2023
Deiana, Davide; Pinardi, Mattia; Noccaro, Alessia; Iandoli, Michela; Pino, Giovanni Di; Formica, Domenico
Validation of Vibrotactile Feedback to Improve Selective Motor Units Recruitment Proceedings Article
In: 2023 IEEE International Symposium on Medical Measurements and Applications (MeMeA), pp. 1–5, 2023.
Abstract | Links | BibTeX | Tags: Augmentation, Firing, Indexes, Measurement units, Motor Units, Muscles, Performance evaluation, Psychometric Measures, Task analysis, Vibrations, Vibrotactile Feedback, Wearable Device
@inproceedings{deiana_validation_2023,
title = {Validation of Vibrotactile Feedback to Improve Selective Motor Units Recruitment},
author = {Davide Deiana and Mattia Pinardi and Alessia Noccaro and Michela Iandoli and Giovanni {Di Pino} and Domenico Formica},
doi = {10.1109/MeMeA57477.2023.10171925},
year = {2023},
date = {2023-06-01},
urldate = {2023-06-01},
booktitle = {2023 IEEE International Symposium on Medical Measurements and Applications (MeMeA)},
pages = {1–5},
abstract = {Recently, muscle interfaces have been used to control external devices through the activation of single motor units. In the present study, we proposed and validated two different vibro-tactile feedback strategies designed to convey information about the firing rate of two motor units active at the same time. In a two-alternative forced-choice task, participants had to discriminate the higher vibration frequency among the ones of two vibrotactile stimulators placed on their arms. Spike strategy and continuous strategy were tested in two different experiments and motor units’ activation was simulated. The spike strategy directly translates the discharge activity of motor units into a vibratory burst with a 1-to-1 conversion, i.e. each spike of one motor unit triggers a single burst of the corresponding vibrator. This was evaluated in two body configurations, i.e. same forearm versus different arms. The continuous strategy mapped the discharge activity of motor units into a continuous vibration exploiting the entire operative range of vibrotactile stimulators. A single-body configuration was tested (i.e. two different arms). Participants’ responses were fitted with a psychometric sigmoid curve (i.e. a psychometric model commonly applied to detection and discrimination tasks), and the discrimination accuracy index was used to evaluate the feedback strategies. Results from Experiment 1 showed that the continuous strategy worked better when the stimulators were placed on two different arms, but overall discrimination performance was poor. Experiment 2 showed that both the continuous strategy conveyed vastly superior overall performance compared to the continuous strategy.},
keywords = {Augmentation, Firing, Indexes, Measurement units, Motor Units, Muscles, Performance evaluation, Psychometric Measures, Task analysis, Vibrations, Vibrotactile Feedback, Wearable Device},
pubstate = {published},
tppubtype = {inproceedings}
}
Recently, muscle interfaces have been used to control external devices through the activation of single motor units. In the present study, we proposed and validated two different vibro-tactile feedback strategies designed to convey information about the firing rate of two motor units active at the same time. In a two-alternative forced-choice task, participants had to discriminate the higher vibration frequency among the ones of two vibrotactile stimulators placed on their arms. Spike strategy and continuous strategy were tested in two different experiments and motor units’ activation was simulated. The spike strategy directly translates the discharge activity of motor units into a vibratory burst with a 1-to-1 conversion, i.e. each spike of one motor unit triggers a single burst of the corresponding vibrator. This was evaluated in two body configurations, i.e. same forearm versus different arms. The continuous strategy mapped the discharge activity of motor units into a continuous vibration exploiting the entire operative range of vibrotactile stimulators. A single-body configuration was tested (i.e. two different arms). Participants’ responses were fitted with a psychometric sigmoid curve (i.e. a psychometric model commonly applied to detection and discrimination tasks), and the discrimination accuracy index was used to evaluate the feedback strategies. Results from Experiment 1 showed that the continuous strategy worked better when the stimulators were placed on two different arms, but overall discrimination performance was poor. Experiment 2 showed that both the continuous strategy conveyed vastly superior overall performance compared to the continuous strategy.
2022
Bräcklein, Mario; Barsakcioglu, Deren Yusuf; Vecchio, Alessandro Del; Ibáñez, Jaime; Farina, Dario
Reading and Modulating Cortical β Bursts from Motor Unit Spiking Activity Journal Article
In: Journal of Neuroscience, vol. 42, no. 17, pp. 3611–3621, 2022, ISSN: 0270-6474, 1529-2401, (Publisher: Society for Neuroscience Section: Research Articles).
Abstract | Links | BibTeX | Tags: Motor Units, neural interfaces, neural oscillations, real-time decomposition, β oscillations
@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}
}
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.
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.