'Waiting impulsivity' in isolation-reared and socially-reared rats: effects of amphetamine.
Rats reared in social isolation exhibit various cognitive and behavioural abnormalities in adulthood. However, impulsivity following this treatment still remains unclear, especially in response to medications used in attention deficit hyperactivity disorder, such as amphetamine.



Using an isolation-rearing (IR) manipulation, the present study examined the effects of IR on impulsive action and impulsive choice when also treated with doses of D-amphetamine, by employing the five-choice serial reaction time task (5-CSRTT) and a temporal discounting of reward task (TDRT), respectively.



IR rats showed similar acquisition of the 5-CSRTT. Amphetamine increased premature responding in both groups; however, IR rats showed less responding overall. For the TDRT, IR rats revealed a greater preference for the large but delayed reward during task acquisition (i.e. were less impulsive) with a higher rate of nose poking during the delay, and exhibited a compressed dose-response function (i.e. reduced dose sensitivity) for amphetamine.



Impulsive action and impulsive choice were reduced in IR rats under certain conditions, and a blunted response to D-amphetamine was found on these measures. These reductions in impulsivity contrast with locomotor hyperactivity normally shown in IR rats and the findings have implications for the utility of IR as a model of psychopathology.
Laboratory of Cognitive Neuroscience, Departments of Physiology and Psychiatry, National Defense Medical Center, Taipei, 11490, Taiwan. yiaping@ndmctsgh.edu.tw.|Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK. yiaping@ndmctsgh.edu.tw.|Department of Psychiatry, University of Cambridge, Cambridge, CB2 0SZ, UK. yiaping@ndmctsgh.edu.tw.
Yia-Ping
YP
Liu
Behavioural Genetics Group, Schools of Psychology & Medicine, Neuroscience and Mental Health Research Institute, Cardiff University, Cardiff, CF10 3AT, UK.
Lawrence S
LS
Wilkinson
Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK.|Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK.
Trevor W
TW
Robbins
D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D000697:Central Nervous System Stimulants / Q000494:pharmacology; D002755:Choice Behavior / Q000187:drug effects / Q000502:physiology; D003913:Dextroamphetamine / Q000494:pharmacology; D007175:Impulsive Behavior / Q000187:drug effects* / Q000502:physiology; D007398:Interpersonal Relations; D008297:Male; D051381:Rats; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D012201:Reward; D012934:Social Isolation / Q000523:psychology*
D000697:Central Nervous System Stimulants; D000661:Amphetamine; D003913:Dextroamphetamine
ADHD; Amphetamine; Behavioural inhibition; Dopamine; Five-choice serial reaction time task; Impulsivity; Isolation rearing; Reward temporal discounting; Social deprivation