title: Individuals with autism spectrum disorder show abnormalities during initial and subsequent phases of precision gripping.
abstract: Sensorimotor impairments are common in autism spectrum disorder (ASD), but they are not well understood. Here we examined force control during initial pulses and the subsequent rise, sustained, and relaxation phases of precision gripping in 34 individuals with ASD and 25 healthy control subjects. Participants pressed on opposing load cells with their thumb and index finger while receiving visual feedback regarding their performance. They completed 2- and 8-s trials during which they pressed at 15%, 45%, or 85% of their maximum force. Initial pulses guided by feedforward control mechanisms, sustained force output controlled by visual feedback processes, and force relaxation rates all were examined. Control subjects favored an initial pulse strategy characterized by a rapid increase in and then relaxation of force when the target force was low (Type 1). When the target force level or duration of trials was increased, control subjects transitioned to a strategy in which they more gradually increased their force, paused, and then increased their force again. Individuals with ASD showed a more persistent bias toward the Type 1 strategy at higher force levels and during longer trials, and their initial force output was less accurate than that of control subjects. Patients showed increased force variability compared with control subjects when attempting to sustain a constant force level. During the relaxation phase, they showed reduced rates of force decrease. These findings suggest that both feedforward and feedback motor control mechanisms are compromised in ASD and these deficits may contribute to the dyspraxia and sensorimotor abnormalities often seen in this disorder.
authors.affiliation: Center for Autism and Developmental Disabilities, University of Texas Southwestern Medical Center, Dallas, Texas;
authors.forename: Zheng
authors.identifier: http://orcid.org/0000-0003-2265-0891
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Center for Autism and Developmental Disabilities, University of Texas Southwestern Medical Center, Dallas, Texas;
authors.forename: Grant C
authors.initials: GC
authors.lastname: Magnon
authors.affiliation: Center for Autism and Developmental Disabilities, University of Texas Southwestern Medical Center, Dallas, Texas;
authors.forename: Stormi P
authors.initials: SP
authors.lastname: White
authors.affiliation: Center for Autism and Developmental Disabilities, University of Texas Southwestern Medical Center, Dallas, Texas;
authors.forename: Rachel K
authors.initials: RK
authors.lastname: Greene
authors.affiliation: Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida; Department of Neurology, University of Florida, Gainesville, Florida; Department of Biomedical Engineering, University of Florida, Gainesville, Florida; and.
authors.forename: David E
authors.initials: DE
authors.lastname: Vaillancourt
authors.affiliation: Center for Autism and Developmental Disabilities, University of Texas Southwestern Medical Center, Dallas, Texas; Departments of Psychiatry and Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas matt.mosconi@utsouthwestern.edu.
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Mosconi
mesh_terms: D000293:Adolescent; D000067877:Autism Spectrum Disorder / Q000175:diagnosis* / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D008297:Male; D010775:Photic Stimulation / Q000379:methods; D011597:Psychomotor Performance / Q000502:physiology; D013997:Time Factors
keywords: autism spectrum disorder; cerebellum; feedback motor control; feedforward motor control; precision grip; visuomotor deficit