Reduction of impulsivity with amphetamine in an appetitive fixed consecutive number schedule with cue for optimal performance in rats.
BACKGROUND
Impulsivity is a key feature of many psychopathologies such as mania, personality disorders or attention deficit-hyperactivity disorder (ADHD). Most experimental paradigms assessing impulsive behaviour also require non-specific capacities such as time estimation. This may interact with the measures and mask the beneficial effects of psychostimulants-the most commonly used treatment for ADHD-on impulsivity, given that these drugs speed up the internal clock.


OBJECTIVE
The present experiment investigated the effects of suppressing behaviours non-specific to impulsivity in a fixed consecutive number (FCN) schedule and examined whether amphetamine, previously shown to increase impulsive responses in this task, could have beneficial effects when impulsive responses are promoted.


METHODS
Food-deprived rats were trained to press one lever of a two-lever operant chamber eight times before pressing the other lever to obtain food. Premature ending of responses resulted in absence of food delivery and reset the counter. A cue light indicating the required number of presses was present (FCN8(cue)) and removed after training (FCN8). Rats were then trained under an FCN16(cue) schedule to be challenged with d-amphetamine (0.125, 0.25 and 0.5 mg/kg).


RESULTS
The cue improved performances, and similar scores were obtained under FCN16(cue) compared to FCN8. Premature responses under these two conditions were unrelated. Amphetamine reduced impulsive responses in FCN16(cue) at the lower dose.


CONCLUSIONS
Suppression of capacities non-specific to impulsivity in the FCN schedule, associated with conditions that permit the expression of inhibitory deficits, allows the beneficial effects of psychostimulants observed clinically to be evidenced experimentally.
Rivalan
Marion
M
Université Bordeaux 2, Université Bordeaux 1, CNRS, UMR 5227, 146 rue Léo Saignat - BP31, 33076, Bordeaux Cedex, France.
Grégoire
Stéphanie
S
Dellu-Hagedorn
Françoise
F
D000818:Animals; D001070:Appetitive Behavior / Q000187:drug effects*; D000697:Central Nervous System Stimulants / Q000008:administration & dosage / Q000494:pharmacology*; D003216:Conditioning, Operant / Q000187:drug effects; D003463:Cues; D003913:Dextroamphetamine / Q000008:administration & dosage / Q000494:pharmacology*; D004193:Discrimination Learning / Q000187:drug effects; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D007175:Impulsive Behavior / Q000188:drug therapy*; D008297:Male; D011597:Psychomotor Performance / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D012055:Reinforcement Schedule
D000697:Central Nervous System Stimulants; D003913:Dextroamphetamine