title: Pupillary contagion: central mechanisms engaged in sadness processing.
abstract: Empathic responses underlie our ability to share emotions and sensations with others. We investigated whether observed pupil size modulates our perception of other's emotional expressions and examined the central mechanisms modulated by incidental perception of pupil size in emotional facial expressions. We show that diminishing pupil size enhances ratings of emotional intensity and valence for sad, but not happy, angry or neutral facial expressions. This effect was associated with modulation of neural activity within cortical and subcortical regions implicated in social cognition. In an identical context, we show that the observed pupil size was mirrored by the observers' own pupil size. This empathetic contagion engaged the brainstem pupillary control nuclei (Edinger-Westphal) in proportion to individual subject's sensitivity to this effect. These findings provide evidence that perception-action mechanisms extend to non-volitional operations of the autonomic nervous system.
authors.affiliation: Wellcome Department of Imaging Neuroscience, Institute of Neurology and Institute of Cognitive Neuroscience, University College London, UK. n.harrison@fil.ion.ucl.ac.uk
authors.forename: Neil A
authors.initials: NA
authors.lastname: Harrison
authors.forename: Tania
authors.initials: T
authors.lastname: Singer
authors.forename: Pia
authors.initials: P
authors.lastname: Rotshtein
authors.forename: Ray J
authors.initials: RJ
authors.lastname: Dolan
authors.forename: Hugo D
authors.initials: HD
authors.lastname: Critchley
mesh_terms: D000328:Adult; D000339:Affect; D004645:Empathy; D005149:Facial Expression; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011681:Pupil Disorders / Q000175:diagnosis* / Q000503:physiopathology*; D012938:Social Perception; D014796:Visual Perception