| The research in this dissertation investigates the neural implementation of conceptual knowledge: a level of representation characterized by broad generality and independence from all sensory or motor channels. Decades of neuropsychological work have established that conceptual knowledge is not represented in a single neural locus, but rather across multiple neural loci, and that these loci are often content-selective: they are responsible for certain aspects of conceptual knowledge (e.g., animals; color) more than others. On what basis are these partitions delineated, and what determines their cortical locations? The present work attempts to unravel some of these principles by identifying neural loci that represent non-concrete attributes of action and artifact concepts, such as functions, intentions, and outcomes. As investigated here, these aspects of concepts are not reducible to any particular sensory or motor qualities. This is beneficial in two ways. First, it presents an essential test case for a dominant theory of neural organization of concepts, which proposes that conceptual knowledge is organized by the sensory modality those concepts refer to. Second, it helps overcome a methodological issue in functional magnetic resonance imaging: the difficulty of dissociating conceptual representations from lower-level/sensory-motor associates. The focus on non-concrete properties enabled us to overcome this challenge. Our findings reveal that distinct portions of the inferior parietal lobe represent functions of artifacts and intentions/outcomes of actions. This suggests that different aspects of non-concrete conceptual knowledge are represented in spatially distinct neural areas, implying that neural organizing factors can be abstract. Furthermore, the cortical locations of these aspects of concepts were adjacent to computationally related cognitive systems: outcomes of actions were near an area involved in theory of mind, and functions were near an area previously shown to be involved in physical manipulation knowledge of tools. These observations suggest that conceptual knowledge is neurally localized according to computational considerations: concepts are localized near to cognitive components that rely on those concepts for their operation. |
