the inferior frontal sulcus. Findings more consistent with the scalp topography of the novelty P3 are the large amplitudes (> 100 μV) and steep gradients in orbitofrontal regions, with polarity inversions at the most medial sites. In a summary of their recordings, Halgren, Marinkovic, and Chauvel (1998) noted “clear inversions of the P3a occurred in the anterior cingulate cortex and its inferior extension, the gyrus rectus” (p. 160) thereby directly implicating these regions as possible generators of the novelty P3.
