Rationale: Motivational drive and its underlying affect-related states are the core mechanisms that precede the seeking and taking of drugs in substance dependence. Objective: The present study aimed to investigate the motivational relevance of cocaine cues and whether or not an appetitive emotional system is involved employing event-related potential (ERP) measurements. Methods: Cocaine-addicted subjects and healthy controls were exposed to neutral and cocaine-related pictures whilst ERPs were recorded simultaneously over frontal, parietal and midline sites. Results: Patients exhibited ERP amplitude discrepancies between neutral and cocaine-related pictures for N300, late slow positive wave (LSPW) and sustained slow positive wave (SSPW), whilst this effect was absent in control subjects. Differences in neutral and cocaine cue-evoked ERP waves were also found at left frontal sites for LSPW and SSPW in the patient group only. No group-specific cue-evoked ERP amplitudes were observed at parietal and midline sites. Conclusion: The findings confirm the assumption that cocaine cues induce motivational relevance in cocainedependent individuals. It is possible that exposure to cocaine cues triggers an appetitive emotional system since left frontal sites are assumed to be involved in processing positive emotional-laden stimuli. The present study provides evidence that the sensitivity of ERP correlates for cocaine cues may be an indicator of motivational and emotional processes in drug-dependent individuals.

This study examined stopping and performance adjustments in four age groups (M ages: 8, 12, 21, and 76 years). All participants performed on three tasks, a standard two-choice task and the same task in which stop-signal trials were inserted requiring either the suppression of the response activated by the choice stimulus (global stop task) or the suppression of the response when one stop-signal was presented but not when the other stop-signal occurred (selective stop task). The results showed that global stopping was faster than selective stopping in all age groups. Global stopping matured more rapidly than selective stopping. The developmental gain in stopping was considerably more pronounced compared to the loss observed during senescence. All age groups slowed the response on trials without a stop-signal in the stop task compared to trials in the choice task, the elderly in particular. In addition, all age groups slowed on trials following stop-signal trials, except the elderly who did not slow following successful inhibits. By contrast, the slowing following failed inhibits was disproportionally larger in the elderly compared to young adults. Finally, sequential effects did not alter the pattern of performance adjustments. The results were interpreted in terms of developmental change in the balance between proactive and reactive control.

This paper applied Donders' subtraction method to examine the processing of global and selective stop signals in the stop-signal paradigm. Participants performed on three different versions of the stop task: a global task and two selective tasks. A global task required participants to inhibit their response to a go signal whenever a stop signal was presented (Stop-a task). A selective stop task required participants to inhibit to one stop signal but not to the other (Stop-c task). Another selective stop task required them to inhibit when the response indicated by go and stop signals was the same but not when they were different (Stop-b task). Stop-signal reaction time (SSRT) was shortest for Stop-a and longest for Stop-b, with intermediate values for the Stop-c task. Additional control experiments that manipulated stop probability confirmed the robustness of global and selective stopping latencies even when the stop-signal probability varied. The current findings contribute to the conclusion that Donders' subtraction method provides a useful tool for estimating the durations of subprocesses that together comprise SSRT.

No abstract

No abstract