title: Population variation in neuroendocrine activity is associated with behavioral inhibition and hemispheric brain structure in young rhesus monkeys.
abstract: Population variation in hypothalamic-pituitary-adrenal (HPA) activity and reactivity was assessed in a healthy sample of 48 juvenile rhesus monkeys. Cluster analysis of the HPA profiles revealed four distinct neuroendocrine phenotypes based on six indices of HPA functioning. Behavioral reactivity was also evaluated in response to novel stimuli, and revealed marked differences between animals in the highest- and lowest-cortisol clusters. Specifically, animals in the high-cortisol cluster showed larger stress-induced cortisol responses and blunted feedback sensitivity to dexamethasone. They were also emotionally reactive, displayed more aggressive behaviors, and were less likely to approach novel objects. In contrast, monkeys in the low-cortisol cluster were more likely to approach and explore novel objects. Representative animals with high or low cortisol profiles were scanned with Magnetic Resonance Imaging to evaluate structural differences in global and regional gray matter (GM) and white matter (WM) volumes. Monkeys with higher cortisol reactivity evinced less hemispheric brain asymmetry, due to decreased GM in the right hemisphere. Stress reactivity was inversely related to global GM and positively related to total cerebrospinal fluid volume. This inverse relationship was also observed in several stress-sensitive regions, including prefrontal and frontal cortices. Our study demonstrates that population variation in pituitary-adrenal activity is related to behavioral disposition and cerebral structure in this nonhuman primate species.
authors: Department of Psychiatry, University of North Carolina, Chapel Hill, NC 27599, USA. Electronic address: sjshort@med.unc.edu.
authors: Sarah J
authors: SJ
authors: Short
authors: Harlow Center for Biological Psychology, University of Wisconsin, Madison, WI 53715, USA.
authors: Gabriele R
authors: GR
authors: Lubach
authors: Department of Human Development and Family Studies, Iowa State University, Ames, IA 50011, USA.
authors: Elizabeth A
authors: EA
authors: Shirtcliff
authors: Department of Psychiatry, University of North Carolina, Chapel Hill, NC 27599, USA; Department of Computer Science, University of North Carolina, Chapel Hill, NC 27599, USA.
authors: Martin A
authors: MA
authors: Styner
authors: Department of Psychiatry, University of North Carolina, Chapel Hill, NC 27599, USA.
authors: John H
authors: JH
authors: Gilmore
authors: Harlow Center for Biological Psychology, University of Wisconsin, Madison, WI 53715, USA.
authors: Christopher L
authors: CL
authors: Coe
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D001921:Brain / Q000033:anatomy & histology* / Q000473:pathology; D005260:Female; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology*; D007266:Inhibition, Psychological; D008253:Macaca mulatta / Q000033:anatomy & histology / Q000502:physiology; D008279:Magnetic Resonance Imaging; D008297:Male; D009490:Neurosecretory Systems / Q000502:physiology*; D009929:Organ Size; D010641:Phenotype; D010913:Pituitary-Adrenal System / Q000502:physiology*; D013315:Stress, Psychological / Q000473:pathology / Q000503:physiopathology
keywords: Behavioral inhibition; Brain structure; Cluster analysis; Cortisol; Emotionality; Hemispheric symmetry; Monkey