RESUMO
Electrophysiological imaging of recognition memory using event-related potentials (ERPs) in intrauterine growth-restricted (IUGR) newborns allows assessment of recognition memory before the onset of multiple confounding variables. Animal models that reproduce the physiologic components associated with IUGR have demonstrated adverse effects on the hippocampus, a structure that is essential to normal memory processing. Previous electrophysiologic studies have demonstrated shortened auditory-evoked potential (AEP) and visual-evoked potential (VEP) latencies in IUGR infants suggesting accelerated neural maturation in response to the adverse in-utero environment. The hypothesis of the current study was that newborns with IUGR and head-sparing would demonstrate altered auditory recognition memory when compared to controls and that the configuration of the alteration would evidence advanced maturation but still be different from that of typically grown newborns. Twelve IUGR newborns born at 34-38 weeks gestation with head-sparing and 16 age-matched control newborns were tested with both a speech/nonspeech paradigm to assess auditory sensory processing and a novel (stranger's voice) and familiar (mother's voice) paradigm to assess recognition memory. In the recognition memory experiment, a three-way interaction of condition, lead, and group was identified for the lateral leads T4, CM3, and CM4 with the response to the mother being of much greater area in the IUGR cohort than in the controls. This ERP configuration has previously been reported for the midline leads in term newborns. The findings indicate that IUGR newborns with head-sparing have electrophysiologic evidence of accelerated maturation of cognitive processing suggesting an atypical process of maturation that may not support typical cognitive development.
