as challenging the view that the hippocampus only stores separate representations of specific items or experiences. Indeed, the findings have been taken as supporting 'encoding-based overlap' models [4,95,99,100], in which it is proposed that the hippocampus supports inference by using representations that integrate or combine overlapping pairs of items (e.g., AB and BC in the triplet version of the PAI task).…”