2002), or target probability (Croft et al., 2003). However, no clear indication about the cerebral mechanisms accounting for the P300 response fluctuations observed during the oddball task could be provided in these studies. We analyzed the trial-by-trial responses recorded by EEG–fMRI to obtain an indirect measure of both the electrophysiological and the hemodynamic correlates of brain activity linked to target detection. In our study, the P300 reference time-course from EEG single trials (Horovitz et al., 2002) was primarily used to interpret the results from the fMRI data.
