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dc.contributor.authorTucker, Murrayen_US
dc.contributor.authorMorrison, Stevenen_US
dc.contributor.authorBarrett, Roden_US
dc.description.abstractAUTHOR BLOCK: M. G. TUCKER1, *S. MORRISON2, R. S. BARRETT1; 1Physiotherapy and Exercise Sci., Griffith Univ., Gold Coast, Australia; 2Sch. Physical Therapy, Old Dominion Univ., Norfolk, VA Abstract: The ability to coordinate the limbs in a purposeful manner during voluntary action is a fundamental property of the motor system. The question of "how" individuals coordinate their limbs across different actions and what is the neurophysiological underpinnings for the coordination process formed the basis for this study. Specifically, the aim was to examine what changes occur in bilateral coupling as individuals perform three fundamentally different classes of movements (e.g., postural, isometric, isotonic). Twelve young adult individuals participated in this study. Each bilateral action was performed using the index fingers. The specific movements involved; a) maintaining a steady state postural position (postural tremor), b) producing isometric force output to match a target force (20%, 40% MVC), and c) performing an alternating isotonic flexion/extension action (in-phase and out-of-phase). Specific kinematic (finger acceleration), kinetic (isometric force output) measures were collected from each participant during each specific task. Surface EMG activity from extensor digitorum and flexor digitorum were also collected. The results of the cross correlation analysis produced a positive incremental trend in the coupling strength between the index fingers from postural to isotonic actions. Coupling was lowest during the postural tremor task (r=0.03), increased during the isometric tasks (r=0.55-0.65) and was highest (r=0.93-0.97) for the voluntary finger flexion/extension (isotonic) tasks. Changes in the level of coupling between limb actions were also reflected by differences in the inter- and intra-muscle relations. For the postural tasks, no significant coupling was seen between contralateral muscle pairs. In comparison, a higher degree of coupling between muscles was observed during the isotonic and isometric actions. The degree of regularity within any given motor output across tasks was also examined using Approximate Entropy (ApEn) analysis. The postural tremor output was the most complex (high ApEn) whereas the isotonic and isometric movement signals was more regular (low ApEn). Overall, the results illustrate that coupling between the index fingers increases from posture to voluntary movement, and that these coordination changes were mediated by coupling changes between homologous muscle pairs. Increased coupling was also associated with increased regularity of the resultant motor output. Together these findings support the general premise that any alteration of the strength of the coupling relations between system elements is a contributing factor in the complex nature of any given systems physiological output. Theme and Topic (Complete): D.17.a. Kinematics and muscle activity ; D.16.d. Kinematics and Muscle Activity Keywords (Complete): Coordination ; Neurophysiology ; Complexity ; Coupling ; Bilateral Presentation Preference (Complete): Poster Only Support (Complete): Support: Noen_US
dc.publisherNo data provideden_US
dc.relation.ispartofconferencenameNeuroscience 2008en_US
dc.relation.ispartofconferencetitleAbstracts Volume 2008en_US
dc.relation.ispartoflocationWashington DC, USAen_US
dc.subject.fieldofresearchMotor Controlen_US
dc.titleChanges in bilateral coupling between the index fingers from posture to voluntary movementen_US
dc.typeConference outputen_US
dc.type.descriptionE3 - Conference Publications (Extract Paper)en_US
dc.type.codeE - Conference Publicationsen_US
gro.hasfulltextNo Full Text

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    Contains papers delivered by Griffith authors at national and international conferences.

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