Perhaps the most well-studied evoked response to a task-related sensory stimuli is the P3 (also called P300), which peaks at approximately 450 ms post-stimulus (Key et al., 2005; Linden, 2005; Polich, 2007). The P3, which is typically measured via electroencephalography (EEG), is known to have amplitude that is modulated by the endogenous state of the subject (Key et al., 2005; Polich, 2007). Extensive evidence from intracranial, lesion, and EEG-fMRI studies shows this response to be generated by a widespread network that includes frontal and temporal-parietal areas (Linden, 2005; Polich, 2007). Frontal activity has been associated with the earlier novelty-related P3a subcomponent, and temporalparietal activity with the later task-related P3b subcomponent, consistent with their EEG scalp topographies (Polich, 2007).
