Organization and Retrieval of Conceptual Knowledge.
One of the key issues in cognitive psychology and cognitive neuroscience is the organization of conceptual knowledge. By conceptual knowledge, I am referring to general knowledge that we have about the world, such as the color of an apple, what scissors are used for, and what telephone ring sounds like. According to one prominent class of models of conceptual knowledge organization, there exists a close relationship between our sensory-motor experiences and our conceptual and neural representations (e.g., Allport, 1985). Under this account, conceptual knowledge is distributed across different sensory (e.g., visual, auditory) and motor (e.g., action, kinesthetic) attribute domains, and that this domain-specific information is stored in or near sensory-motor brain regions that are congruent with knowledge type (e.g., visual information stored in brain regions recruited during visual processing). Across four experiments, we found converging behavioral neuropsychological, and neuroimaging evidence in support of a domain-specific distributed model of conceptual knowledge. Specifically, we found that (a) attribute information (e.g., color and action) about concrete objects is automatically activated during conceptual processing, and the extent to which different information becomes available varies as a function of object class (Experiment 1); (b) damage to sensory-motor brain regions has a direct impact on retrieval of modality-congruent information (Experiment 2); (c) brain activations observed during conceptual knowledge retrieval (via picture naming) is distributed across multiple sensory-motor regions (Experiments 3 & 4); (d) we explored whether functions of left ventrolateral frontal cortex, which has previously been linked to motor knowledge retrieval, can be further dissociated. We identified two distinct neural components within this area: a posterior region, centered in premotor cortex, that responds to motor knowledge retrieval, and an anterior region, centered in the left frontal operculum, that responds to lexical competition (Experiment 4), which is consistent with the proposal that the left frontal operculum is sensitive to selection among competing alternatives (Experiment 3); (e) individual variation in motor experience with manmade objects was highly correlated with the magnitude of the response in a motor region (i.e., premotor cortex; Experiment (4). Taken together, our data provide converging support for a domain-specific distributed model of conceptual knowledge.
|Main Author:||Kan, Irene P.|