EFFECTS OF CIGARETTE-SMOKING AND 12-H ABSTENTION ON WORKING-MEMORY DURING A SERIAL PROBE RECOGNITION TASK

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 effec ts on perceptual and motor processes, as reflected by event-related po tentials (ERPs) and reaction times (RTs), respectively, and that perce ptual effects may be specific to changes in working memory. ERPs, RTs and performance accuracy were recorded from smokers and nonsmokers dur ing 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 o r out-of-set. Smelters were tested in a ''smoking'' and a 12-h ''depri ved'' condition. Smoking-smokers and deprived-smokers exhibited fast R Ts 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 f irst or last item in the memory set. Thus, smokers as a group showed e nhanced primacy and recency effects suggesting that smoking specifical ly facilitates processes related to the motor output aspects of workin g memory. Different effects characterized the electrophysiology, Large r P300s were recorded to in-set compared to out-of-set probes by both subject groups. Smoking smelters exhibited enhanced P300s to both type s of probes. When smokers abstained for 12 h (deprived smokers), the d ifferences in P300 amplitude were reduced but not eliminated. Smoking smokers exhibited faster P300 latencies to in-set probes, while depriv ed smokers showed delayed latencies relative to nonsmokers. Primacy an d recency P300 effects characterized nonsmokers and deprived smokers. However, this relationship was reversed in the Smoking condition. Thes e results support the hypotheses that nicotine has distinct effects on memory-related perceptual and motor aspects of working memory. The in crease in efficiency of the memory search with nicotine is consistent with the functional role of the cholinergic system in maintaining a st ate ''appropriate for efficient information processing.