Behavioral and hormonal effects of attachment object separation in surrogate-peer-reared and mother-reared infant rhesus monkeys.
ABSTRACT Mother-reared and surrogate-peer-reared rhesus monkeys were separated from their respective attachment objects at 6 months of age and tested for the following 9 weeks to determine their home-cage behavior and their pituitary-adrenocortical responses to stress. Both groups displayed a strong immediate behavioral response to separation which was characterized by increased vocalization, increased locomotion, and decreased self-play. However, the surrogate-peer-reared infants showed a subsequent recovery in their levels of self-play whereas the mother-reared infants instead developed stereotypic behavior patterns such as repetitive pacing. The 2 groups displayed similar plasma cortisol responses to weekly sessions in an apparatus equipped with animated toy "monsters". Mother-reared but not surrogate-peer-reared subjects, however, also manifested elevated cortisol levels when an animal in an adjacent cage was captured and removed for stress testing. Mother-reared infant monkeys thus responded in a stronger and more prolonged manner to the loss of their attachment object than surrogate-peer-reared infants. These results suggest that infant rhesus monkeys form stronger attachments to monkey mothers than to inanimate surrogate mothers, a phenomenon which has not been as clearly demonstrated using other indices of attachment strength.
SourceAvailable from: Amanda M Dettmer[Show abstract] [Hide abstract]
ABSTRACT: This report reviews the scientific literature from the past several decades that focuses on nonhuman primates (NHPs) as models of neuropsychiatric disorders, including anxiety, and alcoholism. In particular, we highlight the approaches, advantages, and disadvantages of the rearing, genetic, and epigenetic methodologies behind these studies as a means of evaluating the application of these methods in assessing disorders in NHPs as models of human disease. Finally, we describe the contributions the NHP studies have made to neuropsychiatric research and areas for future research.ILAR journal / National Research Council, Institute of Laboratory Animal Resources 09/2014; 55(2):361-70. DOI:10.1093/ilar/ilu025 · 1.05 Impact Factor
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ABSTRACT: Growing evidence suggests that early social deprivation impacts the activity of the hypothalamic-pituitary-adrenocortical axis. Early adverse care in the form of institutional or orphanage care provides a human model for early social deprivation. The present study examined changes in diurnal cortisol during the transition to family care in the first 2 years post-adoption. Children adopted between 15 and 36 months from institutional care were examined four times during their first 2 years post-adoption (N=58). Comparison groups included same-aged peers reared in their birth families (N=50) and children adopted during their first year from overseas foster care (N=47). Children provided daily cortisol samples at roughly 2, 9, 17, and 25 months post-adoption. Post-institutionalized and post-foster care children exhibited less steep diurnal cortisol compared to non-adopted same-aged peers; these differences did not diminish across the 2 year period. For post-institutionalized children, lower social care quality in institutions was associated with less steep cortisol slopes. Lastly, shallower diurnal cortisol was a mediator between adoption status and increased behavioral problems 2 years post-adoption. Consistent with the non-human primate literature, early social deprivation may contribute to early programming of the HPA axis.Psychoneuroendocrinology 08/2014; 50C:1-13. DOI:10.1016/j.psyneuen.2014.07.028 · 5.59 Impact Factor
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ABSTRACT: Animals develop relationships with intra- and interspecific partners, including humans. In some cases this can lead to strong emotional bonds indicating the existence of attachment. The sheep is well known to develop various forms of social attachment (mothers towards young, lambs towards siblings). The relationship they can develop with humans is much less understood. In this review, based on the attachment theory framework developed in human infants, we outline features and mechanisms that participate in the development and the expression of affiliative behaviours that lambs can develop with their mother or a human. Behavioural tests comparing responses towards a presumed attachment figure with those directed towards unfamiliar or familiar conspecifics demonstrate that lambs do search specifically the proximity of their mother or human caregiver. Differential emotional responses in the presence (calmness) or the absence of the partner (agitation) are also expressed. However, a relationship with a human takes place more easily when lambs are reared without their primary attachment figure, the mother. Human-lamb attachment is then facilitated by positive social contacts (gentling, hand-feeding) provided by a specific caregiver. In the case of attachment with the mother, suckling is the main reward. Although the existence of a sensitive period is still unclear, in both cases attachment develops more rapidly if positive interactions take place immediately after birth. Three neurochemical systems have profound impact on the expression of filial attachment in sheep: the gut peptide cholecystokinin, endogenous opioids, and oxytocin, all known to play a key role in prosocial behaviours in mammals. In addition, positive nutritive or non-nutritive interactions activate specific brain regions that are involved in the expression of social and emotional behaviours. In conclusion, lambs do develop intra- and interspecific attachment but not in a concomitant manner as the presence of the mother strongly reduces their motivation to interact with a human. Nonetheless, under artificial rearing conditions the human becomes a salient attachment figure.Applied Animal Behaviour Science 10/2014; DOI:10.1016/j.applanim.2014.09.013 · 1.63 Impact Factor