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Impacts of early social experience on cognitive development in infant rhesus macaques
Ashley M Murphy1,2,3, Amanda M Dettmer3,4
1Neuroscience and Behavior, California National Primate Research Center, Davis, CA, USA.
Insights
Mother-peer-reared (MPR) rhesus macaque infants showed higher affective reactivity than nursery-reared (NR) infants. Early reactivity correlated with later impulsivity, impacting cognitive task performance.
Area of Science:
- Developmental Psychology
- Neuroscience
- Primatology
Background:
- Early life experiences significantly shape neurobiology and behavior in macaque models.
- Limited research exists on the impact of early rearing on cognitive development in macaques.
Purpose of the Study:
- To investigate the effects of rearing conditions on affective reactivity and cognitive development in infant rhesus macaques.
- To compare mother-peer-reared (MPR) and nursery-reared (NR) infant macaques.
Main Methods:
- Infant rhesus macaques were assigned to either nursery-reared (NR) or mother-peer-reared (MPR) conditions.
- The Primate Neonatal Neurobehavioral Assessment (PNNA) was administered during the first month.
- Cognitive tasks assessing reward association, cognitive flexibility, and impulsivity were conducted starting at 4 months.
Main Results:
- No significant gross cognitive differences were observed between MPR and NR infants.
- MPR infants exhibited higher affective reactivity on the PNNA compared to NR infants.
- Early affective reactivity (PNNA) correlated with later impulsivity, with more reactive infants performing worse on cognitive tasks.
Conclusions:
- Rearing conditions influence affective reactivity in infant macaques.
- Early temperament, specifically affective reactivity, is linked to later cognitive control and impulsivity.
- Findings highlight the critical role of early social experiences in primate development.
Abstract:
Although much is known about the influences of early life experiences on the neurobiology and behavior of macaque models of child development, there is scant literature on cognitive development with respect to early rearing. Here, we examined the effects of rearing condition on affective reactivity and cognitive development in infant rhesus macaques. Infants were pseudo-randomly assigned to one of the two rearing conditions: nursery reared (NR, N = 32; 16 peer-reared, 16 surrogate-peer-reared) or mother-peer-reared (MPR, N = 7). During the first month of life, infants were administered the Primate Neonatal Neurobehavioral Assessment (PNNA). Beginning at 4 months old, infants were tested on cognitive tasks that assessed reward association, cognitive flexibility, and impulsivity. We found no gross cognitive differences between MPR and NR infants. However, MPR infants were more reactive than NR infants on the PNNA. Additionally, reactivity on the PNNA correlated with impulsivity, such that infants who were more reactive at 1 month of age completed fewer trials correctly on this task at 8-10 months. These findings are the first to directly compare cognitive development in MPR and NR infants, and add to the existing literature elucidating the influences of early social experience on temperament and development.
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