Document Type

Journal Article

Publication Title

Physiological Reports

Volume

10

Issue

13

PubMed ID

35778836

Publisher

Wiley

School

School of Medical and Health Sciences

Funders

Natural Sciences and Engineering Research Council of Canada. Grant Number: 312700

Comments

Gill, G., Forman, D. A., Reeves, J. E., Taylor, J. L., & Bent, L. R. (2022). Location‐specific cutaneous electrical stimulation of the footsole modulates corticospinal excitability to the plantarflexors and dorsiflexors during standing. Physiological Reports, 10(13), e15240. https://doi.org/10.14814/phy2.15240

Abstract

Non-noxious electrical stimulation to distinct locations of the foot sole evokes location-specific cutaneous reflex responses in lower limb muscles. These reflexes occur at latencies that may enable them to be mediated via a transcortical pathway. Corticospinal excitability to the plantarflexors and dorsiflexors was measured in 16 participants using motor evoked potentials (MEPs). Spinal excitability was measured in eight of the original participants using cervicomedullary motor evoked potentials (CMEPs). Measurements were collected with and without preceding cutaneous stimulus to either the heel (HEEL) or metatarsal (MET) locations of the foot sole, and evoked potentials were elicited to coincide with the arrival of the cutaneous volley at either the motor cortex or spinal cord. Plantarflexor MEPs and CMEPs were facilitated with cutaneous stimulation to the HEEL for MEPs (soleus p = 0.04, medial gastrocnemius (MG) p = 0.017) and CMEPs (soleus p = 0.047 and MG p = 0.015), but they were unchanged following MET stimulation for MEPs or CMEPs. Dorsiflexor MEPs were unchanged with cutaneous stimulation at either location, but dorsiflexor CMEPs increased with cutaneous stimulation (p = 0.05). In general, the increase in CMEP amplitudes was larger than the increase in MEP amplitudes, indicating that an increase in spinal excitability likely explains most of the increase in corticospinal excitability. The larger change observed in the CMEP also indicates that excitability from supraspinal sources likely decreased, which could be due to a net change in the excitability of intracortical circuits. This study provides evidence that cutaneous reflexes from foot sole skin are likely influenced by a transcortical pathway.

DOI

10.14814/phy2.15240

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

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