Poster E102, Monday, March 27, 2:30 – 4:30 pm, Pacific Concourse
Spread of Activity Following TMS is correlated with Intrinsic Resting Connectivity with the Target Region: A concurrent TMS-fMRI study
Colin Hawco1, Aristotle Voineskos1, Jennifer Steeves2, Erin Dickie1, Joseph Viviano1, Jeff Daskalakis1; 1Centre for Addiction and Mental Health, 2York University
Transcranial magnetic stimulation (TMS) modulates activity to brain regions distal to the site of simulation. Efforts are currently underway to develop biomarkers of the TMS response, such as resting state fMRI (rsfMRI). However, no studies thus far have directly related the spread of activity following TMS to resting state connectivity. In twenty-two participants rsfMRI scans were acquired, followed by concurrent TMS-fMRI over the left dorsolateral prefrontal cortex. Participants received a TMS pulse either at resting motor or 40% motor threshold. Seed-based resting connectivity was performed with the target site using the rsfMRI scan, and a GLM was performed on TMS-fMRI to show the spread of activity following TMS. Across the whole cortex, there was a relationship between TMS included cortical changes and resting connectivity (t=2.39, p = 0.026). At the individual level, twelve participants showed a positive correlation and five showed a negative correlation between TMS-fMRI and rsfMRI. This variability was driven by the TMS-fMRI data as opposed to rsfMRI, and highlights the importance of considering individual responses when considering such relationships. A group analysis was also performed, with group-level correlations between TMS-fMRI and rsfMRI in superior and medial frontal cortex and left insula, and a negative correlation with the posterior cingulate. This is the first study to directly show the relationship between the immediate effects of a TMS pulse and rsfMRI, which appears to be more prominent in participants who have more of a ‘typical’ spread of activity following a TMS pulse.
Topic Area: METHODS: Neuroimaging