bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metamorphosis of behavior in the bullfrog (Rana catesbeiana)
Authors: Stehouwer Donald J. 
Published: January 2005

AbstractThis study describes the development of different spontaneous and elicited behaviors of frogs and their relationship to morphological, physiological, and econological changes of metamorphosis. Tadpoles were studied at all stages of development from STage XVIII, the onset of metamorphosis, to Stage XXV, when metamorphosis of the froglets is complete. Behaviors examined included development of forelimb postural support, postural responses to vestibular stimulation, the hindlimb withdrawal reflex, the corneal reflex, ocular mobility, and habital preference. Results showed that these behaviros differ markedly in their timing and rate of maturation. Forelimb postural support and postural responses to vestibular stimulation improved gradully between Stagez XX and XXV. In contrast, the threshold of the hindlimb withdrawal reflex remained essentially unchanged until Stage XXV, when it increased suddenly and dramatically. The corneal reflex appeared suddenly at Stage XXI with a threshold similar to that of juvenile forgs. The ability to move the eyes in response to visual or vestibulaar stimulation was pronounced it tadpoles, but gradually declined between Stage XIII and Stage XXV, so that froglets showed almost no ocular mobility. The preference of metamoprphosing frogs for deep water, shallow water, shoreline, or land were examined in an aquarium during a 24‐hr observation period using time‐lapse videotape recordings. Results showed that tappoles spent progressively less time in deep water and shallow water as metamorphosis proceeded. Preference for land emerged suddenly at Stage XXII and remainhed high thereafter. There were no stage‐related differences in preferences for the shoreline.
Development of sleep states in normal premature and full‐term newborns
Authors: Curzi‐Dascalova Lilia , Peirano Patricio , Morel‐Kahn Françoise 
Published: January 2005

AbstractThe aims of our study were: (1) to answer the question “Do sleep states exist in normal premature infants;” (2) to anaylze the development of sleep cycle and sleep state characteristics in premature and full‐term newborns. Polygraph recordings were done on 38 normal, appropriate for gestational age newborns, born at 30 to 41 weeks (w) of gestation. All infants fell asleep in active sleep (AS). Postwaking AS was significantly shorter than the next AS. Mean sleep cycle duration increased from approximately 46 min at 31–34 w of conceptional age (CA) to 70 min. at 35–36 w CA. In all infants we observed stable, >5 min AS and quiet sleep (QS) periods, as defined by EEG and REM criteria. Indeterminate sleep was about 30% of the total sleep cycle at 31–34 w; it decreased to 12% at 35–36 w. Both duration and percentage of AS and QS significantly increased at 35–36 w and remained stable up to 39–41 w CA. Values of QS were significantly reduced when defined by additional criteria (respiratory rate, tonic chin EMG or motility). Concordance of QS criteria was not significantly better in older versus younger groups of infants. At all ages, AS values were insensitive to changes in the criteria chosen to define them. The contrast, starting from 31–34 w CA, between AS and QS as defined by EEG and REM criteria could account for state differences in the control of many physiological variables in prematures.
Alarm call responsivity of mallard ducklings: VII. Auditory experience maintains freezing
Authors: Miller David B. , Blaich Charles F. 
Published: January 2005

AbstractMallard ducklings (Anas platyrhynchos) freeze upon hearing the maternal alarm call, which the hen issues when there are disturbances (e.g., potential predators) near the nest. Our previous work indicates that ducklings that have been devocalized embryonically and reared in auditory isolation exhibit a significant reduction in the incidence of freezing, as compared to vocal ducklings or to devocal ducklings that have been exposed to duckling sounds throughout the perinatal period up to the time of testing at 12 hr posthatch. The main purpose of this paper is to assess whether there is a prenatal or postanatal sensitive period for such auditory experience. Two groups of 30 devocalized ducklings were either (a) stimulated with duckling sounds prenatally and tested to the alarm call at 12 hr posthatch (Expt. 1), or (b) stimulated from the time of hatching to the time of testing at 12 hr (Expt. 2). These experiments rendered no conclusive evidence of either a prenatal or postnatal sensitive period, but they suggested that auditory experience might be important in maintaining freezing. To test this hypothesis, a third group of 30 ducklings was stimulated from hatching to 12 hr and tested at 24 hr (Expt. 3). Only those ducklings receiving auditory experience contiguous with the time of testing (Expt. 2) showed high levels of freezing. Whenever a gap occurred between the offset of stimulation and the onset of testing (Expts. 1 and 3), the incidence of freezing dropped. Thus, auditory experience is important in maintaining the freezing response. This effect contrasts markedly with traditional conceptions of sensitive periods.
Neonatal sex‐steroid hormones and cognitive abilities at six years
Authors: Jacklin Carol Nagy , Wilcox Karen Thompson , Maccoby Eleanore E. 
Published: January 2005

AbstractFive sex‐steroid hormones (testosterone, androstenedione, estradiol, estrone, and progesterone) were assayed in umbilical cord blood. Cognitive abilities were assessed as a part of a 6‐year follow‐up laboratory visit. Four subtests were given: reading, numbers, listening, and spatial ability. There were no sinificant differences between boys and girls in cognitive ability scores. Higher levels of perinatal androgens (testosterone and androstenedione) were significantly associated with low age‐6 spatial ability in girls. Multiple regression analyses revealed a significant proportion of the variance in cognitive abilities in girls could be accounted for by testosterone and androstenedione. No significant predictions were found for boys. The finding of a stable inverse association between sex and effect of hormones on abilities is discussed.
Effect of maternal presence on the fear response to an unfamiliar environment as measured by heart rate in rats as a function of age
Authors: Richardson Rick , Siegel Michael A. , Campbell Byron A. 
Published: January 2005

AbstractRats 16 to 60 days of age were placed in an unfamiliar environment either alone or in the presence of an anesthetized lactating dam. Rats of all ages show a dramatic increase in fear, as measured by heart rate (HR), when placed alone in an unfamiliar environment. Adult rats, however, show a rapid decline in heart rate during the course of a 90‐min session, whereas 16‐day‐old rats show no significant decrease in HR during the same period. These results suggest that the adult rats become less fearful of the test environment over time, but that the 16‐day‐olds maintain a high level of fear throughout the 90‐min test period. Twenty‐three‐ and 30‐day‐old rats show an adultlike pattern of adaptation to the unfamiliar environment, i.e., their heart rates return partially but not completely to baseline levels within the 90‐min session.When an anesthetized lactating dam is present in the test environment, a strikingly different pattern of results is obtained. Heart rate in the 16‐day‐old rat is immediately reduced to near baseline levels whereas in the young adult (60‐day‐old) rat the presence of the anesthetized dam has no effect on either initial HR or rate of adaptation. Again the 23‐ and 30‐day‐old rats showed an intermediate pattern of adaptation.In two follow‐up experiments the effects of adding (Expt. 2) or removing (Expt. 3) an anesthetized dam on the 16‐day‐old rats' response to an unfamiliar environment was examined. Both experiments showed that animals were more fearful when the dam was absent from the environment than when it was present.
The ontogeny of exploratory behavior in the house rat (Rattus rattus): The mobility gradient
Authors: Eilam David , Golani Ilan 
Published: January 2005

AbstractInfants of rats and other mammals respond to a novel environment by becoming immobile, and then showing a process of motorial expansion called “warm‐up.” Starting from immobility, new types of movement are incorporated into the stream of behavior according to rather strict rules of order. Once a new type of movement has been performed, the infant reverts to it repeatedly. As a result, the earlier portion of the behavior appears stereotyped, giving the impression of an automatism. Later, as new types of movement are added to the infant's repertoire, the movement becomes increasingly rich and unpredictable, giving the impression of “free” behavior. The same rules of order operate within “warm‐up” sequences of movement, and across such sequences, day by day. Concurrently, there is an increase in the amplitude of movements, resulting in a gradual expansion of the portion of the environment explored by the infant. The same rules of order seem to operate in the development of locomotion in more primitive vertebrates. In rats under the action of psychoactive drugs, the “warm‐up” sequence is performed in reverse.
Early experience and maternal behavior in rats
Authors: Brunelli Susan A. , Shindledecker Richard D. , Hofer Myron A. 
Published: January 2005

AbstractThis study examined the effects of early experience (early weaning with group housing in sibling groups (EG), or early weaning plus social isolation (El) from 14 to 24 days of age) on maternal, play, and social behaviors expressed during 5 days of sensitization at 24 days, and then later at 100 days of age. Our results showed that maternal behaviors at 24 days could be altered by these early experiences. At 24 days of age fewer EI animals retrieved compared with normally weaned controls (NW), but more showed play behavior in the presence of pups. EG animals showed intermediate levels of retrieving relative to NW controls, and no concomitant changes in play behaviors. When retested as adults, females in all groups showed similar levels of all maternal behaviors. But EI adults of both sexes showed persistent intrusion of play behaviors, and higher levels of rearing and undirected activity in the presistent intrusion of play behaviors, and higher levels of rearing and undirected activity in the presence of neonates. Factor analyses revealed that previously sensitized adult males showed patterns of organization of maternal behaviors that resembled adult females rather than those shown by control males reared without sensitization experience. Previously sensitized females also showed a retention of the play behavior patterns characteristic of juveniles, not present in females without sensitization experience. These results show that social experience during the weaning period can affect the development of maternal and play behavior elicited by neonates during the juvenile period that persist into adulthood, and that juvenile sensitization experience exerts longterm effects on adult patterns of maternal behavior in both sexes.
Ontogeny of renin‐induced salt appetite in the rat pup
Authors: Leshem Micah , Epstein Alan N. 
Published: January 2005

AbstractIntracerebroventricular injections of renin in suckling rat pups increased intake of NaCl solutions when they were orally infused 5 hr after injection. The appetite for saline solution was evident in pups as young as 3 days, was greater in females, and was specific insofar as intake of milk, either by suckling or by oral infusion, was not affected. Three‐day‐old pups increased intake only to 12% NaCl, the acceptable concentration of NaCl becoming lower in older pups. These results suggest, first, that, as is true for feeding and drinking, the brain mechanism for salt appetite is competent for expression of the behavior in the very young rat pup, and second, that its angiotensinergic neural substrate is distinct from that which mediates the dipsogenic effect of the hormone.
Maternal and peer imprinting in mallard ducklings under experimentally simulated natural social conditions
Authors: Dyer Antoinette B. , Lickliter Robert , Gottlieb Gilbert 
Published: January 2005

AbstractPrevious studies revealed that if socially reared mallard duckling actively follow a stuffed mallard (Anas platyrhynchos) hen, they later show a visual preference for the familiar mallard mallard hen over an unfamiliar redhead (Aythya americana) hen. The present study determined that the experience of actively following the hen is essential to the induction of a visually controlled, species‐typical, maternal preference. Domestic mallard ducklings that had not been given the opportunity to follow the mallard hen were “passively” reared in social groups consisting of a stuffed mallard hen and seven same‐aged siblings for either 24, 48, or 72 hr after hatching. These birds were largely unresponsive to the hen in a later choice test, even when they were passively exposed to the mallard hen for as long as 72 hr prior to testing. The question arose as to whether passive exposure to the ducklings induced a preference for them that interfered with establishment of maternal imprinting under these simulated natural nest conditions. Results indicated that socially reared ducklings do prefer stuffed ducklings to a stuffed mallard hen in a simultaneous choice test even when the hen is present and vocalizing during social rearing. Further, even ducklings reared individually with the mallard hen were unresponsive to her in the lter choice test. That there is something special about the stimulation provided by ducklings was further demonstrated by the finding that stuffed ducklings were preferred over the mallard hen (1) when the social rearing situation precluded active physical interaction with live ducklings and (2) when reared with inanimate stuffed ducklings. Thus, the ineffectiveness of the stuffed mallard hen in inducing visual imprinting under simulated nesting conditions cannot be attributed to the fact that she was not alive or reciprocally interactive. The present results suggest that mallard ducklings do not become visually imprinted to their hen until after departure from the nest, that the visual component of maternal imprinting likely involves active following subsequent to nest departure, and that early in postnatal development siblings are more visually attractive than is the hen.
Iris pigmentation and sociability in childhood: A re‐examination
Authors: Rubin Kenneth H. , Both Lilly 
Published: January 2005

AbstractDrawing from Rosenberg and Kagan's (1987) finding of an association between iris pigmentation and behavioral inhibition in early childhood, we sought, in the present investigation, to examine the developmental relation between eye color and social withdrawal in kindergarteners and children in grades 2 and 4. In kindergarten and grade 2, blue‐eyed children were found to be overrepresented in groups of extremely withdrawn youngsters. No association was found between eye color and withdrawal in grade 4 or between eye color and extreme sociability at any grade. The results were interpreted as suggestive of the increasing role, with age, of social factors in the determination of extremely inhibited behavior.
Effects of complex experience on somatic growth and organ development in rats
Authors: Black James E. , Sirevaag Anita M. , Wallace Christopher S. , Savin Michael H. , Greenough William T. 
Published: January 2005

AbstractRats kept in complex environments (EC) show an array of brain changes relative to animals housed individually (IC). These effects have been explained as due to (a) information storage, (b) chronic stress that causes brain damage, or (c) neuroendocrine effects on brain maturation. Complex experience also affects somatic growth and organ development, and these may be related to the EC/IC brain differences. We have compared somatic growth and internal organs of 315 weanling and adult rats with various histories. (a)Young EC rats showed slower skeletal and visceral growth, while many brain components expand. (b) Although thymus and spleen were lighter in young ECs, immunocompetence was nonsignificantly (p<.07) higher than in ICs. (c) Somatic growth of adult rats was slow and not very responsive to experience, whereas studies have shown EC/IC brain effects similar to those in young rats. (d) Males had slightly greater EC/IC somatic and visceral differences. (e) The stress index, adrenal weight, varied across age and experiece, so chronic stress can not explain EC/IC brain differences. Training paradigms show brain changes similar to those from complex experience, occurring specifically with learning and in brain regions using the information. Learning and memory, therefore remain the best explanation of the EC brain effects.
Nutritive and nonnutritive sucking and the temporal organization of the sucking behavior of domestic piglets
Authors: Rushen Jeffrey , Fraser David 
Published: January 2005

AbstractDetailed video recordings of the sucking behavior of one piglet from each of four litters were analyzed to determine how the components of piglet suckling behavior are organized in relation to the time of milk ejection and the temporal pattern of grunting by the sow. Early in the suckling episode, most piglets massaged the udder with their snouts, and then changed gradually to suckling the teats with slow mouth movements (1–2/sec). The piglets then had a distinct phase of sucking with rapid mouth movements (4–5/sec), which began suddenly and lasted about 5 to 15 sec. The weight gains of piglets removed at different times showed that piglets consumed milk during the fast sucking but not during the preceding slow sucking, regardless of how much slow sucking had occurred. Three of the four sows showed a characteristic increase in rate of grunting about 20 to 25 sec before fast sucking began. The piglets' change from massaging to slow sucking often coincided with the increase in grunt rate, but the timing of the transition varied greatly. This suggests that the change in grunnting is one but not the only cue used by the piglets to time their suckling behavior. During the slow, nonnnutritive sucking, mouth movements were highly variable in duration, with occasional short bursts of rapid mouth movements. This contrasted with the more uniform duration of fast sucking movements. Evidently, in piglets, nutritive and nonnutritive sucking differ in both rate and temporal patterning.
Lateral asymmetry in attention for three‐month‐old human infants during face‐to‐face interaction with mother
Authors: Fogel Alan , Karns Jeanne , Kawai Masatoshi 
Published: January 2005

AbstractA Soft grip the size of an adult index finger was placed in the palm of 3‐month‐old human infants during face‐to‐face interaction with their mothers. In a between‐subjects experiment, half the subjects interacted with mother for 3 min with no grip, which was followed by a 3 min interaction with the grip in the left hand; for the other half, the grip was placed in the right hand in the second condition. A within‐subjects experiment compared the grip interaction for 3 min first in one hand and then in the other. The grip did not significantly alter the infant's gaze at mother, smiling, or positive vocalizations. The movements of the hand with the grip were suppressed similarly for left and right hands. Lateral asymmetry was found for looking to the left side when the grip was in the left hand, compared to no lateral preference in looking during any other condition. The results support a model of right‐side dominance for attention control in infants.
Early inhibitory learning in the rat I. Learning and memory development
Authors: Mysliveček Jaromír , Hassmannová Jarmila 
Published: January 2005

AbstractThe present status of knowledge on early inhibitory learning and memory is presented. The inhibitory learning (passive avoidance) can be mastered by rat pups several hours after parturition, provided specific characteristics of the newborn organism and its neurobehavioral capabilities are respected. The curve of numbers of trials to criterion displays, as already reported earlier, a generally decreasing trend which is, however, interrupted by a temporary inversion in both strains studied, but at different time, taking place in Long Evans between postnatal day 1 and 2, which is shifted in Wistar pups one day later. Present data show significant learning differences between strains at postnatal days 1–4; from day 5 onward no significant differences are evidenced up to postnatal day 11. A reliable 24‐hour memory shown by positive values of the retention index (RI) is revealed from postnatal day 4, having in Long Evans higher RI values. Moreover, high positive RIs of 24‐hour memory are found in animals trained on the day just before the inversion of the learning development. It is conjectured that the indirect development of the early inhibitory learning is due to the developmental reorganization within CNS, and the necessity to find out its underlying mechanisms is emphasized.
Cognitive profile of rats exposed to lactational hyperphenylalaninemia: Correspondence with human mental retardation
Authors: Strupp Barbara J. , Himmelstein Sharon , Bunsey Michael , Levitsky David A. , Kesler Marilyn 
Published: January 2005

AbstractThe present study was designed to provide further information on the enduring cognitive effects of experimental phenylketonuria (PKU) in rats, produced by the administration of alphamethylphenylalanine and phenylalanine on postnatal days 3–21. These rats evidenced: (1) impaired learning set formation, (2) stimulus preservation, particularly after an error, and (3) difficulty in utilizing the less salient features of their environment in mastering discrimination problems. In contrast, long‐term memory function and the ability to form simple associations did not differ from controls. This pattern of intact and impaired cognitive functions bears remarkable similarity to that of mentally retarded humans and neonatally hyperphenylalaninemic rhesus monkeys, thus affirming the use of rats to study mental retardation. In addition, possible reasons for the mildness of the impairments commonly observed in animal models of severe mental retardation syndromes are discussed. We suggest that transfer of learning paradigms that assess the animal's ability to use information acquired in other problems are more likely to uncover significant cognitive impairments in such models than are procedures that test only the animals' ability to solve a single problem.
Acute ethanol contamination of the amniotic fluid during gestational day 21: Postnatal changes in alcohol responsiveness in rats
Authors: Chotro Maria Gabriela , Molina Juan Carlos 
Published: January 2005

AbstractTwo experiments investigated the effects of an actute 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 no 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.