Mood alters amygdala activation to sad distractors during an attentional task.

BACKGROUND: A behavioral hallmark of mood disorders is biased perception and memory for sad events. The amygdala is poised to mediate internal mood and external event processing because of its connections with both the internal milieu and the sensory world. There is little evidence showing that the amygdala's response to sad sensory stimuli is functionally modulated by mood state, however.
METHODS: We investigated the impact of mood on amygdala activation evoked by sad and neutral pictures presented as distractors during an attentional oddball task. Healthy adults underwent functional magnetic resonance imaging during task runs that were preceded by sad or happy movie clips. Happy and sad mood induction was conducted within-subjects on consecutive days in counterbalanced order.
RESULTS: Amygdala activation to sad distractors was enhanced after viewing sad movies relative to happy ones and was correlated with reaction time costs to detect attentional targets. The activation was higher in female subjects in the right hemisphere. The anterior cingulate, ventromedial and orbital prefrontal cortex, insula, and other posterior regions also showed enhanced responses to sad distractors during sad mood.
CONCLUSIONS: These findings reveal brain mechanisms that integrate emotional input and current mood state, with implications for understanding cognitive distractibility in depression.