Semantic Knowledge of Famous People and Places Is Represented in Hippocampus and Distinct Cortical Networks

Abstract

Studies have found that anterior temporal lobe (ATL) is critical for detailed knowledge of object categories, suggesting that it has an important role in semantic memory. However, in addition to information about entities, such as people and objects, semantic memory also encompasses information about places. We tested predictions stemming from the PMAT model, which proposes there are distinct systems that support different kinds of semantic knowledge: an anterior temporal (AT) network, which represents information about entities; and a posterior medial (PM) network, which represents information about places. We used representational similarity analysis to test for activation of semantic features when human participants viewed pictures of famous people and places, while controlling for visual similarity. We used machine learning techniques to quantify the semantic similarity of items based on encyclopedic knowledge in the Wikipedia page for each item and found that these similarity models accurately predict human similarity judgments. We found that regions within the AT network, including ATL and inferior frontal gyrus, represented detailed semantic knowledge of people. In contrast, semantic knowledge of places was represented within PM network areas, including precuneus, posterior cingulate cortex, angular gyrus, and parahippocampal cortex. Finally, we found that hippocampus, which has been proposed to serve as an interface between the AT and PM networks, represented fine-grained semantic similarity for both individual people and places. Our results provide evidence that semantic knowledge of people and places is represented separately in AT and PM areas, whereas hippocampus represents semantic knowledge of both categories.

A content-based representational scaffold for naturalistic event memories

“…There is strong evidence that the DMN can be broken into smaller sub-networks on the basis of functional attributes and differences in content-sensitivity (Andrews-Hanna et al, 2010Barnett et al, 2020;Braga et al, 2019;Ranganath & Ritchey, 2012), and there is growing evidence that sub-networks may exist even within the PM Network (Ritchey & Cooper, 2020). A recent study by Morton and colleagues (Morton et al, 2021) provides especially compelling evidence for this, and in line with our findings, the authors show pattern similarity among famous people in the AT Network and famous spatial locations in the PM Network on the basis of semantic knowledge. The view of the DMN as consisting of at least two sub-networks is seemingly at odds with views ascribing broad roles in domain-agnostic episodic (Bonnici et al, 2016;Kuhl & Chun, 2014;Lee & Kuhl, 2016;Thakral et al, 2017) or semantic (Binder & Desai, 2011;Devereux et al, 2013;Rugg & King, 2018) memory retrieval across DMN regions, raising the question: what underlies this discrepancy?…”

Prolonged and distributed processing of facial identity in the human brain

“…One such stimulus category may be houses and buildings (Gorno-Tempini and Price, 2001). Indeed, a very recent study compared semantic knowledge for people and places and found separate mechanisms in anterior-temporal and posterior-medial temporal regions but also a joint representation of sematic similarity in the hippocampus (Morton et al, 2021). Testing the identity processing of famous and personally familiar buildings and places might expand the current results over stimulus categories in the future.…”

“…Recent MVPA studies suggest that the FFA and the ventral anterior temporal areas play a role in the image invariant encoding of face identities (Collins et al, 2016;Goesaert and Op de Beeck, 2013;Nestor et al, 2011;Tsantani et al, 2021). The fact that these areas only showed representational correspondence at a later stage, correspond to their sensitivity to intermediate (Visconti Di Oleggio Castello et al, 2017) or high-level information (Tsantani et al, 2021), which is presumably related to the merging of perceptual and conceptual knowledge about the face (Collins et al, 2016;Morton et al, 2021).…”

Lacking social support is associated with structural divergences in hippocampus-default network co-variation patterns

“…The anterior portion of the human hippocampus has also been proposed to be a locus of both semantic (Schacter and Wagner, 1999; Strange et al, 2014) and social (Morton et al, 2021; Vogel et al, 2020) processing. In line with this notion, we identified 21 total hits in the head portion of the hippocampus (66%), and only 11 (34%) in its body portion across all modes.…”