Neural representations of perceived engagement during action observation

Area of Science:

• Neuroscience
• Social Cognition
• Cognitive Neuroscience

Background:

• Interpersonal motor interactions are fundamental to social functioning.
• The neural basis for encoding social cues related to engagement during these interactions is not fully understood.
• The dorsomedial prefrontal cortex (dmPFC) and temporo-parietal junction (TPJ), traditionally linked to mentalizing, show co-activation with the Action Observation Network (AON) during social motor engagement.

Purpose of the Study:

• To investigate how the brain encodes perceived engagement during observed actions.
• To explore the representational geometry within social cognition and sensorimotor brain regions during action observation.
• To determine the distinct roles of the TPJ, dmPFC, and AON in processing action features and engagement cues.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was employed to measure brain activity.
• Representational Similarity Analysis (RSA) was used to compare neural patterns with computational models.
• Participants observed reach-to-grasp actions manipulated for Goal, Perspective, and Gaze visibility to create a gradient of perceived engagement.

Main Results:

• Convergent representational geometry was observed between the TPJ and AON during action observation.
• The right temporo-parietal cortex exhibited a graded organization, with specific subregions encoding perspective (rTPJ), goal (superior temporal regions), and engagement (rIPL).
• The rTPJ and left premotor cortex shared representational geometry for action direction, while the dmPFC showed isolated activity and did not encode action features or engagement.

Conclusions:

• Social engagement cues are encoded through a distributed, sensorimotor network, rather than solely by higher-level mentalizing regions like the dmPFC.
• The findings reveal functional links between mentalizing areas (TPJ) and sensorimotor systems (AON) in processing social interaction cues.
• The study supports a sensorimotor account of engagement encoding and highlights specific roles for TPJ subregions in processing social-motor information.