Figure 9. Contribution of the different sources to the change related response. A, The scalp potential was well approximated [residual variance (0–2000 ms) = 0.64%] by a mixture of six sources in each hemisphere, activating at different times after the change. The sources are located in the auditory cortex (blue, light blue, B, C), the temporo-parietal junction (dark blue, D), the visual cortex (red, E; provided for completeness), the medial-parietal cortex (orange, F), and finally the frontal cortex (green, G). All sources were estimated as bilateral pairs; however, potentials in B–G show averages across pairs. B, The first source activation was located close to the auditory cortex (blue in a A). It exhibited a significant dependence on change size only around 750 ms (bottom, gray, analysis window: 700–850 ms), while the P2-like potential (peak: 350 ms, vertical blue line, correspondingly in the following panels) was borderline insignificant (bottom, black, window: 250–450 ms). C, As before, we estimate a radial component of the AEP, which exhibited a borderline significant dependence on mixing coefficient (bottom, window: 350–550 ms). D, The activation of the temporo-parietal junction was very small and did not contribute significantly (window: 250–500 ms). E, The contribution from the visual source was nonsignificant (window: 500–700 ms). F, The activation in the parietal cortex exhibited a clear and significant dependence on the mixing coefficient. While the onset time remained similar across change sizes, the peak time was slightly delayed for lower change sizes, similar to potentials the scalp level (window: 600–800 ms). G, A further pair of sources was localized in the frontal cortex, which, however, did not show a significant dependence in their size on change size (window: 600–1000 ms). Error hulls and bars indicate ±1 SEM over n = 17 subjects, and only 3-s change time is shown. Effect size is given in parentheses after the p value.