Exploring the roles of the frontal, temporal and parietal lobes in visual learning and categorization
Our perception of the environment is not a faithful registration of its physical attributes. Instead, we carve the world into meaningful groupings, or categories. For example, knowing that a new gadget is a "camera" instantly and effortlessly provides a great deal of information about its relevant parts and functions. The ability to categorize stimuli is a cornerstone of complex behavior. Categories are evident in all sensory modalities and range from relatively simple (e.g., color perception) to the most abstract human concepts. While much is known about how the brain processes simple sensory features (i.e. color, orientation, and direction of motion), less is known about the neuronal processes that encode the category membership, or meaning, of stimuli. This talk will review a series of experiments aimed at understanding the respective roles of several interconnected brain areas during visual categorization. By recording the activity of individual neurons in monkeys trained to categorize visual stimuli, we found that activity in two brain areas, the lateral prefrontal cortex (PFC) and lateral intraparietal area (LIP), robustly encoded the category membership of visual stimuli. This suggests that both the PFC and LIP may be important stages for the transformation of visual information to more abstract representations of the categorical meaning of visual stimuli.