Sensory Entrained TMS (seTMS) enhances motor cortex excitability.

Area of Science:

• Neuroscience
• Human Motor Physiology
• Brain-Computer Interfaces

Background:

• Transcranial magnetic stimulation (TMS) is vital for studying motor physiology but suffers from response variability.
• This variability stems from mistimed TMS pulses relative to ongoing brain oscillations.
• Precise timing of TMS is crucial for enhancing mechanistic insights and clinical applications.

Purpose of the Study:

• To introduce and validate Sensory Entrained TMS (seTMS), a method synchronizing brain oscillations with musical rhythms to optimize TMS timing.
• To investigate if rhythm-evoked sensorimotor alpha phase alignment enhances primary motor cortical (M1) excitability.
• To assess the impact of seTMS on motor-evoked potentials (MEPs) in healthy adults.

Main Methods:

• Electroencephalography (EEG) confirmed that listening to musical rhythms desynchronizes mu oscillations approximately 200 ms before auditory events.
• Single TMS pulses were delivered over M1 200 ms prior to rhythmic auditory stimuli.
• Motor-evoked potentials (MEPs) were recorded to measure M1 excitability.

Main Results:

• Passive listening to rhythms desynchronized sensorimotor mu oscillations, creating a predictable window for stimulation.
• seTMS delivery resulted in significantly larger MEPs compared to standard TMS and a control condition.
• MEP enhancement via seTMS was independent of participants' musical experience.

Conclusions:

• seTMS effectively enhances corticomotor excitability by precisely timing TMS pulses to synchronized brain rhythms.
• This approach offers a practical and cost-effective strategy for optimizing non-invasive brain stimulation.
• seTMS holds promise for improving the efficacy of brain stimulation therapies.