bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of the maternal surrogate on pituitary–adrenal activity and behavior of infant squirrel monkeys
Authors: Hennessy Michael B. , Kaplan Joel N.
Published: January 2005

Squirrel monkey infants reared on surrogates showed an increase in vocalizations, but no change in plasma cortisol levels when the surrogate was removed from the home cage for .5 hr. When the infant was exposed to novelty during separation, there was a further increase in vocalizations, as well as increases in movement and plasma cortisol. Placing the surrogate with the infant in the novel environment reduced the behavioral reaction and led to high levels of infant‐surrogate contact; however, plasma cortisol levels were as high at .5 hr as when the infant was in the novel environment alone. With longer (2–4 hr) exposures to the novel room, cortisol elevations were attenuated by the presence of the surrogate. When the infant was alone, levels of cortisol, but not protest behavior, increased with length of exposure to the novel room. These results indicate that the physiological reaction to separation procedures in infant primates may not be safely inferred from behavioral responses, and, together with earlier findings, suggest a deficiency in the attachment of surrogate‐reared infants.
The ontogeny of heart period patterning in the rat
Authors: Larson Sandra K. , Porges Stephen W.
Published: January 2005

Heart period, heart period variability, and respiration frequency were observed and compared longitudinally in rats from birth to 24 days of age. In addition, V, a quantification of respiratory sinus arrhythmia derived via spectral analysis of the heart period pattern, was observed. It was hypothesized that these heart period parameters would be differentially sensitive to the neural control of the heart and would, therefore, reflect different developmental patterns. Heart period and heart period variability indicated developmental patterns consistent with the literature. The ontogeny of V suggests that it may represent the developmental pattern of tonic vagal influences on the heart.
Mother‐infant interaction and the modulation of pituitary‐adrenal activity in rat pups after early stimulation
Authors: Smotherman William P.
Published: January 2005

In Experiment I, handling or electric shock of 2‐day‐old rat pups triggered pituitary‐adrenocortical activity. Interaction between mother and litter after pup treatment affected the magnitude and the time course of the pups' adrenocortical response. Mother‐infant interactions following pup treatment on Day 2 were found to affect the responsiveness of pups to later stimulation. In Experiment II handled or shocked pups that were returned to a mother‐absent nest were subsequently found to be less responsive to ACTH injection than were pups returned to a mother‐present nest following treatment. These data are discussed in terms of the reciprocity and synchrony in mother‐infant interactions and the Maternal Mediation hypothesis of early experience.
Chemosignal effects on puberty in young female mice: Urine from pregnant and lactating females
Authors: Drickamer Lee C.
Published: January 2005

A series of 8 experiments tested the effects of urine from pregnant and lactating female mice on sexual maturation of young females. Urine collected from females at various intervals during pregnancy and lactation and painted on the nares of young test females produced different effects on the age of puberty depending upon the collection interval. The urinary substance which accelerates puberty is found in the bladder urine of both pregnant and lactating females as well as in the excreted urine of females that are both lactating and also simultaneously pregnant. Four separate experiments demonstrated that grouping pregnant or lactating females at various densities, either with other females in the same stage of reproduction, or with nonreproductive females, resulted in excretion of urine which did not accelerate or delay puberty in young test mice. These results conform with a general hypothesis regarding the release of urinary chemosignals in female house mice as indicators of the adequacy of social and environmental conditions for successful reproduction.
Effects on the behavior of infant common marmosets (Callithrix jacchus) of separation from caregivers and of drug‐induced reduction in caregiver responsiveness
Authors: Chalmers N. R. , Locke‐haydon J.
Published: January 2005

The effects of separating 4‐week‐old twin marmosets for 8 days from their families are compared with the effects of leaving 4‐week‐old infants with their families, but reducing the responsiveness of their caregivers for 8 days by administration of the tranquilizer fluphenazine decanoate. Both treatments reduce infant mobility, abolish play, and increase the time that infants spend with each other. During the period after the termination of the treatment, both treatment groups continue to play and move less than controls, and try to climb onto the mothers more frequently. These results are consistent with the hypothesis that the principal factor precipitating disturbed behaviors in infant monkeys subjected to long‐term separation is disruption of the infant‐caregiver relationship rather than the separation itself. Some post‐treatment differences occur between separated and tranquilized groups. Notably, reunion after separation appears to involve a marked readjustment of the behavior of all family members to the return of the infants, whereas withdrawal of the tranquilizer does not.
High motivation toward food increases food‐sharing in cotton‐top tamarins
Authors: Feistner A. T. C. , Chamove A. S.
Published: January 2005

In order to explore whether or not adult motivation influences transfer of food to infants in cotton‐top tamarins (Saguinus oedipus oedipus), 2 experiments were carried out with 3 large captive family groups. Examination of (a) natural changes in food motivation during feeding, and (b) elevated motivation toward food by giving highly preferred items, showed that the adult monkeys shared food more when their own level of motivation was high. This suggests that food‐transfer is not merely a consequence of adult satiation, but that matching sharing with high adult motivation is a mechanism which ensures that infants receive ample food, the best items, and also rare items of high quality.
Huddling and independent feeding of neonatal rats can be facilitated by a conditioned change in behavioral state
Authors: Sullivan Regina M. , Brake Stephan C. , Hofer Myron A. , Williams Christina L.
Published: January 2005

Infant rat pups were exposed to a novel odor (orange or cedar) while they received tactile stimulation (stroking of the body) or were presented with odor or stroking alone. The effects of these treatments were assessed on pups' performance in a huddling test (Experiment 1 and 2) and an independent feeding test (Experiment 3). During these tests, only pups that had received the simultaneous presentation of the odor and stroking exhibited an increase in huddling and feeding. The increase in these behaviors was dependent on the presence of the conditioned odor during testing.
Preferences of female rhesus monkeys (Macaca Mulatta) for infantile coloration
Authors: Higley J. Dee , Hopkins William D. , Hirsch Regina M. , Marra Lauren M. , Suomi Stephen J.
Published: January 2005

While developmental researchers have long noted that infants of many mammalian species, including primates, have characteristic physical features, such as a distinctive coat or skin color, and some authors have further suggested that these features serve to elicit caretaking and solicitous behavior, few systematic investigations of the actual salience of such features for adult conspecifics have been carried out to date. The present series of 3 studies sought to determine whether natal coat and/or facial skin coloration might provide desirable visual stimulation for rhesus monkey adult females. In these studies the faces and/or fur of 6‐month‐old rhesus monkeys were dyed to simulate the normal coloration of rhesus monkey neonates. Adult females varying in parity and rearing history were then tested for their relative preference between these infantile‐colored 6‐month‐olds and both normally colored 6‐month‐olds and other differentially colored control stimulus monkeys. Results indicated that regardless of parity or rearing history the adult female subjects exhibited consistent preferences for the stimulus animals with neonatal‐like reddish‐pink facial skin coloration.
Sensory modulation of juvenile play in rats
Authors: Siviy Stephen M. , Panksepp Jaak
Published: January 2005

A series of experiments was conducted to determine the extent to which somatosensory stimulation is necessary for the elaboration of juvenile play in rats. Anesthetization of the dorsal body surface of juvenile rats with xylocaine reduced the frequency of pinning, an indicator variable for play, by 35% to 70%, while motivation to play, as measured by dorsal contacts, an index of play solicitation, remained largely intact. These data suggest that dorsal body surface anesthetization impairs the ability of juvenile rats to perceive and/or respond to playful gestures. When untreated animals were paired with xylocaine‐treated animals, the xylocaine‐treated animals consistently pinned the untreated pups more than vice versa, further suggesting that somatosensation may be involved in the establishment and/or maintenance of play dominance relations. A preliminary examination assessing potential involvement of other modalities in the play of rats was also conducted, with the data suggesting a possible role for audition in the play of this species.
Maternal contact inhibits pituitary‐adrenal stress responses in preweanling rats
Authors: Stanton Mark E. , Wallstrom James , Levine Seymour
Published: January 2005

Three experiments examined psychological factors which inhibit pituitary‐adrenal activity in 12‐, 16‐, and 20‐day‐old rats. Infant rats were placed in heated novel test arenas for 30 min—a treatment which increases corticosterone secretion—and were presented with different appetitive stimuli in order to determine whether these stimuli inhibit this increased hormone secretion. The first experiment was a factorial combination of two conditions: suckling an anesthetized dam and milk ingestion through an intraoral cannula. At all ages, suckling inhibited corticosterone secretion but milk ingestion did not, nor was there an interaction of these factors. In the second experiment, the importance of suckling was assessed by allowing pups' contact with an anesthetized dam either with or without the opportunity to suckle. At all ages, contact with suckling and contact alone were equally effective in inhibiting corticosterone secretion. The third experiment asked whether contact with a lactating female is necessary for pituitary‐adrenal inhibition or whether more distal cues associated with lactation are sufficient. Pups were tested under one of four treatments formed by a 2(Lactating vs. Virgin Female) × 2(Contact vs. No Contact) factorial design. At all ages inhibition of corticosterone secretion occurred only in animals which were allowed contact with an anesthetized female. Lactating and virgin females were equally effective for the 12‐ and 16‐day‐old pups, but contact with a virgin female was less effective for the 20‐day‐old pups. These findings indicate that neuroendocrine mechanisms subserving inhibition of the pituitary‐adrenal system exist during the preweanling period in the rat, and suggest the possibility of maternal regulation of this physilogical system during development.
Inhibition of the eyeblink reflex in the human infant
Authors: Hoffman Howard S. , Cohen Michelle E. , Anday Endla K.
Published: January 2005

In human adults the eyeblink elicited by a given stimulus can be inhibited if that stimulus is preceded by another stimulus at an appropriate lead interval. In the present work, pairs of eyeblinkeliciting stimuli separated by 300–1200 msec were presented to sleeping preterm and full‐term infants as well as to adults. Preterm infants did not exhibit reliable inhibition at any interval. Full‐term infants did so, but they required longer interstimulus intervals than were needed for inhibition in the adult subjects. Results imply that the neural systems that mediate reflex inhibition are functional at birth, but that they are relatively slow to act.
Further examination of ontogenetic limitations on conditioned taste aversion
Authors: Hoffmann Heather , Molina Juan C. , Kucharski David , Spear Norman E.
Published: January 2005

This study was to resolve a discrepancy in the literature as to the capability of infant rats in acquiring conditioned taste aversion. Previous studies had indicated that during the 1st postnatal week, an aversion to saccharin could be conditioned when paired with lithium chloride (LiCl). Analogous conditioning with sucrose did not seem to occur until the end of the 2nd postnatal week, however, even though sucrose is discriminated from water and preferred before then. We observed that 5‐ and 9‐day old pups express conditioned taste aversion to both saccharin and sucrose flavors that previously were paired with illness induced by LiCl. This learning occurred only when several hours separated cannulation and conditioning. A number of other factors that seemed likely to determine this early learning were found to have no effect. Thus is appears that rats can learn taste aversions very early in life, but only under certain circumstances. The results are discussed with reference to Vogt and Rudy's (1984) conclusions on the ontogeny of taste guided behaviors in the rat.
Sensory control of the initiation of hatching in chicks: Effects of a local anesthetic injected into the neck
Authors: Bekoff Anne , Sabichi Anita L.
Published: January 2005

Previous work shows that folding a posthatching chick into the hatching position results in the re‐initiation of hatching. Furthermore, bending the neck to the right or left serves as a selective signal for turning on hatching behavior. The present study addresses the issue of whether sensory receptors located in the neck provide this signal. Three groups of chicks were folded into the hatching position and placed in glass eggs. In the experimental group, sensory input from the neck was eliminated with a local anesthetic, lidocaine. In these chicks, hatching was initiated only after a long latency, correlated with the time at which the anesthetic wore off. In the two control groups, in which saline was injected into the neck or lidocaine was injected into the thigh, the latency was much shorter. Therefore sensory receptors located in the neck appear to provide input that serves as a selective signal for initiating hatching.
Changes in the categorization of appetitive and aversive events during postnatal development of the rat
Authors: Camp Laurel L. , Rudy Jerry W.
Published: January 2005

Environmental stimuli are not clearly categorized into appetitive and aversive classes during the first postnatal week. Three‐ and 6‐day‐old rats are highly activated by nominally appetitive (milk infusions) and aversive (foot shock) stimuli. Both evoked the same generalized behavioral responses (rolling, curling). By 12 days of age, these stimuli were responded to differently; mouthing and probing occurred in response to milk while flinching and escape responses were observed to shock. The affective properties of mild shock were found to be hedonically opposite for 6‐ and 12‐day‐old pups. Six‐day‐old showed an acquired preference for an odor paired with shock which increased with intensity (.1–.5 mA) similar to that observed with milk infusions. An acquired odor aversion was displayed by 12 days old using these shock parameters. These results suggest that young rat pups may not differentiate many appetitive and aversive events behaviorally or affectively until the second postnatal week.
Reinforcers in infancy: Classical conditioning using stroking or intra‐oral infusions of milk as UCS
Authors: Sullivan Regina M. , Hall W. G.
Published: January 2005

Six‐day‐old rats received 20 forward pairings of an odor‐conditioned stimulus (CS) with one of two unconditioned stimuli (UCS); (1) intra‐oral milk infusions or (2) stroking with a sable‐hair brush. These UCS's produce a common general response of increased behavioral activity, but different specific behaviors. For each UCS, additional pups received backward pairings of the CS and UCS, random pairings of the CS and UCS, CS only, UCS only, or no stimuli. Four hours later, pups received a two‐odor choice test to assess the development of an odor preference and a CS‐only test to assess the acquisition of conditioned responding (CR). The results of the two‐odor choice test indicated that for both UCS's only forward pairings of the CS and UCS resulted in an odor preference. Similarly, the CS‐only test showed that only forward pairings of the CS and either UCS were effective in producing CR's; pups that received forward pairings exhibited increased behavioral activity during presentations of the CS, which is an unconditioned response (UCR) to both UCS's. Only the forward paired CS‐milk UCS group exhibited increased mouthing and probing during the CS only test; these are UCR's that occur to milk infusions but infrequently to the stroking UCS. These results demonstrate the development of similar conditioned odor preferences using behaviorally activating UCS's, but CR's which are specific to the form of the UCR.
Formation and expression of filial attachment in rhesus monkeys raised with living and inanimate mother substitutes
Authors: Mason William A. , Capitanio John P.
Published: January 2005

The formation and expression of filial attachment was investigated in rhesus monkeys raised with dogs or inanimate mother substitutes in a longitudinal study spanning the first 4 years of life. At 2 months monkeys were identified within each rearing group as strongly attached or weakly attached, as measured by proximity, contact and clinging to the mother substitute in the living cage and in a novel room, and by differences in levels of distress vocalization and heart rate when they were alone and in the presence of the substitute mother in a novel room. By 4 months, all monkeys were attached, and the strongly attached and weakly attached monkeys of the first age‐period were no longer distinguishable on any measure. The attachment was specific to the substitute mother. It was not exclusive, however, inasmuch as similar responses were elicited by a stranger of the same type as the substitute mother, although the stranger was less effective. The attachment figure was also influential when it could be seen but not touched. Evidence of attachment to the substitute mothers persisted until the end of testing at 44 months. Comparison of rearing groups support the hypothesis that the principal effect of living and inanimate mother substitutes is on responsiveness, rather than on the attachment process per se.
Vocalizations of juvenile cowbirds (Molothrus ater ater) evoke copulatory responses from females
Authors: West Meredith J. , King Andrew P.
Published: January 2005

The functional attributes of the vocalizations produced by young male cowbirds during their first fall and winter, termed “vocal precursors,” were tested by playing the sounds back to female cowbirds. Five classes of vocalizations were tested: subsong, plastic, formatted, and stereotyped song, and songs of nonconspecifics. Females responded selectively to the four classes of cowbird vocalizations. Stereotyped songs evoked the most responding but the key eliciting element was the inclusion of note clusters, which first occurred in plastic song. The data suggest that juvenile cowbirds possess vocalizations capable of evoking biologically relevant responses from companions early in development.
Ontogenetic differences in short‐term retention of pavlovian conditioning
Authors: Miller James S. , Spear Norman E.
Published: January 2005

In the present series of studies 16‐ and 21‐day‐old rats acquired an aversion to a black compartment (CS+) paired with footshock, only if given preconditioning exposure to a white chamber (CS‐) not paired with footshock. The strength of conditioning was inversely related to the lenght of the retention interval in both age groups. However, the rate of forgetting was accelerated in the 16‐day‐old subjects, indicating infantile amnesia for the conditioned aversion. Strenght of conditioning was also inversely related to the lenght of the CS‐/CS+ interval in both age groups, indicating that expression of the aversion is critically dependent on an active memory of the CS‐ at the time of conditioning. Additionally, there was an ontogenetic decrease in the rate of forgetting of the CS‐, indicating infantile amnesia for elements of the conditioning episode that did not predict occurrence of US.
Uterine positions and schedules of urination: Correlates of differential maternal anogenital stimulation
Authors: Clark Mertice M. , Bone Suzanne , Galef Bennett G.
Published: January 2005

Lactating Mongolian gerbils, like lactating Norway rats, reliably lick some pups in their litters more than they lick others. Male gerbil pups are licked more by their dams than are their sisters and some males and some females within each litter are licked more often than are their sibs of the same sex. In the present article, we explore the characteristics of same‐sex littermates that are correlated with elicitation of extreme amounts of maternal anogenital licking. We found that both the male pup and the female pup in a litter of gerbils that received the most maternal anogenital licking: (1) released greater quantities of urine and (2) exhibited longer latencies to begin to urinate in response to artificial anogenital stimulation than did the male pup and the female pup in a litter that received the least amount of maternal anogenital licking. We also found that foster mothers rearing Caesarean‐delivered litters spent more time licking the anogenital areas of: (1) those male pups that, as fetuses, had occupied uterine locations adjacent to relatively few females and (2) those female pups that, as fetuses, had occupied uterine locations adjacent to relatively many males. We discuss implications of these findings for understanding of how maternal behavior may mediate hormonal effects on the development of young gerbils.
Behavioral and autonomic responses to peer separation in pigtail macaque monkey infants
Authors: Boccia Maria L. , Reite Martin , Kaemingk Kristine , Held Polly , Laudenslager Mark
Published: January 2005

Brief maternal separations of young nonhuman primates have been used extensively to study the behavior and physiology of attachment, loss, and bereavement. The physiological responses to the loss of alternative attachment figures, such as peers, is less well documented in nonhuman primates. This study examined both autonomic and behavioral responses of pee‐reared pigtail macaque infants to separation. Eight infants were removed from their mothers at birth and reared in four peer pairs. At 6 months of age, each monkey was implanted with a multichannel biotelemetry device which transmitted heartrate, body temperature, EEG, EMG, and EOG. Blood was collected twice weekly for immunological assessment. Behavioral and physiological data, including sleep, were collected for 1 week of baseline, 2 weeks of separation, and 1 week of reunion. Behavioral and physiological results indicated agitation but not depression following separation from their peer attachment figures. We found reduced mitogenic responses to pokeweed consequent to peer separation, suggestive of altered B‐cell function. REM variables were the only sleep measures affected by the separation, and were suggestive of agitation but not depression.
Contextual gating of memory retrieval
Authors: Butler Judith , Rovee‐Collier Carolyn
Published: January 2005

In two experiments, 3‐month‐old infants learned to move a crib mobile (the cue) in the presence of a distintive crib bumper (the context) by operant kicking. In Experiment 1A, infants were trained for 2 days and tested either 1, 3, or 5 days later with one of four same/different cue/context combinations. After all delays, infants tested with the original cue and context exhibited none. Changing the context but not the cue disrupted retention after 3 and 5 days but not after 1 day; in contrast, changing the cue but not the context disrupted retention after all delays. In Experiment 1B, the failure of a contextual change to impair retention after 1 day was replicated. In Experiment 2, three same/different cue/context combinations were used as reminders in a reactivation paradigm, and all infants were tested 1 day later with their original training combination. A change in either the context or the cue significantly impaired the effectiveness of the reminder. These results reveal not only that contextual information is incorporated into the memory representations of very immature infants but also that memory retrieval is highly specific to the context in which an event was originally encoded. This specificity buffers against generalized memory retrieval after long retention intervals. The data are consistent with Reeves and Sperling's 1986 model of attention‐gating. The context appears to serve as the initial gate for attention to potentially effective retrieval cues.
Intersensory functioning in bobwhite quail chicks: Early sensory dominance
Authors: Lickliter Robert , Virkar Pratima
Published: January 2005

Two sensory systems known to be important for the control of early filial behavior in precocial avian neonates are the auditory and visual modalities. This study examined the interaction between naturally occurring auditory and visual stimulation in the control of filial behavior in bobwhite quail (Colinus virginianus) during the first four days of postnatal development. Results revealed a hierarchy in the functional priority of the auditory and visual systems in the days immediately following hatchling. At one and two days of age, species identification in quail hatchling was found to depend on the auditory component of maternal stimulation. Later in development (at three and four days of age), combined auditory‐visual stimulation was necessary to control species‐specific filial behavior. Even at these later stages of development, however, the auditory modality remained dominant over the visual in eliciting responsiveness to the maternal hen. These findings conform well to what is known about the neuroembryological development of the sensory systems, in that the auditory system of birds (and mammals) develops in advance of the visual system. This prenatal sequence of sensory system development appears to influence the nature of early postnatal perceptual preferences and serves to question several traditional assumptions regarding the imprinting process.
The ontogenesis of lithium‐induced effects on suckling: Inhibition and facilitation
Authors: McLaughlin Colleen R. , Lichtman Aron H. , Pretlow Joseph P. , Cramer Catherine P.
Published: January 2005

The ontogenesis of the effect of lithium on suckling behavior was assessed by administering lithium carbonate directly and actuely to 15‐, 20‐, 30‐, and 35‐day‐old rat pups. Lithium significantly interfered with nipple attachment in 15‐day‐old rat pups in a dose‐dependent pattern, but it facilitated attachment at some doses (40, 60, 80 mg/kg) in weanling‐age rat pups. Furthermore, lithium pretreatment reversed quipazine‐induced interference of attachment in weanling‐age rats. These effects are similar to those previously reported with serotonergic anatagonists, suggesting a similar mechanism, perhaps via the inositol phosphate second messenger system.
Development of mother discrimination by single and multiple newborn lambs
Authors: Nowak R. , Poindron P. , Putu I. G.
Published: January 2005

Most research on recognition of the ewe by her lamb has focused on lambs several days or even several weeks old, whereas newly born lambs have received little attention. The aim of this work was therefore to study the attraction of Merino lambs to postparturient ewes and their ability to discriminate between their own and alien mothers in a two‐choice situation 12, 18, 24, 48, and 72 hr after birth. A comparison between singles and multiples was also made in 18 and 24‐hr‐old lambs. When released in the testing pen, approximately 90% of the lambs in each group (older than 12 hr) spent more than 3 min with the two ewes during the 5‐min test. It was only from 24 hr old, however, that a high proporation of singles spending more than 3 min with the ewes or making a correct choice was higher than that of multiples. This effect was related to litter size but not to birth weight. It is concluded that a majority of Merino lambs are clearly attracted to ewes by the time they are 18 hr old and can discriminate their own dams from alien mother at about 24 hr of age. At this stage singies perform better than multiples.
Sexual segregation in the left and right horns of the gerbil uterus: “The male embryo is usually on the right, the female on the left” (Hippocrates)
Authors: Clark Mertice M. , Galef Bennett G.
Published: January 2005

We examined reproductive tracts of 253 female Mongolian gerbils (Meriones unguiculatus) and recorded the uterine locations (relative to siblings of opposite sex) in which 812 male and 823 female fetuses were found. Within‐litter comparisons revealed that sexes were not distributed randomly across uterine horns. The percentage of males in right horns (55.0%) was greater than the percentage of males in left horns (41.8%) and the percentage of females in right horns (45.0%) was significantly less than the percentage of females (58.2%) in left horns. We did not find differences in the total number of fetuses in left and right uterine horns or a sex bias in the total sample of 1635 fetuses. Results were discussed in terms of: (a) effects of sexual segregation of fetuses on expected probabilities of fetuses developing adjacent to 0, 1, or 2 fetuses of opposite sex and (b) consequent alterations in expected frequencies of behavioral phenotypes in populations of gerbils.
Behavioral reactions to gustatory stimuli in young chicks (Gallus gallus domesticus)
Authors: Ganchrow Judith R. , Steiner Jacob E. , Bartana Atida
Published: January 2005

Freely‐moving, posthatch chicks were individually presented 2 concentrations each of quinine, citric acid, fructose, sucrose, sodium saccharin, and distilled water and their behavioral reactions were videotaped and analyzed. Already during the first posthatch day distinct rejection responses to quinine and citric acid could be recognized. Prolonged head shaking and beak clapping episodes were the most dominant features of these reactions. While responses to water and sweet stimuli could be interpreted as acceptance behaviors, the resolution was generally not fine enough to discriminate between reactions to the 2 different sweet concentrations of these stimuli or between them and water. When only water or sugar solutions were presented to other hatchlings in a single session. There was a suggestion of more definite acceptance behavior to some sweet stimuli as compared to water. It is concluded that the systems mediating aversive gustatory responses are present and functioning in posthatching chicks while acceptance responses, though present, are less discriminative among stimuli.
Behavioral and immunological consequences of brief mother‐infant separation: A species comparison
Authors: Laudenslager M. L. , Held P. E. , Boccia M. L. , Reite M. L. , Cohen J. J.
Published: January 2005

The immediate behavioral and immunological consequence of a single 2‐week maternal separation experience were studied in socially housed 7‐month old bonnet and pigtail macaques. Maternal separation was associated with species dependent behavioral changes. Both species showed significant increases in ingestive behaviors associated with separation. Separated and matched controls showed an increase in disturbance behaviors (vocalization, startles, shaking, temper‐tantrums) that subsided after 24–36 hours in control subjects, but continued, albeit with species‐dependent patterns, in the separated monkeys. Allomaternal care of the separated bonnet infants but not the pigtail infants was associated with a progressive reduction of these disturbance behaviors during the separation period. Following a period of agitation, pigtail infants showed a depressive phase characterized by slouched, withdrawn postures and reduced motor activity. As a group, the separated infants of both species were not different from controls with respect to lymphocyte activation by mitogens, a measure of immunocompetence. However, when individual behavioral responses which reflected disturbance, such that the change in lymphocyte activation following in vitro stimulation with the mitogens phytohemagglutinin and Concanavalin A (makers of the immunocompetence of T lymphocytes) was related to levels of vocalization and time spent in slouched postures. The activation of B lymphocytes by pokeweed mitogen was not influenced by the separation experience nor was it associated with specific behavioral responses to separation. The importance of assessing the affective consequences of stressors is discussed.
Weaning in rats: I. Maternal behavior
Authors: Cramer Catherine P. , Thiels Edda , Alberts Jeffrey R.
Published: January 2005

Maternal behavior during the weaning period (postpartum Days 14–35) was described from continuous timelapse videorecordings of Norway rat dams and their litters. Time spent nursing declined steadily after Day 20 but presisted until Day 34, about a week longer than suggested by reports of milk transfer. Most of the decline innursing was due to progressively fewer nursing bouts per day; milk letdowns per day were consequently diminished. Although a private feeding chamber was available to the dams, they did not use this chamber to spend more time away from the pups as weaning progressed. Instead, the dams remained with the pups in the nesting chamber but devoted increasingly less time to nursing. Subtle, progressive changes in maternal behavior are closely orchestrated and coordinated with pup development.
Nest temperature: Effects on maternal behavior, pup development, and interactions with handling
Authors: Jans James E. , Woodside Barbara C.
Published: January 2005

These studies compared the patterns of mother–young contact under different thermal environments and assessed the implications of the differing patterns of contact for pup development and the dam's behavior. In the first experiment, the warm surface dramatically reduced the total amount of contact time between dams and litters and the dam's food intake, but the effects on the pups were limited to smaller adrenal glands. A replication of the first experiment in which daily weighing and handling of the pups was eliminated produced no differences in development. In a third experiment, during which dams had access to a warm surface outside of the next area and the daily weighing and handling was resumed, the pups showed samaller adrenal glands, lower body temperatures and less thermoregulatory ability. A comparison of results suggests that handling increased the weight of adrenal glands of pups reared under the unmanipulated condition, but not the warm‐rearing condition.
Language acquisition in a nonhuman species: Implications for the innateness debate
Authors: Savage‐Rumbaugh E. S.
Published: January 2005

This article approaches the linguistic innateness issue from the perspective of a nonhuman species, the bonobo, an ape which is generally taken to be the best living model for early hominids. Recent studies indicate that a bonobo reared with humans comes spontaneously to comprehend spoken words, to produce novel two word combinations, and to respond appropriately to syntactically ordered sentences.

The differences between the use of word combinations to say what one word can accomplish and combinations that convey a novel idea not transmittable by a single word is emphasized. It is argued that the use of such novel combinations must have preceded the appearance of syntax in the evolution of language. The use of multiword novel combinations has not received sufficient attention in the literature because of the erroneous assumption that novel meanings could only be achieved through syntactical structure. Consequently the significance of the ape's linguistic competence has been severely undervalued.
Input, innateness, and induction in language acquisition
Authors: Morgan James L.
Published: January 2005

Input and innateness compliment one another in language acquisition. Children exposed to different languages acquire different languages. Children's language experience, however, underdetermines the grammars that they acquire; the constraints that are not supplied by input must be available endogenously, and the ultimate origin of these endogenous contributions to acquistion may be traced to the biology of the mind. To the extent that assumptions of innateness encourage greater explicitness in the formulation of theories of acquisition, they should be welcomed. Excessively powerful assumptions of innateness may not be subject to empirical disconfirmation, however. Therefore, attention should be devoted to the development of a theory of language input, particularly with regard to identifying invariants of input. In combination with a linguistic theory providing an account of the end‐state of acquisition, a theory of input would permit the deduction of properties of the mind that underlie the acquisition of language.
Influence of postnatal maternal stress on blood pressure and heart rate of juvenile and adult rat offspring
Authors: Mills Elliott , Bruckert Joseph W. , Smith Peter G.
Published: January 2005

Autonomic control of blood pressure (BP) and heart rate (HR) was tested in offspring of rat dams that were unmanipulated (controls) or exposed repeatedly to either (1) Postnatal restraint, (2) Postnatal s.c. injections of alkaline saline, or (3) Prenatal s.c. alkaline saline. Under urethane anesthesia, BP was higher than control in 20‐day‐old offspring of restrained dams and lower at 80 days. The magnitude of the BP response to autonomic ganglionic blockade (chlorisondamine) changed in parallel; the control HR accelerator response was reversed at 20 days and enhanced at 80 days. Postnatal maternal injections increased BP in 20‐day‐old offspring and lowered it at 80 days. The BP response to blockade was unchanged; HR acceleration was attenuated at 20 days and increased at 80 days. No influence of Prenatal material injections was seen in adult offspring. Conclusion: Post–not prenatal maternal stress disrupts BP and HR control in rat offspring; disruption is greater after restraint than injection. There is sympathetic hyperactivity in preweanlings and hypoactivity in adults.
Nociceptive responses of 3‐day‐old rat pups to IP injection of lithium carbonate
Authors: McLaughlin Colleen R. , Cramer Catherine P.
Published: January 2005

Various authors have suggested that neonatal responses to nociceptive stimuli are different than those observed in adults. However, our own recent observations in rat pups have indicated that neonates may be more responsive to nociceptive stimuli than previously thought. In the present study, the abdominal constrictions or writhing test of visceral nociception was adapted for use in 3‐day‐old rat pups in an effort to more completely assess the nociceptive responses of neonatal rat pups. Pups receiving the irritant showed robust and long‐lasting behavioral differences that were attenuated by morphine sulfate. The results from our study indicate that neonatal rats pups are not insensitive to noxious stimulation as has been previously suggested.
Rhythmic organization of neonatal heart rate and its relation to atypical fetal growth
Authors: Zeskind Philip Sanford , Goff Dennis M. , Marshall Timothy Ray
Published: January 2005

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.
Cortisol and behavioral responses to repeated stressors in the human newborn
Authors: Gunnar Megan R. , Hertsgaard Louise , Larson Mary , Rigatuso Joseph
Published: January 2005

This manuscript reports on the effects of stressors repeated at a 24‐hr interval on three samples of human newborns. In Study 1, newborns meeting criteria for obstetric and perinatal optimality experienced either 2 mock Discharge Exams, viewed as a type of handling stressor, or 2 Heelstick Blood Draws, viewed as a type of nocioceptive stressor. As in a previous study, newborns meeting optimality criteria showed habituation of the adrenocortical response to the repeated Discharge Exam. The adrenocortical response to the repeated Heelstick tended to increase or sensitize. In Studies 2 and 3, samples of newborns with more nonoptimal obstetric complication scale scores were examined. These newborns failed to show habituation of the adrenocortical response to the Discharge Exam, but responded like ‘Optimal’ newborns to the repeated Heelstick. The applicability to these data of the Groves and Thompson (1970) Dual‐Process Model of Habituation is discussed. The results also provided evidence of stability in behavioral distress independent of stability in adrenocortical activity. The implications of these data for studies using cortisol as an index of the physiological basis of early temperament are considered.
Unconfounded evidence of sex‐biased, postnatal maternal effort by mongolian gerbil dams
Authors: Clark Mertice M. , Galef Bennett G.
Published: January 2005

In previous studies of effects of offspring sex on postnatal maternal effort there has often been unintentional confounding of the sex ratio of the pups that a dam reared with the sex ratio of the litter that she gestated. By controlling the sex ratio of litters that female subjects gestated, we showed that (1) the probability of dams retrieving pups was influenced by the sex ratio of the litters dams gestated, not by the sex of litters that dams reared and (2) both frequency of nursing and duration of vaginal closure were influenced by the sex of litters that dams reared, not by the sex ratios of litters that dams gestated.
Differences in salivary cortisol levels in cocaine‐exposed and noncocaine‐exposed NICU infants
Authors: Magnano Catherine L. , Gardner Judith M. , Karmel Bernard Z.
Published: January 2005

To assess whether cocaine exposure in utero affected adrenocortical responsiveness in the neonatal period, salivary cortisol levels were compared between noncocaine‐exposed (n = 35) and cocaine‐exposed (n = 11) healthy preterm infants just prior to hospital discharge. Cortisol levels were measured under three conditions: Basal—120 min after no disrupting event or behavioral distress; Noninvasive Stressor—30 min after a neurobehavioral examination; Invasive Stressor—30 min after a heel‐stick procedure. There were no differences in Basal cortisol levels between the noncocaine‐exposed and cocaine‐exposed infants, but the cocaine‐exposed infants had significantly lower levels in both the Noninvasive and Invasive Stressor conditions. The suppressed cortisol responding to stressful events in cocaine‐exposed infants suggests that these infants may have decreased modulation capability to normally stressful events, which could underlie some of the subtle state regulation problems reported. © 1992 Wiley & sons. Inc.
The effects of early social isolation on the motivation for social play in juvenile rats
Authors: Ikemoto Satoshi , Panksepp Jaak
Published: January 2005

Fifteen‐day‐old rats were subjected to one of three housing conditions: mother‐and‐peer (family), peer, and isolation conditions. At 24 days of age, all subjects were rehoused individually. In Experiment 1, play behaviors were monitored in like‐raised pairs. Despite their gross lack of social experience, isolation‐reared subjects did not exhibit a deficit in frequencies of rough‐and‐tumble play. It is concluded that the fundamental motivation for rough‐and‐tumble play is relatively independent of prior learning in rats. Indeed, their elevated dorsal contacts suggested that isolation‐raised subjects may have higher appetitive motivation for play. In Experiment 2, the levels of social motivation were compared between family‐ and isolation‐raised animals, using a T‐maze. The isolation‐raised animals made reliably more choices for social interaction reward over food reward than family‐raised animals. Although inconclusive, the results from the two experiments suggest that prolonged social isolation increases the appetitive motivation for social play. © John Wiley & Sons, Inc.
Early developmental change in bitter taste responses in human infants
Authors: Kajiura Hideaki , Cowart Beverly J. , Beauchamp Gary K.
Published: January 2005

Human newborns (birth–6 days) and older infants (14–180 days) were allowed to ingest both urea (0.12–0.24 M) in a mildly sweet diluent and the diluent alone, and multiple measures of responsivity were obtained (relative intake, sucking behavior, and hedonic ratings based on facial expressions and body movements). For newborns, there was no indication of rejection of urea relative to the diluent in measures of intake or sucking behavior; rather, their responses were predominantly controlled by the order of presentation of the two tastes. In contrast, older infants tended to reject all concentrations of urea according to these measures. Hedonic ratings provided an indication of limited rejection of the bitter taste by newborns, but older infants were still found to respond more consistently. These data suggest there is an early developmental change in bitter taste perception © 1992 John Wiley & Sons, Inc.