These include 3-D surface extraction and segmentation algorithms, and volume navigation and editing tools that provide a framework for semi-automatic region of interest generation and landmark specification. The approach we are developing is based on edge/surface detection using Gaussian derivative filters, over-segmentation, and hierarchical region combination. The goal is to quickly identify primary surfaces, landmarks, and other image based features, and to use maps of these features to inform segmentation or parcellation of 3-D images.

These fMRI experiments are designed to investigate the organization, operation, and plasticity of cortical areas involved in visual processing at large (20-80 degree) eccentricities. We use light guiding fibers to present flashing stimuli at peripheral locations during functional imaging. Retinotopically mapped visual areas and areas that preferentially respond to peripheral visual stimulation are identified. We are investigating the extent and organization of these visual areas, and how they are modulated by spatial attention. Comparison of hearing and congenitally deaf adults results will elucidate how visual cortical networks are modified and modulated by profoundly different auditory experience.