terça-feira, 21 de dezembro de 2010

Brain's Modality-Specific Systems: Dr. Lawrence Barsalou


Lawrence Barsalou PhD Emory University. The human conceptual system contains categorical knowledge that supports online processing (perception, categorization, inference, action) and offline processing (memory, language, thought). Semantic memory, the dominant theory of the conceptual system, typically portrays it as modular, amodal, abstractive, and static. Alternatively, the conceptual system can be viewed as non-modular, modal, situated, and dynamic. According to this latter perspective, the conceptual system is non-modular and modal because it shares representational mechanisms with modality-specific systems in the brain, such as vision, action, and emotion. On a given occasion, modality-specific information about a category's members is reenacted in relevant modality-specific systems to represent it conceptually. Furthermore, these simulations are situated, preparing the conceptualizer for situated action with the category. Not only do these situated simulations represent the target category, they also represent background settings, actions, and mental states, thereby placing the conceptualizer in the simulation, prepared for goal pursuit. Because the optimal conceptualization of a category varies across different courses of situated action, category representations vary dynamically and are not static. Furthermore, different situations engage different neural systems dynamically when representing a category. Under some circumstances, the linguistic system plays a more central role than simulation, whereas under other circumstances, simulation is more central. Thus, the concept for a category appears to be a widely distributed circuit in the brain that includes modality-specific and linguistic representations, integrated by association areas. Across situations, these circuits become realized dynamically in diverse forms to provide the knowledge needed for cognitive processing. Behavioral and neural evidence is presented to support this view. Learning Sciences Institute