I tell them to look into the distance and they can do so with their own gaze, expression and feeling.
Changeable aspects of faces such as eye gaze, expression, and lip movement are thought to be primarily represented in the posterior part of the superior temporal sulcus (STS) (Allison et al. 2000; Grossman et al. 2000, 2004; Blakemore and Decety 2001; Grossman and Blake 2001 , 2002.
In the monkey brain, there are neurons in the ventral prefrontal cortex that respond more strongly to faces than to non-faces and code gaze, expressions and identity information (e.g., Tsao, Schweers, Moeller, & Freiwald, 2008; Romanski & Diehl, 2011).
One pathway (including posterior superior temporal sulcus, pSTS) is responsible for processing changeable aspects of faces such as gaze and expression, and the other pathway (including the fusiform face area, FFA) is responsible for relatively invariant aspects such as identity.
He returns their gaze, his expression inscrutable.
But a head tilt, a gaze, or expression of love is universal.
We propose that this reflects the critical social importance of monitoring changes in a particular individual's gaze and expression and demonstrate through connectivity analyses a potential mechanism through which this can happen.
In particular, Haxby et al. (2000) proposed that the FG is primarily involved in the perception of invariant facial features, and only marginally involved in perception of changeable facial properties, such as gaze and expression.
Using functional magnetic resonance imaging, we found a region in pSTS that responded more to sequences of faces varying in gaze and expression in which the identity was constant compared with sequences in which the identity varied.
Perception of "changeable" or dynamic facial characteristics, such as gaze, facial expression, and lipspeech was attributed to the pSTS, whereas the recognition of "invariant" facial features that change slowly across time, such as facial identity, was assigned to the FG.
Although Haxby et al. (2000) emphasized the role of the pSTS in processing changeable facial cues (e.g., gaze and expression) and the FG in facial identity, a recent meta-analysis found that FG is also engaged during gaze processing and that this cannot simply be attributed to a response to facial stimuli alone (Nummenmaa and Calder 2009).
