Fractionated simple and choice reaction time in children with prenatal exposure to alcohol.

Abstract

The present study investigated central and peripheral processing speed using simple reaction time (SRT) and choice reaction time (CRT) tasks in children who were exposed to alcohol in utero compared with control subjects. Each RT interval was fractionated into premotor and motor components to assess the central processing of stimulus information and peripheral motor unit recruitment, respectively. Eleven children with confirmed prenatal alcohol exposure (ALC) and 13 control subjects (NC), aged 5 to 10 years, completed 20 trials of both SRT and CRT tasks. Muscle activity was recorded from the biceps brachii muscle of each arm using electromyography to facilitate the fractionating of RT into premotor and motor components. ALC children exhibited significantly slower premotor RTs during the CRT task. Motor RTs were also slower for the ALC group during both SRT and CRT tasks. ALC children exhibited greater response variability compared with control subjects; however, the magnitude of this variability was not greater than would be predicted, given their lengthened RTs. In contrast, response variability was greater for young children of both groups even after accounting for mean RT. Significant age-related differences in premotor and motor RTs were also observed. Alcohol-related increases in CRT were attributable to longer premotor and motor components, reflecting both reduced speed of information processing and peripheral delays in responding. These alterations likely are associated with alcohol-related changes in the central and peripheral nervous systems that could impede or slow neuronal transmission.