ABSTRACT
This chapter explains a neuropsychological Functional magnetic resonance imaging (fMRI) study that tests for necessary contribution of higher dorsal visual regions in the processing of global patterns in intermediate areas. Visual object recognition is frequently attributed to a hierarchically arranged set of processes, in which global representations are formed by integrating local elements into global forms or extracting in parallel different spatial frequency components that characterize local and global elements. According to this local-to-global hierarchical view, local elements are first encoded by early visual areas (V1/V2) and then integrated within intermediate regions (V3/V4). The output of this integration process is forwarded to higher-level regions responding to global pattern structure. Consistent with this view, lesions to intermediate visual areas are associated with disorders in the organization of visual elements into recognizable whole patterns. In contrast to the view that recognition proceeds through hierarchical processing in ventral visual stream, there is increasing evidence for the role of dorsal cortex in form processing.
