Shape and motion are complementary visual features and each appears to
be processed in unique cortical areas.However,object motion is a powerful
cue for the perception of three-dimensional (3-D)shape,implying that the
two types of information motion and form are well integrated.We
conducted a series of fMRI experiments aimed at identifying the brain regions
involved in inferring 3-D shape from motion cues.For each subject,we identified
regions in occipital temporal cortex that were activated when perceiving:(i)motion
in unstructured random-dot patterns, (ii)2-D and 3-D line drawing shapes,and
(iii)3-D shapes defined by motion cues (shape-from-motion,SFM).We found
closely adjacent areas in the lateral occipital region activated by random
motion and line-drawing shapes.In addition,we found that the SFM stimuli
produced a greater MRI signal in only one of the areas identified with
the random motion and line-drawing stimuli:the superior lateral occipital
(SLO)region.High-resolution analysis showed that SFM objects and line drawings
were processed in separate but adjacent sub-regions in SLO,suggesting that
SLO codes object shape but retains topographic segregation based on shape
cues.Expanding the analysistotheentirecortexidentified aparietalareathathad
overlapping activation for both SFM and line drawings and increased MRI
signal for 3-D versus 2-D shapes,suggesting this area is important for
processing shape information.