Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2023 Jun 6;14:3276. doi: 10.1038/s41467-023-39034-y

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

© The Author(s) 2023

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

PMC Copyright notice

Fig. 6 — The lumbar spinal cord is capable of producing stereotyped rhythmic motor outputs with different multi-muscle activation patterns and a range of cycle frequencies in response to epidural electrical stimulation (EES). a (i) Fast rhythmic activity with a cycle frequency of 1.01 Hz and alternation between single phases of synchronous activity in multiple muscles and brief silent phases. (ii) Rhythmic activity with a cycle frequency of 0.45 Hz showing clear alternation between two distinct phases of muscle activation. This pattern exhibits essential elements that define CPG-associated locomotion in reduced animal models⁶, i.e., reciprocal activity in antagonistic muscles (green bursts) and in some homologous muscles of both legs (light blue bursts). Further complexity is seen in the double-bursting pattern of the bifunctional rectus femoris (RF; hip-flexor, knee-extensor). The backgrounds mark phases of dominant activation of the monofunctional flexor muscle tibialis anterior (TA) of the right lower limb. EES was applied throughout the entire time windows displayed, (i) recording EES 4, active contacts: 0+1−, stimulation frequency: 29.4 Hz, stimulation amplitude: 7 V, pulse width: 210 µs; (ii) recording EES 3, 0–3+, 29.4 Hz, 6 V, 210 µs. Same location of the epidural lead, with the four in-line electrodes, labeled as 0 to 3 from rostral to caudal, located at the T12 vertebral level. b Mean electromyographic (EMG) envelopes averaged from all rhythmic cycles displayed in a. c Mean EMG integrals of the rhythmic activity, shown separately for the phases with a dominant activation of the right TA (flex., flexion-like phase) and for the phases in-between (silent phases in (i) and ext., extension-like phases in (ii)). Note the strong activation of the right TA that showed little activation during spinal myoclonus. Radial axes of the polar plots are muscles and polar coordinates are mean integrated EMG activities. AD, adductors; CPG, central pattern generator; cycle_RTA, one cycle of rhythmic activity starting from the onset of right TA bursts; H hamstrings muscle group; L left; R right; TS triceps surae muscle group. Source data are provided in the Source Data file.