The effect of D-amphetamine, clonidine, and yohimbine on human information processing.
Twelve subjects were tested with D-amphetamine, yohimbine, clonidine, and a placebo on a task with two levels of stimulus and two levels of response complexity. The purpose of this study was to test the hypothesis that noradrenergic drugs affect early stimulus processes. D-amphetamine speeded reaction time (RT), clonidine slowed it, and yohimbine had no effect. D-amphetamine and yohimbine decreased N1 latency and clonidine increased it. D-amphetamine and yohimbine decreased P3 latency and clonidine increased it but, in each case, only when latency estimates were based on single trials, not on averages. D-amphetamine's effect on RT, not P3, as measured by the average, is consistent with previous results. Single trial measures appear more sensitive. Speeding of N1 and single-trial P3 data indicate that noradrenergic drugs affect processing of early (visual) information. D-amphetamine's speeding of single-trial P3 estimates was attributed to its noradrenergic actions. Yohimbine's speeding of P3 without changing RT is consistent with neural net (parallel) simulations but not with a serial model. These findings support the assumption that different neurotransmitters modulate specific cognitive processes.
Halliday
R
R
Psychiatry Research, Department of Veterans Affairs, and University of California-San Francisco, 94121, USA.
Naylor
H
H
Brandeis
D
D
Callaway
E
E
Yano
L
L
Herzig
K
K
D000328:Adult; D001288:Attention / Q000187:drug effects; D003000:Clonidine / Q000494:pharmacology*; D003071:Cognition / Q000187:drug effects*; D003913:Dextroamphetamine / Q000494:pharmacology*; D004569:Electroencephalography / Q000187:drug effects; D005074:Evoked Potentials, Visual / Q000187:drug effects*; D006801:Humans; D008297:Male; D011597:Psychomotor Performance / Q000187:drug effects*; D011930:Reaction Time / Q000187:drug effects*; D015016:Yohimbine / Q000494:pharmacology*
D015016:Yohimbine; D003000:Clonidine; D003913:Dextroamphetamine