nigel,
I guess you're right, depending on the task. Here are some abstracts <G>:
Psychopharmacology (Berl) 1998 Aug;138(3-4):266-74
Nicotine enhances sustained attention in the rat under specific task conditions.
Mirza NR, Stolerman IP
Section of Behavioural Pharmacology, Institute of Psychiatry, London, UK. N.mirza@cerebrus.ltd.uk
Although nicotine has cognitive enhancing effects in both animals and humans, most studies in humans have only shown consistent improvements in sustained attention. Moreover, many studies with smokers have been criticised, since nicotine may simply be relieving withdrawal-induced deficits. The present study investigated the effect of nicotine on sustained attention in drug-naive rats using a five-choice serial reaction time task. Initially, the task was demonstrated to satisfy some of the criteria for the construct validity of a vigilance task: reducing signal length and either increasing or decreasing the inter-trial interval significantly (P<0.05) impaired performance. Whether nicotine (0.05-0.4 mg/kg, SC) reversed the deficits induced by a signal length of 0.25 s (weak signal) or an inter-trial-interval of either 20 s (low event rate) or 1 s (high event rate) was assessed. Nicotine (0.15 mg/kg) improved accuracy and decreased omission errors under low event rate conditions only. However, nicotine (0.05/0.15 mg/kg) improved reaction time and increased anticipatory responses under both weak signal and low event rate conditions. There was no effect of nicotine on performance under high event rate conditions. Under the low event rate condition, nicotine enhanced the ability of rats to maintain attention (i.e. accuracy) throughout a session. These findings suggest (i) that nicotine's effect on attention depends upon task characteristics; (ii) these effects on attention may reflect self-reports by smokers that nicotine aids concentration, particularly in stressful situations, and (iii) nicotinic agonists may have therapeutic benefits in patient populations suffering from attentional deficits.
Psychopharmacology (Berl) 1998 Oct;139(4):311-21
Effects of cigarette smoking and 12-h abstention on working memory during a serial-probe recognition task.
Pineda JA, Herrera C, Kang C, Sandler A
Department of Cognitive Science 0515, University of California, San Diego, La Jolla 92093-0515, USA. pineda@cogsci.ucsd.edu
[Medline record in process]
Nicotine has been shown to affect attentional and mnemonic processes. However, whether these effects are due to changes in perceptual and/or motor aspects of the tasks is not at all clear. This study tested the hypothesis that nicotine from cigarette smoking has differential effects on perceptual and motor processes, as reflected by event-related potentials (ERPs) and reaction times (RTs), respectively, and that perceptual effects may be specific to changes in working memory. ERPs. RTs and performance accuracy were recorded from smokers and nonsmokers during a serial-probe recognition memory task in which lists of words or "memory sets" were followed by a probe word that was either in-set or out-of-set. Smokers were tested in a "smoking" and a 12-h "deprived" condition. Smoking-smokers and deprived-smokers exhibited fast RTs to in-set and out-of-set probes relative to a group of nonsmokers. They exhibited even faster RTs when the inset probe word matched the first or last item in the memory set. Thus, smokers as a group showed enhanced primacy and recency effects suggesting that smoking specifically facilitates processes related to the motor output aspects of working memory. Different effects characterized the electrophysiology. Larger P300s were recorded to in-set compared to out-of-set probes by both subject groups. Smoking smokers exhibited enhanced P300s to both types of probes. When smokers abstained for 12 h (deprived smokers), the differences in P300 amplitude were reduced but not eliminated. Smoking smokers exhibited faster P300 latencies to in-set probes, while deprived smokers showed delayed latencies relative to nonsmokers. Primacy and recency P300 effects characterized nonsmokers and deprived smokers. However, this relationship was reversed in the Smoking condition. These results support the hypotheses that nicotine has distinct effects on memory-related perceptual and motor aspects of working memory. The increase in efficiency of the memory search with nicotine is consistent with the functional role of the cholinergic system in maintaining a state "appropriate for efficient information processing." |
