title: Cutaneous sensory feedback plays a critical role in agonist-antagonist co-activation.
abstract: The purpose of this study was to investigate the role of cutaneous feedback in the agonist-antagonist co-activation mechanism during maximum voluntary force (MVF) production by the fingers. Seventeen healthy male subjects (age: 23.8 ± 1.0 years) were asked to press with maximal effort at their fingertips. Finger forces at the fingertips and muscle activities of the flexor digitorum superficialis (FDS, agonist) and extensor digitorum communis (EDC, antagonist) were recorded using force sensors and electromyography, respectively. There were two experimental conditions: with and without administration of a ring block to the fingers (i.e., anesthesia and normal conditions, or AC and NC, respectively). The ring block was used to deprive cutaneous feedback. Consistent with previous studies, finger MVF decreased significantly in AC compared with NC. Moreover, the force production of non-task fingers significantly increased in AC. Muscle activity of the EDC was significantly lower in AC than in NC; no significant changes in the FDS muscle were observed. The findings of this study show that cutaneous feedback not only increases MVF and force accuracy, but facilitates agonist-antagonist co-activation by increasing antagonist muscle activation. The results of this study imply that cutaneous feedback is linked to both primary and adjacent motor neurons.
authors.affiliation: Department of Physical Therapy, College of Health Science, Korea University, Jungneung 3-Dong, Sungbuk-Gu, Seoul, South Korea.
authors.forename: Yushin
authors.initials: Y
authors.lastname: Kim
authors.forename: Jae Kun
authors.initials: JK
authors.lastname: Shim
authors.forename: Young-Ki
authors.initials: YK
authors.lastname: Hong
authors.forename: Sang-Heon
authors.initials: SH
authors.lastname: Lee
authors.forename: Bum Chul
authors.initials: BC
authors.lastname: Yoon
mesh_terms: D000328:Adult; D004576:Electromyography / Q000379:methods; D056228:Feedback, Sensory / Q000502:physiology*; D005385:Fingers / Q000502:physiology*; D006801:Humans; D008297:Male; D009046:Motor Neurons / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D055815:Young Adult