No abstract

The reliability of event-related potentials (ERPs) was studied in 10 healthy adults who were tested 8 times over 7-10 day intervals using a standard auditory oddball paradigm. The difference waveforms, obtained by subtracting the averaged waveforms for frequent trials from those obtained in rare trials, were designed to analyze the components of the ERPs, such as the P300, and to focus on the reliability of the probability effect on the ERPs . The between-session reliability (8 sessions) and the within-session reliability (order of blocks or of different visual procedures) were computed for the obtained difference waveforms. The between-session reliabilities, expressed as the intraclass correlations (r') for the P300 amplitude, area and latency, were 0.70, 0.61 and 0.65, respectively. The within-session reliability, presented as the Pearson correlation coefficients (r) for the three P300 measures were 0.43, 0.35 and 0.25 for different eyes. The values were 0.45, 0.39, 0.42 between the first and the second blocks (eyes-open) and 0.58, 0.47 and 0.29 (eyes-closed). These findings indicate that the P300 amplitude calculated from the difference waveforms may be the most stable marker for the between-session reliabilities. There were no significant differences in the P300 measures over the 8 sessions, suggesting that habituation may not occur with the difference waveform reflecting the probability effect on ERPs. The difference waveform may be useful in research on repetitive group ERPs.

Within session and between session reliabilities of the task-related component (P3b) of the P3 measures (amplitude, area and latency) and their habituation across eight sessions separated by 7-10 days, except for an interval of 1 month between the 6th and 7th sessions, were studied based on the difference waves, which were obtained by subtracting the ignored infrequent event-related potentials (ERP) from the target ERP elicited by a standard auditory oddball paradigm with eyes-open or eyes-closed conditions in 10 normal subjects. The within session reliabilities represented as Pearson correlation coefficients (r) were 0.57-0.66 for the three measures except for those for the latency and amplitude under the eyes-closed condition. The between session reliabilities expressed as intraclass correlation coefficients (R) ranged from 0.54 to 0.60 except for that for latency under eyes-closed conditions. Long-term habituation occurred within the first six sessions for the P3b amplitude and area, and dishabituation took place in the 7th session after an interval of 1 month, whereas no such phenomenon was observed for the P3b latency. Implications of the present results are discussed in terms of the clinical application of the P3 measures.

No abstract

The goal of the present study was to evaluate the effects of acute nicotine administration following 18 h of abstinence from cigarette smoking. Event-related potentials (ERPs) were measured in 13 male volunteers for five successive sessions. The peak amplitude and the area of the P300 significantly increased during acute withdrawal. An increase in P300 values also was observed following resumption of smoking. However, in subjects pretreated with nicotine gum, no increase in P300 values was observed following resumption of smoking. The increase in P300 values persisted for several weeks and returned to control values following 1 month of routine daily smoking. The P300 amplitude was negatively correlated with the daily dose of nicotine. These results suggest that attention and/or arousal may be enhanced by the withdrawal and the resumption of smoking. The mechanisms involved in CNS hypersensitivity to motivate the subject to smoke may persist in the presence of an increased P300 value, even following resumption of routine daily smoking.