Component wave analysis of flash visual evoked potentials in preterm infants

Waveform analyses of flash visual evoked potentials (VEPs) in neurologically normal preterm infants (postconceptional age 31-42 weeks) were performed using an autoregressive moving average (ARMA) model to interpret the evoked potentials as dynamic high-order responses to natural and experimental stimulation. Averaged VEP waveforms obtained were decomposed into 7-11 component impulse response waveforms by an ARMA component wave analysis. Based on the histogram of damping frequencies of different component impulse response waveforms, the waveforms were divided into 6 groups. All characteristic values in Group IV (6.5-12.0 Hz), such as the energy, the percent energy and the damping time of component impulse responses, changed significantly with increasing postconceptional age. Among the component impulse responses, neuronal networks generating impulse responses classified into Group IV appeared to be important to the developmental change of VEPs in preterm infants. The identification of an impulse response component with a dominant frequency which undergoes a well-identified change with age might prove to be a useful tool for discriminating between normal and abnormal changes in the VEP with age in preterm infants and could aid in the early diagnosis of abnormalities.