Ongoing brain rhythms shape I-wave properties in a computational model

This study explores how ongoing brain activity, like sensorimotor rhythms, affects responses to transcranial magnetic stimulation (TMS). Using a computational model, simulating TMS-induced I-waves, the impact of the power and phase of these rhythms is examined. The model shows that TMS responses vary significantly with the phase and power of ongoing activity, showing the strongest response at maximum depolarization of layer 5 neurons. The degree of phase-modulation is also intensity-dependent, with lower intensities showing stronger modulation. The model predicts that responses to TMS are highly variable for low stimulation intensities if ongoing brain rhythms are not taken into account. Closed-loop TMS-EEG holds promise for obtaining more reliable TMS effects.