Children with Heavy Prenatal Alcohol Exposure Experience Reduced Control of Isotonic Force
Reprint requests: Roger W. Simmons, PhD, Motor Control Laboratory, School of Exercise and Nutritional Sciences, San Diego State University, San Diego, CA 92182; Tel.: 619-594-5543; Fax: 619-594-6553; E-mail: email@example.com
Heavy prenatal alcohol exposure can result in diverse and extensive damage to the central nervous system, including the cerebellum, basal ganglia, and cerebral cortex. Given that these brain regions are involved in the generation and maintenance of motor force, we predicted that prenatal alcohol exposure would adversely affect this parameter of motor control. We previously reported that children with gestational alcohol exposure experience significant deficits in regulating isometric (i.e., constant) force. The purpose of this study was to determine whether these children exhibit similar deficits when producing isotonic (i.e., graded) force.
Children with heavy prenatal alcohol exposure and typically developing children completed a series of isotonic force contractions by exerting force on a load cell to match a criterion target force displayed on a computer monitor. Two levels of target force (5 or 20% of maximum voluntary force) were investigated in combination with varying levels of visual feedback.
Compared with control children, children with heavy prenatal alcohol exposure generated isotonic force signals that were less accurate, more variable, and less complex in the time domain. Specifically, interactions were found between group and visual feedback for response accuracy and signal complexity, suggesting that these children have greater difficulty altering their motor output when visual feedback is low.
These data suggest that prenatal alcohol exposure produces deficits in regulating isotonic force, which presumably result from alcohol-related damage to developing brain regions involved in motor control. These children will most likely experience difficulty performing basic motor skills and daily functional skills that require coordination of finely graded force. Therapeutic strategies designed to increase feedback and, consequently, facilitate visual-motor integration could improve isotonic force production in these children.