title: The effect of motor overflow on bimanual asymmetric force coordination.
abstract: Motor overflow, typically described in the context of unimanual movements, refers to the natural tendency for a 'resting' limb to move during movement of the opposite limb and is thought to be influenced by inter-hemispheric interactions and intra-cortical networks within the 'resting' hemisphere. It is currently unknown, however, how motor overflow contributes to asymmetric force coordination task accuracy, referred to as bimanual interference, as there is need to generate unequal forces and corticospinal output for each limb. Here, we assessed motor overflow via motor evoked potentials (MEPs) and the regulation of motor overflow via inter-hemispheric inhibition (IHI) and short-intra-cortical inhibition (SICI) using transcranial magnetic stimulation in the presence of unimanual and bimanual isometric force production. All outcomes were measured in the left first dorsal interosseous (test hand) muscle, which maintained 30% maximal voluntary contraction (MVC), while the right hand (conditioning hand) was maintained at rest, 10, 30, or 70% of its MVC. We have found that as higher forces are generated with the conditioning hand, MEP amplitudes at the active test hand decreased and inter-hemispheric inhibition increased, suggesting reduced motor overflow in the presence of bimanual asymmetric forces. Furthermore, we found that subjects with less motor overflow (i.e., reduced MEP amplitudes in the test hemisphere) demonstrated poorer accuracy in maintaining 30% MVC across all conditions. These findings suggest that motor overflow may serve as an adaptive substrate to support bimanual asymmetric force coordination.
authors.affiliation: Human Performance and Engineering Research, Kessler Foundation, West Orange, NJ, USA.|Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Ave, ND20, Cleveland, OH, 44195, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Cunningham
authors.affiliation: Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Ave, ND20, Cleveland, OH, 44195, USA.
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Roelle
authors.affiliation: Human Performance and Engineering Research, Kessler Foundation, West Orange, NJ, USA.
authors.forename: Didier
authors.initials: D
authors.lastname: Allexandre
authors.affiliation: Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Ave, ND20, Cleveland, OH, 44195, USA.
authors.forename: Kelsey A
authors.initials: KA
authors.lastname: Potter-Baker
authors.affiliation: Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Ave, ND20, Cleveland, OH, 44195, USA.
authors.forename: Vishwanath
authors.initials: V
authors.lastname: Sankarasubramanian
authors.affiliation: Physical Medicine and Rehabilitation, MetroHealth Rehabilitation Institute, Case Western Reserve University, Cleveland, OH, USA.
authors.forename: Jayme S
authors.initials: JS
authors.lastname: Knutson
authors.affiliation: Human Performance and Engineering Research, Kessler Foundation, West Orange, NJ, USA.
authors.forename: Guang H
authors.initials: GH
authors.lastname: Yue
authors.affiliation: Center for Neurological Restoration, Department of Physical Medicine and Rehabilitation, Neurological Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Andre G
authors.initials: AG
authors.lastname: Machado
authors.affiliation: Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Ave, ND20, Cleveland, OH, 44195, USA. plowe2@ccf.org.|Center for Neurological Restoration, Department of Physical Medicine and Rehabilitation, Neurological Institute, Cleveland Clinic, Cleveland, OH, USA. plowe2@ccf.org.
authors.forename: Ela B
authors.initials: EB
authors.lastname: Plow
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006225:Hand; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology*; D011712:Pyramidal Tracts / Q000502:physiology; D013223:Statistics as Topic; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
keywords: Bimanual interference; Inter-hemispheric inhibition; Intra-cortical inhibition; Motor overflow; Transcranial magnetic stimulation