Repetitive Transcranial Magnetic Stimulation for Treating Depression: A Functional Magnetic Resonance Imaging Study

Depression is accompanied by rumination that supports inwardly focused cognitive attention on negative events and emotions. There is evidence to indicate that one aspect of this ruminative behavior lies in an abnormal increase in intra-regional connectivity among elements of the default mode network (DMN). It is also widely recognized that depression is associated with disturbances of cognition that include deficits in attentional processing, including both reductions in processing speed and deficits in selective attentional processing that are considered a part of executive function. Thus, there is at least equal reason to believe that attention and executive control networks might show changes in intra-regional functional connectivity. Given the attentional deficits associated with MDD, we hypothesize that there will be a weakening of intra-network resting state BOLD functional connectivity (rs-fcMRI) in addition to the strengthened connectivity reported by others.Further, we suggest that these shifts in intra-regional connectivity extend to the well-recognized anti-correlated activity between these two networks and support the intrusion of introspective, ruminative thought on cognitive activities that require externally directed attention. To test this hypothesis, we will use fMRI resting state functional connectivity to examine shifts in network connectivity prior to and following rTMS treatment for depression.