Memory integration constructs maps of space, time, and concepts

Abstract

Recent evidence demonstrates that new events are learned in the context of their relationships to existing memories. Within the hippocampus and medial prefrontal cortex, related memories are represented by integrated codes that connect events experienced at different times and places. Integrated codes form the basis of spatial, temporal, and conceptual maps of experience. These maps represent information that goes beyond direct experience and support generalization behaviors that require knowledge be used in new ways. The degree to which an individual memory is integrated into a coherent map is determined by its spatial, temporal, and conceptual proximity to existing knowledge. Integration is observed over a wide range of scales, suggesting that memories contain information about both broad and fine-grained contexts.

SAMPL: The Spreading Activation and Memory PLasticity Model

“…Neuroimaging studies often use representational similarity between two items as a proxy for the strength of association between those items [37][38][39][40][41][42] . For instance, say item A is retrieved and the subsequent spread of activation reaches a distal item G. A region with a large associative scale may show a high activation of G representations, in which case a non-monotonic plasticity update rule would increase the similarity between the representations of A and G. This is known as integration 4,14,40,[43][44][45][46] , generalization, or overlap 47 . Generalization can occur over short time-scales (during the experiment) and long time scales (after overnight consolidation).…”

Rapid improvement of cognitive maps in the awake state

“…The ability to navigate flexibly depends on the formation of accurate cognitive maps—flexible mental representations of the spatial relationships between objects in the world that can be accessed from any perspective and vantage point. These observer‐independent mental representations are formed via the integration of new memories pertaining to a novel spatial experience (for review see: Morton, Sherrill, & Preston, ; Wolbers & Wiener, ). In our recent human behavioral work we revealed that, when probed at a delayed stage, a cognitive map of a navigated virtual environment is more accurate if participants experience awake quiescence for several minutes after being trained on a novel route than if they engage in an unrelated perceptual task in the minutes after route training (Craig, Dewar, Harris, Della Sala, & Wolbers, ; Craig, Wolbers, et al, ).…”

“…spective and vantage point. These observer-independent mental representations are formed via the integration of new memories pertaining to a novel spatial experience (for review see: Morton, Sherrill, & Preston, 2017;Wolbers & Wiener, 2014). In our recent human behavioral work we revealed that, when probed at a delayed stage, a cognitive map of a navigated virtual environment is more accurate if participants experience awake quiescence for several minutes after being trained on a novel route than if they engage in an unrelated perceptual task in the minutes after route training .…”

Representation of Task Structure in Human Hippocampus and Orbitofrontal Cortex

“…A hippocampal schema might also be useful to apply to specific items encountered across overlapping experiences, such as a specific kind of candy bar. This idea is supported by findings showing that the hippocampus organizes experiences with overlapping features to form schema-like knowledge representation and more broadly, with studies indicating that the hippocampus integrates new experiences with overlapping memories for past experiences (Mack, Love, & Preston, 2018;Morton, Sherrill, & Preston, 2017). Another possibility is that the hippocampus maps experiences in a manner that is both flexible (Eichenbaum, 2017;Ekstrom & Ranganath, 2018;Schiller et al, 2015) and goal-directed Duncan et al, 2018;Santoro et al, 2016).…”