title: Human amygdala sensitivity to the pupil size of others.
abstract: Stimulation of the amygdala produces pupil dilation in animal and human subjects. The present study examined whether the amygdala is sensitive to variations in the pupil size of others. Male subjects underwent event-related functional magnetic resonance imaging while passively viewing unfamiliar female faces whose pupils were either unaltered (natural variations in large and small pupils) or altered to be larger or smaller than their original size. Results revealed that the right amygdala and left amygdala/substantia innominata were sensitive to the pupil size of others, exhibiting increased activity for faces with relatively large pupils. Upon debrief, no subject reported being aware that the pupils had been manipulated. These results suggest a function for the amygdala in the detection of changes in pupil size, an index of arousal and/or interest on the part of a conspecific, even in the absence of explicit knowledge.
authors: Department of Psychological and Brain Sciences, Center for Cognitive Neuroscience, Dartmouth College, Hanover, NH 03755, USA. kathryn.e.demos@dartmouth.edu
authors: K E
authors: KE
authors: Demos
authors: W M
authors: WM
authors: Kelley
authors: S L
authors: SL
authors: Ryan
authors: F C
authors: FC
authors: Davis
authors: P J
authors: PJ
authors: Whalen
mesh_terms: D000293:Adolescent; D000679:Amygdala / Q000502:physiology*; D001143:Arousal / Q000502:physiology; D003463:Cues; D005149:Facial Expression; D005260:Female; D007839:Functional Laterality; D006801:Humans; D019359:Knowledge; D008297:Male; D011680:Pupil / Q000502:physiology*; D014792:Visual Acuity; D014796:Visual Perception / Q000502:physiology; D055815:Young Adult