Re-evaluation of an animal model for ADHD using a free-operant choice task.
Previous research using free-operant procedures have reported that the Spontaneously Hypertensive Rat (SHR) is more impulsive and inattentive than the Wistar-Kyoto (WKY) rat. Recently these behavioural differences have been suggested to be a consequence of differences in the overall activity of these strains. This study compared SHRs to WKYs on locomotor activity and delay sensitivity using a delayed reinforcement (DR) and extinction (EXT) task. SHRs maintained higher locomotor activity than WKYs, however no significant group differences were found on the total lever presses in the DR or EXT tasks. During the DR task, SHRs shifted to selecting the immediate small reinforcer significantly faster than WKYs as the delay increased. WKYs predominantly selected the lever previously associated with the delayed large reinforcer throughout the EXT task, while the SHRs showed no such preference. The significant group differences found on lever selection during the DR and EXT tasks suggests that SHRs are more sensitive to delays, therefore providing further support for the face validity of the SHR as an animal model of ADHD.
Pardey
Margery C
MC
Department of Psychology, Macquarie University, Sydney, New South Wales 2109, Australia.
Homewood
Judi
J
Taylor
Alan
A
Cornish
Jennifer L
JL
D000704:Analysis of Variance; D000818:Animals; D001289:Attention Deficit Disorder with Hyperactivity / Q000503:physiopathology*; D002755:Choice Behavior / Q000502:physiology*; D003216:Conditioning, Operant / Q000502:physiology*; D004195:Disease Models, Animal; D005069:Evaluation Studies as Topic; D005108:Extinction, Psychological; D008297:Male; D009043:Motor Activity / Q000502:physiology; D009483:Neuropsychological Tests; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012054:Reinforcement, Psychology; D013997:Time Factors