Pre-surgical training ameliorates orbitofrontal-mediated impairments in spatial reversal learning.
We recently reported that orbitofrontal cortical (OFC) lesions impaired reversal learning of an instrumental two-lever spatial discrimination task, a deficit manifested as increased perseveration on the pre-potent response. Here we examine whether exposure to reversal learning test pre-operatively may have a beneficial effect for future reversal learning of OFC-lesioned animals. Rats were trained on a novel instrumental two-lever spatial discrimination and reversal learning task, measuring both 'cognitive flexibility' and constituent processes including response inhibition. Both levers were presented, only one of which was reinforced. The rat was required to respond on the reinforced lever under a fixed ratio 3 schedule of reinforcement. Following attainment of criterion, two reversals were introduced. Rats were then matched according to their reversal performance and subjected to bilateral excitotoxic OFC lesions. Following recovery, a series of four reversals was presented. OFC lesions impaired neither retention nor reversal phases. These data, together with the previously reported reversal deficit following OFC lesions, suggest that OFC is not needed when task experience has been gained but it is necessary when task demands are relatively high.
Boulougouris
Vasileios
V
Behavioural and Clinical Neuroscience Institute and the Department of Experimental Psychology, University of Cambridge, Cambridge CB2 3EB, United Kingdom. vb257@cam.ac.uk
Robbins
Trevor W
TW
D000818:Animals; D002540:Cerebral Cortex / Q000187:drug effects / Q000503:physiopathology; D003071:Cognition / Q000187:drug effects / Q000502:physiology*; D003216:Conditioning, Operant / Q000187:drug effects / Q000502:physiology*; D004193:Discrimination Learning / Q000187:drug effects / Q000502:physiology; D005625:Frontal Lobe / Q000187:drug effects / Q000503:physiopathology; D008297:Male; D017378:Quinolinic Acid / Q000008:administration & dosage / Q000633:toxicity; D051381:Rats; D011919:Rats, Inbred Strains; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D012055:Reinforcement Schedule; D012054:Reinforcement, Psychology; D012193:Reversal Learning / Q000187:drug effects / Q000502:physiology*; D013028:Space Perception / Q000187:drug effects / Q000502:physiology; D013037:Spatial Behavior / Q000187:drug effects / Q000502:physiology*
D017378:Quinolinic Acid