Me. Houlihan et al., Effects of smoking/nicotine on performance and event-related potentials during a short-term memory scanning task, PSYCHOPHAR, 156(4), 2001, pp. 388-396
Rationale: Nicotine absorbed from cigarette smoke shortens reaction time (R
T) in a wide variety of cognitive tasks. However, relatively few studies ha
ve tried to isolate the specific stage(s) of information processing affecte
d by smoking/nicotine. Objective: The present study was designed to investi
gate the effect of smoking/nicotine on the short-term memory (STM) scanning
stage of information processing in minimally abstaining smokers. Both RT a
nd event-related potentials (ERPs) were measured. Methods: A Sternberg-type
STM-scanning task was performed before and after smoking each of two cigar
ettes. One cigarette had a 0.05-mg nicotine yield ("denicotinized") and the
other had a 1.1-mg yield ("nicotine-yielding"). On each trial, either 2, 3
, or 4 consonants were displayed as a memory set. After a brief interval, a
single probe consonant was displayed. If the probe was in the memory set (
positive probe) a right button press was required, and if the probe was not
in the memory set (negative probe) the left button was pressed. Results: S
moking the nicotine-yielding cigarette but not the denicotinized cigarette
shortened RT. However, memory-scanning speed, as estimated from the increas
e in RT as a function of increasing set size, was not differentially affect
ed by the two types of cigarettes. For the ERPs, smoking the nicotine-yield
ing but not the denicotinized cigarette (a) reduced N200 latency to both th
e memory-set stimuli and negative probes, (b) increased N200 amplitude to n
egative probes and P300 amplitude to both types of probes, and (c) produced
a sustained negative shift in memory-set ERP amplitude beginning around 60
0 rns post-stimulus. Conclusion: While smoking/nicotine shortened probe RT,
it did not affect the speed of STM scanning. Moreover, the ERP-latency eff
ects obtained for the probes were small relative to the effects of smoking/
nicotine on RT, suggesting that smoking/nicotine shortens RT primarily by a
ffecting response-related processes.