Memory and psychostimulants: modulation of Pavlovian fear conditioning by amphetamine in C57BL/6 mice.
OBJECTIVE
With the use of prescription stimulants on the rise, it is important to examine the cognitive effects of low and moderate doses of stimulants rather than only those typical of addicts.


METHODS
The present study examined the effects a range of doses (0.005-8 mg/kg) of D: -amphetamine sulfate on cued and contextual Pavlovian fear conditioning in mice.


RESULTS
In agreement with previous research, subjects administered with a moderately high dose of amphetamine (8 mg/kg) pre-training, typical of what addicts might take, displayed impaired conditioned freezing when tested off-drug. Alternately, subjects injected with a very low dose of amphetamine (0.005, 0.025, or 0.05 mg/kg) pre-training, similar to the therapeutic doses for attention deficit hyperactivity disorder, displayed enhanced memory when tested off-drug. A control study showed that these effects were not due to state-dependent learning.


CONCLUSIONS
Thus, dose is a critical determinant of the cognitive effects of psychostimulants.
Wood
Suzanne C
SC
Molecular Cognition Laboratory, Department of Psychology, University of California, San Diego, 9500 Gilman Dr. MC 0109, La Jolla, San Diego, CA 92093-0109, USA. scwood@ucsd.edu
Anagnostaras
Stephan G
SG
D000161:Acoustic Stimulation; D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D003214:Conditioning, Classical / Q000187:drug effects*; D003463:Cues; D004305:Dose-Response Relationship, Drug; D005239:Fear / Q000187:drug effects* / Q000523:psychology*; D005260:Female; D007274:Injections, Intraperitoneal; D008297:Male; D008568:Memory / Q000187:drug effects*; D051379:Mice; D008810:Mice, Inbred C57BL; D009043:Motor Activity / Q000187:drug effects
D000697:Central Nervous System Stimulants; D000661:Amphetamine