Medial temporal lobe contributions to cued retrieval of items and contexts

Abstract

Several models have proposed that different regions of the medial temporal lobes contribute to different aspects of episodic memory. For instance, according to one view, the perirhinal cortex represents specific items, parahippocampal cortex represents information regarding the context in which these items were encountered, and the hippocampus represents item-context bindings. Here, we used event-related functional magnetic resonance imaging (fMRI) to test a specific prediction of this model – namely, that successful retrieval of items from context cues will elicit perirhinal recruitment and that successful retrieval of contexts from item cues will elicit parahippocampal cortex recruitment. Retrieval of the bound representation in either case was expected to elicit hippocampal engagement. To test these predictions, we had participants study several item-context pairs (i.e., pictures of objects and scenes, respectively), and then had them attempt to recall items from associated context cues and contexts from associated item cues during a scanned retrieval session. Results based on both univariate and multivariate analyses confirmed a role for hippocampus in content-general relational memory retrieval, and a role for parahippocampal cortex in successful retrieval of contexts from item cues. However, we also found that activity differences in perirhinal cortex were correlated with successful cued recall for both items and contexts. These findings provide partial support for the above predictions and are discussed with respect to several models of medial temporal lobe function.

Dissociable neural correlates of item and context retrieval in the medial temporal lobes

“…Our results also accord with previous studies demonstrating that PHC activity is sensitive to memory tests wherein objects (i.e., items) are used to cue the retrieval of an associated scene (i.e., context) (Hannula, Libby, Yonelinas, & Ranganath, 2013; Staresina, Henson, Kriegeskorte, & Alink, 2012). Additionally, PHc activity is also sensitive to non-spatial contextual features, such as items that contain strong associations with particular situational (Bar & Aminoff, 2003; Bar, Aminoff, Ishai, 2008; Bar, Aminoff, & Schacter, 2008), temporal (Jenkins & Ranganath, 2010; Tubridy & Davachi, 2011), categorical (Diana, Yonelinas, & Ranganath, 2008), and semantic (Diana et al, 2012) contexts.…”

“…In addition to differentiating the roles of PRc and PHc in item and context processing, the current results add to support the idea that PRc activity is not simply related to item familiarity, but that it can also support the recollection of item details (Diana et al, 2010; Hannula, Libby, Yonelinas, & Ranganath, 2013; Staresina & Davachi, 2006; 2008; 2010). Our results also accord with previous studies demonstrating that PHC activity is sensitive to memory tests wherein objects (i.e., items) are used to cue the retrieval of an associated scene (i.e., context) (Hannula, Libby, Yonelinas, & Ranganath, 2013; Staresina, Henson, Kriegeskorte, & Alink, 2012).…”

Object and spatial mnemonic interference differentially engage lateral and medial entorhinal cortex in humans

“…Recent human fMRI experiments have found dissociations between PRC and PHC in item and context memory (19,21,(43)(44)(45)(46), although these studies did not manipulate memory interference. Our results are consistent with these data, but extend the findings in two important ways.…”

Impact of schizophrenia on anterior and posterior hippocampus during memory for complex scenes

“…To test hypotheses about the effects of memory for item versus spatial information on hippocampal activation, we used previously established methods (Hannula et al, 2013), utilizing anatomical landmarks to define a single set of structural regions of interest (ROIs) in the head, body, and tail of the hippocampus that were examined for task effects and group differences for each contrast (i.e., item change minus unchanged, spatial change minus unchanged). Given our hypotheses, results are summarized here only for the anterior (head) and posterior (tail) hippocampus, and body results are summarized in Supplementary Materials.…”

“…Functional dissociations between anterior and posterior hippocampus have been attributed to processing of; novel versus repeated stimuli (Ranganath and Rainer, 2003, Strange et al, 2005, Kumaran and Maguire, 2006), emotional versus non-emotional material (Gray and McNaughton, 1982, Murty et al, 2010) and encoding versus retrieval (Spaniol et al, 2009). Work has also linked posterior hippocampus to retrieving memories based on spatial context information, and anterior hippocampus to more global and less context-dependent relational memory processes (Hannula et al, 2013). Moreover, when processing spatial information, a distinction exists between retrieval of fine-grained spatial details (posterior hippocampus) versus more global gist-like information (anterior hippocampus).…”