Nicotine-induced enhancement of attention in the five-choice serial reaction time task: the influence of task demands.
BACKGROUND
Beneficial effects of nicotine on cognitive processes including attention have potential therapeutic uses and have been proposed as incentives for tobacco smoking.


OBJECTIVE
To establish task conditions under which the effects of nicotine on attention are obtained reliably and to characterise such effects further.


METHODS
Rats were trained in a modified version of the five-choice serial reaction time task (5-CSRTT) to detect 1-s light stimuli with greater than 70% accuracy and fewer than 20% omission errors. Nicotine was tested under different task requirements by varying signal event rate, stimulus duration and stimulus predictability, and by introducing white-noise distractors.


RESULTS
Nicotine (0.05-0.2 mg/kg, s.c.) repeatedly improved accuracy and reduced omission errors and reaction times, leading to increases in numbers of reinforcers earned. Anticipatory responding was increased. Parametric modifications intended to increase demands on sustained attention did not affect performance in a manner suggesting that this subtype of attention was being taxed, and the effects of nicotine were not more marked under such conditions. Shorter stimulus durations impaired performance, but this manipulation weakened the effect of nicotine on accuracy. In contrast, the presence of noise distractors facilitated the effects of nicotine to the extent that distractor-induced impairments were abolished by the drug.


CONCLUSIONS
The 5-CSRTT can provide a sensitive rodent model for the attention-enhancing effects of nicotine. Changes made to the procedure may have increased its sensitivity to nicotine, particularly with respect to accuracy. There were indications that the effects of nicotine were largest on processes of selective attention or on disengaging attention from irrelevant events and shifting it to behaviourally significant stimuli.
Section of Behavioural Pharmacology, Institute of Psychiatry, King's College London, De Crespigny Park, London SE5 8AF, UK, b.hahn@iop.kcl.ac.uk
B
B
Hahn
M
M
Shoaib
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IP
Stolerman
D000704:Analysis of Variance; D000818:Animals; D001288:Attention / Q000187:drug effects*; D008297:Male; D009538:Nicotine / Q000494:pharmacology*; D009622:Noise; D051381:Rats; D012691:Serial Learning / Q000187:drug effects*; D013647:Task Performance and Analysis
D009538:Nicotine