The effect of orbital prefrontal cortex lesions on performance on a progressive ratio schedule: implications for models of inter-temporal choice.
In a previous experiment [Kheramin S, Body S, Mobini S, Ho M-Y, Velazquez-Martinez DN, Bradshaw CM, et al. Effects of quinolinic acid-induced lesions of the orbital prefrontal cortex on inter-temporal choice: a quantitative analysis. Psychopharmacology 2002;165: 9-17], destruction of the orbital prefrontal cortex (OPFC) in rats altered choice between two delayed food reinforcers, enhancing preference for the larger reinforcer. Theoretical analysis based on a quantitative model of inter-temporal choice [Ho M-Y, Mobini S, Chiang T-J, Bradshaw CM, Szabadi E. Theory and method in the quantitative analysis of 'impulsive choice' behaviour: implications for psychopharmacology. Psychopharmacology 1999;146:362-72] indicated that the lesion had increased the relative value of the larger of the two reinforcers due to a general reduction of absolute reinforcer value. The present experiment tested this hypothesis using a reinforcement schedule that did not entail either explicit choice or delayed reinforcement. Ten rats received quinolinic acid-induced lesions of the OPFC, and ten rats received sham lesions. The rats were trained under a progressive-ratio schedule of food reinforcement for 60 daily sessions. Response rates in successive ratios were a bitonic (inverted-U) function of ratio size. Analysis of the data using a three-parameter equation derived from a quantitative model of ratio schedule performance [Killeen PR. Mathematical principles of reinforcement. Behav. Brain Sci. 1994;17:105-72] revealed that the parameter specifying hypothetical reinforcer value was significantly lower in the OPFC-lesioned group than in the sham-lesioned group, consistent with the hypothesis that destruction of the OPFC resulted in devaluation of the food reinforcer.
Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Room B109, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK.
S
S
Kheramin
S
S
Body
F Miranda
FM
Herrera
C M
CM
Bradshaw
E
E
Szabadi
J F W
JF
Deakin
I M
IM
Anderson
D000818:Animals; D001070:Appetitive Behavior / Q000502:physiology*; D001931:Brain Mapping; D002755:Choice Behavior / Q000502:physiology*; D003216:Conditioning, Operant / Q000502:physiology; D004193:Discrimination Learning / Q000502:physiology; D005247:Feeding Behavior / Q000502:physiology; D005260:Female; D008962:Models, Theoretical; D009042:Motivation; D017397:Prefrontal Cortex / Q000502:physiology*; D017378:Quinolinic Acid; D051381:Rats; D017208:Rats, Wistar; D013998:Time Perception / Q000502:physiology*
D017378:Quinolinic Acid