title: Changes in Multidigit Synergies and Their Feed-Forward Adjustments in Multiple Sclerosis.
abstract: The authors explored the changes in multidigit synergies in patients with multiple sclerosis (MS) within the framework of the uncontrolled manifold hypothesis. The specific hypotheses were that both synergy indices and anticipatory synergy adjustments prior to the initiation of a self-paced quick action would be diminished in the patients compared to age-matched controls. The MS patients and age-matched controls (n = 13 in both groups) performed one-finger and multifinger force production tasks involving both accurate steady-state force production and quick force pulses. The patients showed significantly lower maximal finger forces and a tendency toward slower force pulses. Enslaving was increased in MS, but only in the lateral fingers (index and little). Indices of multifinger synergies during steady-state force production were lower in MS, mainly due to the lower amount of intertrial variance that did not affect total force. Anticipatory synergy adjustments were significantly delayed in MS. The results show that MS leads to significant changes in multidigit synergies and feed-forward adjustments of the synergies prior to a quick action. The authors discuss possible contributions of subcortical structures to the impaired synergic control.
authors.affiliation: a Department of Kinesiology , The Pennsylvania State University, University Park.
authors.forename: Hang Jin
authors.initials: HJ
authors.lastname: Jo
authors.affiliation: a Department of Kinesiology , The Pennsylvania State University, University Park.
authors.forename: Daniela
authors.initials: D
authors.lastname: Mattos
authors.affiliation: b Department of Neurology , Pennsylvania State University-Milton S. Hershey Medical Center , Hershey.
authors.forename: Elisabeth B
authors.initials: EB
authors.lastname: Lucassen
authors.affiliation: b Department of Neurology , Pennsylvania State University-Milton S. Hershey Medical Center , Hershey.|c Department of Pharmacology , Pennsylvania State University-Milton S. Hershey Medical Center , Hershey.|d Department of Radiology , Pennsylvania State University-Milton S. Hershey Medical Center , Hershey.|e Department of Neurosurgery , Pennsylvania State University-Milton S. Hershey Medical Center , Hershey.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Huang
authors.affiliation: a Department of Kinesiology , The Pennsylvania State University, University Park.
authors.forename: Mark L
authors.initials: ML
authors.lastname: Latash
mesh_terms: D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena / Q000502:physiology; D001921:Brain / Q000473:pathology; D016022:Case-Control Studies; D005260:Female; D005385:Fingers / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement; D009103:Multiple Sclerosis / Q000000981:diagnostic imaging / Q000503:physiopathology*
keywords: anticipatory synergy adjustment; hand; multiple sclerosis; synergy