Priming stimulation: a multimodal approach to evaluate the effects of theta-burst transcranial magnetic stimulation priming on prefrontal cortex functioning in healthy and depressed individuals

Intermittent theta-burst stimulation (iTBS) has been increasingly used to target prefrontal brain regions, such as the dorsolateral prefrontal cortex (DLPFC), to optimize therapeutic outcomes in patients suffering from major depressive disorder. However, despite the promising outcomes, clinical efficacy remains rather modest. Interestingly, fundamental research targeting the motor cortex has suggested the use of priming techniques to enhance iTBS-related changes in cortical excitability. Hence, TBS priming - using a prime TBS protocol to enhance the effects of a subsequent test TBS protocol - can yield improved iTBS efficacy when applied over the prefrontal cortex. Moreover, recent developments in the field indicate that stimulation priming can be highly efficacious in reducing depressive symptoms. However, the mechanisms of action remain to be explored. This research project aims to investigate the effects of TBS priming applied to the DLPFC and the mechanisms by which TBS priming modulates prefrontal cortex functioning. The effects of iTBS alone and in combination with a TBS prime will be assessed by using a multimodal approach, consisting of neuroimaging, psychophysiological and behavioral assessments, to operationalize changes in prefrontal cortex excitability and deepen the insight into the mechanisms through which TBS priming modulates cognitive and affective processes that are related to DLPFC functioning.