The amygdala and FFA track both social and non-social face dimensions

The amygdala is thought to perform a number of social functions and has received much attention for its role in processing social properties of faces In particular it has been shown to respond more to facial expressions than to neutral faces and more to positively valenced and negatively valenced faces than faces in the middle of the continuum However when these findings are viewed in the context of a multidimensional face space an important question emerges Face space is a vector space where every face can be represented as a point in the space The origin of the space represents the average face In this context positively valenced and negatively valenced faces are further away from the average face than faces in the middle of the continuum It is therefore unclear if the amygdala response to positively valenced and negatively valenced faces is due to their social properties or to their general distance from the average face Here we compared the amygdala response to a set of faces that varied along two dimensions centered around the average face but differing in social content In both the amygdala and much of the posterior face network we observed a similar response to both dimensions with stronger responses to the extremes of the dimensions than to faces near the average face These findings suggest that the responses in these regions to socially relevant faces may be partially due to general distance from the average face (C) 2010 Elsevier Ltd All rights reserved