The antisaccade task as an index of sustained goal activation in working memory: modulation by nicotine

The antisaccade task provides a laboratory analogue of situations in which execution of the correct behavioural response requires the suppression of a more prepotent or habitual response. Errors (failures to inhibit a reflexive prosaccade towards a sudden onset target) are significantly increased in patients with damage to the dorsolateral prefrontal cortex and patients with schizophrenia. Recent models of antisaccade performance suggest that errors are more likely to occur when the intention to initiate an antisaccade is insufficiently activated within working memory. Nicotine has been shown to enhance specific working memory processes in healthy adults. MATERIALS AND METHODS: We explored the effect of nicotine on antisaccade performance in a large sample (N = 44) of young adult smokers. Minimally abstinent participants attended two test sessions and were asked to smoke one of their own cigarettes between baseline and retest during one session only. RESULTS AND CONCLUSION: Nicotine reduced antisaccade errors and correct antisaccade latencies if delivered before optimum performance levels are achieved, suggesting that nicotine supports the activation of intentions in working memory during task performance. The implications of this research for current theoretical accounts of antisaccade performance, and for interpreting the increased rate of antisaccade errors found in some psychiatric patient groups are discussed

Acute effects of nicotine on visual search tasks in young adult smokers

Rationale Nicotine is known to improve performance on tests involving sustained attention and recent research suggests that nicotine may also improve performance on tests involving the strategic allocation of attention and working memory. Objectives We used measures of accuracy and response latency combined with eye-tracking techniques to examine the effects of nicotine on visual search tasks. Methods In experiment 1 smokers and non-smokers performed pop-out and serial search tasks. In experiment 2, we used a within-subject design and a more demanding search task for multiple targets. In both studies, 2-h abstinent smokers were asked to smoke one of their own cigarettes between baseline and tests. Results In experiment 1, pop-out search times were faster after nicotine, without a loss in accuracy. Similar effects were observed for serial searches, but these were significant only at a trend level. In experiment 2, nicotine facilitated a strategic change in eye movements resulting in a higher proportion of fixations on target letters. If the cigarette was smoked on the first trial (when the task was novel), nicotine additionally reduced the total number of fixations and refixations on all letters in the display. Conclusions Nicotine improves visual search performance by speeding up search time and enabling a better focus of attention on task relevant items. This appears to reflect more efficient inhibition of eye movements towards task irrelevant stimuli, and better active maintenance of task goals. When the task is novel, and therefore more difficult, nicotine lessens the need to refixate previously seen letters, suggesting an improvement in working memory

Nicotine differentially modulates antisaccade performance in healthy male non-smoking volunteers stratified for low and high accuracy

RATIONALE: Nicotinergic agents are currently examined as possible pro-cognitive drugs for a variety of clinical conditions marked by cognitive deficits, such as attention deficit hyperactivity disorder (ADHD) or schizophrenia. The response to acute nicotine is heterogeneous across subjects and samples; however, only a few reliable predictors of response have been identified. OBJECTIVES: We tested the hypothesis that baseline performance level in cognitive control may be a predictor of the cognitive effects of nicotine. METHODS: We tested 28 healthy Caucasian, male, non-smoking volunteers with the antisaccade task, an oculomotor measure of cognitive control. Participants were given a 7-mg nicotine patch in a double-blind, placebo-controlled, counterbalanced, within-subjects design. Subjects were stratified into high and low performers based on their antisaccade error rate in the placebo condition (median split). RESULTS: Nicotine tended to reduce response time variability of prosaccade latency (p = 0.06). There was no main effect of nicotine on antisaccade error rate (p = 0.31). However, nicotine significantly reduced antisaccade error rate in the low-accuracy probands while leaving performance of the high-accuracy probands unaffected (interaction, p < 0.05). Furthermore, we found a nicotine-induced reduction of response time variability of antisaccade latency at one target location in the low-performing group (interaction, p < 0.05). CONCLUSIONS: The present results demonstrate the importance of baseline performance differences for the effectiveness of pharmacological enhancement of cognitive control. More generally, the results suggest that stimulation of the nicotinic acetylcholine receptor system might be an effective way of improving cognition in people with poor cognitive performance, such as patients with ADHD or schizophrenia

Nicotine improves memory for delayed intentions.

RationaleThe present paper asked first whether the cholinergic agonist nicotine improves memory for delayed intentions (prospective memory, ProM) and second whether pharmacological dissociation would support the psychological distinction that is made between strategic (effortful) and automatic (non-effortful) intention activation in prospective memory.ObjectivesTo use nicotine as a pharmacological tool with which to examine the neurochemical bases of prospective memory and to dissociate strategic from automatic components of ProM retrieval.MethodsIn three experiments, minimally deprived (2 h) smokers either smoked or abstained prior to completing a standard prospective memory study. This involved participants in the simultaneous processing of a ProM task and a cover task (ongoing between the setting and the recall of the intention). Here, the ongoing task involved lexical decision (LDT), while the ProM task required a response to pre-specified target items occurring within the LDT stimuli. Variations in task instructions were used to manipulate the processing requirements of the ProM task, the attention allocated to the ProM task and the balance of importance assigned to the ongoing and ProM tasks.ResultsIn experiment 1, where the ProM processing was automatic, nicotine did not improve ProM accuracy. In experiment 2, where the ProM task involved strategic processing, positive effects of nicotine were observed. In experiment 3, we covaried ProM task instructions, assigned task importance and nicotine conditions. We observed a main effect of nicotine on ProM accuracy, a main effect of task on ProM accuracy and a main effect of assigned task importance on ProM accuracy. There were no interactions between the factors.ConclusionsEmploying both direct and indirect manipulations of strategic engagement, we demonstrated nicotine-induced enhancement of performance on the ProM task. The results are consistent with the view that relatively small changes in instruction and in task variables engage strategic processing in a ProM task and that when these conditions stretch cognitive resources, nicotine may significantly improve performance.</div