The development of spatiotemporal organization of episodic memory in children and its disruption in Williams Syndrome

Abstract

Theories of hippocampal function have proposed that spatiotemporal representations provide a scaffold upon which episodic memories are built. If this is true, does the developmental emergence of adult-like episodic memory in children depend on the successful binding of space with time? To address this question, we report results from two studies aimed at revealing the developmental changes in episodic memory and the specific role of spatiotemporal binding in that process. Study 1 investigated the cognitive mechanisms underlying normal developmental changes in episodic memory across 2-to-8 years of age using an object-hiding game dissociating the content ("what") of memories from their spatial ("where") and temporal ("when") contexts. Study 2 investigated the same episodic memory binding processes in Williams Syndrome patients, who exhibit spatial impairments attributed to their abnormal hippocampal development. Our results indicate that, indeed, the successful binding spatial and temporal memory components emerges first in typical development and is impaired in Williams Syndrome. Furthermore, we found that space-time memory binding not only precedes but also predicts the emergence of episodic memory ability. Finally, an analysis of the separate components of episodic memory suggests that the association of objects to spatial location may play a mediating role in the development of successful episodic memory. Importantly, these effects are not explained by improvements in object or location memory. We interpret these findings to indicate that the ontogenetic origins of episodic memories depend on spatiotemporally organization of memories and that such representations rely, at least in part, on normal hippocampal development and function.