The role of the superior temporal sulcus in face recognition and perception

Electrophysiological experiments in monkeys, and more recent functional magnetic resonance imaging (fMRI) studies in human subjects have shown that the superior temporal sulcus (STS) plays a role in face processing. The various roles of the STS in human cognition, including face processing, language, audio-visual integration, and motion perception, are expected to be subserved by the widespread neural connectivity of the STS with other brain regions, such as the primary sensory, limbic, and prefrontal areas. Among the multiple components involved in face processing, fMRI studies have shown that the STS is predominantly involved in the processing of gaze direction and emotional expression. Peak coordinates reported in previous fMRI studies were plotted on the Montreal Neurological Institute's standard brain template. A large cluster was located along the posterior to middle part of the STS, a role that is not selective for a particular task or for cognitive processing. The author focused on 3 aspects of the functional role of the STS: (i) the STS performs regionally specific functions; the posterior STS has low face-selectivity, and the anterior STS is relatively selective for face stimuli, (ii) the STS not only detects gaze direction and facial expression, but also detects intention, as indicated by the experimental stimuli, and (iii) the STS response increases when the intention and the subsequent results do not match. Based on these findings, the author speculates that the role of the STS in human cognition and emotion is to process "social attention," which is a crucial human skill for making inferences with respect to others' goals, intentions, and actions.