Recent fMRI studies on cerebral connectivity have shown that it is possible to identify multiple highly specific functional networks, which largely account for intrinsic activity (De Luca et al., 2006; Damoiseaux et al., 2006; Mantini et al., 2007b) and are related to trial-by-trial variability in evoked responses (Fox et al., 2006). In target detection studies, activations within the ventral attention network, specialized for the detection of behaviorally relevant stimuli, were consistently observed when comparing the brain responses to target and non-target events (Bledowski et al., 2004a; Calhoun et al., 2006). We further hypothesized that the dorsal attention network, recently found to be dedicated to adaptive task control in a resting state functional connectivity study (Dosenbach et al., 2007), might be engaged during search for targets, hence playing an important role in target detection performance. From this standpoint, the trial-by-trial variability of the P300 amplitude, documented in several EEG studies (Barry et al., 2000; Croft et al., 2003; Gonsalvez and Polich, 2002), might be considered an electrophysiological correlate of ongoing adaptive processes associated with target detection. In addition, other neuroimaging studies
