Characterizing the role of the hippocampus during episodic simulation and encoding

Abstract

The hippocampus has been consistently associated with episodic simulation (i.e., the mental construction of a possible future episode). In a recent study, we identified an anterior-posterior temporal dissociation within the hippocampus during simulation. Specifically, transient simulation-related activity occurred in relatively posterior portions of the hippocampus and sustained activity occurred in anterior portions. In line with previous theoretical proposals of hippocampal function during simulation, the posterior hippocampal activity was interpreted as reflecting a transient retrieval process for the episodic details necessary to construct an episode. In contrast, the sustained anterior hippocampal activity was interpreted as reflecting the continual recruitment of encoding and/or relational processing associated with a simulation. In the present study, we provide a direct test of these interpretations by conducting a subsequent memory analysis of our previously published data to assess whether successful encoding during episodic simulation is associated with the anterior hippocampus. Analyses revealed a subsequent memory effect (i.e., later remembered > later forgotten simulations) in the anterior hippocampus. The subsequent memory effect was transient and not sustained. Taken together, the current findings provide further support for a component process model of hippocampal function during simulation. That is, unique regions of the hippocampus support dissociable processes during simulation, which include the transient retrieval of episodic information, the sustained binding of such information into a coherent episode, and the transient encoding of that episode for later retrieval.

Verbal Paired Associates and the Hippocampus: The Role of Scenes

“…The relational theory suggests that the hippocampus makes associations between any elements, regardless of whether or not space or scenes are involved (Konkel & Cohen, 2009; Cohen & Eichenbaum, 1993). This generic associative process could account for the creation of an association between two unrelated words in the VPA task, while also explaining the involvement of the hippocampus in visuospatial tasks and the combining of individual elements into a coherent memory or the recombination of different elements from past experiences to simulate the future (Roberts, Schacter, & Addis, 2018; St. Jacques, Carpenter, Szpunar & Schacter, 2018; Thakral, Benoit, & Schacter, 2017; Moscovitch, Cabeza, Winocur, & Nadel, 2016; Schacter et al, 2012). However, a purely associative account of hippocampal function is not completely satisfactory, given that patients with hippocampal damage retain an ability to form associations in some circumstances.…”

Verbal paired associates and the hippocampus: The role of scenes

“…This generic associative process could account for the creation of an association between two unrelated words in the VPA task, while also explaining the involvement of the hippocampus in visuospatial tasks, and the combining of individual elements into a coherent memory, or the recombination of different elements from past experiences to simulate the future (Moscovitch, Cabeza, Winocur, & Nadel, 2016;Roberts, Schacter, & Addis, 2017;Schacter et al, 2012;St. Jacques, Carpenter, Szpunar, & Schacter, 2018;Thakral, Benoit, & Schacter, 2017).…”

Identifying the cognitive processes underpinning hippocampal-dependent tasks.

“…In this regard, the autobiographical memory system is equally well equipped to imagine future or atemporal events as well as recalling the past (see also St. Jacques, Carpenter, Szpunar, & Schacter, 2018; Thakral, Benoit, & Schacter, 2017).…”