Asymmetrical modulation of corticospinal excitability in the contracting and resting contralateral wrist flexors during unilateral shortening, lengthening and isometric contractions

Uematsu, Azusa; Obata, Hiroki; Endoh, Takashi; Kitamura, Taku; Hortobágyi, Tibor; Nakazawa, Kimitaka; Suzuki, Shuji

doi:10.1007/s00221-010-2397-x

Cited by 21 publications

(18 citation statements)

References 36 publications

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“…In addition, this enhancement was comparable in magnitude between young and old participants, regardless of which hemisphere was engaged in the task. In this regard, our observations are consistent with many TMS reports in young adults, wherein enhanced corticomotor excitability on the "resting" hemisphere has been described when the other was engaged in various unimanual tasks [4,19,21-25]. The present findings may also be interpreted in light of neuroimaging data showing increases in the activity of the ipsilateral sensorimotor cortex during various unimanual tasks, particularly more complex tasks [1,26].…”

Section: Discussionsupporting

confidence: 93%

Task-related enhancement in corticomotor excitability during haptic sensing with the contra- or ipsilateral hand in young and senior adults

Master

Tremblay

2012

BMC Neurosci

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BackgroundHaptic sensing with the fingers represents a unique class of manipulative actions, engaging motor, somatosensory and associative areas of the cortex while requiring only minimal forces and relatively simple movement patterns. Using transcranial magnetic stimulation (TMS), we investigated task-related changes in motor evoked potential (MEP) amplitude associated with unimanual haptic sensing in two related experiments. In Experiment I, we contrasted changes in the excitability of the hemisphere controlling the task hand in young and old adults under two trial conditions, i.e. when participants either touched a fine grating (smooth trials) or touched a coarse grating to detect its groove orientation (grating trials). In Experiment II, the same contrast between tasks was performed but with TMS applied over the hemisphere controlling the resting hand, while also addressing hemispheric (right vs. left) and age differences.ResultsIn Experiment I, a main effect of trial type on MEP amplitude was detected (p = 0.001), MEPs in the task hand being ~50% larger during grating than smooth trials. No interaction with age was detected. Similar results were found for Experiment II, trial type having a large effect on MEP amplitude in the resting hand (p < 0.001) owing to selective increase in MEP size (~2.6 times greater) for grating trials. No interactions with age or side (right vs. left) were detected.ConclusionsCollectively, these results indicate that adding a haptic component to a simple unilateral finger action can elicit robust corticomotor facilitation not only in the working hemisphere but also in the opposite hemisphere. The fact that this facilitation seems well preserved with age, when task difficulty is adjusted, has some potential clinical implications.

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Section: Discussionsupporting

confidence: 93%

Task-related enhancement in corticomotor excitability during haptic sensing with the contra- or ipsilateral hand in young and senior adults

Master

Tremblay

2012

BMC Neurosci

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“…, 2002; Gruber et al. , 2009; Uematsu et al. , 2010), although this has not been reported in the ipsilateral M1.…”

Section: Discussionmentioning

confidence: 68%

“…, 2001; Hortobágyi et al. , 2003; Perez & Cohen, 2008; Uematsu et al. , 2010) provide evidence that activation of the ipsilateral motor cortical areas and the excitability of the corticospinal path targeting the resting hand increase during contralateral unilateral voluntary isometric contractions, and these responses increase with contraction intensity.…”

Section: Discussionmentioning

confidence: 99%

Ipsilateral motor cortical responses to TMS during lengthening and shortening of the contralateral wrist flexors

Howatson

Taylor

Rider

et al. 2011

European Journal of Neuroscience

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Unilateral lengthening contractions provide a greater stimulus for neuromuscular adaptation than shortening contractions in the active and non-active contralateral homologous muscle, although little is known of the potential mechanism. Here we examined the possibility that corticospinal and spinal excitability vary in a contraction-specific manner in the relaxed right flexor carpi radialis (FCR) when humans perform unilateral lengthening and shortening contractions of the left wrist flexors at the same absolute force. Corticospinal excitability in the relaxed right FCR increased more during lengthening than shortening at 80 and 100% of maximum voluntary contraction (MVC). Short-interval intracortical inhibition (SICI) diminished during shortening contractions and it became nearly abolished during lengthening. Intracortical facilitation (ICF) lessened during shortening but increased during lengthening. Interhemispheric inhibition (IHI) to the "non-active" motor cortex diminished during shortening and became nearly abolished during lengthening at 90% MVC. The amplitude of the H-reflex in the relaxed right FCR decreased during and remained depressed for 20 s after lengthening and shortening of the left wrist flexors. We discuss the possibility that instead of the increased afferent input, differences in the descending motor command and activation of brain areas that link function of the motor cortices during muscle lengthening vs. shortening may cause the contraction-specific modulation of ipsilateral motor cortical output. In conclusion, ipsilateral M1 responses to TMS are contraction-specific; unilateral lengthening and shortening contractions reduced contralateral spinal excitability but uniquely modulated ipsilateral corticospinal excitability and the networks involved in intracortical and interhemispheric connections, which may have clinical implications.

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“…During unilateral muscle contraction, different types of contralateral effects have been reported [9], [22]–[24]. A homologous muscle-dominant effect has been reported in the upper limbs [25]–[27], and this effect is the result of both intra- and inter-hemispheric interactions, as IHI from the contralateral M1 to the ipsilateral M1 and SICI in the ipsilateral M1 have the highest degree of suppression during homologous muscle contraction [6], [8].…”

Section: Discussionmentioning

confidence: 99%

Homologous Muscle Contraction during Unilateral Movement Does Not Show a Dominant Effect on Leg Representation of the Ipsilateral Primary Motor Cortex

Chiou¹,

Wang²,

Liao

et al. 2013

PLoS ONE

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Co-activation of homo- and heterotopic representations in the primary motor cortex (M1) ipsilateral to a unilateral motor task has been observed in neuroimaging studies. Further analysis showed that the ipsilateral M1 is involved in motor execution along with the contralateral M1 in humans. Additionally, transcranial magnetic stimulation (TMS) studies have revealed that the size of the co-activation in the ipsilateral M1 has a muscle-dominant effect in the upper limbs, with a prominent decline of inhibition within the ipsilateral M1 occurring when a homologous muscle contracts. However, the homologous muscle-dominant effect in the ipsilateral M1 is less clear in the lower limbs. The present study investigates the response of corticospinal output and intracortical inhibition in the leg representation of the ipsilateral M1 during a unilateral motor task, with homo- or heterogeneous muscles. We assessed functional changes within the ipsilateral M1 and in corticospinal outputs associated with different contracting muscles in 15 right-handed healthy subjects. Motor tasks were performed with the right-side limb, including movements of the upper and lower limbs. TMS paradigms were measured, consisting of short-interval intracortical inhibition (SICI) and recruitment curves (RCs) of motor evoked potentials (MEPs) in the right M1, and responses were recorded from the left rectus femoris (RF) and left tibialis anterior (TA) muscles. TMS results showed that significant declines in SICI and prominent increases in MEPs of the left TA and left RF during unilateral movements. Cortical activations were associated with the muscles contracting during the movements. The present data demonstrate that activation of the ipsilateral M1 on leg representation could be increased during unilateral movement. However, no homologous muscle-dominant effect was evident in the leg muscles. The results may reflect that functional coupling of bilateral leg muscles is a reciprocal movement.

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Asymmetrical modulation of corticospinal excitability in the contracting and resting contralateral wrist flexors during unilateral shortening, lengthening and isometric contractions

Cited by 21 publications

References 36 publications

Task-related enhancement in corticomotor excitability during haptic sensing with the contra- or ipsilateral hand in young and senior adults

Task-related enhancement in corticomotor excitability during haptic sensing with the contra- or ipsilateral hand in young and senior adults

Ipsilateral motor cortical responses to TMS during lengthening and shortening of the contralateral wrist flexors

Homologous Muscle Contraction during Unilateral Movement Does Not Show a Dominant Effect on Leg Representation of the Ipsilateral Primary Motor Cortex

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