Widespread and lateralized social brain activity for processing dynamic facial expressions

Area of Science:

• Neuroscience
• Social Cognitive Neuroscience

Background:

• Dynamic facial expressions are crucial for social communication.
• Previous neuroimaging studies show inconsistent brain region activation for facial expression processing.
• Laterality of activated regions is rarely evaluated.

Purpose of the Study:

• Investigate neural mechanisms of dynamic facial expression processing.
• Clarify inconsistencies in brain activation across studies.
• Evaluate the laterality of activated brain regions.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used.
• A sample of 51 participants observed dynamic facial expressions (anger, happiness) and dynamic mosaics.
• Laterality was assessed by comparing original and flipped images.

Main Results:

• Dynamic facial expressions, versus mosaics, enhanced activity in bilateral posterior cortices (occipital, fusiform, superior temporal sulci).
• Bilateral limbic regions (amygdalae, ventromedial prefrontal cortex) were more activated by dynamic expressions.
• Right inferior frontal gyrus (IFG) and left cerebellum showed activation; laterality analyses revealed right dominance in STS/IFG and left in cerebellum.

Conclusions:

• Neural mechanisms for dynamic facial expressions involve extensive social brain networks.
• These networks encompass perceptual, emotional, and motor functions.
• A lateralized network (right cortex, left cerebellum) is involved, analogous to language processing.