bluuebunny/crossref_metadata_2025_split huggingface dataset:
Patterns of behavioral development in spontaneously hypertensive rats and Wistar‐Kyoto normotensive controls
Authors: McCarty Richard , Kopin Irwin J. 
Published: January 2005

AbstractWe have examined the behavior of spontaneously hypertensive (SHR) rats and stroke‐prone hypertensive (SP‐SHR) male rats during the development and maintenance of elevated blood pressure and compared this pattern with age‐ and gender‐matched normotensive (WKY) rats of the same Wistar‐Kyoto strain as controls. Rats of each strain (n = 10/age group) were isolated in individual cages and observed for 60 min at 3,4,6,8,10, or 20 weeks of age using a scan sampling technique. At all ages SHR rats were significantly more active than WKY rats whereas SP‐SHR rats were intermediate in level of activity. In a 2nd series, activity of male rats of each strain was monitored continuously for 24 hr in the home cage. No strain differences in amount or pattern of total daily activity were evident at either 4–6 or 16–18 weeks of age. These results indicate that SHR rats are more reactive to environmental change, but the intermediate level of activity of SP‐SHR rats suggests that this response is not related to the degree of blood pressure elevation.
Ontogeny of maternal behavior in the laboratory rat: Early origins in 18‐ to 27‐day‐old young
Authors: Mayer Anne D. , Rosenblatt J. S. 
Published: January 2005

AbstractThe responses of unweaned juveniles, 18 to 27 days of age, in brief tests with pups younger than 10 days were observed during initial exposure and at 4–6‐day intervals. They showed no aversive responses and actively sought contact with the pups until 24 days when contact‐seeking declined sharply. Young exposed to pups before 24 days continued to seek contact with them after 24 days showing an effect of the prior experience. Juveniles given a choice between young pups and a warm bowl chose the pups; given a choice between young pups and age mates, they chose the young pups until day 23, but chose the age mates after then. When housed continuously with young pups at 22 days of age, 5 of 9 retrieved and grouped pups with a latency of 1 day. Our results indicate that timidity or fear of novelty develops in rats in this situation about Day 24 and thereafter is a factor inhibiting the expression of positive social behavior toward pups.
Infant responsiveness to maternal cues in mice of 2 inbred lines
Authors: Hennessy Michael B. , Li Julia , Levine Seymour 
Published: January 2005

AbstractThe present study examined the responsiveness of 19‐ to 20‐day‐old C57BL/6J (C) and A/J (A) mouse pups to maternal cues. The C pups were found to spend more time near their C or A foster mother than they did near a virgin female. The A pups showed no such preference. Attempts to increase the motivation of A pups to approach the mother did not produce any preference for maternal cues. However, when the bedding on which odorous substances had been permitted to accumulate for an extended period of time was used as choice stimuli, pups of both lines showed a preference for the bedding of the mother as opposed to that of a virgin female. These results support findings with other rodents of a change in the female's odor during lactation which increases her attractiveness to her pups; and they demonstrate a genetic difference between pups of 2 inbred strains in their approach to maternal cues.
The first foray: Maternal influences in nest egression in the weanling rat
Authors: Alberts Jeffrey R. , Leimbach Michael P. 
Published: January 2005

AbstractA series of experiments was performed to examine the determinants of the rat pups' 1st excursions from the maternal nest into the novel environment outside the burrow. A standardized, nidic environment consisting of a maternal nest and adjoining open field was studied under a variety of structured test conditions. When the mother was outside the nest, pups readily ventured into the field. The early excursions were not stimulated by the mother's absence from the nest because when the mother was removed from the nest but not placed in the field the pups remained nestbound. Anesthetized dams elicited few excursions, suggesting that olfactory cues are less potent in this situation than behaviorally transmitted signals. Nonlactating adults were not attractive to pups but after induction of “maternal responsiveness” concaveated males facilitated egression. The data from a final experiment suggest that when in the nest, the dam stimulates egression by providing additional “permissive” stimuli that render the weanling more responsive to approach cues outside the nest.
Neonatal stress in lambs: Behavioral and physiological responses
Authors: Moberg Gary P. , Wood Valeria A. 
Published: January 2005

AbstractFor the 1st 5 weeks after birth, experimental lambs reared in small flocks under conditions that approximated the normal social environment for sheep were subjected 3 times a week to an experimental procedure that was designed to expose the lambs to neonatal stress. The experimental procedure consisted of maternal separation, handling, and exposure to a Pavlovian conditioning paradigm. Each lamb responded to this experimental procedure with elevated plasma corticosteroid levels and intense vocalization. In contrast to the experimental (or neonatal stressed) lambs, the control lambs remained undisturbed with their mothers during the time the experimental lambs were being stressed.When both groups of lambs were subsequently exposed to open‐field testing, the 2 groups did not differ in their behavioral responses (e.g., vocalization, latency to 1st movement, or locomotion) even though each of these behaviors has been found to be sensitive to the effects of neonatal social experience. Also no difference existed between the 2 groups in their initial adrenocortical response to open‐field testing; however, the plasma concentration of corticosteroids of the experimental lambs took longer to return to pretest levels.At 5 months of age, the lambs were subjected to brief restraint in a dark chamber, and the effect of this brief stress on heart rate and plasma corticosteroids was measured. No differences were found between the 2 groups in either the heart rate or adrenocortical response to this stress. Thus, we have no evidence from these studies that neonatal stress had any effect on the lambs' subsequent ability to respond to brief behavioral stress.
The ontogeny of play in rats
Authors: Panksepp Jaak 
Published: January 2005

AbstractPlay behavior, as indicated by frequency and duration of pinning behavior, was studied in young rats between 18 and 64 days of age. The incidence of play was markedly increased by social isolation. Play increased from 18–28 days of age, peaked between 32 and 40 days of age, and gradually declined thereafter. Animals developed stable “dominance hierarchies” during the course of testing so that one animal pinned the other on the average 70% of the time. Also, “dominant” animals exhibited the longer pin durations. The data indicate that social play can be efficiently studied in the laboratory rat and, further, that one function of play may be to establish stable social relationships.
Developmental aspects of 2‐way shuttlebox avoidance in the spontaneously hypertensive and normotensive rat
Authors: Sutterer James R. , DeVito William J. , Rykaszewski Irene 
Published: January 2005

AbstractIn Experiment I, male and female rats from the spontaneously hypertensive (SHR) and Wistar‐Kyoto (WKYN) normotensive strains were given 1 session of 2‐way shuttlebox avoidance training at 25–26, 35–36, or 45–46 days of age. The avoidance training was preceded by a pretest which consisted of 10 presentations of the compound conditioned stimulus alone in order to assess any differential tendency of the 2 strains to respond to the presentation of novel stimuli. The WKYN rats made a significantly higher number of pretest avoidance responses and achieved a higher level of avoidance performance than SHR rats. In addition, during the pretest, WKYN rats were more active and had a shorter 1st trial latency. In Experiment II, the pretest phase was replicated with a manipulation of the intensity of the auditory cue. Although the WKYN rats had a higher rate of pretest avoidance than SHR rats, the rate of pretest avoidances increased with intensity in both strains. The WKYN rats had a shorter 1st trial latency and a shorter median latency for the 10 trials and were more active than SHR rats during the pretest. These results relate to age‐independent behavioral characteristics of these strains and the question of reactivity to environmental stimulation.
Maternal touch at 1st contact with the newborn infant
Authors: Trevathan Wenda R. 
Published: January 2005

AbstractHuman mothers have been reported to exhibit a species‐characteristic pattern of tactile contact with their newborn infants that begins with fingertip touch of infant extremities and progresses to palmar massaging of the infant trunk. This study presents data on maternal tactile interaction during 10 min of contact following each of 66 deliveries. Most of the women in the study were of Hispanic origin and delivered with midwives in an El Paso, Texas maternity center. Time‐sampling techniques were used with tactile behaviors recorded every 10 sec. Most observations began less than 10 min after birth. The statistical analysis revealed that maternal tactile behavior in the 1st 10 min of active interaction is more variable than previously reported. No evidence was offered of a pattern of touch progression: active tactile exploration appeared to vary with the gender of the infant and parity and socioeconomic or sociocultural background of the mother.
Effects of early environmental enrichment upon open‐field behavior and timidity in the domestic chick
Authors: Jones R. Bryan 
Published: January 2005

AbstractEarly environmental enrichment was evaluated by its effect on the behavior of 7‐day‐old male and female domestic chicks in an open field or novel environment and in a hole‐in‐the‐wall test of timidity. The chicks were housed in same‐sex groups of 10. The bare environments contained wood litter, food, and water, whereas the enriched boxes also contained various objects. In the open field, immobility was lower while feeding, walking, jumping and vocalization were higher in the enriched birds than in those reared in the bare environment. Enrichment also decreased emergence latencies in the hole‐in‐the‐wall box. The increased stimulation provided by environmental enrichment may decrease fearfulness in subsequent fear‐inducing situations and may enhance the ability of animals to adapt to novelty.
Temporal organization of ultrasonic vocalizations in infant mice
Authors: Elwood Robert W. , Keeling Fergus 
Published: January 2005

AbstractThe number of ultrasonic calls produced per minute by infant mice in response to room temperature increases during the 1st week after birth and decreases during the 2nd. These vocalizations show a distinct bout organization that changes with age. The initial increase in call production is due to an increase in the number of bouts whereas the subsequent decline is primarily due to bouts of fewer calls. The rate of calling within bouts, however, increases steadily with age. These findings are discussed in terms of maturational and motivational changes.
Prenatal and postnatal determinants of the 1st suckling episode in albino rats
Authors: Pedersen Patricia E. , Blass Elliott M. 
Published: January 2005

AbstractConditions under which an odor could elicit the 1st nipple attachment in albino rats were investigated. In Experiment I rats exposed prenatally and immediately after birth to citral, a lemon scent, suckled the washed nipples of an anesthetized, parturient dam when the nipples had been scented with citral. Moreover, these rats did not suckle the normal, unwashed nipples of these dams. In Experiment II rats were exposed to citral either (a) in utero, (b) immediately after birth, (c) both pre‐ and post‐natally, or (d) not at all. Only rats in Group (c) attached to washed, citral‐scented nipples and did not suckle the normal unwashed nipples that elicited suckling in control rats. These findings suggest that prenatal and postnatal events can determine which olfactory stimuli elicit the newborn rat's 1st nipple attachment.
Limitations on input as a basis for neural organization and perceptual development: A preliminary theoretical statement
Authors: Turkewitz Gerald , Kenny Patricia A. 
Published: January 2005

AbstractWe propose an alternative to the conventional view that limitations on infant functioning are handicaps to be overcome. According to our view, limitations, particularly of the sensory systems, produce adaptive advantages for infants by facilitating perceptual organization. During embryogenesis, developmental rates of sensory systems are unequal so that onset of functioning is sequential. We argue that such differential onset results in relative independence among emerging systems, thereby reducing competition which helps regulate subsequent neurogenesis and functioning. In addition to prenatal effects, neonatal sensory limitations are discussed as a major source of perceptual organization. Limitations reduce the amount of information with which the infant must contend and promote temporal contiguity between multimodal attributes of a stimulus. Although we focus on human perceptual development, our view is a broadly based comparative one. Thus, other organisms have evolved means of restricting sensory input, and evidence is cited suggesting the importance of this reduced input in regulating normal perceptual development.
Developmental overproduction and selective attrition: New processes in the epigenesis of birdsong
Authors: Marler Peter , Peters Susan 
Published: January 2005

AbstractAll phases of song development from infancy to adulthood were studied intensively in a group of laboratory‐reared birds. Male swamp sparrows, Melospiza georgiana, trained with tape‐recorded songs in infancy, developed song some 8 months later, averaging 2.2 song types per bird. Analysis of the intermediate stage of plastic song revealed that the birds generated 4 to 5 times more song material than was needed for the species‐specific song repertoire. The excess was discarded at the time of full song crystallization. Indications that the attrition process is selective include tendencies to retain imitated rather than nonimitated elements, and the rejection of heterospecific elements. Attrition may also be influenced by vocal stimulation at the time of song crystallization, providing an opportunity for behavioral adjustment even though new themes can no longer be learned. Attrition has been described in the transition in human infants from babbling to speech.
Effects of nutrition and environment on brain biochemistry and behavior
Authors: Crnic Linda S. 
Published: January 2005

AbstractA factorial design was used to explore the influence of malnutrition and environmental enrichment on brain development and adult behavior. Malnutrition in suckling rats was produced by restricting the intake of their dams to 40% of normal food consumption. Environment was enriched using combined preweaning handling and a postweaning complex environment treatment. Malnutrition produced lasting effects upon brain biochemical composition and behavior. The environmental manipulation had no ameliorative effect on the brain parameters measured but it had pronounced effects on behavior, decreasing latency to move in the open field and increasing some measures of activity while it enhanced passive‐avoidance performance. There was little evidence for any interaction between the nutritional and environmental variables, but all trends were in the direction of the environmental treatment having more effect on the well‐nourished rats.
Determinants of suckling versus drinking in weanling albino rats: Influence of hydrational state and maternal contact
Authors: Bruno John P. , Blass Elliott M. , Amin Farid 
Published: January 2005

AbstractPreferences of weanling albino rats (15, 20, and 25 days of age) for nonnutritive suckling or drinking were determined using a Y‐maze. Age, hydrational state, and the opportunity to contact the mother all influenced choice behavior. When tested in a maze that allowed continuous maternal contact in the “drinking‐goal box,” dehydrated rats chose to drink, while nondehydrated rats chose to suckle. Testing dehydrated rats in a maze that precluded maternal contact in the “drinking‐goal box” eliminated drinking preference at all ages. These observations identify maternal presence as an important condition for the expression of drinking behavior during the weaning period and confirm our previous demonstration of dehydration's inhibition of suckling behavior.
Alarm call responsivity of mallard ducklings: II. Perceptual specificity along an acoustical dimension affecting behavioral inhibition
Authors: Miller David B. 
Published: January 2005

AbstractMallard ducklings (Anas platyrhynchos) inhibit their vocal and locomotor behavior upon hearing the maternal alarm call. An important acoustic feature of the call that affects such inhibition is the slow repetition rate of the notes. This study assesses the range of repetition rates that affect behavioral inhibition in 1‐day‐old domestic mallard (Peking) ducklings. Four hundred and fifty maternally naive ducklings were tested in groups of 30 to repetition rates ranging from 2 to 3.0 notes/sec in 2/10‐sec increments. Various behavioral measures (i.e., incidence of inhibition, latency and duration of inhibition) revealed that the optimal range of repetition rates affecting inhibition extends from.8 to 1.8 notes/sec. Within this range, 1.0 and 1.6 notes/sec are particularly effective. The efficacy of these particular 2 rates may reflect their correspondence with the rates of the modal alarm call and certain kinds of self‐produced embryonic vocalizations, respectively. Unexpectedly, very slow repetition rates (.2 and.4 notes/sec) are not as effective as faster rates in promoting inhibition. Thus, the inhibitory response exhibited by ducklings upon hearing the alarm call reflects auditory perceptual specificity to a range of moderately slow repetition rates that are characteristic of normally occurring sounds of the perinatal environment.
Forty minutes of experience increase the weight and RNA content of cerebral cortex in periadolescent rats
Authors: Ferchmin P. A. , Eterovic Vesna A. 
Published: January 2005

AbstractThe goal of this work was to determine the shortest period of exposure to environmental complexity (EC) that would produce measurable changes in brain weight or RNA content. This period varied with the age of subjects. In young adult rats, 3 months old, 4 days of exposure to EC increased the RNA concentration in the occipital cortex above the level of littermates kept in impoverished condition (IC). Cortical weight was not affected. Seven or one daily hrs of exposure to EC did not produce significant differences between rats in EC and IC. In periadolescent rats, 30‐ to 40‐day‐old, 1 daily hr of enrichment for 4 days increased both the weight of occipital cortex and its RNA content. Exposures of 7 or 24 hrs/day produced similar results. In another experiment with periadolescent rats 1 hr or even 10 min of exposure to EC per day, for 4 days, increased total cortical weight and RNA content. Thus, periadolescent rat brain display remarkably high plasticity. These very short exposure periods are comparable to the duration of learning sessions in simple formal trainings.
Intake and behavioral responsiveness to taste stimuli in infant rats from 1 to 15 days of age
Authors: Johanson Ingrid B. , Shapiro Eleanor G. 
Published: January 2005

AbstractInfant rats from 1 to 15 days of age received oral infusions of various taste solutions, and their intake of and behavioral responses to the infusions were observed. From 1 day of age on, pups responded to strong acid and quinine solutions with certain characteristic aversive responses and suppressed intake (Experiment 1). Although even very young (1‐ and 3‐day‐old) pups suppressed their intake of strong quinine and acid solutions, and rejected them by showing certain aversive responses (gaping and forelimb flailing), other components of the adultlike aversion response sequence (chin scraping and paw treading) did not appear until approximately 12 days of age. This suggests that the failure of pups to engage in chin scraping and paw treading prior to 12 days is not due to an inability to detect aversive solutions, but rather may be due to an immaturity in pups younger than 12 days of the neural substrates subserving these aversive responses. The emergence of chin scraping and paw treading to strong acid or quinine solutions was not influenced to any marked extent by either the deprivational state of the pup (Experiment 2a) or the site of the infusion (Experiment 2b).
Amphetamine reverses learning deficits in 6‐hydroxydopamine‐treated rat pups
Authors: Wool Robert S. , Weldon Douglas A. , Shaywitz Bennett A. , Anderson George M. , Cohen Donald J. , Teicher Martin H. 
Published: January 2005

AbstractAt 5 days of age, rat pups were treated with a combination of desmethylimipramine (DMI) and 6‐hydroxydopamine (6‐OHDA) to selectively deplete brain dopamine (DA) or with vehicle (saline) control solutions. Two days later, all animals received conditioning to a novel odor by pairing the odor with intraoral milk. When the odor was anise, treated pups spent less time near the conditioned stimulus than did controls, but there were no 6‐OHDA effects when the stimulus was a lemon odor (Experiment I). The difference in performance between the treated and control animals was not attributable to alterations in activating effects of the reinforcer (Experiment I), changes in olfactory sensitivity or olfactory preference (Experiment II), or sensitization to the stimulus (Experiment III). In Experiment IV, animals received d‐amphetamine sulfate (0.5 mg/kg) prior to conditioning, testing, or both conditioning and testing. Amphetamine treatment before conditioning produced an improvement in performance in animals previously treated with 6‐OHDA/DMI, but it impaired performance in controls, regardless of the time of injection. The results indicate a role of brain DA in learning in young rats.
Developmental differences in the analgesia produced by the central cholinergic system
Authors: Hamm Robert J. , Knisely Janet S. 
Published: January 2005

AbstractIn order to study the ontogensis of cholinergically mediated analgesia in the central nervous system (CNS), 10‐day‐, 28‐day‐, and 3‐month‐old rats were injected with .025, .05, and .10 mg/kg of oxotremorine, a muscarinic receptor agonist. To restrict the effect of oxotremorine to the CNS, methylscopolamine, a peripheral muscarinic antagonist, was injected simultaneously (.19 mg/kg, a dose equimolar to .10 mg/kg of oxotremorine). Following drug injections the tail‐flick procedure was used to assess analgesia. Results revealed that oxotremorine was completely ineffective in producing analgesia in the 10‐day‐ and 28‐day‐old age groups. By 3 months of age oxotremorine produced a dose‐dependent analgesia. Since most neurochemical markers of cholinergic receptor function are at mature or near mature levels by 28 days of age, neurochemical indexes of receptor function overestimate the analgesic function of the central cholinergic system.