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Poster D39, Thursday, November 9, 6:15 – 7:30 pm, Harborview and Loch Raven Ballrooms

A distributed and dynamic architecture underlies the retrieval of social concepts

Ingrid Olson1, Yin Wang1, Jessica A. Collins1, Jessica Koski1, Tehila Nugiel1, Ahtanasia Metoki1;1Temple University

INTRODUCTION As social creatures, it is essential that we develop a rich storehouse of knowledge about other members of our social network, such as who they are, how they look and sound, where they live, and what they do for a living. Yet little is known about how and where such person knowledge is represented, stored, and retrieved in the brain. This inquiry is challenging because person knowledge is highly multimodal and multifaceted, being linked to both abstract features such as personality and social status as well as more concrete features such as eye color. The neural circuit for person knowledge must therefore have the ability to combine multiple sources of information into an abstract representation accessible from multiplicative cues. The ‘hub-and-spoke’ theory of semantic knowledge proposes that different features of a concept (such as its color or taste) are distributed throughout the brain and that a centralized ‘hub’ integrates these features into a coherent, modality-invariant concept (Patterson, Nestor, Rogers 2007). Here we asked whether portions of the anterior temporal lobe (ATL) serve as a hub for a distributed neural circuit of person knowledge. METHODS Fifty neurologically normal young adults were tested across two studies in which they learned biographical information about fictitious people over two days of training. On Day 3, they retrieved this biographical information while undergoing an fMRI scan. In Study 1, we used stimuli from different categories commonly associated with familiar people (e.g. faces, names, homes, and objects) to cue memories for specific individuals. We compared the similarity of response patterns elicited by stimuli from different categories but associated with the same individual to test the abstract person representation properties of the ATL. In Study 2, we asked participants to recollect specific content of fictitious people’s biographies and examined whether the ATL coordinates the retrieval of different aspects of person knowledge by recruiting the activation of different brain regions depending on task requirements. RESULTS AND CONCLUSIONS In Study 1, findings from a series of MVPA tests consistently showed that the ATL represents person knowledge in an abstract form that is divorced from a person’s face or name. In Study 2, we found that the ATL person identity node is embedded in a neural circuit that is consistently engaged during person memory tasks. Multivariate analyses suggested that different content areas of person knowledge – social status, personality traits, and identity - were represented in discrete nodes within this distributed person-identification circuit. Connectivity analyses (PPI and DCM) further revealed that the ATL may serve as a ‘neural switchboard’, and is capable of coordinating the flow of person-specific information between sensory brain regions that encode incoming cues and other nodes of this circuit that are engaged when retrieving specific person knowledge content. These results suggest that the ATL is a central hub for representing and retrieving semantic knowledge about people.

Topic Area: Meaning: Combinatorial Semantics

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