Abstract
Our group has shown that prosaccades completed after antisaccades are associated with longer response latencies compared to the second of two consecutively completed prosaccades (i.e., so-called task-switch cost). This finding has been attributed to persistent residual inhibition of ocuolmotor networks arising from the response suppression and vector inversion required for the completion of an antisaccade (Weiler and Heath, 2011: Exp Brain Res). Here we sought to determine if a systematic increase in the number of previously completed antisaccades increase the prosaccade switch-cost. More specifically, we asked whether the residual inhibition from antisaccade completion compounds, and thus, further disrupts oculomotor networks supporting prosaccades. To accomplish our objective, 20 participants completed separate blocks of pro- and antisaccades, and two additional task-switching schedules wherein the nature of the saccade task (i.e., pro- or antisaccade) alternated on every second (i.e., AABB) or on every fourth (i.e., AAAABBBB) trial. Our results demonstrated that reaction times for prosaccades completed after antisaccades were longer than their task-repetition counterparts, and most notably, this switch-cost was equivalent across task-switching schedules. In addition, reaction times for prosaccade task-switch trials were longer than their blocked trial counterparts, whereas reaction times were not modulated across the different antisaccade conditions (i.e., switch, repeat and blocked). Thus, results demonstrate that the residual inhibition associated with antisaccade task completion is not compounded over successive antisaccade trials. Furthermore, we provide convergent evidence that the task-switch cost influencing the dedicated oculomotor networks supporting prosaccades does not modulate the performance of cognitively mediated antisaccades.Acknowledgments: NSERC, OGS