Prosaccade errors in the antisaccade task: differences between corrected and uncorrected errors and links to neuropsychological tests.

The relations among spatial memory, Stroop-like colour-word subtests, and errors on antisaccade and memory-guided saccadic eye-movement trials for older and younger adults were tested. Two types of errors in the antisaccade task were identified: short latency prosaccade errors that were immediately corrected and longer latency uncorrected prosaccade errors. The age groups did not differ on percentages of either corrected or uncorrected errors, but the latency and time to correct prosaccade errors were shorter for younger than older adults. Uncorrected prosaccade errors correlated significantly with spatial memory accuracy and errors on the colour-word subtests, but neither of these neuropsychological indices correlated with corrected prosaccade errors. These findings suggest that uncorrected prosaccade errors may be a result of cognitive factors involving a failure to maintain the goal of the antisaccade task in working memory. In contrast, corrected errors may be a consequence of a fixation system involving an initial failure to inhibit a reflexive prosaccade but with active goal maintenance enabling correction to take place.

Effect of nicotine on saccadic eye movement latencies in non-smokers.

OBJECTIVE: Recently, saccadic eye movement tasks have been used to assess the effects of nicotine on higher cognitive processes, including inhibitory control. Saccadic task switching methods suggest that there is prolonged inhibition of the saccadic eye movement system following antisaccade trials. The objective of this research was to examine effects of nicotine on inhibition using saccadic task switching paradigms. METHODS: Nicotine and placebo lozenges were administered on separate days to 40 non-smokers who performed prosaccade and antisaccade tasks. In addition, participants performed a series of trials in which prosaccade and antisaccade tasks were switched. Eye movement latencies were recorded. RESULTS: Participants responded significantly faster for the nicotine condition than for the placebo condition. A switch benefit was observed for only placebo antisaccade trials, in that latencies of repetition trials were significantly longer than those of switch trials. In addition, an analysis of the repetition trials showed an interaction between saccade type and sequence position for the placebo condition, but not the nicotine condition. CONCLUSION: Inhibition persists after antisaccade trials in a switching paradigm, but that the duration of this inhibition is reduced by nicotine.