Cold-water immersion of a single limb reduces inhibition and enhances facilitation in the motor cortex of the opposite limb

Justin Kavanagh*, Eden Delahunty, Daniel McKeown, Jacob Thorstensen

*Corresponding author for this work

Research output: Contribution to conferenceAbstractResearch

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Abstract

Background and Aim: Performing brief strong contractions with a single limb is often accompanied by unintended muscle activity in the contralateral homologous muscle. At the spinal level, reflex activity appear largely unaffected in the contralateral resting muscle. However at the cortical level, TMS-induced motor evoked potentials are increased in the contralateral resting limb when maximal effort contractions are performed. Although a body of evidence indicates that crossed-effects are elicited via strong voluntary contractions, it is unknown if altering sensory input of one limb is capable of changing motor activity on the opposite side of the body.

Methods:
The current study examined if immersing a single upper limb in very cold water (4 degrees Celsius) affected inhibitory and facilitatory motor cortex circuits in the opposite non-immersed limb. Eight healthy subjects (22.1 ± 2.7
yr) participated in the experiment and standard paired-pulse TMS protocols were used to assess motor cortex circuitry associated with the non-immersed limb. Resting motor threshold, short interval intracortical inhibition (SICI), long
interval intracortical inhibition (LICI), and intracortical facilitation (ICF) were assessed for the extensor carpi radialis brevis muscle in the non-immersed limb.

Results:
Visual analogue scales confirmed that each subject experienced significant changes in pain and temperature due to cold water immersion of a single limb. Resting motor threshold did not differ between control and water immersion
conditions. Although no changes were detected for LICI, SICI was significantly reduced in the opposite limb during the immersion condition compared to the control condition (p = 0.035). This reduced inhibition in motor cortical circuits
corresponded to increased ICF during the immersion condition compared to the control condition (p = 0.013).

Conclusions:
The presence of a localised painful stimulus on one side of the body affected cortical circuits responsible for activating muscles on the opposite side of the body. This suggests that functional relationships exists between sensory
areas of one hemisphere and motor areas of the opposite hemisphere.
Original languageEnglish
Pages96-96
Number of pages1
Publication statusPublished - 1 Jun 2018
Externally publishedYes
EventXXII International Society of Electrophysiology and Kinesiology Congress 2018 - University College Dublin, Dublin, Ireland
Duration: 30 Jun 20182 Jul 2018
https://isek.org/past-conferences/

Conference

ConferenceXXII International Society of Electrophysiology and Kinesiology Congress 2018
Abbreviated titleISEK 2018
Country/TerritoryIreland
CityDublin
Period30/06/182/07/18
Internet address

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