Grant: Doctoral: Vanier Canada Graduate Scholarships

Supervisor: Dr. Fidel Vila-Rodriguez, University of British Columbia BACKGROUND: Repetitive transcranial magnetic stimulation (rTMS) is an effective treatment for major depressive disorder for patients who have not responded to pharmacotherapy. rTMS is a non-invasive brain stimulation therapy that works through the principle of electromagnetic induction, where a coil is placed on the scalp to generate an electrical field in the brain, altering neuronal activity. Because the rTMS-induced electrical field is relatively focal, where the coil is applied, or targeted, on the scalp influences treatment outcomes. Specific patterns of brain activity within the prefrontal cortex are thought to be important in the antidepressant effects of rTMS, and thus targeting this pattern of activity may result in better treatment outcomes. Individualized functional targeting (iFT) is a novel technique using functional magnetic resonance imaging (fMRI) to develop a personalized rTMS treatment target based on a patient's unique brain activity. Evidence is lacking to ascertain whether iFT produces superior outcomes compared to current methods of targeting, the use of which are less time- and resource-intensive. Therefore, my project will retrospectively estimate the effect of iFT stimulation on treatment response. METHODS: This study will be conducted on a sample of 340 patients who received fMRI scans before undergoing a course of rTMS using a standard (non-individualized) target. iFT will be computed for each patient, and I will determine whether proximity of the treatment to the iFT was associated with treatment response. Further, I will calculate the strength of the electrical field at the iFT of each patient to determine whether iFT activation was related to treatment response. SIGNIFICANCE: rTMS response rates are approximately 40-60%. This study has the potential to improve targeting practices for rTMS treatment, thereby improving treatment outcomes.