Cross-Activation of the Motor Cortex during Unilateral Contractions of the Quadriceps
Transcranial magnetic stimulation (TMS) studies have demonstrated that unilateral muscle contractions in the upper limb produce motor cortical activity in both the contralateral and ipsilateral motor cortices. The increase in excitability of the corticomotor pathway activating the resting limb has b...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Frontiers Media S.A.
2017-08-01
|
| Series: | Frontiers in Human Neuroscience |
| Subjects: | |
| Online Access: | http://journal.frontiersin.org/article/10.3389/fnhum.2017.00397/full |
| _version_ | 1819228778997481472 |
|---|---|
| author | Ashlee M. Hendy Lilian Chye Wei-Peng Teo |
| author_facet | Ashlee M. Hendy Lilian Chye Wei-Peng Teo |
| author_sort | Ashlee M. Hendy |
| collection | DOAJ |
| description | Transcranial magnetic stimulation (TMS) studies have demonstrated that unilateral muscle contractions in the upper limb produce motor cortical activity in both the contralateral and ipsilateral motor cortices. The increase in excitability of the corticomotor pathway activating the resting limb has been termed “cross-activation”, and is of importance due to its involvement in cross-education and rehabilitation. To date, very few studies have investigated cross-activation in the lower limb. Sixteen healthy participants (mean age 29 ± 9 years) took part in this study. To determine the effect of varying contraction intensities in the lower limb, we investigated corticomotor excitability and intracortical inhibition of the right rectus femoris (RF) while the left leg performed isometric extension at 0%, 25%, 50%, 75% and 100% of maximum force output. Contraction intensities of 50% maximal force output and greater produced significant cross-activation of the corticomotor pathway. A reduction in silent period duration was observed during 75% and 100% contractions, while the release of short-interval intracortical inhibition (SICI) was only observed during maximal (100%) contractions. We conclude that increasing isometric contraction intensities produce a monotonic increase in cross-activation, which was greatest during 100% force output. Unilateral training programs designed to induce cross-education of strength in the lower limb should therefore be prescribed at the maximal intensity tolerable. |
| first_indexed | 2024-12-23T11:02:42Z |
| format | Article |
| id | doaj.art-504c7b753a9741b591c02564b5249102 |
| institution | Directory Open Access Journal |
| issn | 1662-5161 |
| language | English |
| last_indexed | 2024-12-23T11:02:42Z |
| publishDate | 2017-08-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Human Neuroscience |
| spelling | doaj.art-504c7b753a9741b591c02564b52491022022-12-21T17:49:35ZengFrontiers Media S.A.Frontiers in Human Neuroscience1662-51612017-08-011110.3389/fnhum.2017.00397254231Cross-Activation of the Motor Cortex during Unilateral Contractions of the QuadricepsAshlee M. Hendy0Lilian Chye1Wei-Peng Teo2Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Science, Deakin UniversityBurwood, VIC, AustraliaFrailty Research Programme, Geriatric Education and Research InstituteYishun Central, SingaporeInstitute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Science, Deakin UniversityBurwood, VIC, AustraliaTranscranial magnetic stimulation (TMS) studies have demonstrated that unilateral muscle contractions in the upper limb produce motor cortical activity in both the contralateral and ipsilateral motor cortices. The increase in excitability of the corticomotor pathway activating the resting limb has been termed “cross-activation”, and is of importance due to its involvement in cross-education and rehabilitation. To date, very few studies have investigated cross-activation in the lower limb. Sixteen healthy participants (mean age 29 ± 9 years) took part in this study. To determine the effect of varying contraction intensities in the lower limb, we investigated corticomotor excitability and intracortical inhibition of the right rectus femoris (RF) while the left leg performed isometric extension at 0%, 25%, 50%, 75% and 100% of maximum force output. Contraction intensities of 50% maximal force output and greater produced significant cross-activation of the corticomotor pathway. A reduction in silent period duration was observed during 75% and 100% contractions, while the release of short-interval intracortical inhibition (SICI) was only observed during maximal (100%) contractions. We conclude that increasing isometric contraction intensities produce a monotonic increase in cross-activation, which was greatest during 100% force output. Unilateral training programs designed to induce cross-education of strength in the lower limb should therefore be prescribed at the maximal intensity tolerable.http://journal.frontiersin.org/article/10.3389/fnhum.2017.00397/fulltranscranial magnetic stimulationquadricepsbilateral-transfercross-educationmotor evoked potential |
| spellingShingle | Ashlee M. Hendy Lilian Chye Wei-Peng Teo Cross-Activation of the Motor Cortex during Unilateral Contractions of the Quadriceps Frontiers in Human Neuroscience transcranial magnetic stimulation quadriceps bilateral-transfer cross-education motor evoked potential |
| title | Cross-Activation of the Motor Cortex during Unilateral Contractions of the Quadriceps |
| title_full | Cross-Activation of the Motor Cortex during Unilateral Contractions of the Quadriceps |
| title_fullStr | Cross-Activation of the Motor Cortex during Unilateral Contractions of the Quadriceps |
| title_full_unstemmed | Cross-Activation of the Motor Cortex during Unilateral Contractions of the Quadriceps |
| title_short | Cross-Activation of the Motor Cortex during Unilateral Contractions of the Quadriceps |
| title_sort | cross activation of the motor cortex during unilateral contractions of the quadriceps |
| topic | transcranial magnetic stimulation quadriceps bilateral-transfer cross-education motor evoked potential |
| url | http://journal.frontiersin.org/article/10.3389/fnhum.2017.00397/full |
| work_keys_str_mv | AT ashleemhendy crossactivationofthemotorcortexduringunilateralcontractionsofthequadriceps AT lilianchye crossactivationofthemotorcortexduringunilateralcontractionsofthequadriceps AT weipengteo crossactivationofthemotorcortexduringunilateralcontractionsofthequadriceps |