Journal article
Forelimb force direction and magnitude independently controlled by spinal modules in the macaque
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, v 117(44), pp 27655-27666
03 Nov 2020
PMID: 33060294
Abstract
Modular organization of the spinal motor system is thought to reduce the cognitive complexity of simultaneously controlling the large number of muscles and joints in the human body. Although modular organization has been confirmed in the hindlimb control system of several animal species, it has yet to be established in the forelimb motor system or in primates. Expanding upon experiments originally performed in the frog lumbar spinal cord, we examined whether costimulation of two sites in the macaque monkey cervical spinal cord results in motor activity that is a simple linear sum of the responses evoked by stimulating each site individually. Similar to previous observations in the frog and rodent hindlimb, our analysis revealed that in most cases (77% of all pairs) the directions of the force fields elicited by costimulation were highly similar to those predicted by the simple linear sum of those elicited by stimulating each site individually. A comparable simple summation of electromyography (EMG) output, especially in the proximal muscles, suggested that this linear summation of force field direction was produced by a spinal neural mechanism whereby the forelimb motor output recruited by costimulation was also summed linearly. We further found that the force field magnitudes exhibited supralinear (amplified) summation, which was also observed in the EMG output of distal forelimb muscles, implying a novel feature of primate forelimb control. Overall, our observations support the idea that complex movements in the primate forelimb control system are made possible by flexibly combined spinal motor modules.
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Details
- Title
- Forelimb force direction and magnitude independently controlled by spinal modules in the macaque
- Publication Details
- PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, v 117(44), pp 27655-27666
- Publisher
- NATL ACAD SCIENCES; WASHINGTON
- Number of pages
- 0
- Grant note
- This work was supported by grants-in-aid for scientific research from the Ministry of Education, Culture, Sports, Science and Technology of Japan (18020030, 18047027, 26120003, 19K21825, 19H05724, and 19H01092 to K.S. and 19H03975 and 19H05311 to T.T.), the Japan Science Technology Agency Precursory Research for Embryonic Science and Technology program (to K.S.), and the UeharaMemorial Foundation, the Naito Foundation, and the Takeda Science Foundation (to T.T.). D.K. was a Japan Society for the Promotion of Science summer fellow supported by NSF Grant OISE-1108063. We thank C. Sasaki for technical assistance, Jeehee Kim for helping with surgery, Michel Lemay for lending the multiaxis force sensor, and Tomomichi Oya and Jonas Zimmermann for helping with some surgery and recording. We also thank Adam Phillips, PhD for editing a draft of this manuscript.
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Drexel University
- Web of Science ID
- WOS:000587503000076
- Scopus ID
- 2-s2.0-85095664619
- Other Identifier
- 991021860680004721
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- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Neurosciences