title: The Use of Open- and Closed-Loop Control During Goal-Directed Force Responses by Children with Heavy Prenatal Alcohol Exposure.
abstract: BACKGROUND
  Many daily functional activities involve goal-directed responses based on open-loop and closed-loop motor control, yet little is known about how children with heavy prenatal alcohol exposure organize and regulate these 2 types of control systems when completing a goal-directed force response.
  
  
  METHODS
  Children with (n = 19) or without (n = 23) heavy prenatal alcohol exposure were required to match a target force (25 and 50% of maximum voluntary force) in a specified target time (200, 800, and 2,000 ms). Target force and produced force were visually displayed on a computer monitor. The analog force-time record was parsed into 2 segments: the period beginning from force initiation to the first reversal in force was designated the open-loop phase, and the remainder of the response was the closed-loop phase.
  
  
  RESULTS
  Compared to controls, alcohol-exposed children produced a significantly shorter duration of open-loop control, a higher open-loop phase rate of force development, a shorter time to reach maximum force during the closed-loop phase, and greater absolute target force error. Increasing target force magnitude did not differentially alter the performance of the clinical group.
  
  
  CONCLUSIONS
  The results indicate that alcohol-exposed children experience deficits in completing goal-directed force responses that likely stem from an alcohol-related insult to the central nervous system. Therapeutic exercises should be designed to recalibrate internal timing systems and improve visuomotor integration.
authors.affiliation: Motor Control Laboratory, School of Exercise and Nutritional Sciences, San Diego State University, San Diego, California.
authors.forename: Roger W
authors.initials: RW
authors.lastname: Simmons
authors.affiliation: Center for Behavioral Teratology, Department of Psychology, San Diego State University, San Diego, California.|San Diego Joint Doctoral Program in Clinical Psychology, San Diego State University/University of California, San Diego, California.
authors.forename: Tanya T
authors.initials: TT
authors.lastname: Nguyen
authors.affiliation: Center for Behavioral Teratology, Department of Psychology, San Diego State University, San Diego, California.
authors.forename: Jennifer D
authors.initials: JD
authors.lastname: Thomas
authors.affiliation: Center for Behavioral Teratology, Department of Psychology, San Diego State University, San Diego, California.
authors.forename: Edward P
authors.initials: EP
authors.lastname: Riley
mesh_terms: D000293:Adolescent; D000428:Alcohol Drinking / Q000009:adverse effects / Q000453:epidemiology*; D002648:Child; D005260:Female; D006040:Goals; D006801:Humans; D008297:Male; D010775:Photic Stimulation / Q000379:methods; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology*; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology
keywords: Open-Loop and Closed-Loop Control; Prenatal Alcohol Exposure