bluuebunny/crossref_metadata_2025_split huggingface dataset:
Within‐species variation in the development of ultrasonic signaling of preweanling rats
Authors: Graham Mike , Letz Richard 
Published: January 2005

AbstractThe development of litter and individual differences in the rate of ultrasonic signaling neonatal rats was studied. Systematic variations among litters and individuals emerged, without differential treatment. These differences were not correlated with variations in general development as indexed by body weight. Two experiments using a cross‐fostering design showed that litter differences developed independently of variations in postnatal environment. These results indicate that the variations among litters in ultrasound rate have a prenatal, possibly genetic, etiology and may represent reliable indicants of response to environmental stress.
Ontogeny of active avoidance in the rat: Learning and memory
Authors: Mysliveček Jaromir , Hassmannová Jarmila 
Published: January 2005

AbstractOntogenetic development of active avoidance learning, extinction and retention was studied in rats. The learning of a 1‐way active avoidance was most rapid between Weeks 4 and 6, although some slight gender‐related differences were evident. No such unambiguous development was detected in forced extinction. The 24‐hr retention of avoidance peaked at the age of 4 weeks whereas 1‐month retention was best in animals trained at the age of 8 weeks. The retrieval of memory trace also had best values at these ages. Retention of forced extinction was found to peak in 6‐week animals. The existence of developmental “critical periods” must be considered cautiously as various functions have different time courses depending upon the chosen parameters in assessment.
Ontogeny of maternal behavior in the laboratory rat: Factors underlying changes in responsiveness from 30 to 90 days
Authors: Mayer A. D. , Freeman N. C. G. , Rosenblatt Jay S. 
Published: January 2005

AbstractMale and female rats that were nonhandled or that were handled from weaning, and that had intact or impaired olfaction (intranasal zinc sulfate), were sensitized through continuous pup exposure commencing at 30, 45, 60, or 90 days of age. Nonhandled males and females were alike in latencies to become maternal at Day 30 but thereafter latencies of females became shorter and latencies of males lengthened; by 90 days males had markedly longer latencies than females and only 1/3 became maternal. Handling facilitated sensitization at 30 days among males and females but only among males at 45 and 60 days. Intranasal zinc sulfate reduced latencies of both males and females at all ages tested, but appeared most effective after 45 days of age. Gender differences in latencies persisted in adult animals even after combined treatments. Results indicate that both timidity and olfaction inhibit the onset of maternal responses to pups in virgin males and females, but they differ in relative importance by age and gender.
The effect of visual deprivation on pattern recognition in the rat
Authors: Tees Richard C. 
Published: January 2005

AbstractIn 2 experiments the performances of light‐reared (LR) and dark‐reared (DR) 90‐day‐old rats were compared on a variety of transfer tests following acquisition of 3 pattern discriminations. Significant differences due to rearing condition were found in performance on a discrimination involving horizontal separations between pairs of vertical contours. No such differences due to rearing were observed during either acquisition or transfer testing of a discrimination involving pairs of mirror image oblique contours. Significant differences due to rearing were observed in acquisition of a discrimination between a checkerboard pattern and a similar pattern containing an irregularity and in performance on a subsequent series of transfer tests. The results suggest that the spatial integration necessary to discriminate basic as well as complex relational properties between linear elements involves mechanisms which require experience for their development and maintenance.
Emergence of spontaneous alternation in the kitten
Authors: Frederickson Christopher J. , Frederickson M. H. 
Published: January 2005

AbstractTwo studies are reported that describe the development of spontaneous alternation in the kitten. The first indicates that 3‐ and 4‐week‐old kittens do not alternate whereas animals 5 weeks and older do alternate. The second suggests that inability to discriminate maze arms is an unlikely explanation for the lack of alternation among the youngest animals. The approximate simultaneity between the onset of alternation (described here) and the maturation of the kitten hippocampus (described by others) is taken as support for the notion that hippocampal maturation may be related to the development of spontaneous alternation.
Some effects of strain differences in the maternal behavior of inbred mice
Authors: Ward Roger 
Published: January 2005

AbstractThe frequencies of occurrence of a variety of activities were recorded for inbred female mice of 3 strains in the presence of their own offspring, in the presence of isogenic fostered offspring, and in the presence of nonisogenic fostered offspring. Differences in the frequency of nursing, of grooming and handling the offspring, and of the absence of the female from the nest were related to differences in the rate of early postnatal development of 2 of these strains: in general, those pups receiving less maternal attention developed more rapidly. The effective stimulus for accelerated maturation may lie in the sequential organization of the manipulation of the offspring by the foster mother, rather than in the overall quantity of manipulation received.
Development of motor activity in kittens
Authors: Levine M. S. , Hull C. D. , Buchwald N. A. 
Published: January 2005

AbstractDevelopmental alterations in motor activity were quantified for the 1st 7 postnatal months in the kitten. Motor activity measured with a stabilimeter was low and constant for the 1st 9 postnatal days, increased markedly until Day 14, and remained stable until Day 21. Locomotor activity measured in an open field decreased slightly during the 1st 3 weeks, increased markedly during the next 2 weeks, and then remained relatively constant until the 9th week. Activity increased again during the 3rd and 4th month and then declined until 7 months of age. We suggest that the marked increase in motor activity during the 2nd week reflects development of visual and auditory systems whereas the increase in locomotor activity during the 4th and 5th weeks represents maturation of neural systems concerned with motor control. The underlying causes of the final activity changes probably represent the maturation of many neural systems and concomitant development of adult behavior in the cat.
Learned persistence at 11–12 days but not at 10–11 days in infant rats
Authors: Chen Jaw‐Sy , Amsel Abram 
Published: January 2005

AbstractIn 2 experiments using milk‐suckling from an anesthetized dam as the reinforcer, evidence is presented that the transitional age in rat pups for learning of persistence as a result of appetitive partial reinforcement is between 11 and 12 days of age. In Experiment I, pups 12–13 days of age showed the partial reinforcement extinction effect (PREE) whereas 10–11‐day olds did not. In Experiment II, pups trained at 11–12 days and tested at Day 13 did show a PREE at Day 13 but those trained at 10–11 days did not.
Eeg developmental stages
Authors: Epstein H. T. 
Published: January 2005

AbstractData in the literature show that in humans the fraction of the total electroencephalographic (EEG) energy that appears in the alpha frequencies rises from about zero at birth to about 70% in adults. This rise is shown to occur mainly in 5 stages, the ages of which correlate with those of stages of increase in brain weight. Supporting the correlation are data on gender dimorphism in humans in both brain weight and EEG development, as well as limited data on development in kittens, rats, mice, and guinea pigs.
Cultural and biomedical correlates of neonatal behavior
Authors: Coll Cynthia Garcia , Sepkoski Carol , Lester Barry M. 
Published: January 2005

AbstractThe Brazelton Neonatal Behavioral Assessment Scale was administered to 24 each Puerto Rican, Black, and Caucasian, 2‐day‐old, full‐term healthy neonates. Comparisons on 8 Brazelton scale summary scores showed that Puerto Rican infants scored lower on habituation, higher on orientation, and higher on maintaining their organization with increasing stimulation than Black and Caucasian infants. Multiple regression analysis showed that the combination of biomedical variables was significantly correlated with 6 of the Brazelton scale summary scores for the Puerto Rican infants, 1 summary score for the Caucasian infants, and none for the Black infants; it revealed population differences with respect to the synergistic effects of biomedical variables on neonatal behavior.
Compensatory social responses of older pigtailed monkeys to maternal separation
Authors: Bernstein Irwin S. , Dobrofsky Miriam 
Published: January 2005

AbstractThirteen 3‐ to 5‐year‐old pigtailed monkeys were subjected to five 2‐hr maternal separations while remaining in their normal social group. Significant changes in avctivity profiles were noted during separation and reunion phases. This suggests the continued social dependence of older offspring upon the matriarch. The shift in social activities reflected attempts by the juvenile and adolescent subjects to compensate for maternal absence by intensification of other affiliative social behavior and avoidannce of potentially socially disruptive situation. The subjects oriented more towards kin in the absence of the matriarch, but actual time with kin decreased. Upon the return of the matriarch, they intensified some responses depressed during her absence and returned to preseparation social relationships. Play and aggressive responses declined whereas social approaches increased during maternal absences. Submissive responses declined upon the return of the matriarch, and play increased. The subjects also showed a marked, temporary increase of direct interaction, largely sniffing and grooming, with the matriarch upon her return.
Development of infant independence in a captive group of lowland gorillas
Authors: Hoff Michael P. , Nadler Ronald D. , Maple Terry L. 
Published: January 2005

AbstractIn March 1976, 3 lowland gorillas (Gorilla gorilla gorilla) were born to primiparous females living with an adult male in a large compound at the field station of the Yerkes Regional Primate Research Center of Emory University. Observations of parent and infant behavior began at the birth of the infants, using several methods of data collection. This report focuses on the development of independence in these infants over the 1st 1½ years of life. As expected, measures of mother‐infant contact and proximity decreased with age. Several measures suggested that infant independence developed as an interactive process between mothers and infants, with primary responsibility changing over the months of study. Maternal behaviors that served to maintain mother‐infant contact were found to decrease with age, with an eventual shift to infant responsibility for contact maintenance. Additionally, the adult male appeared to influence developing independence as reflected in the maternal protectiveness evoked by his behavior.
Acceleration and delay of puberty in female housemice: Methods of delivery of the urinary stimulus
Authors: Drickamer Lee C. , Assmann Sarah M. 
Published: January 2005

AbstractA series of 7 experiments tested various methods for delivery of male and female urinary chemosignals which affect age of 1st estrus in young female mice. An initial experiment demonstrated that in and of themselves none of the delivery techniques used alters puberty without the accompanying urine stimulus. A series of 4 experiments with male urine revealed that acceleration of puberty occurred only when the females could achieve direct contact with the urine. Possible reception via the vomeronasal organ is suggested as an explanation for these data. In contrast, the urinary chemosignal from grouped females which delays 1st estrus produces its effect regardless of the mode of delivery. Reception of this chemosignal apparently may occur at the olfactory epithelium.
Taste aversion following backward conditioning procedures in preweanling and adult rats
Authors: Franchina Joseph J. , Dietz Sheri 
Published: January 2005

AbstractLaboratory rats, 18 and 90 days old, received an intraperitoneal injection (2% body weight) of .15M lithium chloride or .9% saline 10 or 30 min before 15‐min access to 12% sucrose. Additional control groups received LiCl injection followed by tap water access. Testing with a 2‐bottle choice procedure revealed reliable aversion effects for both age groups at each toxicosis‐flavor interval. Adult rats showed reliably greater persistence of aversion following training with the 10‐ than with the 30‐min interval. Rat pups showed no reliable differences in aversion across training intervals. Reliably greater aversion effects occurred for adults than for pups following training at the 10‐min interval. Following training at the 30‐min interval a similar reliable age effect occurred on Test Trial 1; but from Trial 2 onward the magnitude of aversion was similar for pups and adult rats.
Maturation and d‐amphetamine–induced changes in web building
Authors: Reed Charles F. , Witt Peter N. , Scarboro Mabel B. 
Published: January 2005

AbstractWebs of Araneus diadematus Cl. were obtained under drugged (dextroamphetamine) and control conditions at three age‐periods in the development of the spider from juvenility to sexual maturity. Although certain features of construction are affected in all periods and some exhibit differential effects with age, it was not possible to separate the latter from changes in body mass between periods.
Effects of postweaning rearing condition on recovery of copulatory behavior from lesions of the medial preoptic area in rats
Authors: Meisel Robert L. 
Published: January 2005

AbstractBilateral lesions of the medical preoptic area (MPOA)–anterior hypothalamus of adult male rats markedly disrupt male copulatory behavior. In contrast, more group‐reared then isolated male rats receiving bilateral MPOA lesions as juveniles copulated to ejaculation as adults. The present experiment was designed to analyze the role of rearing condition in promoting copulatory recovery from MPOA lesions in juvenile male rats. Juvenile male rats were given bilateral MPOA lesions or a sham operation and reared in isolation without handling, in isolation with daily handling, across a perforated Plexiglas divider from a male peer, or together with a male peer (social). Socially reared and handled males, but not isolated and divided males, with MPOA lesions showed evidence of copulatory recovery (combined socially reared and handled males vs combined isolated and divided males). These results support previous findings that postweaning rearing condition can affect copulatory recovery following juvenile MPOA lesions, but indicate that play experiences involving physical contact with peers are not necessary for such recovery to occur.
The role of intraoral and gastrointestinal cues in the control of sucking and milk consumption in rat pups
Authors: Brake Stephen C. , Jayne Sager D. , Sullivan Regina , Hofer Myron 
Published: January 2005

AbstractNutritive deprivation, suckling deprivation, gastronintestinal fill, and milk availability contribute to the control of sucking (as measured by jaw‐muscle electromyograph) and ingestion of milk (provided via a tongue cannula) in 11–13‐day‐old rat pups. Depriving pups of the opportunity to suckle reliably increases subsequent sucking and milk intake. Intraoral delivery of milk also increases sucking, regardless of whether or not pups are suckling‐deprived. Gastrointestinal preloads have no effect on sucking if pups are not receiving milk, but reliably block the increase in sucking which accompanies milk delivery. Finally, milk delivered to the pup's mouth prior to a suckling opportunity can either enhance or attenuate subsequent sucking depending on whether pups are allowed to consume milk while suckling. In all cases, a particular mode of sucking (“rhythmic” sucking) is most affected by experimental manipulation, and appears to be an important component of the pup's ingestive behavior.
Odor‐aversion learning by rats following LiCl exposure: Ontogenetic influences
Authors: Rudy Jerry W. , Cheatle Martin D. 
Published: January 2005

AbstractThe influence of LiCl preexposure on odor‐aversion conditioning produced by an odor‐LiCl pairing was studied in rats 7–31 days old. LiCl preexposure interfered with the acquisition of the odor aversion in both young and old pups. The time course of this effect depended, however, on the age of the pups. It lasted much longer (over 24 hr) if pups 8–17 days old were preexposed to LiCl than if the pups were preexposed when 30 days old (less 12 hr). Alternative interpretations of these data were discussed, and it was suggested that the age‐dependent differences in the time course of the LiCl preexposed effect may be determined in part by age‐related differences in the rat's excretory processes that clear lithium from the circulatory system.
Shifting patterns of bilateral coordination and lateral dominance in the leg movements of young infants
Authors: Thelen Esther , Ridley‐Johnson Robyn , Fisher Donna M. 
Published: January 2005

AbstractPatterns of interlimb coordination and lateral preference of spontaneous leg kicks were described for 8 normal human infants observed biweekly from 2 to 26 weeks of age. Newborn infants showed a high percentage of alternating movements, which were often supplanted by unilateral movements between 1 and 4 months. Simultaneous (in‐phase) kicks matured later than alternating kicks. No consistent lateral preferences were detected. The developmental course was marked by variability and discontinuities within each infant. We propose that asynchronous and asymmetrical maturation of subcortical tracts and/or muscle strength could account for these behavioral shifts.
Neonatal sex‐steriod hormones and timidity in 6‐18‐month‐old boys and girls
Authors: Jacklin Carol Nagy , Maccoby Eleanor E. , Doering Charles H. 
Published: January 2005

AbstractFive sex‐steroid hormones (testosterone, androstenedione, estradiol, estrone, and progesterone) are assayed in umbilical cord blood. Timidity is assessed in home and laboratory observations by reactions to a range of novel toys in children from 6 to 18 months of age. Significant short‐ (1 week) and long‐ (several months) term stability in timidity is demonstrated. Girls have higher mean scores on observed timidity than do boys in 2 of the 3 samples tested. An across‐age timidity score is computed which shows significant correlations with neonatal progesterone, testosterone, and estradiol for boys, but is not significantly predicted by hormone concentrations in girls.
Behavioral responses of infant rats to maternal licking: Variations with age and sex
Authors: Moore Celia L. , Chadwick‐dias Ann‐Marie 
Published: January 2005

AbstractBehavioral interactions of Norway rat pups and their dams during maternal anogenital licking (AGL) were observed. Regulatities in posture and orientation that may facilitate AGL were noted, and age‐related changes in the pup's postural adjustments that may contribute to the decline of AGL in the 3rd postpartum week were described. It was found that cutaneous stimulation of the perineum, such as that provided by AGL, stimulates a characteristic leg extension response from pups. It was concluded that this response, which includes immobility and extenstion of all limbs, may permit maternal licking to continue long enough to stimulate the pup to eliminate and to allow the dam to ingest the urine. Males and females were found to exhibit similar responses and similar age‐related changes. However, the latency from onset of AGL to performance of the leg extension response was shorter in males.
Physical and behavioral sequelae of low birthweight in spiny mice (Acomys cahirinus)
Authors: Porter Richard H. , Makin Jennifer W. , Matochik John A. 
Published: January 2005

AbstractPhysical and behavioral sequelae of low birthweight (LBW) were investigated in spiny mice (Acomys cahirinus). When raised by their biological mother, pups whose Day‐2 weights were 1 SD or more below the population mean remained smaller through the first 30 days postpartum than pups born within normal (N) weight ranges. LBW pups fostered onto mothers who gave birth to N pups gained weight more rapidly than LBW pups remaining with their own mother. Similarly, N Pups fostered onto mothers of LBW pups displayed reduced weight gain relative to N siblings raised by their biological mother. It appears that rate of weight gain is influenced by an interaction between birthweight and maternal rearing environment. LBW pups also were less responsive than N pups to maternal chemical cues, indicating that low birthweight is correlated with deficits in adaptive behavior.
Exploratory behavior, learning ability, and thyroid hormonal responses to stress in female rats rehabilitating from postnatal hypothyroidism
Authors: Tamasy V. , Meisami E. , Du J‐Z , Timiras Paola S. 
Published: January 2005

AbstractNewborn female Long‐Evans rats were divided into groups of normal, hypothyroid [0.1% propylthiouracil (PTU) a reversible antithyroid goitrogen in the litter's drinking water], and hypothyroid rehabilitated (PTU water from birth to day 25, normal water thereafter). The rats were tested for several adaptive behavioral tasks between 40 and 90 days of age. At day 50, serum concentration of TSH and thyroid hormones revealed no detectable amounts of T4 and a 10‐fold increase in TSH in the hypothyroid rats. At the same age in the rehabilitated animals, TSH levels were still below normal, a deficit fully normalized by day 90. Normal 50‐day‐old rats responded to pain stress (electric footshocks) by a significant depression of serum T4 and elevation of T3 levels within 10 min of treatment, whereas the rehabilitated animals exhibited an opposite pattern of response, i.e., an increase in the circulating T4 and a decrease in T3. At 50 days of age, both hypothyroid and rehabilitated rats showed decreased exploratory activity and no habituation in the hole‐board test, whereas the locomotor activity of the rehabilitated females was significantly higher than that of the normals. No differences were found in the scores of passive avoidance learning (one trial step‐through) among the three groups. Similarly, the rate of acquisition of the active one‐way conditioned avoidance response (CAR) of the hypothyroid and rehabilitated rats did not differ significantly from that of the controls. However, the hypothyroid rats required significantly more unconditioned stimuli (footshocks) to acquire CAR and showed longer response latency and less intertrial responses. Although the hypothyroid rats showed no extinction of CAR, the rehabilitated rats were capable of extinction to an extent indistinguishable from normal rats. But compared with the normal animals, the rehabilitated rats showed significantly higher intertrial activity during both the acquisition and extinction phases of CAR.