Distinct amygdala–autonomic arousal profiles in response to fear signals in healthy males and females

• Published in: NeuroImage (Orlando, Fla.) Vol. 28; no. 3; pp. 618 - 626
• Main Authors: Williams, Leanne M., Barton, Matthew J., Kemp, Andrew H., Liddell, Belinda J., Peduto, Anthony, Gordon, Evian, Bryant, Richard A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.11.2005; Elsevier Limited
• Subjects: Adult; Amygdala; Amygdala - physiology; Arousal - physiology; Autonomic Nervous System - physiology; Brain; Data Interpretation, Statistical; Facial emotion; Facial Expression; Fear; Fear - physiology; Female; Functional Laterality - physiology; Functional MRI; Galvanic Skin Response - physiology; Gender differences; Humans; Image Processing, Computer-Assisted; Male; Males; Medical imaging; Rodents; Sex Characteristics; Sex differences; Skin conductance; Studies; Fear; Sex differences; Skin conductance; Functional MRI; Amygdala; Facial emotion
• ISSN: 1053-8119; 1095-9572
• DOI: 10.1016/j.neuroimage.2005.06.035

The amygdala has a key role in regulating arousal and vigilance, and responds to both visual and vocal signals of fear, including facial expressions of fear. In this study, we used functional MRI to examine sex differences in the magnitude, extent, lateralization and time course of amygdala responses to facial signals of fear, in a relatively large sample of males and females. Skin conductance was recorded simultaneously with functional imaging to examine concomitant changes in emotional arousal, and to provide an independent index of response attenuation. Scanning and skin conductance recording was undertaken during perception of facial fear stimuli. Sex differences were apparent in the laterality and time course of fear perception. In males, the right amygdala and autonomic arousal attenuated over the late half of the experiment. By contrast, females showed persistent bilateral amygdala responses, with a tendency towards greater left amygdala engagement during the late phase. Females also showed a greater general extent of amygdala response. We suggest that distinct evolutionary pressures might contribute to a lower threshold for vigilance to signals of danger in females, reflected in a profile of sustained amygdala–arousal interaction.