Here we review human functional neuroimaging studies suggesting that the amygdala may play a key role in depression. We begin by reviewing animal and human data concerning the function of the amygdala. We then compare these results with those of neuroimaging studies of normal human amygdala function. Finally, we discuss functional neuroimaging studies of the amygdala in depression in light of the animal and human data. We conclude that the initial studies of this disorder provide evidence of amygdala involvement. Furthermore, we suggest that the scope of the amygdala's involvement may go beyond its well-known role in fear to its more subtle and generalized role in modulating moment-to-moment vigilance levels.

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