The posterior superior temporal sulcus is involved in social communication not specific for the eyes

Neuroimaging and lesion studies suggest that the superior temporal sulcus (STS) region is involved in eye gaze processing. Hence, the STS region is suggested to be the location of the "eye-direction detector", a key element in the "mindreading model" proposed by Baron-Cohen [Baron-Cohen, S. (1995). Mindblindness: An essay on autism and theory of mind. Cambridge: The MIT Press]. Not only the eyes, but also a pointing finger of another person can inform us about the direction of attention of the other one. In an event-related functional magnetic resonance imaging experiment, healthy human subjects actively followed a directional cue provided either by the eyes or, alternatively, the pointing finger of another person to make an eye movement toward an object in space. Our results show clearly that the posterior STS region is equally involved in processing directional information from either source. The only difference between the two cues was found in the lingual gyrus, in which a stronger blood-oxygen-level-dependent (BOLD) response was observed during the finger pointing compared to the gaze following task. We suggest that different structures might be involved in the initial processing of directional information coming from the eyes or the pointing finger. These different streams of information may then converge in the posterior STS region, orchestrating the usage of a wider range of socially relevant directional cues able to inform us about the direction of attention and the intentions of another person.