Network Dynamics Mediating Ipsilateral Motor Cortex Activity during Unimanual Actions

Verstynen, Timothy D.; Ivry, Richard B.

doi:10.1162/jocn.2011.21612

Cited by 55 publications

(47 citation statements)

References 51 publications

(99 reference statements)

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“…Although we correctly hypothesised an increase in contralateral synergist muscle strength, we thought (incorrectly) this would be accompanied by increased corticomotor excitability projecting to the untrained synergist wrist flexors. This hypothesis was based on well-established evidence, that unilateral voluntary contractions not only activate the contralateral motor pathway, but also the ipsilateral motor pathway targeting the resting or untrained limb Hortobágyi et al 2003;Ruddy et al 2017;van Duinen et al 2008;Perez and Cohen 2008;Verstynen and Ivry 2011;Carson and Ruddy 2013;Hendy and Kidgell 2014;Zult et al 2016). On this basis, it was likely that the untrained synergist wrist flexors would experience increased excitability following training, because of its isometric role in the strength training protocol and because of the contribution of shared corticospinal inputs between agonists and synergists (Smith and Fetz 2009;Capaday et al 2013).…”

Section: Corticomotor Excitability Is Spatially Confined To the Untramentioning

confidence: 99%

Ipsilateral corticomotor responses are confined to the homologous muscle following cross-education of muscular strength

Mason

Frazer

Horvath³

et al. 2018

Appl. Physiol. Nutr. Metab.

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Northumbria University has developed Northumbria Research Link (NRL) to enable users to access the University's research output. Copyright © and moral rights for items on NRL are retained by the individual author(s) and/or other copyright owners. Single copies of full items can be reproduced, displayed or performed, and given to third parties in any format or medium for personal research or study, educational, or not-for-profit purposes without prior permission or charge, provided the authors, title and full bibliographic details are given, as well as a hyperlink and/or URL to the original metadata page. The content must not be changed in any way. Full items must not be sold commercially in any format or medium without formal permission of the copyright holder. The full policy is available online: http://nrl.northumbria.ac.uk/policies.html This document may differ from the final, published version of the research and has been made available online in accordance with publisher policies. To read and/or cite from the published version of the research, please visit the publisher's website (a subscription may be required.) men, aged 18-35 years; training group; n = 10 and control group; n = 10) before and after 3-weeks of strengthtraining the right biceps brachii at 80% of 1-repetition maximum (1-RM). Recruitment-curves for corticomotor excitability and inhibition of the untrained homologous and non-homologous muscle were constructed and assessed by examining the area under the recruitment curve (AURC). Strength-training increased strength of the trained elbow flexors (29%), resulting in a 18% increase in contralateral strength of the untrained elbow flexors (P <0.0001). The trained wrist flexors increased by 19%, resulting in a 12% increase in strength of the untrained wrist flexors (P = 0.005). TMS showed increased corticomotor excitability and decreased corticomotor inhibition for the untrained homologous muscle (P < 0.05); however, there were no changes in the untrained non-homologous muscle (P > 0.05). These findings show that the cross-education of muscular strength is spatially distributed; however, the neural adaptations are confined to the motor pathway ipsilateral to the untrained homologous agonist.

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Section: Corticomotor Excitability Is Spatially Confined To the Untramentioning

confidence: 99%

Ipsilateral corticomotor responses are confined to the homologous muscle following cross-education of muscular strength

Mason

Frazer

Horvath³

et al. 2018

Appl. Physiol. Nutr. Metab.

View full text Add to dashboard Cite

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“…Existing literature reported that primary motor cortex ipsilateral (M1 ipsi ) to the active limb is active during unilateral movement (Bütefisch, et al, 2014;Chiou, et al, 2014;Hinder, et al, 2010;Howatson, et al, 2011;Kim, et al, 1993;Lee, et al, 2010;McMillan, et al, 2006;Verstynen & Ivry, 2011). To understand the movement representation of the activity in M1 ipsi , we first examined the timing and the coordinate frames of movement that is represented in the M1 ipsi to the active limb in Chapter 2.…”

Section: Summary Of Resultsmentioning

confidence: 99%

“…Neural adaptation induced through experience by unilateral training could be encoded in a neural network that is responsible for use-dependent learning in both hemispheres and is accessible by the untrained limb (Carroll, et al, 2014;Verstynen & Ivry, 2011;Verstynen & Sabes, 2011). Accessibility of the information by the untrained limb could be brought about via the corpus callosum because of massive connections between hemispheres (van der Knaap & van der Ham, 2011;Wahl & Ziemann, 2008).…”

Section: Possible Mechanisms For Transfer Of Use-dependent Learning Ementioning

confidence: 99%

“…Neuroimaging and transcranial magnetic stimulation (TMS) studies showed activity in both hemispheres during unilateral movements (Bütefisch, et al, 2014;Chiou, et al, 2014;Hinder, et al, 2010;Howatson, et al, 2011;Kim, et al, 1993;Lee, et al, 2010;McMillan, et al, 2006;Verstynen & Ivry, 2011). Many different brain areas, such as parietal and prefrontal regions, have been identified to be involved in motor planning and these areas receive multiple representations of targets in visual guided movements (Cohen & Andersen, 2002;McGuire & Sabes, 2009;Sabes, 2011).…”

Section: Possible Mechanisms For Transfer Of Use-dependent Learning Ementioning

confidence: 99%

“…During unilateral movements involving the upper limbs, the primary motor cortex contralateral to the active limb (subsequently referred to as M1 contra ) exerts control over voluntary movements via the ~80 % corticospinal fibres that cross over to the contralateral hemicord at the pyramidal decussation (Kertesz & Geschwind, 1971;Levy, 2013;Siegel & Sapru, 2011). However, there is increasing evidence, gathered from neuroimaging and transcranial magnetic stimulation (TMS) studies that the primary motor cortex ipsilateral to the active limb (subsequently referred to as M1 ipsi ) is also involved during unilateral movement (Bütefisch, et al, 2014;Chiou, et al, 2014;Hinder et al, 2010;Howatson, et al, 2011;Kim et al, 1993;Lee, et al, 2010;McMillan et al, 2006;Verstynen & Ivry, 2011). Yet, it is still unclear whether, and if so in what coordinate frame, the activity in M1 ipsi during unilateral movement represents functionally relevant characteristics of the movement executed with the ipsilateral limb, such as the movement direction.…”

Section: Introductionmentioning

confidence: 99%

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Interhemispheric interactions associated with unilateral ballistic motor tasks

Chye¹

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The aim of this research was to enhance our understanding of the spatial reference frames in which movement is represented in the primary motor cortices of both hemispheres during unilateral ballistic actions. The broader goal was to reveal how the coordinate systems of movement representation influence the interactions between the two cerebral hemispheres which presumably underlie cross limb transfer of motor skill.The issue of reference frames may be critical for cross-limb interactions because definitions of space and movement often conflict for opposite limbs in intrinsicallyreferenced coordinate systems (e.g. muscle or joint-based coordinates) due to their mirror symmetry. This thesis describes a series of experiments to investigate the reference frames in which movement representations are shared bilaterally, and whether alignment of reference frames influences the transfer of performance to the untrained limb after unilateral ballistic training.There is increasing evidence that the primary motor cortex ipsilateral to the active limb is active during unilateral movement. Yet, the extent to which such activity represents functional details of movement with the ipsilateral limb, and the coordinates of any such representation, is unclear. Hence, Chapter 2 reports work aimed at understanding the timing and coordinates of interactions between the two motor cortices when movement with one hand is being prepared. Studying the time course of changes in twitch directions evoked by transcranial magnetic stimulation (TMS) enabled us to examine whether activity in the "resting" motor cortex functionally represents the impending movement, and the reference frame of any such representation. Our results showed that twitch directions in the resting limb shifted toward the impending direction of the active hand in a musclebased reference frame. Evident changes in TMS-evoked twitch parameters right before movement onset might be associated with decreases in interhemispheric inhibition and intracortical inhibition, brought about by the release of motor commands to the active limb.Use-dependent learning was previously reported to generalise according to extrinsic coordinates when posture changes were used to dissociate reference frames within the active limb, however it is unclear whether this form of learning generalises to the untrained limb. Chapter 3 assessed whether use-dependent bias in aiming performance occurred in the opposite untrained limb under postural manipulations that varied the extent to which spatial coordinates were aligned for the two limbs according to extrinsic, musclebased and midline reference frames. The results revealed that systematic bias occurred ii only when both limbs were oriented such that training and aiming targets were aligned according to all reference frames. The data suggest that aiming biases in the untrained limb after contralateral ballistic training are represented according to a combination of coordinate systems.In order to understand the role of reference frame conflicts in...

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Corticospinal and transcallosal modulation of unilateral and bilateral contractions of lower limbs

et al. 2016

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Network Dynamics Mediating Ipsilateral Motor Cortex Activity during Unimanual Actions

Cited by 55 publications

References 51 publications

Ipsilateral corticomotor responses are confined to the homologous muscle following cross-education of muscular strength

Ipsilateral corticomotor responses are confined to the homologous muscle following cross-education of muscular strength

Interhemispheric interactions associated with unilateral ballistic motor tasks

Corticospinal and transcallosal modulation of unilateral and bilateral contractions of lower limbs

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