Electromyographic investigation of order of participation of trunk and lower limb muscles of patients with total and partial transection of the spinal cord

Intermuscular coherence allows the investigation of common input to muscle groups. Although beta-band (15–30 Hz) intermuscular coherence is well understood as originating from the cortex, the source of intermuscular coherence at lower frequencies is still unclear. We used a wearable device that recorded electromyographic (EMG) signals during a 24-h period in four lower limb muscles of seven spinal cord injury patients (American Spinal Cord Injury Association impairment scale: A, 6 subjects; B, 1 subject) while they went about their normal daily life activities. We detected natural spasms occurring during these long-lasting recordings and calculated intermuscular coherence between all six possible combinations of muscle pairs. There was significant intermuscular coherence at low frequencies, between 2 and 13 Hz. The most likely source for this was the spinal cord and its peripheral feedback loops, because the spinal lesions in these patients had interrupted connections to supraspinal structures. This is the first report to demonstrate that the spinal cord is capable of producing low-frequency intermuscular coherence with severely reduced or abolished descending drive. NEW & NOTEWORTHY This is the first report to demonstrate that intermuscular coherence between lower limb muscles at low frequencies can be produced by the spinal cord with severely reduced or abolished descending drive.

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Evaluation of Descending Spinal Cord Tracts in Patients With Thoracic Cord Lesions Using Motor Evoked Potentials Recorded From the Paravertebral and Lower Limb Muscles

Journal of Spinal Disorders & Techniques ◽

10.1097/00024720-200304000-00008 ◽

2003 ◽

Vol 16 (2) ◽

pp. 163-170 ◽

Cited By ~ 2

Author(s):

Taku Ogura ◽

Hiroshi Takeshita ◽

Hitoshi Hase ◽

Taturo Hayashida ◽

Masaki Mori ◽

...

Keyword(s):

Spinal Cord ◽

Evoked Potentials ◽

Lower Limb ◽

Motor Evoked Potentials ◽

Lower Limb Muscles ◽

Limb Muscles ◽

Thoracic Cord

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Differential activation of lumbar and sacral motor pools during walking at different speeds and slopes

Journal of Neurophysiology ◽

10.1152/jn.00167.2019 ◽

2019 ◽

Vol 122 (2) ◽

pp. 872-887 ◽

Cited By ~ 4

Author(s):

A. H. Dewolf ◽

Y. P. Ivanenko ◽

K. E. Zelik ◽

F. Lacquaniti ◽

P. A. Willems

Keyword(s):

Spinal Cord ◽

Body Mass ◽

Lower Limb ◽

Power Production ◽

Negative Slope ◽

Differential Activation ◽

Lower Limb Muscles ◽

Negative Center ◽

Limb Muscles ◽

Differential Involvement

Organization of spinal motor output has become of interest for investigating differential activation of lumbar and sacral motor pools during locomotor tasks. Motor pools are associated with functional grouping of motoneurons of the lower limb muscles. Here we examined how the spatiotemporal organization of lumbar and sacral motor pool activity during walking is orchestrated with slope of terrain and speed of progression. Ten subjects walked on an instrumented treadmill at different slopes and imposed speeds. Kinetics, kinematics, and electromyography of 16 lower limb muscles were recorded. The spinal locomotor output was assessed by decomposing the coordinated muscle activation profiles into a small set of common factors and by mapping them onto the rostrocaudal location of the motoneuron pools. Our results show that lumbar and sacral motor pool activity depend on slope and speed. Compared with level walking, sacral motor pools decrease their activity at negative slopes and increase at positive slopes, whereas lumbar motor pools increase their engagement when both positive and negative slope increase. These findings are consistent with a differential involvement of the lumbar and the sacral motor pools in relation to changes in positive and negative center of body mass mechanical power production due to slope and speed. NEW & NOTEWORTHY In this study, the spatiotemporal maps of motoneuron activity in the spinal cord were assessed during walking at different slopes and speeds. We found differential involvement of lumbar and sacral motor pools in relation to changes in positive and negative center of body mass power production due to slope and speed. The results are consistent with recent findings about the specialization of neuronal networks located at different segments of the spinal cord for performing specific locomotor tasks.

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