bluuebunny/crossref_metadata_2025_split huggingface dataset:
Behavioral interactions of postweaning male and female rats with a complex environment
Authors: Juraska Janice M. , Meyer Monica 
Published: January 2005

AbstractRats reared from weaning in a complex environment with other rats and numerous objects display sex differences in several brain areas, yet there is little systematic information on the types of interactions that rats have within complex environments or whether there are sex differences in these interactions. Therefore, male and female rats were observed in the complex environment over a 15–30‐day period in three separate replications that included same‐sex and mixed sex groups of rats. The rats spent considerably more time interacting with the objects than in social interactions in all replication, and the types of interactions varied little over the length of the study. A few sex differences appeared, such as in play fighting, but these differences were small and not consistent across replications. Male and female rats interacted with the environment in a very similar manner.
Divergent effects of early hydrocortisone treatment on behavioral and brain development in meadow and pine voles
Authors: Prohazka Donna , Novak Melinda A. , Meyer Jerrold S. 
Published: January 2005

AbstractDevelopmental effects of a single hydrocortisone (HC) injection (80 μg/g on day 2 postnatal) were compared in two closely related species, meadow voles (Microtus pennsylvanicus) and pine voles (M. pinetorum). Effects of hormone administration were assessed in terms of the development of swimming behavior (head/nose position and front paw movement), alterations in social interactions (spatial location with respect to a stimulus animal), and by changes in somatic and brain growth. Although adult patterns of swimming behavior were found to be quantitatively different in meadow and pine voles, normal maturation in both species involved a progressive elevation of head/nose position along with a gradual inhibition of front paw movement. Compared with saline controls, HC‐treated meadow voles showed an accelerated attainment of their adult pattern, whereas hormone‐treated pine voles displayed a retardation in their swimming development. HC administration similarly led to increased body weights in developing meadow voles but decreased body weights in young pine voles. There was a tendency for hormone‐treated meadow voles to spend more time near a stimulus animal than their control counterparts, whereas the opposite was observed for pine voles. In both species, the HC group displayed decreased cerebral and cerebellar weights in adulthood, whereas other organs were generally unaffected by hormone administration. Neurochemical analyses revealed no treatment effects or treatment by species interactions with respect to cerebral DNA levels. On the other hand, treated meadow voles but not pine voles showed an elevated concentration of sulfatide, a myelin‐related lipid. These results are the first to demonstrate divergent behavioral and neurochemical effects of early glucocorticoid administration in closely related species studied under the same conditions. Furthermore, in accordance with earlier experiments on rats, swimming behavior was shown to be a useful measure for assessing changes in neuromuscular maturation.
Olfactory‐guided orientation in neonatal rats is enhanced by a conditioned change in behavioral state
Authors: Sullivan Regina M. , Hofer Myron A. , Brake Stephen C. 
Published: January 2005

AbstractIn Experiment 1, 3–6‐day‐old rats were simultaneously exposed to an unfamiliar odor which they will normally avoid (orange extract) and the odor of maternal saliva, or to either orange alone or saliva alone. One hour later, in a two‐odor choice test, those pups which were simultaneously exposed to orange and saliva exhibited an enhanced orientation to the orange odor. In Experiment 2, orange odor was presented while pups were exposed to the odor of saliva, or while they received one of two types of tactile stimulation (stroking or tailpinching). Pups in control groups were first presented with saliva or tactile stimulation and then the orange odor. Pups that had received any of the three simulataneous exposure treatments subsequently exhibited an enhanced orientation toward the orange odor, but not the pups in the control groups. The results suggest that the tendency of neonates to avoid a novel odor can be reversed by pairing that odor with events that elicit significant increases in behavioral activity. The possibility that this phenomenon reflects a classical conditioning process is discussed.
The golden‐mantled ground squirrel (Spermophilus lateralis) as a model for the effects of environmental enrichment in solitary animals
Authors: Renner Michael J. , Rosenzweig Mark R. 
Published: January 2005

AbstractIt has been proposed that the brain effects induced by laboratory environmental enrichment may be a product of the social stimulation inherent in the standard enriched environment. This experiment was conducted in order to study the suitability of the golden‐mantled ground squirrel Spermophilus lateralis (a solitary‐living species) for studies attempting to dissociate social factors from other effects in brain and behavioral effects of environmental enrichment. Juvenile Spermophilus lateralis, born in the laboratory of mothers wild‐caught while pregnant, were assigned singly to individual enriched conditions (I‐EC) or impoverished (IC) conditions at 55–62 days (an age at which wild individuals would disperse from the natal burrow and live alone). After 30 days, the subjects were videotaped in two 10‐min opportunities for exploration; following this, they were sacrificed and their brains dissected. Multiple indications of isolation stress were observed, including unusual difficulty in handling, stereotyped pacing behavior, and escape behaviors in the exploration arena. Comparisons between I‐EC and IC showed no differences in whole‐brain weight or weights of several brain regions. These results indicate that S. lateralis is not suitable for this type of study; in addition, this species' reported nonsociality is questioned, based on these subjects' reactions to isolation housing and field observations of social interactions in this species.
Behavioral states of premature infants: Implications for neural and behavioral development
Authors: Davis Diane Holditch , Thoman Evelyn B. 
Published: January 2005

AbstractNine premature and 28 full‐term infants were observed in their homes for 7 hr when they were 2, 3, 4, and 5 weeks post‐term, and the sleeping and waking states displayed by these infants were compared. For these comparisons, the observation day was divided into two mutually exclusive contexts: times when the baby was alone and times when the baby was with the mother. The premature infants spent more time alone (mean of 5.4 hr a day) than the full‐terms (4.6 hr).Over the total 7‐hr day, the premature infants spent more time in alert, nonalert waking activity, and sleep‐wake transition than the full‐terms, and they spent less time in drowse and total sleep. These results clearly indicate that, at the same post‐term ages, the sleep‐wake states of premature infants differ markedly from those of full‐terms. Four states showed significant Group × Context interactions indicating that state differences between premature and full‐term infants were also a function of the context in which the infants were observed. For example, the prematures exhibited more fuss or cry and more drowse when alone; whereas the full‐terms exhibited more of these states when with their mothers. This finding of context‐related differences between prematures and full‐terms has implications for the conflicting reports in the literature, as heretofore the states of prematures and full‐terms have been compared from observations made in a single situation.The results indicate that prematures exhibit significant commonality in their neurobehavioral development through the early post‐term period despite heterogeneity among them in their exposure to prenatal, perinatal, and early postnatal stresses.
Preweanling behavioral development in spontaneously hypertensive, borderline hypertensive, and wistar‐kyoto normotensive rats
Authors: Cierpial Mark A. , McCarty Richard 
Published: January 2005

AbstractPreweanling physical and behavioral development was studied in spontaneously hypertensive (SHR), borderline hypertensive (BHR), and Wistar‐Kyoto normotensive (WKY) rat pups. Measures of physical development included body weight, onset of various morphological landmarks, and speed of surface righting. Behavioral tests assessed locomotor development, exploratory behavior, and cliff avoidance in pups of the 3 groups. On all measures employed, SHR pups exhibited a delay in physical maturation compared to age‐matched BHR and WKY pups. Results from the locomotor development test revealed that young WKY pups (ages 1–7 days) spent more time locomoting than SHR pups, with BHR times being intermediate. In contrast, older SHR pups (ages 17–30 days) displayed greater activity in an exploratory maze than WKY pups, with BHR values again intermediate. Finally, SHR pups were more behaviorally reactive in the cliff avoidance task compared to BHR and WKY pups. These group differences may be useful in understanding the development of genetic hypertension and may serve as early behavioral markers of a predisposition to cardiovascular disease.
Regulation of nursing in chimpanzees
Authors: Dienske Herman , Van Vreeswijk Willem 
Published: January 2005

AbstractThe regulation of nursing was studied in captive chimpanzees from birth to 6 months of age. It was asked whether regulation was predictable or timing was irregular. A search for unimodal frequency distributions resulted in a distinction among nursing bouts, nursing episodes (bouts with brief interruptions) and nursing pauses. The frequency distributions of these types were either normal with very large standard deviations or exponential (i.e., randomly terminated). This implies a very irregular timing. Longer nursing episodes were followed by somewhat longer pauses; pauses with daytime sleep (that were relatively long) were followed by longer nursing. However, these regulatory effects were only slight. Most of this loose regulation of nursing was due to the infant, as the mothers did not put the infant on the breast and usually were permissive. Comparisons with humans suggest a similarly loose organization as well as frequent feeding in societies that provide relatively unlimited access to the breast. The regular 4‐hr, meal‐like schedule in industrial countries seems mainly to be due to human mothers and their advisors.
Maternal dietary NaCl intake influences weanling rats' salt preferences without affecting taste nerve responsiveness
Authors: Bird Edythe , Contreras Robert J. 
Published: January 2005

AbstractThe present study examined the relationship between maternal dietary NaCl intake during the period from conception through weaning and weanling rats' elective consumption of salt; the study asked whether or not changes in offsprings' salt intake was mediated by altered taste responsiveness. The subjects were the 21‐day‐old offspring of 24 adult female rats fed diets containing. 08% (low), 1% (mid), or 4% (high) NaCl from conception through weaning. Maternal dietary salt levels influenced offsprings' salt intake. In long‐term food choice tests, the mid and high salt rats ate more salted food and had higher salt preferences than the low salt animals; in long‐term solution choice tests, the mid and high salt rats drank more saline and less water and had higher saline preferences than the low salt rats. Nevertheless, the group differences in salt preference were not due to changes in taste responsiveness. There were no differences between the groups in saline preferences in short‐term tests or in the amplitudes of chorda tympani nerve responses to concentration series of several salts. The implications of these data for understanding the physiological basis for group differences in salt preference are discussed.
The development of the crying state during early infancy
Authors: Hopkins Brian , Von Wulfften Palthe Titia 
Published: January 2005

AbstractThe development of the crying state was studied in 14 infants from 3 to 18 weeks in two situations: the infant alone and in interaction with the mother. A major transformation occurred in the crying state after 3 months, with the appearance of what is termed interrupted fussing, which consists of rapid alternations between fuss sounds and cooing vocalizations. This change was only found in the alone situation. The functional implications of this finding are discussed within the contexts of motor development and the behavioral state concept.
Suppression of adult copulatory behaviors following LiCl‐induced aversive contingencies in juvenile male rats
Authors: Koch Paul C. , Peters Ronald H. 
Published: January 2005

AbstractSexually immature juvenile male rats received an injection of .3 M (20 ml/kg) lithium chloride (LiCl) during each of 8–10 pairings (spaced at 2–3‐day intervals) with an estrous female. Approximately seven weeks later, these males displayed fewer copulatory behaviors in pairings with estrous females than saline control rats. Noncontingent .3 M LiCl injections administered to juvenile males did not affect adult copulatory behaviors. Males that were either group or individually housed during the retention interval displayed comparable suppression, which suggests that copulatory suppression does not represent a generalized aversion to social interactions with another animal. Males housed during the retention interval in an environment that contained the odors of estrous females also displayed suppression comparable to that of males housed in the absence of such odors. This suggests that the associations that mediate copulatory suppression are not elicited solely by the odor cues of estrous females. These data demonstrate that LiCl‐induced aversive contingencies in juvenile male rats subsequently suppress adult copulatory behaviors.
Preweaning stimulation with urinary chemosignals and age of puberty in female mice
Authors: Drickamer Lee C. 
Published: January 2005

AbstractSix experiments were conducted to assess the effects of preweaning stimulation with urinary chemosignals from four different sources on the age of sexual maturation in young female mice. The urinary chemosignals tested were those in male urine, urine from females in estrus, urine from pregnant or lactating females, and urine from females housed in groups. The split‐litter technique was used for assignig mice to particular treatments. When treatments were applied during the period from 2 to 11 days postpartum, none of the chemosignals exerted any detectable influence on the age of first vaginal estrus. All 4 chemosignal treatments were effective in altering the age of puberty when treatment was applied daily from Days 12 to 21 postpatrtum. For urine from males and urine from estrous females, 3 days of treatment during the last 10 days prior to weaning at 21 days of age were sufficient to produce an acceleration of puberty. For urine from pregnant or lactating females, 5 days of treatment just prior to weaning were necessary to produce an acceleration of sexual development. For urine from grouped females, delays in puberty were produced only when the treatment lasted for 7 of the last 10 days prior to weaning. These findings suggest that the preweaning stimulus environment of young female mice may be important for their later sexual development. Further, use of the split‐litter technique permitted the determination that variation in the age of puberty was smaller within than between litters; inheritance and/or maternal influences are clearly important factors affecting the age of sexual maturation.
The effect of nonnutritive sucking on heart rate in preterm infants
Authors: Woodson R. , Hamilton C. 
Published: January 2005

AbstractA laboratory and a field experiment used within‐subject designs to test the hypothesis that nonnutritive sucking (NNS) reduces heart rate (HR) in preterm infants. Infants in Experiment A were provided a standard pacifier nipple for 30 min under strictly controlled conditions. In the field Experiment B, nursing staff provided infants with a standard pacifier during alternate intervals in a sequence of four interfeed intervals spanning 12 hr. NNS significantly reduced average HR in each experiment. Given the strongly positive relationship between HR and energy expenditure, these results suggest that NNS reduces energy expenditure in preterm infants. Such an effect, in turn, could help to explain how the opportunity to engage in NNS enhances growth in preterms.
Social specificity: Interaction with own species is necessary to foster species‐specific maternal preference in ducklings
Authors: Lickliter Robert , Gottlieb Gilbert 
Published: January 2005

AbstractPrevious studies have shown that if domestic mallard ducklings are allowed social interaction with broodmates after their initial exposure to a stuffed mallard (Anas platyrhynchos) hen, they later show a visual preference for the familiar mallard over an unfamiliar redhead (Aythya americana) hen. Birds kept in social isolation do not make htis difficult discrimination. In the present study, we examined whether this social enhancement of imprintability to a natural maternal model is merely the result of social stimulation in its most general sense of if its effects are specific to social interaction with conspecifics. 24‐hr‐old domestic mallard ducklings were allowed to follow a stuffed mallard hen for 30 min (training). This experience resulted in visual preference for the familiar mallard hen over the unfamiliar redhead hen in simultaneous choices tests at 48 hr and 72 after hatching only if the birds were allowed social experience with a group of same‐age undomesticarted mallard hatchlings. No visual preference for the familiar mallard hen was found if the ducklins were permitted social experience with a group of same‐age (Gallus domesticus) hatchlings or muscovy (Cairina moschata) duclings. Thus, it appears that for duclins to show a visually imprinted preference for a natural maternal model, they must be allowed social interaction with broodmates of their own species. Social rearing with other precocial bird hatchlings, even other duclings, is without apparent effect. These results provide further evidence of the importance of nonobvious experiental factors in the development of species‐typical behavior. They also suggest that in the evolution of the species‐specific learning underlying early species identification, natural selection has operated on the entire (organism‐environment) developmental manifold and not merely on genetic, or organisimic aspects of that system.
Evidence for a maternal effect on infant hand‐use preferences
Authors: Harkins Debra A. , Michel George F. 
Published: January 2005

AbstractLeft‐handed offspring occur more frequently when one or both parents are left‐handed. Among parental pairs with discordant handedness, left‐handed mothers have more left‐handed offspring than do left‐handed fathers. No previous study has looked for this maternal effect in the hand‐use preferences of infants. Handedness of 42 infants (21 females) 6–13 months of age (M = 10 months) was assessed by a reliable and valid procedure that provides hand‐use preference scores separately for reaching and unimanual manipulation of objects. Equal numbers of age‐matched male and female infants were formed into three groups representing different patterns of parental handedness: neither parent lefthanded, father left‐handed, mother left‐handed. Infants of left‐handed mothers showed more left hand‐use than infants of left‐handed fathers or infants of right‐handed parents. Indeed, 64% of infants with left‐handed mothers had significant left hand‐use preference scores whereas none of the infants in the other groups had significant left hand‐use preference scores. Possible mechanisms for this maternal effect on infant hand‐use preferences are discussed.
Enhancement of passive avoidance learning through small doses of intra‐amygdaloid physostigmine in the young rat. Its relation to the development of acetylcholinesterase
Authors: Dumery Vincent , Derer Paul , Blozovski Denise 
Published: January 2005

AbstractPassive avoidance learning was studied in young rats 7‐20 days old, in control conditions and after bilateral injections of physostigmine into the lateral amygdaloid nucleus. Acquisition in controls was possible from postnatal Day 8 on, progressed markedly after Day 11, and nearly reached maturity by Day 20. Physostigmine differentially altered acquisition depending on the dose: facilitation with low doses, no effect with moderate doses, and impairment with high doses. Enhanced learning through small doses of physostigmine was observed at all ages from Day 8 on, and was greater with 0.2 μg than with 0.1 μg. Maturation of the cholinergic innervation of the amygdaloid region was also studied between Days 9‐20 using acetylcholine‐esterase histochemistry. The results suggest that passive avoidance learning is dependent on amygdaloid cholinergic mechanisms early in life. In addition, very immature cholonergic systems, which are known to be uninfluenced by anticholinesterases.
Long‐term effects of early mothering behavior on responsiveness to the environment in vervet monkeys
Authors: Fairbanks L. A. , McGuire M. T. 
Published: January 2005

AbstractThe long‐term effect of early mothering style on juvenile responsiveness to the external environment was studied in vervet monkeys living in two naturally composed, undisturbed social groups. Mothering behavior for 35 mother‐infant dyads was analyzed by principal components analysis which revealed two independent dimensions: protectiveness and rejection. Protectiveness was characterized by high levels of approach, making contact, restraint, and inspection from mother to infant, and rejection was associated with high levels of rejection, breaking contact, and leaving. When observed as yearlings and 2‐year‐olds, juveniles who had had more protective early mothering showed less interest in the external environment, as measured by the percentage of time they spent looking outside the home enclosure. They also took longer to enter a completely novel environment compared to juveniles who had had less protective mothers. Maternal rejection was not significantly associated with looking out or with latency to enter the novel environment. These results were independent of the effects of age, sex, and dominance rank on behavior.
Prestimulation effects on blink and cardiac reflexes of 15‐month human infants
Authors: Balaban Marie T. , Anthony Bruno J. , Graham Frances K. 
Published: January 2005

AbstractReduction of reflex startle by brief changes in prestimulation is a robust phenomenon in adults of several species. Although the phenomenon does not require structures above midbrain, it has a long and uneven developmental course. This study of human infants assessed prestimulus effects at 15 months, within a period which has failed, in past work, to show the usual inhibitory modulation. Magnitude and onset latency of the startle blink and concurrent changes in heart rate were measured under four conditions: 2 single‐stimulus conditions, 25‐msec, 84‐dB, 1000‐Hz tone or 50‐msec, 109‐dB white noise; 2 paired‐stimulus conditions, noise bursts preceded by tone at lead times of 125 msec or 225 msec. Compared to noise‐alone, paired conditions elicited insignificant increases in blink size, significant shortening of blink onset latency, and significant attenuation of heart rate responses. The findings add to growing evidence of a dissociation between modulating effects on blink magnitude and latency and of a dissociation between modulating effects on somatic and autonomic reflexes.