Abstract
Holistic processing plays an important role in face perception. In this study, to better understand the role of processing of low spatial frequency components in face perception, we trained to increase the sensitivity of low spatial frequency components in patients with body dysmorphic disorder (BDD). BDD patients suffer from distressing occupation of slight defects in their appearances including faces and are deficient in holistic processing. BDD patients (N = 9) and healthy control subjects (N = 10) performed a 2IFC detection task on face images with only low-spatial frequency components over 6 days. During the pre- and post-tests, subjects’ BOLD activity was measured with fMRI while subjects performed the 2IFC detection tasks on both faces and houses with each of the low and high spatial-frequency components. We obtained the following training effects. First, both BDD and control groups showed comparable improvements on detecting face images with the low spatial frequency components. Second, only in the BDD group, BOLD activity decreased in the temporoparietal junction (TPJ) in the dorsal face processing pathway. Third, in the BDD group, the dominance of BOLD activity in the fusiform face area (FFA) in the ventral face processing pathway switched from the left to right hemispheres. In the control group, the dominance in FFA switched from right to left hemispheres. Fourth, in the BDD group, the functional connectivity (FC) between the TPJ and occipital face area (OFA) in the ventral pathway increased, while the FC between the left and right FFA decreased. Finally, BOLD activity did not change in the early visual areas for BDD and control groups. These results indicate that learning to improve a task involving low spatial frequency components of faces is associated with substantial changes of face processing in the brain, suggesting a fundamental role of low spatial frequency in face processing.