Individualized fuctional targets optimize the effectiveness of TMS in modulation of brain activity

Abstract

The site of stimulation target is critical for transcranial magnetic stimulation (TMS) modulation of brain cognitive function. However, targets in previous studies were usually identified through anatomical but not functional location method. This study aims to set up the functional target based on individual task functional magnetic resonance imaging (fMRI), and further explore whether this individualized functional target could optimize the modulation effect of TMS on brain activity. Fifty seven healthy volunteers were randomly recruited as anatomical group (14 female, 19±1 years old) and functional group (14 female, 18±1 years old). Two fMRI sessions of resting state and emotional face task were performed before and after a 40 s train of continuous theta burst TMS. The stimulation target of anatomical group was located in 5 cm anterior on aparasagittal line from the point of maximal stimulation of the first dorsal interosseous muscle. The target of functional group was located based on the functional connectivity of peak individual activation of amygdala in emotional face task. Modulation effect of TMS on brain activity was assessed through the analysis of amplitude of low-frequency fluctuation (ALFF) performed on the data of resting state sessions. Our results showed significant difference of the target location between the two groups in the coodinates of x (functional group -32±8 versus anatomical group - 37±7, p<0.01) and z (functional group 48±6 versus anatomical group 38±8, p<0.001). ALFF changes between pre-and post-TMS scans were mainly observed in functional group but not in anatomical group. These changes in bilateral amygdala, pregenual anterior cingulate cortex, bilateral posterior cingulate cortex were potentially related to emotional processing, suggesting that TMS with individualized functional targets could optimize the effectiveness of TMS in modulation of specific brain function. These findings will provide methodology references to further application and research of individualized TMS.