Similar to the human findings, in studies with monkeys, the presence of the mother buffers elevations of cortisol to threat, even in the absence of physical contact (Wiener et al., 1990). Disturbing the attachment relationship in Rhesus can produce long-term changes in ACTH and GC activity and in cerebral spinal fluid concentrations of CRH (Coplan et al., 1996). The few studies with monkeys that have examined naturally-occurring variations in parental care and GC responses to stressful stimulation implicate variations in maternal responsiveness as critical in determining whether the presence of the mother is capable of buffering the infant’s HPA responses to stressors. Following a two week separation, for example, Rhesus infants whose mothers had been non-responsive (rejecting) of the infants’ bids prior to the separation exhibited elevations in cortisol to reunion, while for those whose mothers were responsive to their signals, reunion produced a marked decrease in cortisol levels (Gunnar et al., 1981). Additionally, as noted earlier, CSF serotonin metabolites in maltreated and control Rhesus infants varied with how much the mother rejected their bids for attention, not with the
