Effects of clonidine and scopolamine on multiple target detection in rapid serial visual presentation.
BACKGROUND
The specific role of neuromodulator systems in regulating rapid fluctuations of attention is still poorly understood.


OBJECTIVE
In this study, we examined the effects of clonidine and scopolamine on multiple target detection in a rapid serial visual presentation task to assess the role of the central noradrenergic and cholinergic systems in temporal attention.


METHODS
Eighteen healthy volunteers took part in a crossover double-dummy study in which they received clonidine (150/175 μg), scopolamine (1.2 mg), and placebo by mouth in counterbalanced order. A dual-target attentional blink task was administered at 120 min after scopolamine intake and 180 min after clonidine intake. The electroencephalogram was measured during task performance.


RESULTS
Clonidine and scopolamine both impaired detection of the first target (T1). For clonidine, this impairment was accompanied by decreased amplitudes of the P2 and P3 components of the event-related potential. The drugs did not impair second-target (T2) detection, except if T2 was presented immediately after T1. The attentional blink for T2 was not affected, in line with a previous study that found no effect of clonidine on the attentional blink.


CONCLUSIONS
These and other results suggest that clonidine and scopolamine may impair temporal attention through a decrease in tonic alertness and that this decrease in alertness can be temporarily compensated by a phasic alerting response to a salient stimulus. The comparable behavioral effects of clonidine and scopolamine are consistent with animal studies indicating close interactions between the noradrenergic and cholinergic neuromodulator systems.
Cognitive Psychology Unit, Institute of Psychology, Leiden University, Leiden, The Netherlands. sbrebrown@gmail.com.|Leiden Institute for Brain and Cognition, Leiden, The Netherlands. sbrebrown@gmail.com.
Stephen B R E
SB
Brown
Brain and Cognition Unit, Department of Psychology, University of Amsterdam, Amsterdam, The Netherlands.|Amsterdam Brain and Cognition Center, University of Amsterdam, Amsterdam, The Netherlands.
Heleen A
HA
Slagter
Department of Psychiatry, Leiden University Medical Center, Leiden, The Netherlands.
Martijn S
MS
van Noorden
Department of Psychiatry, Leiden University Medical Center, Leiden, The Netherlands.
Erik J
EJ
Giltay
Leiden Institute for Brain and Cognition, Leiden, The Netherlands.|Department of Psychiatry, Leiden University Medical Center, Leiden, The Netherlands.
Nic J A
NJ
van der Wee
Cognitive Psychology Unit, Institute of Psychology, Leiden University, Leiden, The Netherlands.|Leiden Institute for Brain and Cognition, Leiden, The Netherlands.
Sander
S
Nieuwenhuis
D000293:Adolescent; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000328:Adult; D054518:Attentional Blink / Q000187:drug effects; D003000:Clonidine / Q000494:pharmacology*; D018592:Cross-Over Studies; D004569:Electroencephalography / Q000187:drug effects; D005071:Evoked Potentials / Q000187:drug effects; D005260:Female; D006801:Humans; D008297:Male; D018727:Muscarinic Antagonists / Q000494:pharmacology*; D009638:Norepinephrine / Q000378:metabolism; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000187:drug effects*; D011930:Reaction Time / Q000187:drug effects; D012601:Scopolamine / Q000494:pharmacology*; D055815:Young Adult
D000316:Adrenergic alpha-Agonists; D018727:Muscarinic Antagonists; D012601:Scopolamine; D003000:Clonidine; D009638:Norepinephrine
Acetylcholine; Attentional blink; Noradrenaline; Rapid serial visual presentation; Temporal attention