Age-related differences in brain activation during emotional face processing

Advancing age is associated with significant declines on neurobehavioral tasks that demand substantial mental effort. Functional imaging studies of mental abilities indicate that older adults faced with cognitive challenges tend to activate more regions, particularly frontal, than their younger counterparts, and that this recruitment of additional regions may reflect an attempt to compensate for inefficiency in cortical networks. The neural basis of emotion processing in aging has received little attention, and the goal of the present study was to use functional magnetic resonance imaging (fMRI) to examine the influence of age on facial emotion processing and activation in cortical and limbic regions. Participants (eight old and eight young adults) viewed facial displays of happiness, sadness, anger, fear, disgust, and neutrality in alternating blocks of emotion and age discrimination. We predicted that in response to an emotion discrimination task, older adults would demonstrate increased use of frontal regions relative to younger adults, perhaps combined with diminished use of regions recruited by younger adults, such as temporo-limbic regions. During the emotion discrimination task, young participants activated, visual, frontal and limbic regions, whereas older participants activated parietal, temporal and frontal regions. A direct comparison between emotion and age discrimination revealed that while younger adults activated the amygdala and surrounding temporo-limbic regions, older adults activated left frontal regions. The results of this study suggest that older adults may rely on different cortical networks to perceive emotional facial expressions than do their younger counterparts.