Behavioural NeuroscienceResearch PaperInterest in infants by female rhesus monkeys with neonatal lesions of the amygdala or hippocampus
Section snippets
Experimental procedures
All experimental procedures were carried out in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals and developed through consultation with the veterinary staff at the California National Primate Research Center (CNPRC). All protocols were also approved by the University of California, Davis, Institutional Animal Care and Use Committee. Group sizes chosen represent the minimum required to achieve adequate statistical power. All efforts were made to
MRI and histological evaluation of lesions
T2-weighted images of coronal sections are illustrated in previous publications, providing substantial reassurance that the ibotenic acid was injected and was focused in the amygdaloid complex or hippocampal formation (Bauman et al 2004a, Bauman et al 2004b). The extent of the targeted lesion was confirmed in one amygdala-lesioned subject that died due to an unrelated illness and whose brain was subjected to histological evaluation of the lesion (see Fig. 2 in Bauman et al., 2004b). Analysis of
Discussion
The present study provides evidence that monkeys that received lesions to the amygdala in early infancy displayed significantly decreased species-typical interest in infants, as compared to monkeys that received lesions to the hippocampus or a control sham surgical procedure. Lesion groups differed very little in their reactions to the stimulus females prior to the birth of the infant. There were few differences between groups for the majority of behavioral measures assessed during the
Conclusion
In sum, rhesus female monkeys that sustained amygdala lesions as neonates, but not those with neonatal lesions to the hippocampus, demonstrate less species-typical interest in infants of other mothers later in life. Positioning this work within a broader picture of amygdala function is an experimental challenge for the future. One of the hallmark findings in lesion work in non-human primates and rodents is that removal of the amygdala compromises fear processing. In the present study, however,
Acknowledgments
This research was supported by a grant from the National Institute of Mental Health (R37MH57502) and by the base grant of the CNPRC (RR00169). This work was also supported through the Early Experience and Brain Development Network of the Macarthur Foundation. We thank the veterinary and husbandry staff of the CNPRC for excellent care of the animal subjects. We also thank Jeffrey Bennett and Pamela Tennant for assistance with surgical procedures, Melissa Marcucci for assistance with behavioral
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