Date of Award

Summer 2023

Document Type

Open Access Dissertation

Department

Psychology

First Advisor

Rutvik H. Desai

Abstract

Understanding the meaning of words and concepts is vital for communication, forming relationships, and navigating everyday life. Loss of this knowledge through brain damage can have drastic consequences for one’s health and well-being. It is therefore important to learn how this information is organized anatomically in the brain. In this dissertation, I report a series of structural and functional neuroimaging studies in healthy adults and survivors of stroke seeking to understand how lexical semantics are represented. Specifically, I used a variety of tasks to examine the contributions of putative ‘hubs’ and distributed action-perception systems. Results indicated that damage or disruption of the anterior temporal lobe was associated with impaired lexical access, but not necessarily nonverbal semantic difficulties. Damage to temporoparietal regions, on the other hand, was associated with impaired semantic access or tasks requiring percept-concept linkages. Disconnection of the left inferior frontal cortex from the lexical semantic network was related to worse canonical sentence comprehension, and its role in executively or semantically demanding tasks was supported. Further, damage and disruption of DAPS was shown to be related to impairments in action-related conceptual understanding for both nouns and verbs. Finally, a novel neuroimaging training paradigm in healthy adults revealed a likely role for the ATL in memory and identification of unique entities, independent from semantic demands. Together, these findings provide valuable insight about the anatomical organization of the lexical semantic system in the brain.

Rights

© 2023, Nicholas Andrew Riccardi

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