Unidirectional switch-costs in oculomotor control are a result of a stimulus-response updating: Evidence from electroencephalography
23.427, Saturday, 17-May, 8:30 am - 12:30 pm, Banyan Breezeway
Jeff Weiler1, Cameron Hassall2, Olave Krigolson2, Matthew Heath1, 3; 1School of Kinesiology, The University of Western Ontario, 2Department of Psychology and Neuroscience, Dalhousie University, 3Graduate Program in Neuroscience, The University of Western Ontario
Antisaccades require the top-down suppression of a stimulus-driven prosaccade (i.e., response suppression) and updating of normally direct stimulus-response (S-R) mappings to a context-dependent mirror-symmetrical location. Notably, the top-down control of antisaccades results in a response with longer reaction times (RT) than their prosaccade counterparts. Moreover, recent work by our group has shown the completion of an antisaccade lengthens the RT of a subsequent prosaccade; however, the converse ‘switch’ does not influence RT (i.e., the unidirectional prosaccade switch-cost). Thus, results demonstrate that response suppression and/or S-R context-updating engenders a residual inhibition of the oculomotor networks which support prosaccade planning. In order to determine whether response suppression and/or S-R context-updating contributes to the unidirectional prosaccade switch-cost we examined the event-related brain potentials (ERPs) associated with oculomotor task-switching. Specifically, we examined whether ERPs attributed to response suppression (i.e., N2) and/or S-R context-updating (i.e., P3) are related to the unidirectional prosaccade switch-cost. To that end, participants alternated between pro- and antisaccade in a randomized task-switching order while concurrently recording electroencephalography data. As expected, prosaccades preceded by antisaccades (i.e., task-switch prosaccades) had longer RTs than prosaccades preceded by prosaccades (i.e., task-repetition prosaccades), whereas the RTs of antisaccades were not modulated by the nature of the preceding task-type. In addition, the amplitude of the P3 – but not the N2 – elicited a reliable difference between task-switch and task-repetition prosaccades, whereas task-switch and task-repetition antisaccades did not yield reliable differences for either ERP component. Thus, RT differences associated with task-switch and task-repetition prosaccades are related to amplitude differences in the P3 waveform. As such, we propose that the unidirectional prosaccade switch-cost is not related to response suppression; rather, results suggest updating an internal mental model related to S-R compatibility engenders a residual inhibition of the oculomotor networks supporting the planning of prosaccades.