A locus in human extrastriate cortex for visual shape analysis.

Positron emission tomography (PET) was used to locate an area in human extrastriate cortex that subserves a specific component process of visual object recognition. Regional blood flow increased in a bilateral extrastriate area on the inferolateral surface of the brain near the border between the occipital and temporal lobes (and a smaller area in the right fusiform gyms) when subjects viewed line drawings of 3-dimensional objects compared to viewing scrambled drawings with no clear shape interpretation. Responses were Seen for both novel and familiar objects, implicating this area in the bottom-up (i.e., memory-independent) analysis of visual shape.