State-dependent TMS effects in the visual cortex after visual adaptation: A combined TMS-EEG study

Objective: The impact of transcranial magnetic stimulation (TMS) has been shown to depend on the initial brain state of the stimulated cortical region. This observation has led to the development of paradigms that aim to enhance the specificity of TMS effects by using visual/luminance adaptation to modulate brain state prior to the application of TMS. However, the neural basis of interactions between TMS and adaptation is unknown. Here, we examined these interactions by using electroencephalography (EEG) to measure the impact of TMS over the visual cortex after luminance adaptation. Methods: Single-pulses of neuronavigated TMS (nTMS) were applied at two different intensities over the left visual cortex after adaptation to either high or low luminance. We then analyzed the effects of adaptation on the global and local cortical excitability. Results: The analysis revealed a significant interaction between the TMS-evoked responses and the adaptation condition. In particular, when nTMS was applied with high intensity, the evoked responses were larger after adaptation to high than low luminance.Conclusion: This result provides the first neural evidence on the interaction between TMS with visual adaptation. Significance: TMS can activate neurons differentially as a function of their adaptation state.(c) 2021 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Automated summary

The impact of transcranial magnetic stimulation (TMS) on the brain depends on the initial brain state. Visual/luminance adaptation has been used to modulate brain state prior to TMS application, aiming to enhance TMS effects. This study used electroencephalography to investigate the interactions between TMS and adaptation in the visual cortex.