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

. 2021 Jul 21;11:14900. doi: 10.1038/s41598-021-94047-1

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

© The Author(s) 2021

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 licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence 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 licence, visit http://creativecommons.org/licenses/by/4.0/.

PMC Copyright notice

Modes of stimulation. (a) Examining the evoked muscle responses at each position along the spinal cord with both point-to-point (PTP) and point-to-reference (PTR) stimulation revealed positions where each mode induced distinct responses within the spinal cord. Each measurement demonstrates muscle activity at 400 µA constant current stimulation. The shaded box indicates the spinal level of stimulation and the intensity of red in the rat forelimb diagram indicates the level of activation of a given muscle group by relative muscle activity. This information is displayed below each diagram as a bar graph displaying muscle activity at each location normalized as a fraction from 0 to 1 where 1 is the maximal evoked response observed for each muscle at any stimulated position. (b) Thresholds were also affected by PTR vs PTP stimulation. For instance, at the C5/6 level, the thresholds of the wrist flexor and extensor were 15.7 and 17.1% lower respectively when stimulated at the same position in PTR vs PTP mode and there was a trend to lower overall thresholds in PTR mode. (c) Following a spinal stimulation doublet with a 30 ms interstimulation interval, we observed changes in the second evoked potential where the second amplitude was (i) lowered indicating signal suppression or (ii) raised indicating spinal facilitation. (d) (i) We analyzed the relative facilitation/suppression observed in both modes at various stimulation intensities and observed, (ii) PTP mode resulted in a greater degree of spinal facilitation.