title: Increased Force Variability Is Associated with Altered Modulation of the Motorneuron Pool Activity in Autism Spectrum Disorder (ASD).
abstract: Force control deficits have been repeatedly documented in autism spectrum disorder (ASD). They are associated with worse social and daily living skill impairments in patients suggesting that developing a more mechanistic understanding of the central and peripheral processes that cause them may help guide the development of treatments that improve multiple outcomes in ASD. The neuromuscular mechanisms underlying force control deficits are not yet understood. Seventeen individuals with ASD and 14 matched healthy controls completed an isometric index finger abduction test at 60% of their maximum voluntary contraction (MVC) during recording of the first dorsal interosseous (FDI) muscle to determine the neuromuscular processes associated with sustained force variability. Central modulation of the motorneuron pool activation of the FDI muscle was evaluated at delta (0-4 Hz), alpha (4-10 Hz), beta (10-35 Hz) and gamma (35-60 Hz) frequency bands. ASD patients showed greater force variability than controls when attempting to maintain a constant force. Relative to controls, patients also showed increased central modulation of the motorneuron pool at beta and gamma bands. For controls, reduced force variability was associated with reduced delta frequency modulation of the motorneuron pool activity of the FDI muscle and increased modulation at beta and gamma bands. In contrast, delta, beta, and gamma frequency oscillations were not associated with force variability in ASD. These findings suggest that alterations of central mechanisms that control motorneuron pool firing may underlie the common and often impairing symptoms of ASD.
authors.affiliation: Schiefelbusch Institute for Life Span Studies, University of Kansas, 1000 Sunnyside Ave., Lawrence, KS 66045, USA. zhengwang@ku.edu.|Clinical Child Psychology Program, University of Kansas, 1000 Sunnyside Ave., Lawrence, KS 66045, USA. zhengwang@ku.edu.|Kansas Center for Autism Research and Training (K-CART), University of Kansas Medical School, Overland Park, KS 66213, USA. zhengwang@ku.edu.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Schiefelbusch Institute for Life Span Studies, University of Kansas, 1000 Sunnyside Ave., Lawrence, KS 66045, USA. minhyuk.kwon@marquette.edu.|Clinical Child Psychology Program, University of Kansas, 1000 Sunnyside Ave., Lawrence, KS 66045, USA. minhyuk.kwon@marquette.edu.|Kansas Center for Autism Research and Training (K-CART), University of Kansas Medical School, Overland Park, KS 66213, USA. minhyuk.kwon@marquette.edu.
authors.forename: Minhyuk
authors.initials: M
authors.lastname: Kwon
authors.affiliation: Center for Autism and Developmental Disabilities, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA. smohanty3@humana.com.
authors.forename: Suman
authors.initials: S
authors.lastname: Mohanty
authors.affiliation: Schiefelbusch Institute for Life Span Studies, University of Kansas, 1000 Sunnyside Ave., Lawrence, KS 66045, USA. lmschmitt@ku.edu.|Clinical Child Psychology Program, University of Kansas, 1000 Sunnyside Ave., Lawrence, KS 66045, USA. lmschmitt@ku.edu.|Kansas Center for Autism Research and Training (K-CART), University of Kansas Medical School, Overland Park, KS 66213, USA. lmschmitt@ku.edu.
authors.forename: Lauren M
authors.initials: LM
authors.lastname: Schmitt
authors.affiliation: Center for Autism and Developmental Disabilities, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA. Stormi.White@UTsouthwestern.edu.
authors.forename: Stormi P
authors.initials: SP
authors.lastname: White
authors.affiliation: Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL 32611, USA. eachristou@hhp.ufl.edu.
authors.forename: Evangelos A
authors.initials: EA
authors.lastname: Christou
authors.affiliation: Schiefelbusch Institute for Life Span Studies, University of Kansas, 1000 Sunnyside Ave., Lawrence, KS 66045, USA. mosconi@ku.edu.|Clinical Child Psychology Program, University of Kansas, 1000 Sunnyside Ave., Lawrence, KS 66045, USA. mosconi@ku.edu.|Kansas Center for Autism Research and Training (K-CART), University of Kansas Medical School, Overland Park, KS 66213, USA. mosconi@ku.edu.
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Mosconi
mesh_terms: D000293:Adolescent; D000328:Adult; D000067877:Autism Spectrum Disorder / Q000503:physiopathology*; D058256:Brain Waves; D016022:Case-Control Studies; D019054:Evoked Potentials, Motor; D005260:Female; D005385:Fingers / Q000502:physiology; D006801:Humans; D007537:Isometric Contraction; D008297:Male; D009046:Motor Neurons / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology
keywords: autism spectrum disorder (ASD); decomposition-based electromyography (dEMG); first dorsal interosseus (FDI) muscle; force variability; index finger abduction; motorneuron pool