Optimization of ITBS for Depression

Repetitive TMS (rTMS) is a well-established method for modulating brain activity. Through successive stimulations in the form of magnetic fields, it is possible to modify the sensitivity of neurons in the brain, also known as cortical excitability. Cortical excitability is important for the induction of brain plasticity, the ability of the brain to reorganize itself and form new connections in response to stimuli. A particular class of rTMS, intermittent theta burst TMS (iTBS), is commonly used to modulate cortical excitability and induce plasticity for therapeutic purposes, notably for treatment-resistant depression. Different iTBS stimulation parameters can be used to induce plasticity. This study will focus on two parameters, namely, the form and duration of the electromagnetic stimulation. The shape of the electromagnetic pulse refers to how the electromagnetic wave is configured over time, while the duration is simply the period during which this electromagnetic pulse remains active. These parameters are expected to influence the effectiveness of iTBS in modulating cortical activity but remain little studied. The main aim of this study will be to compare the effectiveness of different stimulation parameters in the induction of plasticity, which will then make it possible to improve the rTMS protocols used for treatment-resistant depression.