Abstract
The Fusiform Face Area (FFA) is associated with stronger BOLD responses to faces than to other objects (Kanwisher et al., 1997). Expertly processed objects also are associated with stronger activity within this region (Gauthier & Tarr, 1997; Gauthier et al., 2000), suggesting the FFA may not be devoted to faces per se, but to within-category discrimination of expertly-learned objects. However, these studies have not addressed the effect of learning on regions beyond the FFA.
Using whole brain imaging, we examined the activity associated with faces, and trained and untrained houses before and after 5 days of training on a 4AFC house-discrimination task. The parahippocampal place area (PPA) responds preferentially to houses and scenes (Epstein & Kanwisher, 1998), so we sought to determine whether training induces a shift in the cortical locations responsive to houses (for example, a shift from PPA to FFA activation), or a change specifically within the PPA.
A partial least squares analysis showed that the data were well described by a contrast of the activity for houses versus faces. The strength of this contrast grew with training, suggesting greater differentiation of faces from houses after training. Despite this global change, a region of interest analysis indicated no significant activity changes within either FFA or PPA.
Together, these results suggest that house training enhances the global patterns of activity differentiating faces from houses, without substantially altering activity within more localized object processing regions.
This work was supported by NSERC Discovery Grants 42133 and 105494 and Canada Research Chairs to PJB and ABS, and an NSERC PGS-D award to JSH