Figure 5. Effects of location on the correlation between the local field potential and the fMRI signal change. Data from both tasks (noun and verb naming) were pooled together as in Figure 3. A, B, Pearson's r (A) and p (B) values at each frequency bin are computed as a function of lobar location of the recording electrode. Significance of correlation was strongly affected by numbers of electrodes; therefore, lobes with the greatest numbers of samples (frontal and temporal) had the highest levels of significance. C, D, Locations and distributions of electrodes are shown colocalized on a single brain surface to which they were registered using a 12 parameter affine transform. The number of electrodes included in the analysis varied slightly between the two tasks (due to slight variations in noisy channels between the recording sessions for each task). In both tasks there were 454 electrodes over the frontal lobe and 265 over the temporal lobe. During verb naming there were 157 electrodes over the parietal lobe and 51 over the occipital lobe, while in common naming there were 158 and 49, respectively. E, The mean correlation values for each lobe with 95% CIs are plotted. Mean response with 95% CIs across all electrodes is plotted in gray. Significance levels: *p < 0.01, **p < 0.001, ***p < 0.00001.