Dynamic pupillary exchange engages brain regions encoding social salience

Area of Science:

• Neuroscience
• Social Psychology
• Autonomic Nervous System Research

Background:

• Covert autonomic responses, like pupillary mirroring, influence social-affective behavior.
• Pupillary responses are a key indicator of autonomic nervous system activity and emotional processing.

Purpose of the Study:

• To investigate how dynamic coherence between one's own and another's pupil size modulates brain activity, independent of facial expressions.
• To explore the neural correlates of processing congruent and incongruent pupillary signals during social interaction.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to measure brain activity in 14 participants.
• Continuous pupillometry with biofeedback dynamically altered the size of observed pupils, correlating them with participants' own pupillary changes.
• Participants viewed static and dynamic eye stimuli, including conditions with positively or negatively correlated pupil size changes.

Main Results:

• Viewing both static and dynamic stimuli activated the right fusiform gyrus.
• Dynamic pupillary changes engaged the superior temporal sulcus (STS) and amygdala.
• Pupillary discordance enhanced activity in the anterior insula, amygdala, and anterior cingulate cortex.
• Congruent pupillary changes increased activity in the left frontal operculum.

Conclusions:

• Pupillary signals are continuously monitored during social interactions.
• Incongruent pupillary changes activate brain regions associated with motivational salience and attention.
• Autonomic synchrony and asynchrony in pupillary responses provide insights into social dynamics and internal states.