Novel, threatening or highly arousing images activate a brain area called the amygdala that is involved in emotional processing. Pictures of African-American faces are known to activate the amygdala more strongly than Caucasian- American faces, at least in Caucasian-American people, but the underlying reason for that activity has remained controversial. A paper in the June issue of Nature Neuroscience now reports that African-American people show a similar racially specific pattern of amygdala activation, suggesting that this brain activity may result from learned cultural responses to racial groups.

In participants of both races, brain regions involved in emotion and motivation were more active in response to African-American faces than to Caucasian-American faces. Since African-American subjects are presumably exposed to many faces of their own race in their daily lives, the authors conclude that amygdala activity in response to African-American faces may reflect the learning of cultural associations about the group rather than novelty. Verbally labeling the faces as African-American reduced the amygdala activity in both groups, suggesting that putting race into words may reduce its emotional impact.