bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential effects of handling on exploration in male and female rats
Authors: Weinberg Joanne , Krahn Emily A. , Levine Seymour
Published: January 2005

In this study, sex differences in the exploratory behavior of handled and nonhandled animals were measured under conditions of both high and low stimulus variation. The apparatus used was a hole‐board, which provided an exploratory response independent of ambulation. Significant effects of handling were found: nonhandled animals decreased head‐dipping over days whereas handled animals maintained a high rate. Sex differences were also observed: patterns of head‐dipping for males and females differed over days depending on whether objects were present (high stimulus variation) or absent (low stimulus variation) under the hole‐board; females also head‐dipped for longer durations than males when objects were present; further, males and females showed completely opposite patterns of exploration depending on handling treatment and on level of stimulus variation. We conclude that handling differentially affects males and females, particularly as level of stimulus variability changes.
Maternal behavior of wild and domestic Rattus norvegicus recorded continuously in dual‐chambered cages
Authors: Hughes Carroll W. , Harlan Rebecca S. , Michael Plaut S.
Published: January 2005

Continuous measurements of maternal behavior–the amount of time the mother was in contact with the litter and quality of nest–indicated no differences between these 2 stocks of rats. A decrease in both measures was found for both stocks over the 22 days of postnatal observation. The data indicated that the mother was with the litter more during the light portion of the 24‐hr light‐dark cycle and that wild rat mothers were in contact with their litters more than domestic mothers in the period around light offset.
The effects of litter size during gestation and lactation on rat development prior to weaning
Authors: Wehmer Francine , Jen Kai‐Lin Catherine
Published: January 2005

Physiological and behavioral development of rats was affected by prenatal nutrition and postnatal litter size. Prenatal nutrition was manipulated by combining differences in maternal nutrition with variation of prenatal litter size produced by pre‐mating isolation of 1 uterine horn. The pups were reared in postnatal litters of either 4 or 12. During the 1st postnatal week, development and free behavior were affected only by the prenatal treatments. During the 2nd postnatal week, both prenatal and postnatal effects were observed. Development and behavior during the 3rd postnatal week reflected only postnatal litter size. Brain weight at weaning was influenced by both the prenatal and postnatal treatments.
Response of the infant rat to light prior to eyelid opening: Mediation by the superior colliculus
Authors: Routtenberg Aryeh , Strop Marguerite , Jerdan Janice
Published: January 2005

Although the influence of light on the infant rat before Day 14, when its eyelids open, are presumed to be minimal, we have shown that as early as postnatal Day 6, male and female albino rats demonstrate negative phototaxis. Bilateral enucleation eliminates negative phototaxis. whereas unilateral enucleation does not. Rearing in the dark does not prevent the expression of the behavior. Knife cuts on postnatal Day 5, which undercut the dorsal midbrain involving the superior colliculus, prevent the expression of this response to light. Unilateral dorsal midbrain knife cuts and posterior cortex lesions have no effect. These results call attention to an early period in the postnatal development of the rat when it is capable of exhibiting negative phototaxis. The superior colliculus in the dorsal midbrain appears to be crucial for demonstrating this behavior.
Alleviation of forgetting in preweanling rats
Authors: Spear Norman E. , Smith Gregory J.
Published: January 2005

Three experiments tested the learning and retention of neonatal rats (7, 9, and 12 days of age) with a nondirectional active avoidance task, using a vibrotactile conditioned stimulus. The hypothesis was that the substantial deficit of these animals in 24‐hr retention is due, at least in part, to a deficiency in memory retrieval. In Experiment I, a reactivation treatment was found to alleviate the forgetting over the 24‐hr period for 12‐day olds although having somewhat lesser effect for animals 9 days of age. The reactivation treatment seemed ineffective for rats 7 days of age. Experiments II and III confirmed the reliability of the reactivation effects with 9‐ and 12‐day olds, while adding further control conditions and providing new information concerning the ontogenesis of latent inhibition.
Neurological development of kittens
Authors: Villablanca Jaime R. , Olmstead Charles E.
Published: January 2005

The neurological development of the kitten was studied from birth to 120 days of age. Three motor features present at birth disappeared within the 1st 45 days of life. The labyrinthine head and body righting reactions were present at birth; the latter matured only by 25 days of age when the air righting reaction (mature by 35 days) started to appear. Limb placing reactions developed progressively with proprioceptive components being present at birth whereas tactile components evolved slowly from early contact lifting to forepaws contact placing (60 days) and narrow plank walking (75 days). Standing and walking were well developed by 45 days. Eye opening occurred at 9.5 days and several eyeblink reactions (including blink to light) were present at birth. Adequate binocular coordination was seen by 47 days. Vision progressed parallel to the clearing of the ocular media which were fairly transparent by 32 days. Visually guided paw placing and the visuopalpebral blink reflex matured later (by 37 and 59 days, respectively). The external auditory canal and pinna were fully developed by 12 and 31 days, respectively; spontaneous and tactile pinna movements were present at birth; orienting to animal and nonanimal sounds was well developed by 6.5 and 18 days, respectively; spatial sound localization was developed by 16 days and differential responding to animal sounds matured by 24.5 days. Somatic responses and olfaction were present at birth but matured further thereafter. Playful interactions between kittens started by 10–15 days and well developed play behavior was seen by 36–40 days. In brief, all neurological functions mature progressively during the 1st 3 postnatal months.
Within‐species variation in the development of ultrasonic signaling of preweanling rats
Authors: Graham Mike , Letz Richard
Published: January 2005

The 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

Ontogenetic 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

Male 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

In 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

Two 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

The 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

Developmental 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

In 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

Data 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

The 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

Thirteen 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

In 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

A 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

Laboratory 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

Webs 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

Bilateral 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

Nutritive 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

The 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

Patterns 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

Five 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

Behavioral 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

Physical 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

Newborn 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.
Differences in maternal behavior of rats and the sociosexual development of the offspring
Authors: Birke Lynda I. A. , Sadler Dawn
Published: January 2005

This paper describes experiments designed to investigate long‐term behavioral consequences for offspring of changes in maternal behavior directed toward them as pups. Specifically, the hypothesis was considered that experimentally induced alterations in maternal behavior would result in general and wide‐ranging effects on offspring development, including effects on later social and sexual behavior. The first experiment looked at the effects of changing pup odors on maternal responsiveness toward those pups, and showed that the application of perfume, particularly to the anogenital region, resulted in significant lowering of maternal anogenital licking of pups. Non‐pup‐directed behavior did not differ between groups. The behavior of those pups that had thus differed in infant experience was then followed in three subsequent experiments. In Experiment 2, social behavior during the juvenile period was investigated, focusing particularly on the expression of social play. The most noticeable difference to emerge in this experiment was that male pups that had been anogenitally perfumed as infants showed much higher levels of social play than male or female pups from other treatment groups. The last two experiments considered adult behavior. Experiment 3 showed that there are no lasting effects of the neonatal treatment on the attractiveness an animal has for its conspecifics. In the final experiment, “masculine” sexual behavior of males (mounts with intromission), and “feminine” sexual behavior of females (i.e., lordosis and proceptive behavior) were investigated. This confirmed previous reports by Moore (1984) (Moore, C. L. (1984). Maternal contributions to the development of masculine sexual behavior in laboratory rats. Dev. Psychobiol., 17:347–363) that those male pups that had received lower rates of anogenital licking as pups showed longer intermount intervals, when tested as adults. The results are discussed in relation to the development of sexually differentiated behavior.
Mothers' recognition of their newborns by olfactory cues
Authors: Kaitz M. , Good A. , Rokem A. M. , Eidelman A. I.
Published: January 2005

We report that 90% of women tested in the present study identified their newborns by olfactory cues after only 10 min‐1 hr exposure to their infants. All of the women tested recognized their babies' odor after exposure periods greater than 1 hr. The robust results are due in part to the implementation of an initial screening phase in which individuals with obvious olfactory deficits were excluded from the sample. These results suggest that odor cues from newborns are even more salient to their mothers than have been thought heretofore.
Effects of odor familiarity on the development of systematic exploration in the spiny mouse, Acomys cahirinus
Authors: Birke Lynda I. A. , Sadler Dawn
Published: January 2005

Developmental changes in patterns of exploration by infant spiny mice, Acomys cahirinus are described. These were investigated using an unbaited radial maze and under three odor conditions; that is, animals were tested in the presence of either familiar (own) odors, unfamiliar conspecific odors, or no odors (washed floor). Two hypotheses were tested. The first was based on the results of a pilot study, and was that adult animals would explore the radial maze in a systematic and predictable fashion tending to move from one arm to the next sequentially. It was hypothesized that infants would adopt this sequential strategy only gradually, as they matured. The second hypothesis was that such patterns of exploration would depend upon the olfactory environment; the presence of familiar odors might facilitate systematic patterns of exploration in very young Acomys. The results showed that both adults and juveniles were less likely to move sequentially when tested with no conspecific odor present; sequential patterns of movement were most likely in the presence of unfamiliar odor, however. The only significant change with age in infants was found for animals tested with unfamiliar odors; these animals showed a dramatic increase in sequential behavior between 3 and 7 days of age. Two additional experiments are reported, which investigated the preferences of infant Acomys for unfamiliar conspecific odors, and it was found that very young (about 3 days) animals exhibit a preference for odors derived from unfamiliar conspecific litters, even when tested in the physical presence of their own parents. The results are discussed with reference to the use of olfactory information as directional cues for animals exploring the radial maze.
Early experience influences adult retention of aversively motivated tasks in normal, but not DSP4‐treated rats
Authors: Cornwell‐Jones Catherine A. , Velasquez Pattijo , Wright Eileen L. , McGaugh James L.
Published: January 2005

Sprague‐Dawley rat pups were injected with DSP4 or water within 48 hr of birth and tested as adults in an inhibitory avoidance task and in a Y‐maze discrimination reversal task. Half of the animals were also tested as juveniles during postnatal weeks 4–5, in tasks assessing odor preferences and general investigatory behavior. Controls, but not drug‐treated adults, which received the juvenile testing, showed significantly better retention on both tasks than either controls or drug‐treated animals not tested as juveniles. Neonatal DSP4 significantly reduced norepinephrine concentrations in the hippocampus and frontal cortex, but not the heart. The results suggest that central norepinephrine may modulate the effects of early experience on adult learning.
Play‐fighting in the Syrian golden hamster Mesocricetus auratus waterhouse, and its relationship to serious fighting during postweaning development
Authors: Pellis Sergio M. , Pellis Vivien C.
Published: January 2005

In the Syrian golden hamster Mesocricetus auratus, play‐fighting preceds serious fighting during postweaning development, and so may be thought to be a developmental precursor to adull aggression. However, based on both the targets attacked—that is, the cheek pouches during play‐fighting and the rump or flanks during serious fighting, and the behavior patterns employed to attakc and defend these targets—these two forms of fighting are shown to remain distinct from each other throughout development, even during the ages where they overlap. The decline of play in post‐sexually‐mature animals is shown to result from an increasing intolerance to contact between animals, and hence greater difficulty in the maintenance of a “playful mood.” Therefore, these data show that play‐fighting does not grade into serious fighting, and thus does not serve as a developmental precursor to adult aggression.
Human interlimb coordination: The first 6 months of independent walking
Authors: Clark Jane E. , Whitall Jill , Phillips Sally J.
Published: January 2005

The organization of interlimb coordination was studied in newly walking infants with and without support and in infants who had been walking 0.5, 1, 3, and 6 months. Analysis of the temporal and distance phase relationships between the limbs revealed that newly walking infants exhibit interlimb coordination similar to that of mature walkers. The coupling between the limbs, however, is loosely constrained, approaching adult‐like consistency after 3 months of walking. Providing support for the newly walking infant afforded a more consistent, mature coordination suggesting that neuromuscular development is in advance of its ability to function in the physical world.
Infants of diabetic mothers: Late normalization of fetal cyclic motility persists after birth
Authors: Robertson Steven S.
Published: January 2005

The prenatal development of cyclic motility (CM) in the human is disrupted by maternal diabetes, but appears normal by the end of gestation. To determine whether birth and adaptation to postnatal life reveal new or persisting abnormalities in CM, 24 newborn infants of insulin‐dependent diabetic mothers (IDMs) and 24 normal newborns were studied for 2–4 hr in a controlled environment. Spectral analysis of spontaneous movement revealed that CM was common in both groups. Measures of its cyclic organization in each state did not differ between IDMs and controls. State differences were the same in the two groups, and replicated the pattern found in a previous study of normal newborns. For IDMs, there were no differences associated with neonatal evidence of increased glucose supply in utero (macrosomia, postnatal hypoglycemia), or with determinations of prenatal maternal hyperglycemia. IDMs had also been studied as fetuses, and the pattern of continuity and change in CM across birth replicated the pattern previously reported for normal fetuses. The results suggest that the development and control of CM is buffered from the prenatal metabolic insults suffered by IDMs, and support speculations that cyclic activation is a general and robust property of the developing motor system in the human.
Development of species identification in ducklings: XV. Individual auditory recognition
Authors: Gottlieb Gilbert
Published: January 2005

The present experiments examined the ability of domestic mallard ducklings (Anas platyrhynchos) to learn individual mallard maternal calls by either repetition‐rate differences or spectral (Hz) differences, both of which are present in such calls recorded in nature. The ducklings could learn both kinds of differences within the first 24 hr after hatching, corresponding to the period prior to the exodus from the nest in nature. The hatchlings were able to learn these differences based upon only 12 min of exposure to the maternal calls during the first day after hatching. They were also able to retain (remember) the familiar call for an additional day after exposure. Embryos, on the other hand, could learn the spectral differences after either 12 or 24 min of exposure but could not retain the information under either exposure condition. An additional difference between the auditory learning competence of hatchlings and embryos was that the hatchlings were capable of learning the spectral features of a maternal call even if it was pulsed at different repetition rates during exposure (familiarization) and the subsequent test for recognition. The evolutionary significance of the results was discussed in terms of the general importance of familiarization as a basic behavioral mechanism underlying not only parental attachment but dietary and habitat preferences and the like.
Early‐life malnutrition impairs the performance of both young and adult rats on visual discrimination learning tasks
Authors: Castro Carl Andrew , Rudy Jerry W.
Published: January 2005

Previously malnourished young (20–40‐day‐old) and mature (70–77‐day‐old) rats were compared on position, brightness, and pattern discrimination problems using an aquatic version of the Lashley jump stand. Malnutrition did not affect performance on the position discrimination. In contrast, previously malnourished 24–34‐day‐olds failed to solve the brightness discrimination, 40‐day‐olds were impaired on the brightness problem, and 40–77‐day olds were impaired on the pattern problem. The impaired performance of the 40‐day‐olds on the brightness problem was eliminated by prior training on the pattern discriminations, and the impaired performance of the 70‐day‐olds on the pattern discrimination could be eliminated if they were first trained on the brightness problem. These impairments were attributed to the effects of early‐life malnutrition on the maturation of attention processes that enable the rat to suppress responding to irrelevant cues. The relevance of a contextual‐organismic perspective for understanding the effects of early‐life malnutrition was discussed.
Activity states and motor activity in an infant capuchin monkey (Cebus apella) from birth through eleven weeks
Authors: Fragaszy Dorothy Munkenbeck
Published: January 2005

Behavioral states and motor activity of an infant capuchin monkey reared by its mother in a social group were studied for 11 weeks after birth. Manipulative activity was infrequent through the first four weeks after birth; what little occurred was mediated by other animals interacting with the infant. The rate of manipulation increased the most between weeks 8 and 9. At the same time, the most frequent targets of manipulation shifted from the infant's own body and the bodies of others to surfaces and inanimate objects in the cage. Large increases in the proportion of time in an Alert/active state and improvement in postural control also occurred at the end of the second month. The data suggest that major organizational changes in motor coordination and the regulation of behavioral state occurred jointly over a short period of time at about 8 weeks of age. In comparison to other species of monkeys, the capuchin infant displayed later development of manipulation, postural control, and independent locomotion, and greater dependence on social contacts for early interaction with its environment. These characteristics are in accord with the greater neurological immaturity of the capuchin infant at birth compared to other monkeys.
Visual head extension: Transitional head coordination in the pigeon squab (Columbia livia)
Authors: Davies Mark N. O. , Green Patrick R.
Published: January 2005

We describe a previously unreported visuomotor behavior of the developing pigeon squab, which we term “visual head extension.” The behavior consists of extension and lowering of the head as the bird descends towards a surface or experiences the optical equivalent of such a descent. A peak in performance occurs 10 days after hatching. Evidence obtained shows that both vestibular and dynamic visual information can independently produce head extension. We go on to place the new behavioral response in the context of a dynamic, relational approach to perceptuomotor coordination, and outline the corresponding advantages of studying the single‐limb, head‐neck system in the pigeon.
Contour variables in vocal communication between squirrel monkey mothers and infants
Authors: Biben Maxeen , Symmes David , Bernhards Deborah
Published: January 2005

This study investigates the occurrence and structure of the caregiver call, a form of communication in squirrel monkeys that is almost exclusively infant‐directed. Caregiver calls exhibit variability in several acoustic features, most notably pitch range and contour, which are significantly associated with particular context of infant care; e.g., nursing or retrieval. The use of caregiver calls by squirrel monkeys is compared to the use of motherese (infant‐directed speech) by humans. The possible functional and motivational basis for specific acoustic variable in the caregiver call is discussed.
Environmental factors and age of puberty in female house mice
Authors: Drickamer Lee C.
Published: January 2005

Genetics, urinary chemosignals and related social influences, and ambient conditions affect reproduction in female mice. Five experiments tested the effects of environmental stressors on age at first vaginal estrus in female house mice. Environmental disruption in the form of changing the cage bedding and/or nesting material at various prescribed intervals resulted in different degrees of puberty delay relative to non‐disrupted control mice. Disruption in the form of a male chasing the female for one to three 15‐min intervals each day or the female being trapped and held in a live‐trap for one to three 15‐min intervals each day resulted in delays in puberty for treatments involving multiple daily disruptions. Food deprivation, but not water deprivation, influenced the onset of puberty. Variations in temperature and humidity resulted in differences in the age of puberty; low but not high temperatures and extremely low humidity levels delayed sexual maturation.
The ontogeny of thermal nociception in domestic fowl: Thermal stimulus intensity and isolation effects
Authors: Hughes Richard A. , Sufka Kenneth J.
Published: January 2005

Socially housed leghorn cockerels were confined to a heated grid (55, 57, or 59°C, Experiment 1; 59, 61, or 63°C, Experiment 2) and tested at posthatch ages of 14 days (Experiment 1) and 1, 3, 7, or 14 days (Experiment 2). In Experiment 1, chicks performed a discrete jump response only at 59°C. In Experiment 2, jump latency was inversely related to temperature at each age but significantly so only at 7 and 14 days posthatch. At the highest temperature, jump latency did not differ significantly across ages. At medium and low temperatures, latency increased from 1 and 3 to 7 days posthatch (antinociceptive effect) and decreased thereafter. Chicks raised in isolation from hatch to 7 days posthatch (Experiment 3) did not display the increased jump latency (antinociceptive effect) displayed by socially raised chicks. Developmental increases in jump latency may reflect stress‐induced antinociceptive concomitants of neophobia that emerge with age in this precocial species and social experience may be required for the normal development of this stress‐induced antinociception.
The ontogeny of antiphonal calling in European starlings
Authors: Chaiken Marthaleah
Published: January 2005

The ontogeny of antiphonal calling was studied in free‐living European starlings. Nestlings participate in three types of vocal exchanges: (1) Broodmates exchange calls while the parents are away; (2) parents and nestlings exchange calls during feeding; (3) nestlings exchange calls with parents approaching from a distance. Analysis of the temporal patterning of vocal interactions revealed call alternation and avoidance of acoustic overlap in exchanges of the first and third types. The antiphonal exchanges between parents and young develop shortly before fledging and appear to help family groups maintain contact after the young have left the nest. Early antiphonal exchanges between broodmates are as smooth as later ones between parents and chicks, suggesting that chicks quickly attain proficiency at antiphonal interactions and do not rely on an adult partner to maintain the pattern. There are parallels with the development of vocal turn‐taking in human infants.