Long-term effects of neonatal hippocampal lesions on novelty preference in monkeys

• Type of Material: Article
• Authors: Alyson Zeamer, Emory University; Jocelyne Bachevalier, Emory University
• Language: English
• Date: 2013-09-01
• Publisher: Wiley: 12 months
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2013 Wiley Periodicals, Inc.
• Final Published Version (URL): http://dx.doi.org/10.1002/hipo.22139
• Title of Journal or Parent Work: Hippocampus
• ISSN: 1050-9631
• Volume: 23
• Issue: 9
• Start Page: 745
• End Page: 750
• Grant/Funding Information: This research was supported by the National Institute for Mental Health (MH58846), National Center for Research Resources (P51RR165 currently supported by the Office of Research Infrastructure Programs/OD P51OD11132), and the National Science Foundation (NSF IBN9876754).
• Keywords: Photic Stimulation; Neurons; incidental recognition; Time Factors; Analysis of Variance; Pattern Recognition, Visual; Animals, Newborn; developmental amnesia; Male; Animals; Follow-Up Studies; Hippocampus; Female; Brain Injuries; Macaca mulatta; Color Perception; Recognition (Psychology); memory
• Research Categories: Biology, Neuroscience; Psychology, Developmental

Abstract

In a recent longitudinal study to assess the development of incidental recognition memory processes in monkeys, we showed that the effects of neonatal hippocampal lesions did alter incidental recognition memory only when the animals reached the juvenile period (Zeamer et al.,). The current follow-up study tested whether this incidental memory loss was long-lasting, i.e., present in adulthood, or only transitory, due to functional compensation with further brain maturation. The same animals with neonatal hippocampal lesions and their sham-operated controls were re-tested in the visual paired-comparison task when they reached adulthood (48 months). The results demonstrated that, at least for easily discriminable color pictures of objects, the involvement of the hippocampus was only transitory, given that when re-tested as adults, animals with neonatal hippocampal lesions performed as well as sham-operated controls at all delays. Yet, significant recognition memory impairment was re-instated when the discriminability of the stimuli was made more difficult (black/white pictures of similar objects). The data demonstrate profound functional remodeling within the hippocampus and its interactions with different medial temporal lobe structures from the juvenile period to adulthood, which is substantiated by a parallel morphological maturation of hippocampal intrinsic circuits (Lavenex et al.,; Jabès et al., 2011).