Due to the simplicity of the task, the subjects’ minds were free to wander, and this enabled observation of natural fluctuations in task engagement and the underlying spatial redistribution of attentional resources throughout the duration of each trial. Specifically, our results revealed task-relevant and primarily right-lateralized frontal areas engaged immediately following the stimuli, and default-mode-region activations following the behavioral response. These findings are consistent with the role Polich (2007) proposed for the P3 in rapid inhibition of ongoing neural processes to facilitate the transfer of stimulus information from frontal to temporal-parietal areas. They also provide evidence for a role of the default mode network in task-related processing. Furthermore, our findings demonstrate the utility of our methods for noninvasively investigating the temporal ordering of many widely distributed BOLD activations. We believe these techniques will be important in future investigations of brain function, as the information they provide is complementary to that which can be obtained from intracranial-EEG, MEG, and resting state studies.
