Measuring reward assessment in a semi-naturalistic context: The effects of selective amygdala, orbital frontal or hippocampal lesions

• Type of Material: Article
• Authors: Christopher J. Machado, University of Texas Houston; Jocelyne Bachevalier, Emory University
• Language: English
• Date: 2007-09-07
• Publisher: Elsevier: 12 months
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2007 IBRO.
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1016/j.neuroscience.2007.06.035
• Title of Journal or Parent Work: Neuroscience
• ISSN: 0306-4522
• Volume: 148
• Issue: 3
• Start Page: 599
• End Page: 611
• Grant/Funding Information: This work was supported by grants from the National Institutes of Mental Health (MH- 58846), the National Institute of Child Health and Human Development (HD-35471), and the National Institutes of Health (RR00165) to Dr. Bachevalier, and by a National Research Service Award Predoctoral Fellowship from the National Institutes of Mental Health (MH-63577) to Dr. Machado.
• Keywords: Denervation; Behavior, Animal; Macaca mulatta; Brain Injuries; Hippocampus; Reward; Male; Goals; Amygdala; Species Specificity; Prefrontal Cortex; Neuropsychological Tests; Animals; Feeding Behavior; Decision Making; Reinforcement (Psychology)
• Research Categories: Psychology, Behavioral; Biology, Neuroscience

Abstract

Studying the neural mechanisms underlying complex goal-directed behaviors, such as social behavior, reward seeking or punishment avoidance, has become increasingly tractable in humans, nonhuman primates and rodents. In most experiments, however, goal-directed behaviors are measured in a laboratory setting, which is vastly different from the context in which these behaviors naturally occur. This study adapted a reward assessment paradigm, previously conducted with rhesus monkeys (Macaca mulatta) in the controlled environment of a Wisconsin General Testing Apparatus (WGTA) [Machado CJ, Bachevalier J (2007) The effects of selective amygdala, orbital frontal cortex or hippocampal formation lesions on reward assessment in nonhuman primates. Eur J Neurosci 25:2885-2904], to a more naturalistic context. We used this new paradigm to examine the effects of bilateral amygdaloid, hippocampal or orbital frontal cortex lesions on established food and nonfood preferences. Behavioral modification following reinforcer devaluation was also measured. Consistent with our previous study, none of the lesions produced changes in preference for palatable foods relative to pre-surgery, but animals with amygdala lesions displayed heightened preference for unpalatable foods that control or other operated animals typically avoided. In contrast to several previous WGTA-based experiments, nonfood preference was not affected by any of the lesions. Finally, animals with orbital frontal cortex lesions continued to select preferred foods after satiation, but those with amygdala, hippocampal or sham lesions altered their foraging behavior appropriately and selected less of the sated food. These findings parallel food devaluation results obtained with these same animals when tested in the WGTA. Overall, this study stresses the importance of testing context when measuring decision-making abilities in nonhuman primates with selective brain lesions.