Developmental Psychobiology

doi: 10.1002/dev.420240601pmid: N/A

Fragaszy, Dorothy M.; Baer, Janet; Adams‐Curtis, Leah

doi: 10.1002/dev.420240602pmid: 1783220

Fourteen infant capuchins and eight squirrel monkeys reared by their mothers in captive species‐typical social groups were observed from birth through 7 months. Motoric altriciality of the neonatal capuchin relative to the squirrel monkey is a key feature of behavioral differences between the species in the first few months after birth. Infants of the two species differed substantially in age at onset of independent locomotion, the developmental profile of independent activities, and the overall amount and rate of particular social activities. Capuchins displayed a lag of 7 weeks relative to squirrel monkeys in the pattern of increasing time spent alone; lags in other indices of independent activity and exploratory behaviors were also evident, although not as clear‐cut. The species also differed substantially in the nature and frequency of social interactions between infants and others. Capuchins, especially laterborn infants of multiparous mothers, experienced a more socially interactive infancy than squirrel monkeys. Contrasts in behavioral developmental and infant care in the two species are related to the timing and duration of the weaning process.

Bulman‐Fleming, Barbara; Wahlsten, Douglas

doi: 10.1002/dev.420240603pmid: 1783221

Measures of several intrauterine position variables as well as an index of abnormality of fetal commissure development (z score) were obtained for fetuses of two substrains of BALB mice, BALB/c Wah 1 and BALB/c Wah2, known to differ as adults in the proportion of animals exhibiting deficient corpus callosum (about 55% & 20% respectively). The extent of midline commissure development at embryonic Day 17.5 for most strain 1 fetuses was significantly reduced compared to strain 2 fetuses of the same chronological age. The two substrains also differed with respect to mean litter size and mean body weight (strain 2 > strain 1 for both measures). The ovarian and cervical positions for strain 2 uteri were found to be the most favorable for body and placental growth; no such differences were evident in strain 1. In strain 2, fetuses in the left uterine horns showed lower z scores (more retardation) than littermates on the right side, but this difference was not evident in strain 1; no other right/left differences were found in strain 2 which could help to explain the right side advantage. None of the other position variables either separately or in combination was found to be important in predicting the z score index. Tests for randomness failed to provide evidence for nonrandom distribution of severely affected fetuses. We suggest that nongenetic variability resulting from stochastic events early in development and intrinsic to the fetus may be responsible for only certain BALB fetuses within a litter exhibiting the callosal anomaly.

Zeskind, Philip Sanford; Goff, Dennis M.; Marshall, Timothy Ray

doi: 10.1002/dev.420240604pmid: 1783222

The rhythmic organization underlying long‐term heart rate variability was examined in 36 newborn infants. Heart rate was registered every 30 s for 2 continuous hr while infants rested in a temperature‐controlled isolette. Spectrum analysis of the time‐series of the 240 observations detected rhythmically organized changes in the heart rates of 33 of the 36 infants. Thirty of the 33 infants showed a basic rhythm at 1.5 ± 5 cycles per hr (one cycle every 30 to 60 min). While 9 infants showed this single cycle in behavioral activity, 24 infants showed additional cycles at a wide range of faster frequencies. Infants with signs of atypical fetal growth less often showed evidence of these multiple cycles, had reliably fewer cycles in heart rate, and had a marginally lower power in their basic cycle than infants with typical patterns of fetal growth. Infants with multiple cycles in the power spectra, independent of fetal growth group, were more often observed in Alert and Active Alert behavioral states and less often in Active Sleep than comparison infants. Results indicate that (1) heart rates of newborn infants show evidence of the 30‐ to 60‐min cycle characteristic of the Basic Rest‐Activity Cycle found in other behaviors, and (2) the complexity of behavioral rhythms may be affected by prenatal malnutrition. Viewed within a dynamical systems approach to development, results suggest that the complexity of rhythms in behavior may reflect the complexity of behavioral organization.

Chotro, María Gabriela; Córdoba, Nancy E.; Molina, Juan Carlos

doi: 10.1002/dev.420240605pmid: 1783223

Prenatal alcohol acute contamination of the amniotic fluid and different postnatal manipulations with this drug alter subsequent responsiveness to EtOH's chemosensory cues. In this study, the interaction between prenatal and postnatal alcohol‐related experiences was examined. Alcohol administered in the amniotic fluid during gestational Day 21 potentiated subsequent alcohol‐odor conditioned preferences resulting from postnatal pairings between the odor and sucrose intraoral infusions. No interaction was attained when examining the impact of the in utero experience with postnatal aversive conditioning defined by alcohol odor‐citric acid pairings (Exps. la & lb). In Exp. 2, infantile alcohol aversions derived from a state of acute ethanol intoxication were inhibited by prior alcohol experience in utero. Examination of alcohol levels in fetal trunk blood and the amniotic fluid suggests that the antenatal experience is related to the chemosensory perception of the drug rather than its intoxicating properties (Exp. 3). These results strongly suggest that the alcohol‐related memory generated proximal to birth can modulate subsequent learning with the drug.