Pervasive alterations of emotional and neuroendocrine responses to an acute stressor after neonatal amygdala lesions in rhesus monkeys

• Type of Material: Article
• Authors: Jessica Raper, Emory University; Mark Wilson, Emory University; Mar Sanchez, Emory University; Christopher J. Machado, University of California; Jocelyne Bachevalier, Emory University
• Language: English
• Date: 2013-07
• Publisher: Elsevier
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2012 Elsevier Ltd. All rights reserved.
• License: Creative Commons Attribution-NonCommerical-NoDerivs 3.0 Unported
• Final Published Version (URL): http://dx.doi.org/10.1016/j.psyneuen.2012.10.008
• Title of Journal or Parent Work: Psychoneuroendocrinology
• ISSN: 0306-4530
• Volume: 38
• Issue: 7
• Start Page: 1021
• End Page: 1035
• Grant/Funding Information: The studies were also supported by the Center for Behavioral Neuroscience (NSF IBN 9876754), and Integrated Training in Psychobiology and Psychopathology Fellowship (NIMH T32 MH732505), as well as by the National Center for Research Resources to the Yerkes National Research Center (P51 RR00165; YNRC Base grant) which is currently supported by the Office of Research Infrastructure Programs/OD P51OD11132.; This research was supported by the National Institute for Mental Health (MH58846 & MH050268) and the National Institute for Child Health and Human Development (NICHD35471).
• Keywords: Emotion; Development; Amygdala; HPA-axis
• Research Categories: Health Sciences, Mental Health; Psychology, Behavioral

Abstract

The current study examined the long-term effects of neonatal amygdala lesions on emotional and hypothalamic-pituitary-adrenal (HPA) axis reactivity to an acute stressor in rhesus monkeys. Rhesus monkeys received either bilateral MRI-guided ibotenic acid amygdala (Neo-Aibo; n = 6) or sham (Neo-C; n = 7) lesions between 7–14 days of age. Emotional reactivity was assessed using the Human Intruder paradigm at 2 months, 4.5 months, and 6–8 years of age, whereas stress neuroendocrine response was only assessed in adulthood (6–8 years). The modulation of defensive and emotional behaviors based on the gaze direction of the intruder emerged between 2–4 months of age in surrogate-peer reared sham-operated infant monkeys, as already shown for mother-reared infants. Although neonatal amygdala lesions did not impair the ability to exhibit defensive and emotional behaviors, it altered the modulation of these responses based on the intruder’s gaze direction. The changes in emotional reactivity after neonatal amygdala lesions emerged in infancy and persisted throughout adulthood when they were associated with a reduction of basal cortisol levels and a blunted cortisol response to the stressor. These changes are reminiscent of those found after adult-onset amygdala lesions, demonstrating little functional compensation following early amygdala damage.