One recent study (Horacek et al., 2007) combined brain imaging with PET and EEG analysis in patients receiving rTMS for auditory hallucinations. Importantly, PET and EEG were done in the resting state before and after rTMS therapy, which consisted of ten 20-minute sessions of rTMS at 0.9 Hz delivered to the left temporoparietal region. The authors found that rTMS significantly improved auditory hallucinations. The analysis of the PET data revealed that rTMS caused a pronounced decrease in metabolic activity in the left temporal cortex and cerebellum, and an increase in metabolism in the bilateral middle frontal gyrus and in the right temporo-occipital cortex, suggesting that the improvement in auditory hallucinations might be secondary to a relative increase in frontal executive control and interhemispheric inhibition from the contralateral cortex. The authors then explored how the metabolism of different brain regions covaried with metabolism in the left superior temporal gyrus. Prior to rTMS, metabolism within the left superior temporal gyrus was positively correlated with a large distributed network including the bilateral temporal cortices and anterior cingulate, and negatively correlated with a number
