We evaluated the effects of postconceptional age and postnatal experience on the development of neonatal auditory recognition memory. Three groups were tested: a premature newborn group (tested at 35-38 weeks postconceptional age, < or = 1 week old), a full-term newborn group (tested at 39-42 weeks postconceptional age, < or = 1 week old), and a full-term experienced group (tested at 39-42 weeks postconceptional age, > 1 week old; range 8-30 days). Event-related potentials were collected while infants listened to the maternal voice alternating with a stranger's voice. Postconceptional age was correlated with the development of recognition memory for the maternal voice while there were qualitative effects of postnatal experience on latency measurements. Maturity of auditory cortical responses was not correlated with recognition memory abilities. We conclude that maturation of the recognition memory pathways is primarily a function of postconceptional age with qualitative effects of postnatal experience. Maturation of the auditory recognition memory pathway is not contingent upon maturation of the "P2" peak thought to arise from primary auditory cortex.

Preterm infants are at increased risk for cognitive disorders, including impairments in recognition memory. This study evaluated the effects of extreme prematurity on the neural pathway for auditory recognition memory using event-related potentials (ERPs), a neurophysiological technique widely used in cognitive neuroscience. ERPs were recorded at term postmenstrual age in 35 preterm infants born at less than 32 weeks' gestation (22 males, 13 females; mean birthweight ([BW] 1154g, SD 374g) with normal brain ultrasounds, compared with 40 healthy, term newborns (1 to 3 days of age; 20 males, 20 females; BW 3672g, SD 420g). Because infants must be able to detect and discriminate sounds before recognizing them, two paradigms were used to assess these functions. The first evaluated the detection and discrimination of speech sounds. The second tested recognition of the mother's voice compared with a stranger's. Results showed significantly different patterns of speech sound discrimination in preterm infants compared with term infants. No evidence of maternal voice recognition was elicited from the preterm infants. No specific patterns of auditory detection or discrimination were associated with patterns of recognition memory, suggesting that the function of multiple neural pathways may have been altered in this group of preterm infants. These results provide a functional corroboration of magnetic resonance imaging studies showing effects of prematurity on early brain development, even among preterm infants with normal cranial ultrasonography.

ABSTRACT. Objective. The objective of this study was to evaluate the relationships between chronic physiologic instability, as assessed by the cumulative daily Score for Neonatal Acute Physiology (SNAP), and neurodevelopmental morbidity in premature infants at 1 year and at 2 to 3 years of age.Design. The subjects of this retrospective study were extremely premature (<30 weeks' gestational age [GA]) infants born in 1993 and 1994 who were seen in follow-up at least once between 1 and 3 years of age. Cumulative daily SNAP scores were calculated over the entire neonatal intensive care unit course for 96 infants (mean GA, 27.3 ؎ 1.6 weeks; mean birth weight, 1065 ؎ 270 g). The Mental and Psychomotor Developmental (MDI and PDI) of the Bayley Scales of Infant Development (II) were administered at 1 year and at 2 to 3 years of age; the Receptive-Expressive Emergent Language Scale (REEL) was administered at 2 to 3 years of age.To compare the most stable infants with the most unstable infants, the subjects were divided into three quartile groups based on their cumulative SNAP scores (<25th percentile, 25 to 75th percentile, and >75th percentile). MDI, PDI, and REEL scores were compared for the three groups using analysis of variance. To evaluate the relative contributions of physiologic stability, intracranial abnormalities, GA, and early postnatal nutritional intakes, multiple regression analyses were performed using cumulative SNAP score, an intraventricular hemorrhage (IVH) score (incorporating IVH and periventricular leukomalacia), GA, and a weight-change score for the first month as independent variables, and MDI, PDI, and REEL quotients as dependent variables. Regression analyses were repeated, with cumulative SNAP subscores for oxygenation, hypotension, acidosis, and hypoxia/ischemia included with IVH score, GA, and first month weight z score change as independent variables, and MDI, PDI, and REEL quotients as dependent variables.Results. The infants with the highest degree of physiologic instability (cumulative SNAP scores greater than the 75th percentile) had significantly lower MDI scores at 1 year of age and lower PDI scores at 1 year and at 2 to 3 years of age than did infants who were more physiologically stable.Sixty-seven percent of infants with cumulative SNAP scores greater than the 75th percentile had neurodevelopmental abnormalities at 2 to 3 years of age (cerebral palsy or delayed mental, motor, or language development). Using multiple regression analyses, higher cumulative SNAP scores, IVH scores, and GA were associated with lower 1-year MDI scores. Higher cumulative SNAP scores and IVH scores were associated with lower 1-year PDI scores. By 2 years, only higher cumulative SNAP scores were significantly associated with lower MDI and PDI scores. With respect to language development, only lower weight-change scores over the first month were significantly associated with poorer receptive language development. Lower weight-change scores over the first month and higher hypotension scores were significantl...

A male patient with a de novo proximal interstitial deletion of the short arm of chromosome 1 (46XY, del(1)(p13p22.3) is described with multiple anomalies and developmental delay. This patient's clinical manifestations are compared to previously reported patients with deletions of chromosome 1p.