Abstract
fMRI studies at standard-resolution (SR-fMRI) found responses in the fusiform face area (FFA) for non-face objects of expertise, but because high-resolution fMRI (HR-fMRI) in FFA (e.g., Grill-Spector et al., 2006) and neurophysiology in face patches in the monkey brain (Tsao, et al., 2006) reveal no reliable selectivity for objects, FFA responses to objects at SR-fMRI could be due to spatial blurring. As the focus of the strongest claims for modularity and the clearest predictions about expertise, FFA responses to objects of expertise are critical in evaluating the claim that face perception is a "cognitive function with its own private piece of real estate in the brain" (Kanwisher, 2010). Using HR-fMRI at 7 Tesla with a radiofrequency-spoiled 3D FFE acquisition sequence with SENSE, we characterized responses to faces, animals, cars and planes in 25 subjects who varied in car and plane expertise quantified behaviorally. Analyses were performed on flattened cortex. Group-average mean responses replicated prior work, with reliable selectivity for faces and animals but not for objects. However, relating HR signals to expertise, we find that selectivity for objects in FFA increased with expertise, including in the most highly face-selective voxels within the 25 mm2 peak of face selectivity. The proportion of car- or plane-selective voxels in the FFA was also predicted by behavioral expertise, and partial correlations revealed largely independent effects for each category. Critically, FFA responses to objects were restricted to a 200mm2 area centered on the FFA peak. While increased attention with expertise might account for the magnitude of activation, it cannot explain its spatial distribution, which matches the location and size of the patch of face selectivity. Considering individual differences in expertise with HR-fMRI suggests that experience with a category may be sufficient to explain the spatially clustered selectivity for faces observed in this region.
Meeting abstract presented at VSS 2012