Publications

@article{bracklein_reading_2022,

title = {Reading and Modulating Cortical β Bursts from Motor Unit Spiking Activity},

author = { Mario Bräcklein and Deren Yusuf Barsakcioglu and Alessandro Del Vecchio and Jaime Ibáñez and Dario Farina},

url = {https://www.jneurosci.org/content/42/17/3611},

doi = {10.1523/JNEUROSCI.1885-21.2022},

issn = {0270-6474, 1529-2401},

year  = {2022},

date = {2022-04-01},

urldate = {2022-04-01},

journal = {Journal of Neuroscience},

volume = {42},

number = {17},

pages = {3611–3621},

abstract = {β Oscillations (13–30 Hz) are ubiquitous in the human motor nervous system. Yet, their origins and roles are unknown. Traditionally, β activity has been treated as a stationary signal. However, recent studies observed that cortical β occurs in “bursting events,” which are transmitted to muscles. This short-lived nature of β events makes it possible to study the main mechanism of β activity found in the muscles in relation to cortical β. Here, we assessed whether muscle β activity mainly results from cortical projections. We ran two experiments in healthy humans of both sexes (N = 15 and N = 13, respectively) to characterize β activity at the cortical and motor unit (MU) levels during isometric contractions of the tibialis anterior muscle. We found that β rhythms observed at the cortical and MU levels are indeed in bursts. These bursts appeared to be time-locked and had comparable average durations (40–80 ms) and rates (approximately three to four bursts per second). To further confirm that cortical and MU β have the same source, we used a novel operant conditioning framework to allow subjects to volitionally modulate MU β. We showed that volitional modulation of β activity at the MU level was possible with minimal subject learning and was paralleled by similar changes in cortical β activity. These results support the hypothesis that MU β mainly results from cortical projections. Moreover, they demonstrate the possibility to decode cortical β activity from MU recordings, with a potential translation to future neural interfaces that use peripheral information to identify and modulate activity in the central nervous system. 

SIGNIFICANCE STATEMENT We show for the first time that β activity in motor unit (MU) populations occurs in bursting events. These bursts observed in the output of the spinal cord appear to be time-locked and share similar characteristics of β activity at the cortical level, such as the duration and rate at which they occur. Moreover, when subjects were exposed to a novel operant conditioning paradigm and modulated MU β activity, cortical β activity changed in a similar way as peripheral β. These results provide evidence for a strong correspondence between cortical and peripheral β activity, demonstrating the cortical origin of peripheral β and opening the pathway for a new generation of neural interfaces.},

note = {Publisher: Society for Neuroscience 

Section: Research Articles},

keywords = {Motor Units, neural interfaces, neural oscillations, real-time decomposition, β oscillations},

pubstate = {published},

tppubtype = {article}

}