Gradient descent decomposition of force-field motor primitives optogenetically elicited for motor mapping of the murine lumbosacral spinal cord

Salmas, Paola

doi:10.24272/j.issn.2095-8137.2022.276

Cited by 6 publications

(6 citation statements)

References 44 publications

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“…The interneurons that synapse onto motor neurons have divergent projections to motor neuron pools throughout the spinal cord, including those that innervate synergist and antagonist muscles (Ronzano et al, 2021(Ronzano et al, , 2022. These spinal premotor interneurons are presumed to coordinate activity across multiple pools of motor neurons, which may contribute to the correlated discharge rates of motor units in different muscles (Lemay et al, 2001;Mussa-Ivaldi et al, 1994;Puskár & Antal, 1997;Salmas & Cheung, 2023). The change in the percentage of motor units associated with the shared modes after both interventions (Table 3) likely reflect a shift in distribution of inputs delivered by premotor interneurons.…”

Section: Motor Unit Modes As Synergiesmentioning

confidence: 99%

Motor unit modes in the calf muscles during a submaximal isometric contraction are changed by brief stretches

Weinman,

Del Vecchio,

Mazzo

et al. 2024

The Journal of Physiology

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The purpose of our study was to investigate the influence of a stretch intervention on the common modulation of discharge rate among motor units in the calf muscles during a submaximal isometric contraction. The current report comprises a computational analysis of a motor unit dataset that we published previously (Mazzo et al., 2021). Motor unit activity was recorded from the three main plantar flexor muscles while participants performed an isometric contraction at 10% of the maximal voluntary contraction force before and after each of two interventions. The interventions were a control task (standing balance) and static stretching of the plantar flexor muscles. A factorization analysis on the smoothed discharge rates of the motor units from all three muscles yielded three modes that were independent of the individual muscles. The composition of the modes was not changed by the standing‐balance task, whereas the stretching exercise reduced the average correlation in the second mode and increased it in the third mode. A centroid analysis on the correlation values showed that most motor units were associated with two or three modes, which were presumed to indicate shared synaptic inputs. The percentage of motor units adjacent to the seven centroids changed after both interventions: Control intervention, mode 1 decreased and the shared mode 1 + 2 increased; stretch intervention, shared modes either decreased (1 + 2) or increased (1 + 3). These findings indicate that the neuromuscular adjustments during both interventions were sufficient to change the motor unit modes when the same task was performed after each intervention. imageKey points Based on covariation of the discharge rates of motor units in the calf muscles during a submaximal isometric contraction, factor analysis was used to assign the correlated discharge trains to three motor unit modes. The motor unit modes were determined from the combined set of all identified motor units across the three muscles before and after each participant performed a control and a stretch intervention. The composition of the motor unit modes changed after the stretching exercise, but not after the control task (standing balance). A centroid analysis on the distribution of correlation values found that most motor units were associated with a shared centroid and this distribution, presumably reflecting shared synaptic input, changed after both interventions. Our results demonstrate how the distribution of multiple common synaptic inputs to the motor neurons innervating the plantar flexor muscles changes after a brief series of stretches.

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Section: Motor Unit Modes As Synergiesmentioning

confidence: 99%

Motor unit modes in the calf muscles during a submaximal isometric contraction are changed by brief stretches

Weinman,

Del Vecchio,

Mazzo

et al. 2024

The Journal of Physiology

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“…The processing of EMG signals for the purpose of intramuscular analyses in the intramuscular space were uniform across datasets 1-3. This processing firstly included the filtration of the raw, unrectified EMG signals into specific frequency bands (Delta [0.1-4 Hz], Theta [4][5][6][7][8], Alpha [8][9][10][11][12], Beta [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30], Low-Gamma (Piper rhythm) , High Gamma (Gamma) [60-80 Hz]) using a low-and high-pass filter combination (bi-directional 4 th order Butterworth filters with zero-phase distortion). Then the absolute values from a Hilbert transform of the filtered signals representing their oscillatory amplitudes were extracted for further analysis.…”

Section: Intramuscular Analysesmentioning

confidence: 99%

“…Next, to elucidate the functional interactions within muscles underlying whole-body reaching movements, we applied the proposed methodology to pairwise combinations of amplitude signals from six frequency-bands ([𝑓 𝑥 , 𝑓 𝑦 ]) (Delta [0.1-4 Hz], Theta [4][5][6][7][8], Alpha [8][9][10][11][12], Beta [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30], Low-Gamma (Piper rhythm) [30-60 Hz], High Gamma (Gamma) [60-80 Hz]) (see 'Quantifying diverse muscular interactions in the task space' and 'Data pre-processing' sections of the Materials and methods) extracted from the right anterior deltoid muscle. This computation serves as a novel, nonlinear measure of coherence decomposed into its task-relevant informational constituents, which we used here to determine the multifarious effects of [𝑓 𝑥 , 𝑓 𝑦 ] on the right, reaching finger anteroposterior kinematic (Fig.…”

Section: Hierarchical and Functionally Diverse Muscular Interactions ...mentioning

confidence: 99%

“…The motor redundancy problem motivating this concept describes how common neural inputs map to the task space through inter-muscular representations [13]. However, the end-effectors of this mapping operation are in fact individual muscles with their own unique anatomical attachments and activation timings [16,23], thus, as recognized by several lines of recent research [9,15,18,24], the muscle group may not be the smallest unit of modular control. Only more recently has the muscle synergy concept been formally applied at the intramuscular level [24], revealing that intramuscular synergies are independent of the muscles' compartmentalized structure and may be complementary to inter-muscular analyses as a window into the neural control of movement [25,26].…”

Section: Introductionmentioning

confidence: 99%

“…Indeed, from a more coarse-grained view, these emergent functional modules themselves, through hierarchies of complementary interactions [8], form parts of greater wholes (i.e. submodules-within-modules) [9].…”

Section: Introductionmentioning

confidence: 99%

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Quantifying the diverse contributions of hierarchical muscle interactions to motor function

O’Reilly,

Shaw,

Hilt

et al. 2023

Preprint

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The muscle synergy concept suggests that the human motor system is organised into functional modules comprised of muscles ‘working together’towards common task-goals. However, recent innovative work has added further nuance to this idea, showing how muscles may also work together towards functionally different and independent task-goals, representing crucial attributes of flexible motor behaviour. Here we probed this proposed functional neural architecture by building upon an established theoretical framework to characterise distinct types of muscle interactions, i.e. functionally similar, complementary and independent, across scales. Through a novel application of the Partial Information Decomposition to large-scale muscle activations, we unveiled complex networks of inter- and intra-muscular interactions with distinct functional roles as well as independent muscle contributions to task performance. We showcased the effectiveness of this approach by extracting hierarchical and functionally diverse motor components that were a) generalisable across participants and tasks and b) predictive of balance performance across trials and of differences in motor variability between young and older adults. In aligning muscle synergy analysis with the forefront of understanding on human movement modularity, our findings suggest the proposed methodology can offer novel biological insights into the neural control of movement and research opportunities towards health and engineering applications.

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Motor patterns of patients with spinal muscular atrophy suggestive of sensory and corticospinal contributions to the development of locomotor muscle synergies

Cheung,

Ha,

Zhang-Lea

et al. 2024

Journal of Neurophysiology

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Complex locomotor patterns are generated by combination of muscle synergies. How genetic processes, early sensorimotor experiences, and the developmental dynamics of neuronal circuits contribute to the expression of muscle synergies remains elusive. We shed light on the factors that influence development of muscle synergies by studying subjects with spinal muscular atrophy (SMA, types II/IIIa), a disorder associated with degeneration and deafferentation of motoneurons and possibly motor cortical and cerebellar abnormalities, from which the afflicted would have atypical sensorimotor histories around typical walking onset. Muscle synergies of SMA children were identified from electromyographic signals recorded during active assisted leg motions or walking, and compared with those of age-matched controls. We found that the earlier the SMA onset age, the more different the SMA synergies were from the normative. These alterations could not just be explained by the different degrees of uneven motoneuronal losses across muscles. The SMA-specific synergies had activations in muscles from multiple limb compartments, a finding reminiscent of the neonatal synergies of typically developing infants. Overall, while the synergies shared between SMA and control subjects may reflect components of a core modular infrastructure determined early in life, the SMA-specific synergies may be developmentally immature synergies that arise from inadequate activity-dependent interneuronal sculpting due to abnormal sensorimotor experience and other factors. Other mechanisms including SMA-induced intraspinal changes and altered cortical-spinal interactions may also contribute to synergy changes. Our interpretation highlights the roles of the sensory and descending systems to the typical and abnormal development of locomotor modules.

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Gradient descent decomposition of force-field motor primitives optogenetically elicited for motor mapping of the murine lumbosacral spinal cord

Cited by 6 publications

References 44 publications

Motor unit modes in the calf muscles during a submaximal isometric contraction are changed by brief stretches

Motor unit modes in the calf muscles during a submaximal isometric contraction are changed by brief stretches

Quantifying the diverse contributions of hierarchical muscle interactions to motor function

Motor patterns of patients with spinal muscular atrophy suggestive of sensory and corticospinal contributions to the development of locomotor muscle synergies

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