Our bilateral angular gyri clusters, which are subregions of the intra-parietal lobules (IPL) (Udin et al., 2010), are consistent with many reports of IPL in P3 coupling (Linden, 2005). Similar to our late (525–550 ms relative to stimulus) activations, Bledowski et al. (2004a, 2004b) found bilateral IPL correlated with EEG amplitude variability, reported around 540 ms (in 2004b). Our stimulus-locked correlates appear later than the peak amplitude of the P3, which suggests that the IPL is more closely linked to P3 latency variability than amplitude variability. This is consistent with findings that activity in parietal areas correlates with P3 latency but not with amplitude (Warbrick et al., 2009).
