Age-related differences in the medial temporal lobe responses to emotional faces as revealed by fMRI

Age-related differences involved in the neural substrates of emotional face perception were investigated in young and old healthy volunteers. The subjects were scanned using functional magnetic resonance imaging while they were judging the gender of faces with negative, positive, or neutral emotional valence. The results showed that both the predominant activation in young subjects and reduced activity in old subjects contributed to a significant age difference in the left amygdala during the perception of negative faces. Activity in the right parahippocampal gyrus during the perception of positive faces diminished with advancing age. Neural activity in the angular gyrus and lingual gyrus of the right hemisphere was reduced in the old subjects during the perception of positive faces. There was no region where old subjects had greater activity than young subjects during the task. In old subjects, the overall activity in the right hippocampus during the task correlated negatively with age, whereas the activity in the right parahippocampal gyrus correlated positively with neuropsychological performance. There was no significant correlation between subjects' characteristics and signal change in young subjects. These results indicate the age-associated vulnerability of the medial temporal lobe structures including the amygdala, hippocampus, and parahippocampal gyrus during face perception. The dissociation with reduced activity in the left amygdala and the right parahippocampal gyrus may suggest that aging differentially affects neural responses to faces with negative or positive emotional valence. The parieto-occipital lobe, which has been found to be involved in face processing, also showed a functional decline associated with aging.