| Abstract No.: | C-C3118 |
| Country: | Canada |
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| Title: | ERROR AND CONFLICT MONITORING DURING SACCADE COUNTERMANDING IS NOT IMPAIRED IN PATIENTS WITH SCHIZOPHRENIA |
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| Authors/Affiliations: | 1 Emiliano Brunamonti*; 1 Clair Boudet; 1 Nalini Stiemerling; 1 Nicholas Delva; 1 Martin Paré ;
1 Queen’s University, Kingston, ON, Canada
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| Content: | Objectives: The ability to detect erroneous actions and conflicts in information processing are core executive function, which enables us to correct our behavior according to the demands of a changing environment, and their importance is highlighted by the prevalence of self-monitoring deficits in psychiatric disorders such as schizophrenia. For instance, several studies have reported that patients with schizophrenia do not display significant post-conflict or post-error behavioral adjustments (Frith, 1992; van Veen & Carter, Clin EEG Neurosci, 2006). It has also been found (Kerns et al., Am J Psychiatry, 2005) that schizophrenia patients show both decreased conflict- and error-related activity in the anterior cingulate cortex, an important brain region involved in cognitive control. Here we used the countermanding paradigm to assess the basis of self-monitoring defects with respect to the control of saccadic eye movements.
Materials and Methods: We assessed the monitoring performance of 19 schizophrenic patients and healthy controls matched for age and sex during a saccade countermanding task consisting of 67.5% GO trials, in which subjects had to make a saccade to a visual target, interleaved with 32.5% STOP trials, in which a STOP signal instructed subjects to cancel their targeting saccades. The STOP signal consisted of the initial fixation spot reappearing after a variable (50-250 ms) delay relative to the target onset. Post-conflict and post-error adjustments were quantified by the extent of slowing in GO-trial responses following, respectively, successful and failed inhibition in a STOP trial (Emeric et al., Vision Res, 2007).
Results: Our previous results demonstrated that patients with schizophrenia failed to cancel commanded saccades as frequently as healthy control individuals, but that when they succeeded to cancel they did so with normal reaction times (Boudet et al., Soc Neurosci Abstr, 2005). In addition, the latencies their GO-trial responses did not differ significantly from control subjects (279 vs. 282 ms). Here we report that schizophrenia patients showed post-conflict and post-error slowing in their GO-trial responses that did not differ significantly from controls. The extent of speeding in their GO-trial responses following another GO trials also did not differ significantly from controls. Finally, even though schizophrenia patients failed to cancel their saccades as frequently as controls, both subjects groups cancelled similarly more often their saccades in STOP trials following a STOP trial than they did in STOP trials following a GO trial.
Conclusions: Our results demonstrate that patients with schizophrenia adjust their saccade countermanding performance as efficiently as healthy individuals. This finding suggests that the monitoring of erroneous actions and conflict in information processing does not contribute to the defective control of action observed in the countermanding performance of patients with schizophrenia. Their deficits in this task appear limited to an imperfect 'triggering' of the neural process underlying the cancellation of commanded movements. |
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