and to be significantly right-lateralized (Downar et al., 2000). The same set of brain areas was also specifically and consistently found to be associated with transient responses at task onset and offset (Fox et al., 2005; Konishi et al., 2001), an effect thought to be related to transitions from and to a state of readiness (Corbetta and Shulman, 2002; Shulman et al., 2002). Deactivations were mainly found in precuneus, medial prefrontal cortex and medial parietal cortex,. All these areas, typically associated with the default-mode system, were shown to be more active during rest, and to be transiently or consistently deactivated during many different types of cognitive tasks (Shulman et al., 1997; Binder et al., 1999). The dorsal attention network, characterized by the involvement of parietal and prefrontal regions, was usually engaged during voluntary orienting (Corbetta and Shulman, 2002). Interestingly, our analysis revealed that the time-course of this network reflected a modulation that was averaged out if time-locked to the presentation of targets, but was nevertheless correlated with the P300 response fluctuations across trials. This specific system was previously found to be related to P300 responses by Eichele and colleagues, who combined the ERP response at different latencies with the simultaneously
