Abstract

568 nature neuroscience • volume 2 no 6 • june 1999 articles Evidence for specialization in the fusiform gyrus for human face perception comes from both neuroimaging and neuropsychological studies Subjects were trained with novel objects called greebles 14 RESULTS We localized the brain areas more involved in face than object processing by subtracting the activation when subjects passively viewed non-face common objects from that obtained when viewing faces (localizer task 6 ). This led to the selection of two 8 ´8 voxel (each voxel, 1.3 ´1.7 mm; see Methods) regions of interest (ROIs) located bilaterally in the middle and the anterior fusiform gyri. These ROIs are consistent with the brain regions previously associated with face processing in multiple studies 1,2,5-9 (see coordinates in Our prediction was that expertise training with upright greebles would lead to an increase in activation for upright minus activation for inverted greebles in the face-specific ROIs but no comparable change for faces. The data were combined into three blocks (sessions 1 and 2, 3 and 4, 5 and 6; see Methods). An ANOVA was used to test the prediction that the activation for greebles would increase with training to the level of activation obtained for faces in the average of all sessions (contrast, faces block 1 = faces block 2 = faces block 3 = greebles block 3 > greebles block 2 > greebles block 1). This prediction contrast was highly significant (F 1,4 = 88.9, p ² 0.005) but also left a significant residual, indicating that the prediction did not account for all of the variance in the omnibus interaction. We also obtained a main effect of hemisphere (F 1,4 = 12.97, p ² 0.03) and an interaction of hemisphere with ROI (F 1,4 = 8.15, p ² 0.05). In the right hemisphere, there was more activation in the middle fusiform gyrus (Scheffé test, p = 0.05) but not in the anterior fusiform gyrus. The interaction of the contrast with hemisphere (F 1,4 = 8.5, p ² 0.05) left no significant residual: the predicted pattern was present in the right but not the left hemisphere. Thus, by the end of training, the preference for faces over greebles in right hemisphere face-specific I.G. (isabel.gauthier@yale.edu) Part of the ventral temporal lobe is thought to be critical for face perception, but what determines this specialization remains unknown. We present evidence that expertise recruits the fusiform gyrus 'face area'. Functional magnetic resonance imaging (fMRI) was used to measure changes associated with increasing expertise in brain areas selected for their face preference. Acquisition of expertise with novel objects (greebles) led to increased activation in the right hemisphere face areas for matching of upright greebles as compared to matching inverted greebles. The same areas were also more activated in experts than in novices during passive viewing of greebles. Expertise seems to be one factor that leads to specialization in the face area.