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.
Kheramin
S
S
Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Room B109, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK.
Body
S
S
Herrera
F Miranda
FM
Bradshaw
C M
CM
Szabadi
E
E
Deakin
J F W
JF
Anderson
I M
IM
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