Spatiotemporally Precise Neuromodulation by Transcranial Magnetic Stimulation Guided by Multimodal Neuroimaging

Background:

Transcranial magnetic stimulation (TMS) is a non-invasive technique that uses a transient electromagnetic field over a small area of the scalp to alter neuronal activity. It has been approved by Health Canada for the treatment of major depressive disorder and obsessive-compulsive disorder. Despite its clinical prevalence, TMS has a response rate of less than 50% and high intra- and inter-subject variability. Even among healthy subjects, the probability of inducing neuro-modulatory effects can be as low as 50%.

Design:

Depending on the study's aims, participants will have to visit Sunnybrook Health Sciences Centre two or three times on separate days. Participants will be screened with a medical record review before their first visit.

In the first visit, participants will have a magnetic resonance imaging (MRI) session. During the MRI session, participants will be brought inside an MRI scanner to collect images, including structural and functional MRI scans. During structural scans, participants will be asked to stay inside the MRI while images are taken. During functional MRI scans, participants will be asked to take rests with eyes open, watching and/or listening to audiovisual stimuli, and respond to stimuli by button pressing. Before starting MRI scans, a short training on the task will be taken. An additional assessment and, if necessary, training sessions will be conducted to ensure that participants undergo imaging while being able to keep their heads sufficiently for acceptable fMRI data quality. Before entering the MRI room, participants will be asked to remove any metal or magnetic sensitive objects (e.g., jewelry, keys, credit cards) to ensure safety. Earplugs or earphones will be provided to participants to reduce the loud noise produced by the MRI scanner. During the MRI scans, participants will perform the same task as notified in the training session. Short breaks will be arranged between tasks. The entire MRI procedure will take approximately one hour. If electroencephalograph (EEG) is to be recorded during MRI scans, an additional one hour is needed for EEG preparation before the MRI scans. After MRI scans, participants may be asked to rate their feelings toward the audiovisual stimuli, cognitive states, and emotional states on a computer.