title: Cortical Effects on Ipsilateral Hindlimb Muscles Revealed with Stimulus-Triggered Averaging of EMG Activity.
abstract: While a large body of evidence supports the view that ipsilateral motor cortex may make an important contribution to normal movements and to recovery of function following cortical injury (Chollet et al. 1991; Fisher 1992; Caramia et al. 2000; Feydy et al. 2002), relatively little is known about the properties of output from motor cortex to ipsilateral muscles. Our aim in this study was to characterize the organization of output effects on hindlimb muscles from ipsilateral motor cortex using stimulus-triggered averaging of EMG activity. Stimulus-triggered averages of EMG activity were computed from microstimuli applied at 60-120 μA to sites in both contralateral and ipsilateral M1 of macaque monkeys during the performance of a hindlimb push-pull task. Although the poststimulus effects (PStEs) from ipsilateral M1 were fewer in number and substantially weaker, clear and consistent effects were obtained at an intensity of 120 μA. The mean onset latency of ipsilateral poststimulus facilitation was longer than contralateral effects by an average of 0.7 ms. However, the shortest latency effects in ipsilateral muscles were as short as the shortest latency effects in the corresponding contralateral muscles suggesting a minimal synaptic linkage that is equally direct in both cases.
authors.affiliation: Department of Molecular and Integrative Physiology.
authors.forename: William G
authors.initials: WG
authors.lastname: Messamore
authors.affiliation: Department of Molecular and Integrative Physiology.
authors.forename: Gustaf M
authors.initials: GM
authors.lastname: Van Acker
authors.affiliation: Department of Molecular and Integrative Physiology.
authors.forename: Heather M
authors.initials: HM
authors.lastname: Hudson
authors.affiliation: Department of Molecular and Integrative Physiology.
authors.forename: Hongyu Y
authors.initials: HY
authors.lastname: Zhang
authors.affiliation: Department of Anesthesiology.
authors.forename: Anthony
authors.initials: A
authors.lastname: Kovac
authors.affiliation: Department of Neurosurgery, University of Kansas Medical Center, Kansas City, KS 66160, USA.
authors.forename: Jules
authors.initials: J
authors.lastname: Nazzaro
authors.affiliation: Department of Molecular and Integrative Physiology.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Cheney
mesh_terms: D000818:Animals; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D004576:Electromyography / Q000379:methods; D007839:Functional Laterality; D006614:Hindlimb / Q000502:physiology*; D008253:Macaca mulatta; D008297:Male; D008839:Microelectrodes; D009043:Motor Activity / Q000502:physiology*; D009044:Motor Cortex / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D013997:Time Factors
keywords: EMG; hindlimb; ipsilateral; motor cortex; stimulus-triggered average