Illuminating posterior targets for TMS beyond the prefrontal cortex.

Transcranial Magnetic Stimulation (TMS) is rapidly developing as a therapeutic tool for multiple psychiatric disorders. All current FDA-cleared TMS indications for psychiatric illness target the frontal lobes. Historically, TMS target selection was based on reports of brain lesion locations that cause illness or functional neuroimaging correlates within the prefrontal cortex. In addition to prefrontal targets, however, these neuroimaging studies have also consistently implicated posterior brain regions in a variety of psychiatric disorders. To date, these posterior regions have rarely been tested in TMS clinical trials. In this perspective, we consider the role of posterior regions in psychiatric disorders such as the occipital cortex, precuneus, inferior parietal lobules (IPL), and cerebellum. We synthesize preliminary evidence across few existing TMS trials targeting posterior regions and consider the risks and benefits of stimulating posterior targets for the treatment of psychiatric illness.