title: Preserved stimulus-reward and reversal learning after selective neonatal orbital frontal areas 11/13 or amygdala lesions in monkeys.
abstract: Neither lesions of orbital frontal (OFC) areas 11/13 nor selective amygdala lesions alter the ability to learn stimulus-reinforcer association and reversal discriminations in adult monkeys. Here, we investigated whether the same conclusion will hold true when the same lesions occur in infancy. Infant rhesus monkeys received sham-operations, neurotoxic amygdala lesions, or aspiration OFC 11/13 lesions at 8-15 days of age and were trained on object discrimination reversal (ODR) tasks. Performance on a single pair (1-Pair) ODR was assessed at the age of 3 months and 3 years, and then animals were tested in a 5-Pair ODR task in which they had to concurrently learn and reverse five discrimination problems. The results indicated that the ability to solve a single-pair discrimination problem followed by six reversals appears to be late maturing in monkeys but is spared following selective lesions of either OFC areas 11/13 or amygdala, even with the use of the more challenging 5-object ODR task. Finally, performance in the 1 and 5-Pair ODR at 3 years was comparable to that following adult-onset lesions, indicating that neither OFC areas 11/13 nor amygdala are critical for the development of reversal learning.
authors.affiliation: Department of Psychology and Yerkes National Primate Research Center, Emory University, 954 Gatewood Road, Atlanta, GA 30329, USA.
authors.forename: Andy M
authors.initials: AM
authors.lastname: Kazama
authors.forename: Jocelyne
authors.initials: J
authors.lastname: Bachevalier
mesh_terms: D000679:Amygdala / Q000254:growth & development / Q000293:injuries / Q000502:physiology*; D000818:Animals; D001930:Brain Injuries / Q000503:physiopathology*; D004192:Discrimination, Psychological / Q000502:physiology; D005260:Female; D005625:Frontal Lobe / Q000254:growth & development / Q000293:injuries / Q000502:physiology*; D007266:Inhibition, Psychological; D008253:Macaca mulatta; D008279:Magnetic Resonance Imaging; D008297:Male; D009483:Neuropsychological Tests; D011597:Psychomotor Performance / Q000502:physiology; D012193:Reversal Learning / Q000502:physiology*; D012201:Reward