Different Spatial Scales of Shape Similarity Representation in Lateral and Ventral LOC

We investigated the relationship between stimulus similarity for a set of parameterized shapes and the spatial scale of neural representation within subregions of the lateral occipital complex (LOC) using a carryover functional magnetic resonance imaging design. In ventral but not lateral LOC, a linear recovery from adaptation proportional to shape dissimilarity was seen. In contrast, a strong correspondence of the distributed neural pattern and stimulus similarity was observed in lateral LOC but not ventral LOC. Further, ventral LOC voxels were found to be broadly tuned and represent all aspects of stimulus similarity, whereas lateral LOC voxels were narrowly tuned and preferentially represented the shape of small features rather than their orientation within the shape. The results, indicating a coarse spatial coding of shape features in lateral LOC and a more focused coding of the entire shape space within ventral LOC, may be related to hierarchical models of object processing.