Early postpartum pup preference is altered by gestational cocaine treatment: associations with infant cues and oxytocin expression in the MPOA.

Cross-fostering studies suggest cocaine-induced deficits in maternal behavior could be associated with altered behavior of offspring following prenatal cocaine-exposure. Neonatal vocalizations are an important offspring cue facilitating early interactions between dam and rodent pup offspring and have been shown to be altered following prenatal cocaine-exposure. It is unclear how variations in acoustic parameters of USVs impact maternal behavior and the mechanism(s) underlying these processes. The present study examined differences in cocaine-exposed and control rodent dam maternal preference of cocaine-exposed or untreated pups in a dual choice apparatus. Relationship of preference-like behavior with pup USVs and dam oxytocin expression was explored. Gestational cocaine-exposure interfered with preference-like behavior of dams on postpartum day 1 with cocaine-exposure associated with decreased time spent on the cocaine-exposed pup side compared to the control pup side, and decreases in preference-like behavior associated in part with decreased number of USVs being emitted by cocaine-exposed pups. On postpartum day 5, decreased oxytocin expression in the medial preoptic area was associated with altered preference-like behavior in cocaine-exposed dams, including frequency and latency to touch/sniff pups. Results indicate cocaine's effects on the mother-infant relationship is likely synergistic, in that cocaine influences mother and offspring both independently and concertedly and that variations within pup vocalizations and the oxytocin system may be potential mechanism(s) underlying this synergistic relationship during the postpartum period.

Delayed developmental changes in neonatal vocalizations correlates with variations in ventral medial hypothalamus and central amygdala development in the rodent infant: effects of prenatal cocaine.

While variations in neonatal distress vocalizations have long been shown to reflect the integrity of nervous system development following a wide range of prenatal and perinatal insults, a paucity of research has explored the neurobiological basis of these variations. To address this, virgin Sprague-Dawley rats were bred and divided into three groups: [1] untreated, [2] chronic-cocaine treated (30 mg/kg/day, gestation days (GDs) 1-20); or [3] chronic saline treated (2 mg/kg/day, GDs 1-20). Pregnant dams were injected with Bromodeoxyuridine (10 mg/kg) on GDs 13-15 to label proliferating cells in limbic regions of interest. Ultrasonic vocalizations (USVs) were recorded on postnatal days (PNDs) 1, 14, and 21, from one male and female pup per litter. Variations in acoustic properties of USVs following cocaine-exposure were age and sex-dependent including measures of total number, total duration and amplitude of USVs, and percent of USVs with at least one harmonic. Following USV testing brains were stained with standard fluorescent immunohistochemistry protocols and examined for variations in neuronal development and if variations were associated with acoustic characteristics. Limbic region developmental differences following cocaine-exposure were sex- and age-dependent with variations in the ventral medial hypothalamus and central amygdala correlating with variations in vocalizations on PND 14 and 21. Results suggest maturation of the ventral medial hypothalamus and central amygdala may provide the basis for variations in the sound and production of USVs. As vocalizations may serve as a neurobehavioral marker for nervous system integrity, understanding the neurobiological basis of neonatal vocalizations may provide the basis for early intervention strategies in high-risk infant populations.

Acoustic characteristics of naturally occurring cries of infants with "colic".

Although infantile colic has long been defined by a perceived excessive amount of crying, acoustic attributes of the cry sound may also contribute to perceptions that this early social behavior is excessive or problematic. From an original sample of 76 infants (38 infants referred to physicians for problematic crying, or "colic," and 38 pair-matched comparison infants), 48 infants who produced naturally occurring cry bouts both before and after an evening feeding were studied: 11 infants with Wessel's colic, 15 infants with non-Wessel's colic, and 22 comparison infants. Standard and vociferous cry segments were selected from up to 2 min of tape-recorded crying for spectrum analysis. Vociferous cry segments had a longer duration, a higher fundamental frequency, and a greater percentage of dysphonation than did standard segments. No differences between infant groups were found in cries before feeding. After feeding, infants who were problematic criers, independent of Wessel's criteria, showed a greater percentage of dysphonation in the vociferous cry segment than did comparison infants. This finding resulted from a decrease in dysphonation in the cries of comparison infants after feeding and an increase in those of infants with non-Wessel's colic. The dominant frequency also increased after feeding in the vociferous cries of infants with Wessel's colic, resulting in these infants having higher-pitched cries after feeding than infants in the other 2 groups. Results indicate that infants who are perceived to have problematic crying have objectively different acoustic features in their cry sounds that are particularly aversive, and that complaints about excessive crying cannot be accounted for simply on the basis of reporting bias in overly concerned or emotionally labile parents.

Cry threshold predicts regulatory disorder in newborn infants.

Studied the autonomic regulation of 37 infants with a typical cry threshold and 17 infants with a high cry threshold (typical of problems in nervous system function). Infants with a high cry threshold had a longer latency to cry, a shorter first cry sound, and a shorter overall bout of crying. Spectrum analysis of 2 hours of heart rate variability showed that a high cry threshold was predictive of fewer reliable rhythms and a lower power of the basic 40-min rhythm in heart rate. High cry threshold infants also showed fewer startles and changes in behavioral state. Results suggest a high cry threshold predicts disrupted autonomic regulation and poor coordination among rhythmic systems affecting cardiac activity.

Rhythmic organization of the sound of infant crying.

The purpose of the present study was to examine the temporal morphology and rhythmic structure underlying the repeated bursts of expiratory sounds in a sustained bout of crying of twenty-three 1-month-old infants. Durations of expiratory sounds and bursts were determined from a 90-s bout of naturally occurring cries recorded in the home before feeding. Results indicated wide individual differences in temporal morphology between infants and within infant cry sounds. Binary spectrum analysis of the presence of expiratory sounds in the cry sound detected rhythms in temporal organization at a wide range of dominant frequencies. Spectral complexity (higher numbers of peaks in the power spectrum) was related to a longer time since infants were last fed and shorter expiratory sounds. Results emphasize the importance of viewing cries of young infants as dynamic signals. An ontogenetic history of the rhythms of infant cry sounds may contribute to understanding organismic and environmental experiences which contribute to development.

Psychophysiological and perceptual responses to infant cries varying in pitch: comparison of adults with low and high scores on the Child Abuse Potential Inventory.

Based on their scores on the Child Abuse Potential (CAP) Inventory, 30 nonparent adults were classified as either having high CAP scores (n = 15) or low CAP scores (n = 15). Subjects' heart rate and skin conductance were assessed as they listened to audio-taped presentations of four "normal" phonated infant cries and four high-pitched, hyperphonated infant cries. Subjects also rated the cries on several perceptual items. Results showed that both groups of subjects found hyperphonated cries more aversive, distressing, urgent, arousing, and sick than phonated cry sounds. Similarly, all listeners' showed higher skin conductance levels (SCL) in response to hyperphonated than phonated cries. SCL became attenuated over time in response to phonated, but not hyperphonated, cries. Adults in the high-CAP group, showed marginally higher heart rates than low-CAP adults following presentation of all infant cry sounds and responded to phonated cries with marginally higher skin conductance levels than low-CAP adults. The responses of high-CAP nonparent adults are similar to those of parents with histories of physically abusive interactions with their infants.

Rhythmic organization of neonatal heart rate and its relation to atypical fetal growth.

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.

Adult perceptions of pain and hunger cries: a synchrony of arousal.

180 male and female nonparent adults rated tape-recordings of the initial, middle, and final 10-sec segments of pain and hunger cries on 4 7-point Likert-type scale items describing how urgent, arousing, aversive, and sick the cry segments sounded. Multivariate analyses of variance showed that the final segment of the pain cry was perceived as less urgent, arousing, and aversive than the initial and middle segments. The hunger cry was perceived as increasingly more urgent, arousing, and aversive from the initial to the middle to the final cry segments, with the final segment receiving higher ratings than the final segment of the pain cry. The middle segment of both cries was the most sick sounding. While females were more aroused than males as the hunger cry intensified, and females were less aroused than males as the pain cry subsided, the initial segments of the pain cry were particularly potent stimuli to both males and females. These results suggest that different segments of cries resulting from the same stimulus provide different messages that communicate the presumed level of infant arousal.

Effects of maternal visitation to preterm infants in the neonatal intensive care unit.

Mothers' visitation of their preterm infants in the neonatal intensive care unit (NICU) may have important consequences for the optimal development of the mother-infant relationship. This study investigates whether directing mothers to make weekly appointments to visit the NICU would generalize to increase the frequency of independent maternal visitation as well as affect maternal perceptions of the infant and the infant's length of hospitalization. Assessments of mothers' perceptions of their infants were made at the initiation of the intervention program, immediately following the first maternal visit to the NICU, at discharge, and at a 6-week postdischarge follow-up. Results showed that the intervention program significantly increased the frequency of independent maternal visitation, decreased the mother's positive perceptions of her infant's behavior, and increased the mother's positive perceptions of her infant's prognosis for the future. Infants in the intervention group were hospitalized a significantly shorter period of time than infants in the control group. It is suggested that the mother's greater contact and familiarity with her infant, as a result of increased visitation, resulted in more realistic observations of her preterm infant's behavior and may have facilitated the recovery of the infant.

The effects of within-group and between-group methodologies in the study of perceptions of infant crying.

Recent studies have indicated that various infant cry patterns can be reliably distinguished when directly compared with other infant cry patterns. The purpose of this study was to compare the effects of this within-group method of cry presentation (in which listeners are exposed to 2 types of cry patterns) with the effects of a between-group methodology (in which listeners are exposed to only 1 type of infant cry pattern). 4 groups of adult listeners rated the tape-recorded cries of low- and high-risk infants on 4 Likert-type scale items during experimental phases. In phase 1, subjects were exposed to either the cries of low-risk or high-risk infants but not both. In phase 2, subjects were exposed to both low-risk and high-risk infant cries. In phase 3, subjects were exposed to the cries they heard in phase 1. Whereas all scale items differentiated the low- and high-risk infant cries during the within-group analyses of phase 2, all scale items did not differentiate low- and high-risk infant cries during the between-group phase of the experiment. The specific pattern of results indicate that within-group methods of cry presentation accentuate the perceptual distance among cry types and may actually create many reliable differences that would not be found in between-group comparisons.

Cross-cultural differences in maternal perceptions of cries of low- and high-risk infants.

The tape-recorded cries of low- and high-risk newborn infants were rated by 150 inner-city Anglo-American, Black-American, and Cuban-American mothers during the hospital lying-in period following childbirth. Half of each cultural group was primiparous and half was multiparous. The mothers rated the cries along 4 perceptual and 6 caregiving response scale items. Reliable differences were found between low- and high-risk infant cries on all perceptual responses with the effects of culture and parental experience affecting the degree of differences. Generally, Anglo-American mothers found the cries more distressing, urgent, arousing, and sick sounding than Black-American mothers, while Cuban-American mothers showed similarities to both Black- and Anglo-American mothers depending on the scale items. The ratings on the caregiving response scale items paralleled cultural differences found on the perception scale items and previous reports of the mother-infant interaction patterns of other Anglo-, Black-, and Cuban-American samples. The results are discussed as being important in developing nonethnocentric views of the functional significance of the behaviors of the infant at risk, yet as providing evidence of the cross-cultural significance of the cry sound of the infant at risk.

Preventing intellectual and interactional sequelae of fetal malnutrition: a longitudinal, transactional, and synergistic approach to development.

This report presents continuing longitudinal data of a natural experiment in which fetally malnourished infants and their controls were randomly assigned to 2 environments differing in intellectually supportive characteristics. Whereas a previous report of these infants from 3 to 24 months of age provided evidence supporting the bidirectionality of effects of infant and environmental attributes, this study shows the continuation of the detrimental effects through 36 months of age on intellectual, behavioral, and social-interactional development in a nonsupportive caregiving environment, and the continued amelioration of those effects in a supportive caregiving environment. Further, analyses of maternal variables showed that the mothers of fetally malnourished infants may have had life histories of increased risk when compared to mothers of control infants. The results are discussed in terms of the convergence of dynamic intergenerational, prenatal, and postnatal influences on development.

Analysis of cry features in newborns with differential fetal growth.

This article describes the relation between neonatal cry features and anthropometric indices of fetal growth. Ponderal indices were calculated to characterize 57 2-day-old infants as underweight for length, average weight for length, or overweight for length. Although no differences were found between the cry features of underweight and overweight infants, these infants at the extremes of the distribution of ponderal indices required more stimulation to elicit a pain cry and had a longer latency from the stimulus to cry onset and a higher fundamental frequency in the cry sound than infants with average ponderal indices. Whereas overweight infants cried for shorter amounts of time than average-weight infants, no differences were found in this sample between the underweight and average-weight infants. Test of differences in the variances of the groups paralleled the tests of mean differences. Because these cry features have been used to distinguish infants along a wide continuum of conditions where the functioning of an infant's central nervous system has been impaired or stressed, it was suggested that certain cry features may reflect the risk status of individual infants with anthropometric signs of both retarded and accelerated fetal growth.

Fetal malnutrition: an experimental study of its consequences on infant development in two caregiving environments.

Infants from low socioeconomic status families were randomly assigned to an instructional day-care program designed to prevent socioculturally caused mental retardation or to a nonintervention control group. This assignment procedure resulted in an equal distribution of full-term, full-birth-weight, fetally malnourished babies in 2 environments varying in intellectually supportive characteristics. The condition of fetal malnourishment was defined by infants having low ponderal indices (PI). At 3 months of age low-PI infants showed lower Bayley Mental Development Index (MDI) scores than normal-PI infants, independent of the environment. In the control group low-PI infants still had lower MDI scores than normal-PI infants at 18 months of age. However, at that time in the day-care group, low-PI infants scored as well as normal-PI infants. These findings were replicated when the infants were 24 months of age with Stanford-Binet intelligence tests. Observations of mothers' involvement with their infants showed that, although all groups had similar amounts of maternal involvement when the babies were 6 months of age, the mothers of low-PI infants in the control group showed less involvement with their infants at 18 months of age than the other mothers. We suggest that this longitudinal study provides experimental evidence for a transactional model of development which emphasizes both newborn infant characteristics and environmental quality as cocontributors to the process of development.

Acoustic features and auditory perceptions of the cries of newborns with prenatal and perinatal complications.

This article describes 2 experiments which examine the relation between neonatal cry features and obstetric histories. Experiment 1 shows that 24 clinically healthy, normal newborns who may be at risk due to a high number of prenatal and perinatal complications can be distinguished from 24 low-complications infants by harmonic and durational features of the cry. High-complications infants required more stimulation to elicit the cry, had a longer latency to cry onset, a shorter first cry expiration, a higher cry pitch, and cried less in total time than low-complications infants. In experiment 2, naive adults rated the high-complications infant cries as more aversive, grating sick, urgent, distressing, piercing, discomforting, and arousing than low-complications infant crues. Factor analyses showed that although the low-complications infant cries were described along one dimension of discomfort, a second factor emerged conveying the "sick" nature of the sound of the cry of the high-complications infants. It was suggested that certain cry features may reflect the risk status of the infant.