The present study aimed to quantify, through power spectral analysis, the dynamics (temporal pattern and temporal interrelationship) of the EEG power in the low-delta (delta) and in the sigma-spindle (sigma) frequency band during quiet sleep (QS) in 5 malnourished infants (MI), 5.5 to 13.5 months old, and in 5 age-matched, healthy control infants (CI). Malnutrition results in modification of the temporal pattern of delta and sigma band power during QS. The delta band power increases faster in MI than in CI, leading to higher power levels in MI at the same time segment. However, the overall trend of the delta band power throughout QS is similar in MI and CI. The premature ending of QS phases (uninterrupted QS periods), and the reduced total amount of QS which have been reported in MI could result in an increased slow wave sleep (SWS) "pressure". This SWS pressure could account for both the higher level and the faster increase of the delta band power during the QS phase which are found in MI when compared to CI.
The hybrid offspring of reciprocal crosses between C57BL/10J and Swiss Albino mice were fostered at birth to Swiss Albino mouse mothers or to Purdue-Wistar rat mothers.
Measures were taken of incidence of survival, body weight, open-field performance, passive avoidance learning, and fighting. As compared to mice reared by mouse mothers after birth, mice reared by rat mothers (a) had a lower incidence of survival at weaning; (b) weighed more; (c) were less active in the open field, defecated less in the field, and had a greater latency to initiate movement in the field; and (d) had poorer passive learning scores. The findings indicate that the postnatal maternal environment has pervasive effects upon a number of behavioral and morphological characters, but reveal a minimal effect of the prenatal environment. Moreover, they indicate that the absence of differences in fighting scores among the 4 groups may be caused by dominant genes.
In 2 experiments using milk-suckling from an anesthetized dam as the reinforcer, evidence is presented that the transitional age in rat pups for learning of persistence as a result of appetitive partial reinforcement is between 11 and 12 days of age. In Experiment I, pups 12-13 days of age showed the partial reinforcement extinction effect (PREE) whereas 10-11-day olds did not. In Experiment II, pups trained at 11-12 days and tested at Day 13 did show a PREE at Day 13 but those trained at 10-11 days did not.
Infant hand-use preferences for apprehending objects were assessed three times at 7, 9, and 11 months of age for 154 infants (79 males) using a reliable and valid procedure. Two classification procedures (differing in Type I classification error rates) were used to identify an infant's preference (right, left, no preference) at each age, and these data were examined using two- and three-group latent class analysis models. These analyses revealed the importance of using a handedness classification procedure with low Type I error rates and evidence of a right-shift factor similar to that expressed in child and adult handedness. Thus, infant hand-use preferences for apprehending objects are likely a developmental precursor of adult handedness. The relation of the right-shift factor to increased susceptibility to social influences during development and the evolution of human abilities also is discussed.
The present study examined the effects of chronic and acute treatment with methylphenidate hydrochloride (Ritalin) on isolation-induced ultrasonic vocalizations, spontaneous locomotor activity, and neuromotor coordination in 3- to 11-day-old CD-1 mouse pups. In Experiment 1, 3- to 11-day-old pups received daily injections of saline, 5 mg/kg or 20 mg/kg of methylphenidate hydrochloride, or no injection and were tested on postnatal Days 3, 5, 7, 9, and 11. Both doses of methylphenidate resulted in significant increases in locomotor activity at all ages, but had no significant effect on body weight, neuromotor development, or emission of ultrasonic vocalizations. In Experiment 2, pups were given a single dose of methylphenidate (5 or 20 mg/kg), saline, or no injection on one of postnatal Days 5, 7, 9, or 11. This acute methylphenidate treatment increased locomotor activity, but had no significant effects on ultrasonic vocalizations or neuromotor coordination. These results indicate that short-term, chronic methylphenidate treatment elevates locomotor responses, but has no immediate effects on anxietylike responses or on the development of neuromotor behavior of CD-1 mice in the first 11 days of life.
Three experiments describe the consummatory behavior of 11-13-day-old rat pups during and following experience with a model aversive taste, quinine hydrochloride. Pups were observed while away from the dam and while suckling. Results show that pups actively reject quinine adulterated solutions in both situations. They do so by spitting the solution from the mouth when away from the nipple and by leaving the nipple and/or decreasing their sucking effort when with the dam.
Rats housed in social isolation show heightened levels of object-contact in an open-field and are slower than socially-housed controls to emerge from a small enclosure into an unfamiliar environment. Isolation between 25 and 45 days of age produced an irreversible effect upon object contact but had no lasting effect if between 16 and 25 days or after 45 days. In contrast to object contact, emergence was affected by isolation at any age and the effect was reversed by subsequent social housing. Thus the effects of isolation upon object contact and upon emergence apparently do not depend upon a single underlying variable.
In this study, young rats were deprived of early social interactions during weeks 4 and 5 of life. Different behavioral tests were conducted in adulthood to study the behavioral responses of rats lacking early social experiences. Juvenile deprivation resulted in decreased social activity and an altered sexual pattern, but did not affect locomotor activity or the performance in the elevated plus maze. Furthermore, behavioral and neuroendocrine responses of juvenile isolated rats were dramatically altered when they were confronted with territorial aggression. Juvenile deprived rats did not readily display a submissive posture in response to the resident and showed no immobility behavior after being returned to the resident's territory, while their plasma corticosterone and adrenaline concentrations were significantly increased compared to nonisolated controls. In contrast, behavioral responses in the shock prod test were not affected by previous isolation. The results suggest that early social experiences are vital for interactions with conspecifics later in life, i.e., aggression, sexual, and social interactions.
Expression of multiple object management skills (manual acquisition and storage of objects) was examined longitudinally at 7, 9, 11, and 13 months for 38 infants (19 females) whose hand use preference was either stable (consistently right or left across the ages) or nonstable (either no hand-use preference exhibited or inconsistent preference across the ages). Four separate sets of four distinctive objects each were presented singly to the infant's right and left side, with the presentation of each subsequent object contingent on the infant manipulating the previous object. Expression of multiple object management skills significantly increased with age. Infants with stable hand-use preferences produced more object acquisition and storage acts than those without a stable hand-use preference. Older infants with stable hand-use preferences exhibited more "sophisticated" sequences of multiple object management acts than those without. The role of stable hand-use preference in the development of manual skill and cognition is discussed.
To investigate social influences on human suckling behavior, 25 healthy, full term, 7 to 14-week-old infants were each bottle-fed their own formula twice by their mother and once in each of four experimental conditions: (a) held, provided social interaction; (b) held, without interaction; (c) not held, provided interaction; (d) not held, without interaction. Volume intake (VI), Total Sucks, infant gaze direction, and time elapsed since the last feeding were determined. There were three major findings: (1) social interaction increased VI; (2) VI was linearly related to the time since the last feeding in held infants; (3) Total Sucks and VI were both highly correlated with privation length when infants did not look at the feeder and when fed by the mother. Thus, social influences exert strong immediate impacts on suckling. Accordingly, suckling functions to obtain both nutrition from and social information about the feeder.
It has been established that administration of 5-HT1A agonists attenuates the rate of isolation-induced ultrasonic vocalizations (USV) in 10-day-old rat pups. In this study we extended these findings by examining the effects of administration of the serotonergic 1A receptor agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), and mixed 5-HT1A antagonist/beta adrenergic antagonist, (+/-)-pindolol, in 3-, 10-, and 14-day-old rat pups in order to assess the effect of these drugs from a developmental perspective. At all three ages, 8-OH-DPAT significantly reduced the rate of isolation-induced USV. While only the highest dose (1.0 mg/kg) of 8-OH-DPAT administered to the 10- and 14-day-olds significantly reduced the rate of vocalization, both the 0.1- and 1.0-mg/kg doses significantly attenuated the vocalization rate in the 3-day-olds. Pindolol administration did not alter the rate of USV at any age nor did it block the quieting effect that generally occurs when an anesthetized littermate is placed with the isolated pup. We conclude that 8-OH-DPAT is effective as early as 3 days of age in the quieting of isolation-induced USV and that the regional age-dependent development of 5-HT1A receptors and projections are important factors in the observed differential sensitivity to 8-OH-DPAT administration during development.
Hand preference in bimanual feeding was assessed in 140 captive chimpanzees (Pan troglodytes). Bimanual feeding was defined as the active use of one hand for feeding with the opposite hand holding other food items. In terms of strength of hand preference, adults were more lateralized than sub-adults. Additionally, mother-reared chimpanzees were more lateralized than nursery-reared chimpanzees. The number of subjects with no hand preference was more prevalent in sub-adults compared with young and older adults. Of those subjects with a significant hand preference, a larger proportion exhibited a right-hand preference. These results are discussed in relation to previous reports of handedness and bimanual feeding in gorillas and bonobos.
The effect of undernutrition on the rate of protein synthesis and the development of metabolic compartmentation of glutamate in the brain was investigated by using [U -14 C] leucine as precursor. In the brain of normal rats the incorporation rate of [14C] leucine into protein was at a maximum during the 3rd week after birth, but in the undernourished animal this rate was markedly lower. The biochemical maturation of the brain, followed in terms of the age-dependent increase in the glutamine/glutamate specific radioactivity ratio, was severly retarded in the undernourished animals, mainly as a result of a marked depression in the conversion of leucine carbon into glutamine. However these biochemical effects of undernutrition were reversible: on rehabilitation from Day 21-35 the rate of conversion of leucine carbon, both into proteins and glutamate and glutamine, was restored to normal.
Behavioral and neuromorphological data have suggested at least a partial interaction between the effects of norepinephrine-depleting neonatal 6-OHDA lesions and the effects of rearing in enriched environments. The present study examined the impact of both of these early manipulations upon regional brain uptake of 14C-2-deoxyglucose (14C-2DG) in adulthood. Newborn rats received 6-OHDA (50 mg/kg s.c.) or vehicle and, after weaning at 25 days, were reared in isolated versus enriched conditions. Regional brain 14C-2DG uptake was then examined at 70-80 days of age--either in the home cage or while animals were being exposed to novel, presumably arousing, stimulation. Ninety-seven brain regions were examined in eight separate groups. Results indicated that (1) Under baseline conditions, neither neonatal 6-OHDA nor differential rearing conditions produced widespread alterations in regional brain 14C-2DG uptake profiles. An overall enrichment effect was seen on only five brain areas, with rats reared in enriched environments showing lower levels of 14C-2DG uptake (-20% to -30%) than isolated rats. Neonatal 6-OHDA produced no main effect on 14C-2DG uptake in any brain region. (2) In contrast, when 14C-2DG uptake was assessed during exposure to a novel environment, five brain areas showed differential 14C-2DG uptake in 6-OHDA-treated rats, and 20 brain areas showed differential uptake in rats reared in enriched conditions. (3) No significant interaction effect on brain regional 14C-2DG uptake was observed between neonatal 6-OHDA and environmental complexity factors. These results are consistent with the notion that enduring effects of rearing and early 6-OHDA treatment may, independently, relate to a general reactivity factor. They also indicate that some effects of early neurochemical injury and subsequent experiential factors may not be apparent under normal resting conditions, but only become evident in the presence of appropriate "activating" stimulation.
Virtually no information is currently available regarding the relative effects of innate and experiential factors on the development of species identification in fish. Those studies which have approached the problem through schooling behavior have confounded species identification with attraction to a single available school of species-mates. In this study, isolated Brachydanio rerio spent significantly less time in nonpolarized schools with species-mates than controls when animals of a related species were available as an alternative. This difference suggests the involvement of experiential factors in species identification and questions the assumption that species identification is entirely innate.
Twenty alert 16-week-old infants were presented with 20-sec tones at variable intertrial intervals for 10 trials while beat-by-beat heart rate responses were recorded to assess response at offset as well as onset of each stimulus. Consistent with past research, onsets elicited deceleratory responses which habituated and showed some evidence of dishabituation with a change in stimulus frequency on the last 2 trials. Offsets also elicited significant deceleratory responses overall, but inspection of pre-offset heart rate suggested that deceleration in anticipation of the offset event appeared after a few stimulus repetitions and increased in magnitude over trials. However, individual variability was considerable and although the anticipatory response was significant averaged over all trials, the apparent increase over trials did not reach statistical significance. The evidence clearly indicates infants quickly process and act upon temporal information in a stimulus.
The responses of unweaned juveniles, 18 to 27 days of age, in brief tests with pups younger than 10 days were observed during initial exposure and at 4-6-day intervals. They showed no aversive responses and actively sought contact with the pups until 24 days when contact-seeking declined sharply. Young exposed to pups before 24 days continued to seek contact with them after 24 days showing an effect of the prior experience. Juveniles given a choice between young pups and a warm bowl chose the pups; given a choice between young pups and age mates, they chose the young pups until day 23, but chose the age mates after then. When housed continuously with young pups at 22 days of age, 5 of 9 retrieved and grouped pups with a latency of 1 day. Our results indicate that timidity or fear of novelty develops in rats in this situation about Day 24 and thereafter is a factor inhibiting the expression of positive social behavior toward pups.
Cortisol levels were compared in children born preterm at extremely low gestational age (ELGA; 24-28 weeks), very low gestational age (VGLA; 29-32 weeks), and full-term in response to cognitive assessment at 18 months corrected age (CA). Further, we investigated the relationship between maternal interactive behaviors and child internalizing behaviors (rated by the mother) in relation to child cortisol levels. EGLA children had higher "pretest" cortisol levels and a different pattern of cortisol response to cognitive assessment compared to VGLA and full-terms. Higher cortisol levels in ELGA, but not full-term, children were associated with less optimal mother interactive behavior. Moreover, the pattern of cortisol change was related to internalizing behaviors among ELGA, and to a lesser degree VLGA children. In conclusion, our findings suggest altered programming of the hypothalamic-pituitary-adrenal (HPA) axis in preterm children, as well as their greater sensitivity to environmental context such as maternal interactive behavior.
Separation-induced calling in the young of many species can be modulated by the opioid system. Morphine reduces ultrasonic vocalizations (USVs) produced by isolated rat pups, an effect blocked by naltrexone. Central administration of the mu and delta opiate receptor agonists DAMGO and DPDPE reduce USV; kappa receptor agonist U50,488 increases them. We now find that peripheral U50,488 not only boosted calling rates in isolated 3-, 10-, and 18-day-old rat pups, but also induced calling in pups of these ages tested in the home cage with their littermates, where USVs are seldom heard in nature. U50,488 lowered rectal temperature, although temperature loss and USV were not correlated within drug treatment groups.
Five sex-steroid hormones (testosterone, androstenedione, estradiol, estrone, and progesterone) are assayed in umbilical cord blood. Timidity is assessed in home and laboratory observations by reactions to a range of novel toys in children from 6 to 18 months of age. Significant short- (1 week) and long- (several months) term stability in timidity is demonstrated. Girls have higher mean scores on observed timidity than do boys in 2 of the 3 samples tested. An across-age timidity score is computed which shows significant correlations with neonatal progesterone, testosterone, and estradiol for boys, but is not significantly predicted by hormone concentrations in girls.
The stability of infant temperament and autonomic patterning (heart period and cardiac vagal tone) was examined longitudinally when infants were 5, 10, and 18 months of age. Behavioral measures of reactivity and regulation to frustration tasks, and maternal perceptions of infant temperament were obtained at each age along with baseline measures of cardiac activity. No stability was found from 5 to 10 months while some stability of behavior and autonomic patterning was identified from 10 to 18 months, with the exception of negative reactivity. High levels of cardiac vagal tone (V) were associated with negative reactivity at 18 months. When examining groups based on degrees of reactivity and regulation, we found infants who responded negatively to frustration but who also displayed more regulatory behavior to have higher V.
Two experiments examine the hypothesis that brain differences found in environmental enrichment are due to differences in social interaction. Both experiments compare enriched versus group housed rats using videotape records of home cage activity, scored with a protocol developed by the authors. Experiment 1 examines social interactions in group and enriched housed rats in the first 30 days postweaning; In Experiment 2 rats were housed in the differential environments from 90 to 120 days of age, an age at which rats have been reported no longer to engage in play; in addition, weights of sections of the brain were obtained at sacrifice and these showed typical patterns of differences among rats from differential environments. Neither experiment revealed any consistent pattern of differences in social interaction, either by chi-square comparisons of overall profiles of social activity or by discriminant analysis applied to behavioral observations. No evidence was found in support of the hypothesis that play is responsible for the effects of environmental enrichment.
Long-Evans rats were trained on spatial delayed alteration (SDA) in a T-maze following medial prefrontal cortical (mPFC) infusions of different doses of the noncompetitive NMDA-receptor antagonist, MK-801 (.125 microl; .25 microl; or .25 microlsaline, bilaterally), on postnatal day (PND) 19, 26, or 33. Pups trained on PND 19 showed almost no learning of SDA, regardless of drug condition (including saline). On PND 26, both doses of MK-801 significantly and equivalently prevented SDA learning, with performance during the final three training blocks remaining near chance levels, in contrast with 85% correct performance in the saline control group. On PND 33, substantial SDA learning was evident regardless of dose, although a modest impairment appeared in mid-training at both doses. These findings confirm previous reports of mPFC involvement in the early postnatal ontogeny of SDA and suggest a developmentally transient role of mPFC NMDA-receptor function in this task.
The purpose of this study was to develop a standardized protocol to measure preejection period (PEP), a measure of sympathetic nervous system, and respiratory sinus arrhythmia (RSA), a measure of parasympathetic nervous system, during resting and challenging states for 6- and 12-month-old infants and to determine developmental changes and individual stability of these measures. A 7-min reactivity protocol was administered to Latino infants at 6 months (n=194) and 12 months (n=181). Results showed: (1) it is feasible to measure PEP and RSA in infants, (2) the protocol elicited significant autonomic changes, (3) individual resting autonomic measures were moderately stable from 6 to 12 months, but reactivity measures were not stable, and (4) heart rate and RSA resting and challenge group means changed significantly from 6 to 12 months. Findings suggest that although infants' autonomic responses show developmental changes, individuals' rank order is stable from 6 to 12 months of age.
Conditions under which an odor could elicit the 1st nipple attachment in albino rats were investigated. In Experiment I rats exposed prenatally and immediately after birth to citral, a lemon scent, suckled the washed nipples of an anesthetized, parturient dam when the nipples had been scented with citral. Moreover, these rats did not suckle the normal, unwashed nipples of these dams. In Experiment II rats were exposed to citral either (a) in utero, (b) immediately after birth, (c) both pre- and postnatally, or (d) not at all. Only rats in Group (c) attached to washed, citral-scented nipples and did not suckle the normal unwashed nipples that elicited suckling in control rats. These findings suggest that prenatal and postnatal events can determine which olfactory stimuli elicit the newborn rat's 1st nipple attachment.
Retrieval by lactating and virgin mice was compared in a straight alley and a T-maze. In both test situations the retrieval performance of the lactating mouse was superior to that of the virgin animal. No discrimination was seen between a live pup and a dead pup; a rubber toy, however, was retrieved least by both the lactating and virgin mice. Contrary to previous results, these experiments demonstrate a significant difference in maternal behavior between lactating and virgin mice.
Two experiments investigated the effects of an acute alcohol prenatal experience during gestational Day 21 in the rat. At postnatal Days 8 and 9, this experience was sufficient to significantly increase ethanol odor preference as well as alcohol intake. Fetuses treated with a nonethanol stimulus (lemon) also exhibited changes suggesting increased lemon olfactory acceptance patterns (Exp. 1). Furthermore, when the olfactory component of the solutions experienced in utero were later paired with a novel tactile cue, responsiveness to such cue was strongly affected. Pups prenatally exposed to alcohol exhibited significantly lower tactile preference scores when texture was postnatally paired with ethanol odor when compared to specific controls. This effect was also observed in lemon-treated subjects after pairing defined by lemon-texture trials (Exp. 2). The results reported in alcohol-treated subjects appear not to be related with postabsorptive effects of the drug. It is suggested that sensory prenatal experience with alcohol is responsible for the reported changes in postnatal alcohol responsiveness patterns.
Laterality (hand, foot, ear, and eye) was assessed in participants with Trisomy 21 (62) and Williams-Beuren syndrome (WBS) (39). Handedness was also assessed in a card reaching task. The comparison group included 184 typically developing persons. Two independent age sub-groups were formed: 7 to 10 years old and 11 to 34 years old. We confirmed previous data: individuals with T21 were more frequently left- or mixed-handed than typically developing persons; individuals with WBS had intermediate scores. The two groups with genetic disorders had less right foot preference. Manual and foot inconsistencies characterized both groups with genetic disorders. Cross hand-foot preference was lower in the typically developing group. Differences in IQ levels did not correlate with differences in laterality scores. Overall laterality profiles were not the same in the two groups with genetic disorders: the greatest differences were observed between typically developing persons and persons with Trisomy 21.
Children with trisomy 21 display atypical manual skills that change to some extent during development. We examined grasp characteristics and their development in 35 children with trisomy 21, aged 4-18 years, who performed simple manual tasks (two manual tasks of the Movement Assessment Battery for Children, and grasping of five wooden blocks whose size was determined by their hand size). The age-matched comparison group included 35 typically developing children. Children with trisomy 21 were found to use fewer fingers than children in the comparison group in each task. They also used specific grasps and tended to extend fingers that were not involved in the grip. While some specific grasp characteristics of children with trisomy 21 decreased with age, other did not, and remained present throughout development. The perceptual-motor development of children with trisomy 21 should be analyzed in terms of atypical development rather than developmental delay.
This article responds to the continuing obituaries for Comparative Psychology. We understand the field to be a general psychology, a way of understanding the origins of all behavior of all species. We outline a methodological and conceptual foundation for comparative psychology to enter the new millennium-with an anagenetic and dynamic systems perspective. We see an important role to be played by comparative psychologists in managing resources, increasing our activity in social and political issues, and transcending our traditional role as the study of animal behavior to one that makes significant contributions to psychology and humanity by studying relationships between animals and changing environments, and by providing a historical perspective on human evolution.
Mice given a single large dose of corticosterone at 2 days of age, and tested when adult, have shown lasting alterations in operant behavior, associated with reductions in cerebral weight and DNA content. When mice were given corticosterone at 22 days, no changes appeared in cerebral weight, DNA, or in operant behavior, but an apparent decrease did occur in open-field activity. The results suggest that the effects of corticosterone treatment at 2 days on the developing brain are mediated by one or more types of sensitivity to the steroid that have been largely lost by 22 days.
Research on the ways in which different species of birds learn to sing is used to illustrate the necessity of taking innate factors into account in studies of behavioral development. Experiments on two species of songbirds are described that reveal innate species differences in responsiveness to tape-recorded songs. Conspecific songs are favored over those of other species. These patterns of innately varying responsiveness provide a basis for the development, not of stereotyped behavior, but of variable, individually learned behavior. The viewpoint is presented that mechanisms that differ innately from species to species, some with general functions, others specialized for particular ontogenetic assignments, provide the necessary substrates with which experience interacts.
The effects of a single injection of a dopamine D1 antagonist, SCH 23390, at doses of 0, 0.05, 0.1, and 0.2 mg/kg on three different kinds of immobility behavior were tested in rats of 10, 15, 20, and 30 days of age. Each animal was tested for the dorsal immobility response (DIR), vertical cling catalepsy, and bar catalepsy. A different pattern of results was found for each of the three immobility behaviors. SCH 23390 significantly increased the DIR at each age except 15 days; there was a progressive increase in effect from 10 to 20 to 30 days of age. At the lowest dose, drug-induced bar catalepsy peaked at 15 days of age and declined at 20 and 30 days of age. The effect of SCH 23390 on vertical cling catalepsy increased with age, plateauing at 20 days. Thus, the developmental pattern of immobility responses to this dopamine D1 antagonist differs with each behavior measured.
Feeding behaviors were measured during six feeding sessions distributed throughout a 24-hr period in 10 normal 3-day-old female infants. Infants were individually videotaped during feeding sessions at 13:00, 17:00, 21:00, 01:00, 05:00, and 09:00 hours. Total mealtime, nutritive sucking time, pause time, number of nutritive sucks, and amount of nutrient consumed were measured. None of these feeding variables were affected by the time of day an infant was fed. Maternal interactions with their infants such as auditory stimulation, caretaking touches or tender touches were unaffected by the time of a feed. These maternal behaviors did not correlate with any of the feeding variables. These findings suggest that 3-day-old infants experiencing routine nursery care do not express specific day-night feeding differences and that certain maternal behaviors do not influence the infants' feeding pattern.
Despite the call for multilevel observation of negative affect, including multiple physiological systems, too little empirical research has been conducted in infants and young children, and physiology-affect associations are not consistently reported. We examined changes in heart rate, respiratory sinus arrhythmia, and preejection period in 24-month-olds across four increasingly challenging, emotion-eliciting tasks. We predicted that changes in cardiac reactivity would be systematically related to changes in negative affect. Results largely support the predictions with one important exception. With increasing distress across the tasks, HR increased and RSA decreased. However, no significant changes in PEP were observed. HR was associated with negative affect during all tasks, and changes in HR were related to changes in negative affect. PEP and negative affect were associated, but only marginally so. Within-subject analyses confirmed the predicted associations. Finally, the associations between physiology and negative affect were different for boys and girls. We discuss these results in the context of implications for future research on cardiac-affect associations in young children.
Developmental aspects of behavioral organization were investigated in 29 healthy fetuses from 24-weeks gestation onwards: (a) short-term association between body (GM) and eye (EM) movements; (b) linkage of pairs of the three state variables [fetal heart rate pattern (FHRP), GM, and EM]; and (c) sequence of change of state variables during transitions. Linkage and sequence were also studied in complicated pregnancies. Short-term association between GM and EM was well established after 28 weeks. Linkage of state variables improved considerably after 32-34 weeks. FHRP was the first variable to change during synchronized transitions from 1F to 2F between 28-39 weeks, and the last variable during 2F to 1F transitions between 32-39 weeks. Although clear developmental patterns could be recognized, the interfetal variability was such that identification of the abnormal fetus is still difficult. Only transitions were significantly different in growth-restricted fetuses, as they showed no specific sequence of change. Assessing the temporal organization of fetal behavior seems, therefore, until now, not of great clinical value.
The motility of 10 low-risk infants, aged between 34 and 40 weeks of postmenstrual age, has been continuously recorded for 24 h. Four codes were distinguished: code 1 (absence of motility or occasional occurrence of startles), code 2 (presence of small general or isolated body movements, startles, smiles, grimaces, and other facial activity), code 3 (forceful and prolonged general movements, startles, and stretches), code 4 (vigorous and abrupt general body movements accompanied by crying). Changes with age concern mainly the increase of the duration of code 1 (quiescence) episodes. Confrontation between day and night showed higher levels of motility during the night than during the day. The last weeks before term represent a time for increase in the ability to sustain a quiet behavior and to reorganize day-night motility distribution.