Neonatal Hippocampal Damage Impairs Specific Food/Place Associations in Adult Macaques

• Type of Material: Article
• Authors: Courtney Glavis-Bloom, Emory University; Maria Alvarado, Emory University; Jocelyne Bachevalier, Emory University
• Language: English
• Date: 2013-02
• Publisher: American Psychological Association
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2013 American Psychological Association
• Final Published Version (URL): http://www.apa.org/
• Title of Journal or Parent Work: Behavioral Neuroscience
• ISSN: 0735-7044
• Volume: 127
• Issue: 1
• Start Page: 9
• End Page: 22
• Grant/Funding Information: This work was supported by the National Institute of Mental Health (MH-58846), National Center for Research Resources P51RR165, and is currently supported by the Office of Research Infrastructure Programs/OD P51OD11132, and by Center for Behavioral Neuroscience grant NSF IBN-9876754.
• Keywords: episodic; monkey; hippocampus; spatial; memory
• Research Categories: Biology, Neuroscience; Psychology, Behavioral

Abstract

This study describes a novel spatial memory paradigm for monkeys and reports the effects of neonatal damage to the hippocampus on performance in adulthood. Monkeys were trained to forage in eight boxes hung on the walls of a large enclosure. Each box contained a different food item that varied in its intrinsic reward value, as determined from food preference testing. Monkeys were trained on a spatial and a cued version of the task. In the spatial task, the boxes looked identical and remained fixed in location whereas in the cued task, the boxes were individuated with colored plaques and changed location on each trial. Ten adult Rhesus macaques (5 neonatal sham-operated and 5 with neonatal neurotoxic hippocampal lesions) were allowed to forage once daily until they preferentially visited boxes containing preferred foods. The data suggest that all monkeys learned to discriminate preferred from nonpreferred food locations, but that monkeys with neonatal hippocampal damage committed significantly more working memory errors than controls in both tasks. Furthermore, following selective satiation, controls altered their foraging pattern to avoid the satiated food, whereas lesioned animals did not, suggesting that neonatal hippocampal lesions prohibit learning of specific food-place associations. We conclude that whereas an intact hippocampus is necessary to form specific item-in-place associations, in its absence, cortical areas may support more broad distinctions between food types that allow monkeys to discriminate places containing highly preferred foods.