How the New Interacts With the Old? Hippocampal Processing During Memory Encoding of Creative Associations With Remote or Close Inherent Semantic Relatedness.

Creativity means the formation of novel and useful associations. Meanwhile, the role of the hippocampus in episodic memory and some forms of creative thinking has been identified, but it remains unclear how the hippocampus participates in the formation of memory for creative associations. In particular, considering creative associations are often formed on the basis of old ones, it is important to identify how the hippocampus and its associated neural network represent the interactions between the new and old associations during the encoding of creative associations. Thus, using the subsequent memory effect (SME) paradigm, the present study asked participants to learn a set of creative combinations (a common object paired with a creative alternate use, for example, basketball-buoy, which means a basketball is used as a buoy) during fMRI scanning. Moreover, we also quantified the degree of pre-existing semantic connections individually according to subjective ratings of inherent semantic relatedness between the objects and their alternate uses in the relatedness judgment task, resulting in a 2 (memory: remembered vs. forgotten) by 2 (semantic relatedness: remote vs. close) factorial design. Multivariate analysis revealed higher inter-item hippocampal pattern similarity for remembered relative to forgotten trials in both close relatedness and remote relatedness conditions, indicating that hippocampal representations become less separable supporting successful memory for creative associations. However, univariate analyses of the hippocampus and its neural network showed that enhanced hippocampal activation was associated with successful encoding in the remote relatedness but not close relatedness condition, whereas increased hippocampal functional connectivity with prefrontal and parietal cortices contributed to successful memory in the close relatedness but not remote relatedness condition. These observations suggest that hippocampal-dependent processes and distributed hippocampal network patterns selectively support successful memory for creative associations with either remote or close inherent semantic relatedness, which implies the interactions between pre-existing semantic connections and newly formed creative associations.