Abstract
Faces activate specific brain regions in fMRI, including the fusiform gyrus (FG) and the posterior superior temporal sulcus (pSTS). The fact that the FG and pSTS are frequently co-activated suggests that they may interact synergistically in a distributed face processing network. Alternatively, the functions implemented by these regions may be encapsulated from each other. It has proven difficult to evaluate these two accounts during visual processing of face stimuli. However, if the FG and pSTS interact during face processing, the substrate for such interactions may be apparent in a correlation of the BOLD timeseries from these two regions during periods of rest when no faces are present. To examine face-specific resting correlations, we developed a new partial functional connectivity approach in which we removed variance from the FG that was shared with other category-selective and control regions. The remaining face-specific FG resting variance was then used to predict resting signals throughout the brain. In two experiments, we observed face-specific resting functional connectivity between FG and pSTS, and importantly, these correlations overlapped precisely with the face-specific pSTS region obtained from independent localizer runs. Additional region-of-interest and pattern analyses confirmed that the FG–pSTS resting correlations were face-specific. These findings support a model in which face processing is distributed among a finite number of connected, but nevertheless face-specialized regions. The discovery of category-specific interactions in the absence of visual input suggests that resting networks may provide a latent foundation for task processing.
Highlights
Faces are one of the most important sources of information in the visual environment
Similar to our increasingly precise understanding of the functions of individual brain regions, the current results provide initial evidence that the division of the brain into gross sensory, motor, and default networks may underestimate the number and specificity of resting networks
Even specific types of information processing – such as face processing – may be reflected in fMRI as activation changes in single brain regions, and in the degree to which these changes are synchronous across regions
Summary
Faces are one of the most important sources of information in the visual environment. They allow us to identify friend from foe, and to interpret the mental states of others. Given this importance, it is no surprise that the brain has evolved specialized mechanisms for processing faces. Adaptation in the FG to a morphed face is released only to a new morph that crosses an identity boundary (Rotshtein et al, 2005). Neuropsychological studies of prosopagnosia further implicate the FG in identity recognition (Barton et al, 2002), and subdural stimulation of FG sites results in transient prosopagnosia and visual face hallucinations (Allison et al, 1994; Puce et al, 1999)
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