To update or to create? The influence of novelty and prior knowledge on memory networks

Abstract

Schemas are foundational mental structures shaped by experience. They influence behaviour, guide the encoding of new memories and are shaped by associated information. The adaptability of memory schemas facilitates the integration of new information that aligns with existing knowledge structures. First, we discuss how novel information consistent with an existing schema can be swiftly assimilated when presented. This cognitive updating is facilitated by the interaction between the hippocampus and the prefrontal cortex. Second, when novel information is inconsistent with the schema, it likely engages the hippocampus to encode the information as part of an episodic memory trace. Third, novelty may enhance hippocampal dopamine through either the locus coeruleus or ventral tegmental area pathways, with the pathway involved potentially depending on the type of novelty encountered. We propose a gradient theory of schema and novelty to elucidate the neural processes by which schema updating or novel memory traces are formed. It is likely that experiences vary along a familiarity-novelty continuum, and the degree to which new experiences are increasingly novel will guide whether memory for a new experience either integrates into an existing schema or prompts the creation of a new cognitive framework. This article is part of the theme issue 'Long-term potentiation: 50 years on'.

Keywords: hippocampus; medial prefrontal cortex; memory network; novelty; schemas.

Figure 1.

A gradient theory of schema and novelty. Events can be schema congruent and familiar (e.g. giving a lecture on your topic of expertise). Events may also be familiar by themselves but may occur in an incongruent context (e.g. giving a lecture on a farm). Although we may have very specific expectations with regard to familiar events, such prior knowledge typically lacks for novel events. To some extent, even novel events may be schema-congruent (e.g. getting unexpected questions during the middle of your talk) but can also be schema-incongruent (e.g. the very first time you give a lecture). Congruent information leads to assimilation in an existing schema. In contrast, incongruent information—either novel or familiar—may lead to updating of memories and in extreme cases may result in the creation of a new schema network.