The role of the hippocampus in memory and mental construction

Abstract

Much has been learned about the processes that support the remembrance of past autobiographical episodes and their importance for a number of cognitive tasks. This work has focused on hippocampal contributions to constructing coherent mental representations of scenarios for these tasks, which has opened up new questions about the underlying hippocampal mechanisms. We propose a new framework to answer these questions, which incorporates task demands that prompt hippocampal contributions to mental construction, the online formation of such mental representations, and how these demands relate to the functional organization of the hippocampus. Synthesizing findings from autobiographical memory research, our framework suggests that the interaction of two task characteristics influences the recruitment of the hippocampus: (1) the degree of task open-endedness (quantified by the presence/absence of a retrieval framework) and (2) the degree to which the integration of perceptual details is required. These characteristics inform the relative weighting of anterior and posterior hippocampal involvement, following an organizational model in which the anterior and posterior hippocampus support constructions on the basis of conceptual and perceptual representations, respectively. The anticipated outcome of our framework is a refined understanding of hippocampal contributions to memory and to the host of related cognitive functions.

Episodic future thinking: mechanisms and functions

“…These findings point toward a link between hippocampal activity and the construction of specific and detailed imaginary future episodes, which strengthen previous observations along similar lines (57–60). Other fMRI studies have linked hippocampal activity during imagining to the process of scene construction (61–62), encoding of episodic simulations into long-term memory (63), and detail recombination (64).…”

“…Thus questions concerning the precise role of the hippocampus in episodic future thinking continue to be debated, with the evidence suggesting that different subregions of the hippocampus make distinct contributions to particular subprocesses that comprise episodic future thinking and related phenomena (59–60, 62). …”

Imagining the future: The core episodic simulation network dissociates as a function of timecourse and the amount of simulated information

“…There are alternative proposals of hippocampal function that may also be compatible with the current hippocampal temporal dissociation (e.g., Sheldon & Levine, 2016; Zeidman, Mullally, & Maguire, 2016). Regardless of which proposal is correct, however, the current findings have implications for any theoretical proposal of hippocampal function during episodic simulation because they highlight the necessity of considering when hippocampal processes are engaged and not simply what processes are engaged.…”

Characterizing the role of the hippocampus during episodic simulation and encoding

“…We note that the model of Addis and Schacter () is not exhaustive in its ability to accommodate all hypothetical processes engaged during simulation. There are a number of theoretical models of hippocampal function during remembering and imagining that also specify anterior‐posterior dissociations (e.g., Sheldon & Levine, ; Zeidman & Maguire, ). Regardless of which model is correct, it is important to recognize the variety of hippocampal processes that support simulation and the possibility that in any given experiment these processes may be confounded (cf., Gaesser et al, ).…”