Abstract
There is a well-established posterior network of cortical regions that plays a central role in face processing and has been investigated extensively. In contrast, while responsive to faces, the amygdala is not considered a core face-selective region and its face selectivity has never been a topic of systematic research in human neuroimaging studies. Prior fMRI studies relied on localizer tasks in which participants are presented with photographs of faces and objects from other visual categories (e.g., houses) to identify face-selective BOLD responses. We show that the lack of focus on the face selectivity of the amygdala results from limited statistical power in the standard localizer approach. First, the amygdala’s small size and location make it difficult to image because of a reduced signal-to-noise ratio relative to cortical regions. Second, group analyses of localizer data are not typically reported to avoid cortical misalignment, which compounds the problem because of increased measurement error. To overcome these challenges, we performed group analyses of functional localizer data from over 200 human participants across 10 studies, using emotionally neutral faces and various visual control categories. Beyond the posterior network of cortical regions observed in prior studies, we found robust face-selective responses in the amygdala, which displayed high reliability over time. Furthermore, examining the covariance of reliability scores across face-selective regions revealed separable cortical and subcortical face-processing networks. Finally, connectivity analyses confirmed a context-dependent relationship between the amygdala and fusiform, whereby functional connectivity between these regions increased during face presentations, compared to control stimuli. These results bridge a gap between single-unit recording studies — where face selectivity has been better characterized — and neuroimaging studies, suggesting that the amygdala has comparable face selectivity to putative "face" areas in posterior visual cortex, and providing some of the first evidence that subcortical regions can be specialized for high-level cognitive processes.
Meeting abstract presented at VSS 2013