Neural correlates of maternal separation in rhesus monkeys.
BACKGROUND
The neurobiological basis of stress and anxiety in primates remains poorly understood. In this study, we examined the neural response to a naturalistic social stressor: maternal separation. We used rhesus monkeys as an animal model because of their close phylogenetic affinity with humans.


METHODS
Six juvenile rhesus monkeys received [(18)F]-fluorodeoxyglucose positron emission tomography scans following 1) a period together with their mothers and again after separation from their mothers 2) with or 3) without visual contact. Image subtraction revealed brain regions that exhibited altered activity during separation. In addition, plasma cortisol concentrations obtained following each condition were tested for correlations with regional brain activity.


RESULTS
Maternal separation activated the right dorsolateral prefrontal cortex and the right ventral temporal/occipital lobe. There was also decreased activity in left dorsolateral prefrontal cortex associated with separation stress. Correlational analyses demonstrated these activated and deactivated regions to be positively and negatively correlated with cortisol, respectively. Additionally, correlational analyses revealed cortisol-related activation in brainstem areas previously implicated in stress and anxiety.


CONCLUSIONS
In juvenile rhesus monkeys, the stress of maternal separation is associated with activation in the right dorsolateral prefrontal cortex and ventral temporal/occipital lobes and decreased activity in the left dorsolateral prefrontal cortex.
Rilling
J K
JK
Department of Psychiatry and Behavioral Sciences, Emory University, 1639 Pierce Drive, Suite 4000 Woodruff Memorial Research Building, Atlanta, GA 30322, USA.
Winslow
J T
JT
O'Brien
D
D
Gutman
D A
DA
Hoffman
J M
JM
Kilts
C D
CD
D000374:Aggression; D000818:Animals; D001010:Anxiety, Separation / Q000000981:diagnostic imaging / Q000503:physiopathology*; D001921:Brain / Q000000981:diagnostic imaging / Q000502:physiology*; D019788:Fluorodeoxyglucose F18; D005625:Frontal Lobe / Q000473:pathology; D006854:Hydrocortisone / Q000097:blood; D007091:Image Processing, Computer-Assisted; D008253:Macaca mulatta; D008279:Magnetic Resonance Imaging; D008297:Male; D008425:Maternal Behavior / Q000502:physiology; D019275:Radiopharmaceuticals; D012931:Social Environment; D013315:Stress, Psychological / Q000000981:diagnostic imaging / Q000503:physiopathology; D014055:Tomography, Emission-Computed
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D006854:Hydrocortisone