Combined TMS-EEG-fMRI. The level of TMS-evoked activation in anterior cingulate cortex depends on timing of TMS delivery relative to frontal alpha phase

Daily prefrontal closed-loop repetitive transcranial magnetic stimulation (rTMS) produces progressive EEG quasi-alpha phase entrainment in depressed adults

“…The hardware setup and software used to administer the EEG-guided rTMS is described in more detail in S.2 of supplementary materials (also see Refs. [24,37].…”

“…(For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.) so it may more efficiently engage the therapeutic target and affect the dynamics of the circuit that includes more than the DLPFC [24,34]. As this is a blinded ongoing trial, we are not yet able to test whether the entrainment effect seen here is linked to improved clinical response.…”

“…Most have also studied the motor system and have used motor evoked potentials as their output marker. Notably, we have found in previous work that TMS-evoked BOLD response, particularly in the dorsal ACC, depends on the frontal alpha phase prior to TMS delivery [24,34]. The data we report here is part of a randomized, active-comparator controlled clinical trial in depression we are currently completing comparing phase dependent prefrontal TMS to the standard approach that does not take phase-dependence into account.…”

“…The phase at which we synchronized the first pulse in each TMS pulse train is based on a unique targeting approach using an integrated fMRI-EEG-TMS (fET) system (see Refs. [24,34,37] and supplemental material; another separate manuscript about the fET system is also in preparation [38]), where the preferred prefrontal alpha phase 4 pre is the phase which yielded the strongest BOLD fMRI activation in the ACC. The method used to estimate 4 pre is described in the Materials and Methods section and the supplementary material (see S.1 in supplementary material for details).…”

Cell type-specific excitability probed by optogenetic stimulation depends on the phase of the alpha oscillation

“…Though, the lack of such phasedependency was also observed [41]. In addition to MEP or phosphenes-based methods most suitable for primary motor and visual cortices, TMS-evoked responses in EEG [42] and functional magnetic resonance imaging (fMRI) [43] were also found to depend on the alpha phase. Yet, EEG and fMRI responses are complex macroscopic outcomes of neuronal responses e the connection to neuronal excitability is indirect.…”