Amphetamine decreases the expression and acquisition of appetitive conditioning but increases the acquisition of anticipatory responding over a trace interval.
The effects of amphetamine on selective learning were tested in a trace conditioning procedure, in which the informativeness of the conditioned stimulus (CS) (noise) was manipulated through the introduction of a time interval before the delivery of the unconditioned stimulus (UCS) (food). The results showed that d-amphetamine (0.5 and 1.5 mg/kg) impaired both the expression (Experiment 1b) and acquisition (Experiment 2) of appetitive conditioning. This was true for both trace and contiguously conditioned groups. The effects of the 0.5 mg/kg dose of d-amphetamine were not attributable to general motor (measured pre-CS) or motivational (measured post-UCS) effects of the drug. Moreover, the same pattern of effects (impaired appetitive conditioning, irrespective of the trace interval between CS and UCS) was confirmed in drug-free extinction tests. By contrast to the general depression in the acquisition and expression of associative learning observed under amphetamine, the 0.5 mg/kg dose promoted the acquisition of anticipatory responses made later in the trace interval (in Experiment 2 but, again, not the expression of previous conditioning in Experiment 1b). This suggests a dissociable effect of low-dose d-amphetamine on learning about the temporal relationship between CS and UCS.
Kantini
E
E
School of Psychology, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
Norman
C
C
Cassaday
H J
HJ
D000161:Acoustic Stimulation; D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D001066:Appetite / Q000187:drug effects*; D001522:Behavior, Animal / Q000187:drug effects; D003216:Conditioning, Operant / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005108:Extinction, Psychological / Q000187:drug effects; D005502:Food; D008297:Male; D051381:Rats; D017208:Rats, Wistar
D000661:Amphetamine