Brain regions involved in processing gestural, facial, and actor-orientation cues in short video clips revealed by functional MRI

How is the human brain able to process social gestures so quickly and with (seemingly) so little effort? Answering this question is one of the most pivotal ones when attempting to understand the neural basis of social cognition. This is a very important area of research given that social skills is what makes humans an inherently social species, and further since deficits in social cognition in certain clinical conditions are highly handicapping to afflicted individuals. Neuroimaging studies on the neural basis of social cognition have been rapidly increasing in number, but there have been relatively few studies where processing of several social cues (e.g., gestures, facial expressions, orientation of social gestures towards vs. away from the subjects) have been included in the same study design. 

In their recent study, Saggar et al. (2013) showed short 2-sec video clips depicting social vs. non-social gestures oriented away vs. towards the subjects and with face occluded (blurred) vs. clearly visible, during functional magnetic resonance imaging. The authors observed enhanced hemodynamic activity in amygdala and brain areas relevant for theory of mind when contrasting social vs. non-social gestures. Activity in lateral occipital cortex and precentral gyrus was further observed when comparing responses elicited by gestures towards vs. away from the subjects. Visibility of facial gestures in turn modulated activity in posterior superior temporal sulcus and fusiform gyrus. Taken together, these highly interesting findings shed light on how multiple social cues that signal information about the intentions of other persons are processed in the human brain, and significantly pave way for clinical research in patient groups with social cognition deficits. 

Reference: Saggar M, Shelly EW, Lepage J-F, Hoeft F, Reiss AL. Revealing the neural networks associated with processing of natural social interaction and the related effects of actor-orientation and face-visibility. Neuroimage (2013) e-publication ahead of print. http://dx.doi.org/10.1016/j.neuroimage.2013.09.046

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