TMS bursts can modulate local and networks oscillations during lower-limb movement in elderly subjects

High order lower-limb functions involve processing information via motor and cognitive control networks. Measuring oscillations is a key element in communication within and between cortical networks during high order motor functions. Increased midfrontal theta oscillations are related to improved lower-limb motor performances in patients with movement disorders. Non-invasive neuromodulation approaches have not been explored extensively to understand the oscillatory mechanism of lower-limb motor functions. Transcranial magnetic stimulation (TMS) bursts (4 pulses) were applied to the midfrontal lead (vertex) before a GO-Cue pedaling task, to examine the effects on local and network electroencephalogram oscillations in healthy elderly subjects. TMS bursts increased the theta activity in the local, as well as the associated network during the lower-limb pedaling task. TMS bursts increased the midfrontal cue-triggered post-imperative negative variation component. Furthermore, after task-related TMS bursts sessions, increased resting-state alpha activity was observed in the midfrontal region. TMS burst-induced changes have been associated with improvement in motor performance with cognitive control. Our study suggests the ability of midfrontal TMS bursts to directly modulate local and network oscillations in a frequency manner during lower-limb motor task. TMS bursts-induced modulation may provide insights into the functional roles of oscillatory activity during lower-limb movement in normal and disease conditions.