This project investigates how rhesus monkeys and other nonhuman primate species born and raised under different laboratory conditions adapt to placement into environments that contain specific physical and social features of the monkey's natural habitat. Adaptation is assessed by examining behavioral repertoires and by monitoring a variety of physiological systems in these subjects, yielding broad-based indices of relative physical and psychological well-being. The responses of subjects to experimental manipulation of selected features of their respective environments are also assessed in similar fashion. Whenever possible, field data are collected for appropriate comparisons. An additional focus is on investigating the cognitive, behavioral, and social processes involved in adaptation to new settings or circumstances. ? ? This past year we continued to monitor maternal and fetal heart rate and blood pressure throughout the third trimester of pregnancy in several rhesus monkey females who had been surgically implanted with indwelling catheters that enabled us to record these measures online continuously via a tethering device that permitted unimpeded locomotor and exploratory activity within the caging unit. Each pregnant female subsequently successfully delivered an infant who exhibited normal neurological and behavioral postnatal development. Analyses of the prenatal data collected to date were focused on changes in maternal and fetal heart rate and blood pressure following two types of short-term experimental manipulations ? cage restraints and presentation of food treats, respectively, each of which reliably produced comparable short-term increases in maternal heart rate. Significant increases in maternal heart rate in the context of cage restraint were associated with concomitant increases in both maternal and fetal blood pressure and significant decreases in fetal heart rate, whose recovery to baseline values essentially tracked those of maternal heart rate (albeit in the opposite direction). In contrast, significant increases in maternal heart rate following presentation of food treats were not associated with any significant changes in maternal blood pressure or in either fetal heart rate or blood pressure.? ? This past year we also expanded our initial efforts to determine if rhesus monkey neonates are capable of ?imitating? specific facial expressions and hand movements directed toward them by a human ?model? in their initial days of life. Such early imitative capabilities have been reported for human neonates, and they are thought to be reflexively mediated by ?mirror? neurons, a recently characterized class of visual-motor neurons found in Area F5 of the ventral premotor cortex. We found that some (but not all) of the newborns tested were able to mimic specific facial expressions involving differential mouth and tongue movements, but not until their second or third day of life. Interestingly, those infants who demonstrated this imitative capacity spent significantly more time visually focusing on facial stimuli on Day 1 than those who did not exhibit any imitative behaviors on subsequent days. We are now carrying out follow-up behavioral observations and biological sampling of these infants to determine if individual differences in their early imitative capabilities are predictive of individual differences in their biobehavioral functioning throughout subsequent development.? ? We also expanded an ongoing program of research designed to assess emerging cognitive capabilities in nursery-reared monkeys during their initial months of life. We have long assessed infants on a variety of tests of neurobehavioral functioning throughout their first 5 weeks of life, but this past year we began assessing the development of object permanence in nursery-reared infants, starting in their 6th week. We additionally introduced these infants to a different cognitive assessment paradigm utilizing a WGTA test battery; some infants began adaptation testing at 2 months of age, others at 3 months, and the remainder at 4 months. Although the infants who began adaptation training at 2 months took longer to complete the training regiment than those who started at older ages, once trained they solved the initial discrimination task more rapidly than the other groups, suggesting that some degree of latent learning may have occurred during their adaptation training. Across all age groups, performance on the object permanence task appeared to be unrelated to performance on discrimination tasks in the WGTA test battery, suggesting that the two test paradigms are assessing qualitatively different aspects of rhesus monkey cognitive development.? ? Preventing the development of self-injurious behavior (SIB), currently exhibited by as many as 10 % of the rhesus monkeys maintained in the 8 National Primate Centers across the US, represents a major challenge for primate veterinarians and colony managers alike. Prospective longitudinal research has indicated that virtually all monkeys who engage in SIB as adults began exhibiting non-injurious self-biting behavior during their juvenile years. This past year we completed a study designed to identify risk factors for and early predictors of self-biting behavior in our colony. Incidents of self-biting were observed only in a small subset of rhesus monkeys who had been reared in the nursery with artificial surrogate ?mothers? and limited (2 hrs/day) access to peers; no self-biting was ever observed in infants reared by their biological mothers or with continuous contact with peers during their first 6 months of life. Among the surrogate-peer-reared monkeys, those individuals who engaged in the lowest level of physical contact with peers during their daily interaction sessions were the most likely to develop self-biting behavior during their juvenile years.? ? Finally, this past year we developed and pilot-tested surrogate ?mothers? designed to generate infant-initiated movement in nursery-reared monkeys by hanging the surrogates from the top of the infant?s rearing cage rather than the standard floor-mounted design that has been utilized in most primate nurseries for the past half-century. Initial comparisons of infants reared on hanging surrogates with those reared on the standard model revealed that hanging surrogate-reared infants had superior visual and auditory orienting capabilities during their first month, developmentally accelerated crawling behavior and greater activity levels in novel settings during their second month, superior performance on object permanence tests during their third month, and higher levels of locomotion and environmental exploration during months 6-8. We are currently collecting additional behavioral and biological data from these infants during their second and third years of life to see if these developmental advantages persist throughout the childhood years.
| Ruggiero, Angela M; Novak, Matthew F S X; Woodward, Ruth A et al. (2009) Successful behavioral strategy to unite mother and infant rhesus monkeys (Macaca mulatta) after cesarean delivery. Am J Primatol 71:510-22 |
| Byrne, Gayle; Suomi, Stephen J (2009) Intimate social behavior in infant interactions in Cebus apella. Am J Primatol 71:77-85 |
| Miller, Kimran E; Laszlo, Katalin; Suomi, Stephen J (2008) Why do captive tufted capuchins (Cebus apella) urine wash? Am J Primatol 70:119-26 |
| Novak, Matthew Fsx; Kenney, Caroline; Suomi, Stephen J et al. (2007) Use of animal-operated folding perches by rhesus macaques (Macaca mulatta). J Am Assoc Lab Anim Sci 46:35-43 |
| Lutz, Corrine K; Davis, Ernie B; Ruggiero, Angela M et al. (2007) Early predictors of self-biting in socially-housed rhesus macaques (Macaca mulatta). Am J Primatol 69:584-90 |
| Roma, Peter G; Silberberg, Alan; Huntsberry, Mary E et al. (2007) Mark tests for mirror self-recognition in capuchin monkeys (Cebus apella) trained to touch marks. Am J Primatol 69:989-1000 |
| Roma, Peter G; Champoux, Maribeth; Suomi, Stephen J (2006) Environmental control, social context, and individual differences in behavioral and cortisol responses to novelty in infant rhesus monkeys. Child Dev 77:118-31 |
| Roma, Peter G; Silberberg, Alan; Ruggiero, Angela M et al. (2006) Capuchin monkeys, inequity aversion, and the frustration effect. J Comp Psychol 120:67-73 |
| Silberberg, Alan; Roma, Peter G; Ruggiero, Angela M et al. (2006) On inequity aversion in nonhuman primates. J Comp Psychol 120:76 |
| Suomi, Stephen J (2005) Aggression and social behaviour in rhesus monkeys. Novartis Found Symp 268:216-22; discussion 222-6, 242-5 |
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