Abstract
High-resolution fMRI have identified six face-responsive regions in the left and right ventral occipital-temporal cortex (mFus-medium fusiform; pFus-posterior fusiform; and IOG-Inferior Occipital Gyrus), but the degree and nature of these regions’ face selectivity and their information representation are not yet clear. Here, we use single-image approach combined with regional-average activation and representational connectivity analysis (RCA) to investigate their selectivity and representational properties. The mean response level and the representational dissimilarity matrix associated with 96 object images from 16 categories were computed for each ROI to characterize their selectivity and representational content. In terms of the mean responses, R-mFus showed the highest degree of response specificity to faces, whereas the other five regions showed much weaker face preference. In terms of the spatial patterns of the responses, all ROIs had small dissimilarities between individual faces compared to other image categories, indicating a more consistent spatial response to faces. In the MDS plot reflecting relationships between different ROI’s representational properties, R-IOG, L-IOG , L-mFus, L-pFus typically formed a tight cluster whereas R-pFus and R-mFus were loosely related, with R-mFus most distinguished from the other ROIs. Further RCA confirmed this relationship and showed that certain pairs of objects eliciting more dissimilar response patterns in R-mFus tended to elicit more dissimilar responses patterns in R-pFus, and for the majority pairs of objects the same held for pairwise correlations of L-mFus, L-pFus, L-IOG and R-IOG. Our findings show that R-mFus had the highest face selectivity among all regions and the most distinct spatial representation of the 96 images, followed by R-pFus; while the representations of L-mFus, L-pFus, L-IOG and R-IOG were similar to each other and generally less face-selective.
Meeting abstract presented at VSS 2013