An Electrophysiological Study of School-aged Children with a History of Failure to Thrive during Infancy ROSCOEA. DYKMAN, PHILIP C. LOlZOU, PEGGY T. ACKERMAN, PATRICK H. CASEY, W. BRIAN MCPHERSON Department of Pediatrics, University of Arkansas for Medical Sciences, Arkansas Children's Hospital Research Institute, and Arkansas Children's Nutrition Center Abstract--Sixty-five subjects, ages 8 to 12, participated in a visual electrophysiological study. Twenty-two of the subjects had received a diagnosis of nonorganic failure-to-thrive (FTT) before the age of three. The remaining 43 subjects had no history of FFT and served as Controls. IQs were obtained with the abbreviated WISC-III, and the Controls were split into two groups, LO IQ and HI IQ, to provide a LO IQ Control group with an average IQ equivalent to the FTT group. Event-related brain potentials (ERPs) were recorded from five scalp locations during a cued continuous performance task (CPT). Subjects had to press a button every time they saw the letter "X" following the letter "A" (50 targets out of 400 stimuli). During the CPT, the FTT subjects made marginally more errors of omission to targets than the LO IQ Control group and significantly more errors of omission than the HI IQ Control subjects. The groups did not differ significantly on errors of commission (false alarms) or reaction times to targets. ERP averages revealed a group difference in amplitude in a late slow wave for the 50 non-X stimuli (false targets) that followed the letter A. This difference was greatest over frontal sites, where the FTT group had a more negative going slow wave than each control group. Late frontal negativity to No Go stimuli has been linked with post-decisional processing, notably in young children. Thus, the FFT subjects may have less efficient inhibitory processes, reflected by additional late frontal activation. FAILURE TO THRIVE(FTT) is a term used by pediatricians to describe infants and toddlers with abnormally low weight for age and gender and/or with an abnormally low weight gain over a period of time (Casey, 1992). Although there are no strict criteria for FTT, the FTT diagnosis usually implies the child weighs less than the 5th percentile on the National Center for Health Statistics (NCHS) curves (referenced against children of same gender and gestation adjusted age) and the child's weight to height ratio is less than the 25th percentile (on the NCHS curves). Additionally, genetic growth expectation is considered, i.e., the parents' height and weight. Thus, for a small child in a small family to be labeled FTT, the child would have to be low in weight for height or show low weight gain velocity, since weight for age would normally be low. Some children above the 5th percentile in weight are called FTT if they show abnormally slow weight gain. Abnormal weight gain can be defined as moving down across two major percentile lines on the Address for correspondence: Roscoe A. Dykman, Ph.D., Dept. of Pediatrics/C.A.R.E., Arkansas Children's Hospital, 800 Marshall Street, Little Rock, AR 72202. Integrative Physiological and Behavioral Science, October-December 2000, Vol. 35, No. 4,284-297. 284