bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of selective interruption and deprivation of sleep in the human newborn
Authors: Anders Thomas F. , Roffwarg Howard P.
Published: January 2005

In two separate studies, newborn infants' responses to sleep stage deprivation were investigated. In the first study, neonates were selectively awakened from either REM or NREM sleep during 1 interfeeding sleep period and allowed to recover in an undistrubed second. In the 2nd study, infants were kept totally awake for 1 interfeeding period and allowed to sleep undisturbed during the next. The results indicate that selective sleep stage deprivation by manual awakenings was impossible to achieve during the newborn period. Rather, the infants were partially sleep deprived (both stages of sleep were reduced) with increased amounts of wakefulness. During the disturbance the interrupted sleep stage demonstrated considerable “tenacity.” During undisturbed recovery sleep, in both studies, total sleep time was markedly increased. NREM sleep demonstrated a greater tendency for preferential recovery than REM sleep.
Avoidance conditioning in mice as a function of their mothers' training
Authors: Ressler Robert H. , Anderson Lowell T.
Published: January 2005

Prior to mating, inbred female mice were exposed to 1 of 4 conditions for 15 days: 50 trials of avoidance conditioning per day; equivalent (yoked) exposure to conditioned stimulus (CS) and shock, but without the response contingency; yoked exposure to the CS alone; or no experimental treatment. Within 48 hr after birth the offspring of these females were transferred to unrelated foster mothers. The treated females served as foster mothers for the offspring of untreated females. When the adult avoidance conditioning performance of the offspring was analyzed, an interaction was found between the sex of the offspring, the treatment of the mothers, and the developmental period during which the maternal treatment influenced the offspring. In general, the prenatal effect of maternal treatment was the reverse of the postnatal effect, and its effect, while somewhat greater on female offspring, also was the reverse of its effect on male offspring.
Avoidance conditioning in mice as a function of their mothers' exposure to shock
Authors: Ressler Robert H. , Anderson Lowell T.
Published: January 2005

Inbred female mice received treatment either prior to mating or following birth of offspring. When treatment was administered, females were either not handled or received 0, 5, 15, or 30 shocks per day. When the adult avoidance conditioning performance of the offspring was analyzed an interaction was found between the sex of the offspring, the frequency of maternal shock, and the developmental period during which shock was administered. Maternal treatment had a more coherent and pronounced effect on female offspring than on their male littermates. The functional relationship between frequency of maternal shock and offspring avoidance was consistently nonmonotonic; its direction was highly dependent upon the period of life during which the mother encountered the shock.
Response to a conditioned aversive event in mice as a function of frequency of premating maternal shock
Authors: Anderson Lowell T. , Ressler Robert H.
Published: January 2005

Prior to mating, female mice were exposed to either 0, 1, or 60 shocks per day for 20 days. When the food reinforced operant responding of their adult offspring was observed in the presence of a conditioned aversive stimulus, a nonmonotonic relationship was found between frequency of maternal shock and degree of conditioned suppression in female offspring. During the 2nd session of a 3‐session test period the females reared by mothers that had received either 0 or 60 shocks per day showed greater conditioned suppression than those whose mothers had received 1 shock per day. Maternal treatment also had significant effects on maternal weight, offspring litter size and weaning weight, and frequency of defecation during the conditioned suppression procedure. In the latter instances, however, negative monotonic relationships were observed in both sexes. The data indicate that an interpretation in terms of an a priori classification of “emotionality” is not adequate.
The influence of stagnant hypoxia on the activity of some dehydrogenases and aminotransferases in the brain of rats during ontogenesis
Authors: Jílek L. , Janata V. , Londonová A. , Makč Z. , Trojan S. , Vorel F.
Published: January 2005

Ligation of both common carotid arteries produces stagnant hypoxia (oligemia) in the brains of rats. The character and the intensity of the hypoxic metabolic changes depend directly on the developmental maturity of the nerve tissue, which is also true of the activity of the enzymes, LDH, aldolase, SDH, MDH, G‐6‐PDH, GDH, GPT, and GOT. In the 5‐day‐old rat after 4 hr of oligemia, enzyme activity either did not change or increased. In the 12‐day‐old rat the activity of LDH, MDH, and GPT increased and the activity of GDH, aldolase, and G‐6‐PDH decreased. At the age of 25 days and in adulthood, the activity of SDH, MDH, aldolase, and GOT decreased. The changes in enzyme activity are related to changes in proteosynthesis and appear to support the concept of a “metabolic adaptive reaction” of the immature nervous system in response to changes of the inner milieu.
Maternal influence on the response of wild and domestic norway rats to a novel environment
Authors: Price Edward O. , Loomis Stephen
Published: January 2005

The influence of the maternal environment on the response of adult wild and domestic Norway rats to a novel environment was assessed by comparing the behavior of reciprocal hybrid groups to each other and to the parental strains. Wild rats exhibited shorter latencies for activity, greater total activity, more time grooming, smaller body weights, and larger adrenals than domestic rats. (Defecation rates were similar.) Reciprocal hybrids were intermediate to the parent strains for all variables. With the exception of total activity little evidence was obtained for a maternal influence on the behavioral responses studied. Differences between wild and domestic rats in response to a novel environment are more readily explained by genetic changes accompanying the domestication process than by differences in the maternal environments.
Activity states in premature and term infants
Authors: Michaelis Richard , Parmelee Arthur H. , Stern Evelyn , Haber Audrey
Published: January 2005

Generally, studies which have compared full term infants shortly after birth with prematurely born infants tested at the date of their expected birth (i.e., 40 weeks conceptional age) have stressed the similarities rather than any differences which have appeared in the data. Nonetheless, numerous differences have been noted, and the present study documented an additional discrepancy in function between full term and premature infants at 40 weeks conceptional age as well as maturational changes in state responsivity during the premature period.

Premature infants were given repeated neurological examinations at 31‐33, 34‐36, and 38‐42 weeks conceptional age. Full term infants were tested at 38‐42 weeks conceptional age. Included in the scoring of the examination were 37 measures of state, designed to assess the infant's responsivity to the increasingly stressful items of the neurological examination. The younger prematures were more often judged to be asleep and had lower scores throughout the examination when compared to the 38‐42 week infants. Crying occurred significantly more often with increasing age. In addition, the full term infants had significantly more crying scores than the prematures of the same conceptional age.
Reversal learning in the neonatal rhesus monkey
Authors: Zimmermann Robert R.
Published: January 2005

Twenty‐one day old and 31 day old monkeys were presented with a black‐versus‐white discrimination reversal problem after having completed 20 days of learning on the original problem. Age at the time of reversal was not a significant factor, but reversing to the white stimulus was significantly faster than reversing to the black stimulus. This preference persisted over repeated reversals. The infant monkey shows improvement in repeated reversal learning that is very similar to the behavior of the adult rat.
Neural systems underlying climax movements in the domestic chicken
Authors: Bakhuis Walter L. , Corner Michael A.
Published: January 2005

Bilateral removal or disconnection of the entire telencephalon in the chick embryo failed to show any effect upon the characteristic repetitive phasic behavior pattern at hatching, or “climax.” Surgical disconnection of the spinal cord caused a minor facilitation of these stereotyped motility bursts which persisted, otherwise unaltered, only above the level of transection. Lesions encroaching upon the anterior diencephalon, on the other hand, led to varying degrees of slowing down of the “hatch rhythm.” Continuous electrical stimulation of peripheral nerves evoked typical bursts of hatching movements in chicks prevented from emerging from the egg, at intervals inversely related to the shock intensity employed. Apparently, the forebrain at climax need only provide a tonic excitatory outflow, with the patterning into repetitive phasic discharges being accomplished within the brainstem.
Ontogenetic aspects of central cholinergic involvement in spontaneous alternation behavior
Authors: Egger Garry J. , Livesey Peter J. , Dawson Ronald G.
Published: January 2005

Four studies are reported examining the development of spontaneous alternation behavior in rats. Spontaneous alternation was found to increase from a rate of around 20% in 15‐16 day old rats to around 90% in 100‐day olds. Increasing the length of confinement in the 1st chosen goal arm did not affect alternation rats. Spontaneous alternation could be disrupted or facilitated in mature animals by the administration of either scopolamine hydrobromide or physostigmine sulphate, drugs which had no effect on the typical alternation pattern of 16‐day olds, but appeared to begin to have an effect at around 24 days. Dose response curves revealed certain age‐dose level interactions which were consistent with the hypothesis that cholinergic inhibitory mechanisms in the brain develop gradually in the rat.
Ontogeny of “aberrant” responses in the mating pattern of male guinea pigs
Authors: Harper Lawrence V.
Published: January 2005

Analysis of the behavioral development of 64 socially‐reared guinea pigs revealed that the head‐shaking which frequently in trudes into the mating pattern of adult isolation‐reared males is a common response among young animals. The behavioral context in which young socially‐reared animals typically display head‐shaking includes the pre‐copulatory hip‐sway‐purring display and running (pursuit). The aberrant behavior of adult isolation‐reared males may stem from a post‐isolation “stimulus overload” which causes the mating pattern to get sidetracked into another pattern with which it shares common elements.
Statistical procedure in developmental studies on species with multiple offspring
Authors: Abbey Helen , Howard Evelyn
Published: January 2005

Calculations are given illustrating appropriate and inappropriate methods of statistical evaluation of data involving effects on offspring of experimental treatments given to pregnant rats. Failure to recognize the cluster effect in experiments of this nature can give rise to erroneous utilization of statistical procedure.
Ontogenesis of electroencephalographic seizure patterns in developing chick embryos during recovery from hypothermic hypoxia
Authors: Peters Joseph J. , Hilgeford Eric J. , Vonderahe Alphonse R.
Published: January 2005

Chick embryos between the 15th and 20th day of incubation were subjected to hypothermia of 20°C followed by nitrogenous hypoxia until the cerebral EEG showed no fluctuations of potential. The embryos were exposed to air 15 or 30 min later. Body temperature was raised to 30°C and maintained there for 1 hr before being raised to 36°C, during which time 2 types of seizure episodes of rhythmic waves appeared. Type I was characterized by an ontogenetically later appearance (after the 15th day), larger amplitude, spike and slow wave patterns, a frequency of .3‐3.5 Hz with the slowest in the younger embryos, and a duration of 1 to several minutes. Type II was characterized by an earlier ontogenetic appearance, small amplitude, a frequency of 1‐30 Hz, and a duration of a few seconds to several minutes. None of these seizure episodes was observed after body temperature had reached 36°C. About the 17th day of incubation, the physiological components responsible for producing EEG patterns during episodes seem to undergo an abrupt maturational change indicated by the increase in percentage of embryos undergoing Type I episodes, and by changes in frequency of waves and duration of episodes.
Effects of amphetamine on electroshock responses in developing rats
Authors: Vernadakis Antonia , Robb Douglas
Published: January 2005

Convulsive responses were studied after chronic and acute amphetamine treatment in developing rats. Under chronic treatment, 27 litters of male rats received d‐amphetamine either at 3‐6, 8‐11, or 22‐25 days after birth and the electroshock seizure threshold (EST) was studied during maturation; each litter consisted of controls and rats treated with 1, 3, or 6 mg/kg body‐weight amphetamine. Under acute treatment, groups of rats (16 per group) received amphetamine 45 min before electroshock testing at 8, 16, or 25 days after birth. The EST was significantly higher for the 1st week after treatment in rats given amphetamine (3 mg/kg) from 8‐11 days after birth; no changes were observed in the other groups tested chronically with amphetamine. The EST was lower in rats treated acutely at 8 or 16 days and higher in rats treated at 25 days. These data demonstrate that the effects of amphetamine on convulsive responses are dependent not only on the stage of central nervous system (CNS) maturation at the time of drug administration, but also on the duration of drug treatment.
The effect of monosodium glutamate on the early biochemical and behavioral development of the rat
Authors: Berry H. K. , Butcher R. E. , Elliot L. A. , Brunner R. L.
Published: January 2005

Sprague Dawley rats were given monosodium glutamate (MSG) (4 mg/g) on each of the first 10 days of life and subsequently tested in a swimming maze at 50 days. They appeared less able to learn the maze than littermate controls that had received only saline. Amino acid analyses performed on animals prepared identically but sacrificed on Day 10 showed increased levels of aspartic and glutamic acids, taurine, urea, and glutathione in the brain, liver, and blood of the MSG animals as compared to their controls. Tyrosine and histidine levels were consistently lower. These abnormalities of amino acid metabolism appear to be of sufficient magnitude to alter the structural development of the CNS. The behavioral changes observed suggest an enduring impairment of function.
Experimental maternal hyperphenylalaninemia: Biochemical effects and offspring development
Authors: Copenhaver J. H. , Carver M. J. , Schalock R. L.
Published: January 2005

Subcutaneous injections of para‐chloro‐D, L‐phenylalanine (pCl‐Phe) and phenylalanine (Phe) over the last third of pregnancy were found to produce hyperphenylalaninemic states in maternal and fetal rats. The pCl‐Phe, when administered to maternal animals alone or in conjunction with Phe, was associated with maternal muricide. The muricide was counteracted by the administration of 5‐hydroxy‐D, L‐tryptophan prior to delivery. Prolonged treatment of maternal animals with pCl‐Phe and Phe suppressed normal weight gain and resulted in smaller offspring. The elevated levels of maternal plasma Phe decreased with time, reflecting a lessening of pCl‐Phe inhibition of maternal phenylalanine hydroxylase and normal Phe clearance. Fetal plasma Phe levels mirrored those of treated maternal animals. Similarly, fetal brain Phe reflected the increase in fetal plasma Phe.
Phrenoblysis: Special brain and mind growth periods. I. Human brain and skull development
Authors: Epstein H. T.
Published: January 2005

Although gross brain properties averaged over many individuals are highly unlikely to exhibit possible special growth periods, the hypothetical spurts in brain growth can be recovered to some extent from averaged data by computing multiyear weight increments. And, since brain weight correlates very well with skull circumference, similar spurts may be found in that parameter. A review of the literature shows that, indeed, characteristic spurts in brain and skull occur, roughly, at ages 6‐8, 10‐12, 14‐17, and possibly 2‐4 yr. The spurts are, as expected, especially clear in data from longitudinal studies, although spurts are detectable in the data from every study thus far found in the literature.
Early restriction of tactile stimulation and visual functioning in the kitten
Authors: Turkewitz Gerald , Gilbert Michel , Birch Herbert G.
Published: January 2005

Twelve kittens with vibrissae clipped on the 1st day of life were compared to matched controls for the development of a preferential behavior in a visual cliff situation in an effort to examine the developmental relationship between sense systems. The kittens with reduced tactile input (vibrissae‐clipped) were found to discriminate between the “shallow” and “Sdeep” sides of the visual cliff at younger ages and with greater consistency than controls. The results for which there are alternative explanations available support the hypothesis that reduction of input in one modality reduces competition between sense systems, thereby resulting in the precocial use of another sense system.
The effect of protein malnourishment and caging on growth and behavior of laboratory mice
Authors: Goodrick Charles L.
Published: January 2005

Inbred (A/J and C57BL/6J) and hybrid mice were given access to low‐ or normal‐protein diets (4 or 26% casein) at 5 weeks of age and housed 1, 2, or 5 mice per cage. For all groups body weights of mice fed normal‐protein diets were greater for group‐caged than for isolated mice, and body weights of mice fed low‐protein diets were less for group‐caged than for isolated mice. At 15 and 16 weeks of age, mice fed low‐protein diets engaged in more exploratory behavior and were less emotional than mice fed normal‐protein diets. Mice that were group caged engaged in less exploration and were more motional than isolated mice. In addition to the major effects of caging and diet on behavior, mode of inheritance was significantly modified.
Infantile handling and sex differences in shock‐elicited aggressive responding of hooded rats
Authors: Thor Donald H. , Ghiselli William B. , Ward Thomas B.
Published: January 2005

Infantile handled (Days 1‐20) and nonhandled, male and female Long Evans hooded rats were tested at maturity (90‐100 days) over 10 daily sessions for aggressive response to footshock. Individual jump and flinch thresholds for reactivity to shock, as well as paired aggressive responding to shock, were not significantly influenced by the handling procedure, although handled females ultimately adopted higher levels of fighting than nonhandled females. Handled rats were heavier than nonhandled rats of the same sex before and after testing for social aggression. Males fought significantly more than females; the discrepancy increased with additional sessions of paired exposure to shock. Male and female fight trends over sessions were linear and positive with a greater acceleration for males. The results were interpreted as indicative of a social learning variable occurring with repeated aggressive contact and primarily affecting males.
Induced parental care in male convict cichlid fish
Authors: Krischik Vera Aber , Weber Peter G.
Published: January 2005

Three parameters of parental care were recorded for pairs of cichlid fish (Cichlasoma nigrofasciatum) caring for their own young to determine the normal parental role of the male. Nonreproductive adult males were induced to exhibit parental behavior (e.g., herding, fin‐digging, and defense of young) by daily presentation of free‐swimming conspecific young. This process of sensitization to young appears to be species‐specific in that males did not exhibit parental care toward alien (Hemichromis bimaculatus) young. Parental behavior in reproductive and nonreproductive males, as well as the implications and function of sensitization in these fish, is discussed.
Short‐term changes in incubation temperature: Behavioral and physiological effects in the chick embryo from 6 to 20 days
Authors: Oppenheim Ronald W. , Levin Hinda L.
Published: January 2005

In 3 experiments we have attempted to determine the extent to which the chick embryo is behaviorally and physiologically responsive to short term changes (.5–2 hr) in the normal ambient incubation temperature. Embryos ranging in age from 6–20 days of incubation have been examined after exposure to temperatures ranging from 30.5° to 44.4°C (normal incubator and nesting tempertures are 37–38°C). At 6, 9, and 12 days of age the heart rate and the duration of amnion contractions were significantly altered by exposure to tempertures either higher or lower than normal although overt neuromuscular activity (motility) remains unchanged. At 15 and 20 days, however, (hatching occurs on Day 21) the rate of neuromuscular activity is altered at both low and high temperatures. At 20 days, beak‐clapping, vocalization, and respiration rates also change reliably upon short‐term exposure to both high and low temperatures. The possibility is discussed that embryonic responsiveness to temperature changes in the environment during natural incubation may play some role in later behavioral capabilities.
Effects of early experience and dexamethasone on adrenocortical reactivity
Authors: Grota Lee J.
Published: January 2005

This investigation tested the hypothesis that changes in circulating adrenocortical hormones mediate the long term effects of shocking infant rats. Dexamethasone administered through the mothers' milk was used to block adrenocortical responses to peripheral shock stimulation by the young. Control experiments indicated that the dexamethasone was present in the pups as early as 2 days after the mothers began drinking water containing dexamethasone. Shock reduced adrenocortical reactivity under conditions where the mother and the young were capable of an adrenocortical response to the shock, where either the mother or the young could have a response, and where neither the mother nor the young could have an adrenocortical response to this early stimulation. These data do not support the hypothesis that a pituitary‐adrenocortical response of either the mother or the young mediates the effects of stimulation in infancy on subsequent adrenocortical reactivity.
Adaptation to novel environments by the rat: Effects of age, stimulus intensity, group testing, and temperature
Authors: Goodrick Charles L.
Published: January 2005

Adaptation of operant bar pressing in a dark 2‐bar test box was determined during 2‐hr tests for singly tested rats 16–18, 24–32, 120–150, and 750–800 days old. Rats 16–18 days old failed to adapt during the test, although all other age groups did. Adaptation occurred more slowly for the 120–150 day‐old group than for the remaining 2 age groups. Experiments with the 2 youngest groups showed that bright light lowered response levels of both age groups, compared with controls, but failed to alter the course of adaptation. In contrast, group testing resulted in lowered response levels and faster adaptation for 16–18 day‐old rats, but higher response levels for 24–32 day‐old rats compared with singly tested controls. High temperature (32.5°C) resulted in adaptation for the 2 younger groups. The failure of 16–18 day‐old rats to adapt may have been due to lower body temperature while in the test chamber than while in the home cage nest area.
Learning deficits in rats with malnourished grandmothers
Authors: Bresler David E. , Ellison Gaylord , Zamenhof Stephen
Published: January 2005

Female rats (F0) were maintained on a protein‐restricted or a normal diet 1 month prior to mating and throughout pregnancy. Their female offspring (F1) were maintained on a normal protein diet and mated with normal males. In previously reported studies, the 2nd generation offspring (F2) of the malnourished rats have been found at birth to have significantly lower cerebral DNA (a measure of cell number), cerebral weight, and cerebral protein than normal controls. We now report that these F2 animals show marked learning deficits at maturity on 2 different successive reversal tasks, even though they themselves have never directly experienced malnutrition. Thus, certain behavioral as well as biochemical effects of malnutrition appear in the next generation of animals.
Experimental studies of the ontogeny of ultrasonic vocalizations in bats
Authors: Gould Edwin
Published: January 2005

The ontogeny of FM pulses emitted by bats is a process of maturation that is not easily altered by experimental manipulation during early development. Infants that were hand‐raised and infants that were raised by mothers with altered voices (the superior laryngeal nerves were cauterized pre‐ and postpartum) emitted normal adult calls. Effects of pinching the superior laryngeal nerves of young bats with a cold forceps on their vocalizations suggest that the development of this nerve and its associated musculature occurs early in the bat's postnatal life.
Behavioral and hormonal effects of attachment object separation in surrogate‐peer‐reared and mother‐reared infant rhesus monkeys
Authors: Meyer Jerrold S. , Novak Melinda A. , Bowman Robert E. , Harlow Harry F.
Published: January 2005

Mother‐reared and surrogate‐peer‐reared rhesus monkeys were separated from their respective attachment objects at 6 months of age and tested for the following 9 weeks to determine their home cage behavior and their pituitary‐adrenocortical responses to stress. Both groups displayed a strong immediate behavioral response to separation which was characterized by increases vocalization, increased locomotion, and decreased self‐play. However, the surrogate‐peer‐reared infants showed a subsequent recovery in their levels of self‐play whereas the mother‐reared infants instead developed stereotypic behavior patterns such as repetitive pacing. The 2 groups displayed similar plasma cortisol responses to weekly sessions in an apparatus equipped with animated toy “monsters.” Mother‐reared but not surrogate‐peer‐reared subjects, however, also manifested elevated cortisol levels when an animal in an adjacent cage was captured and removed for stress testing. Mother‐reared infant monkeys thus responded in a stronger and more prolonged manner to the loss of their attachment object than surrogate‐peer‐reared infants. These results suggest that infant rhesus monkeys form stronger attachments to monkey mothers than to inanimate surrogate mothers, a phenomenon which has not been as clearly demonstrated using other indices of attachment strength.
Effect of undernutrition on metabolic compartmentation of glutamate and on the incorporation of [14C] leucine into protein in the developing rat brain
Authors: Patel A. J. , Atkinson D. J. , Balázs R.
Published: January 2005

The effect of undernutrition on the rate of protein synthesis and the development of metabolic compartmentation of glutamate in the brain was investigated by using [U –14C] leucine as precursor. In the brain of normal rats the incorporation rate of [14C] leucine into protein was at a maximum during the 3rd week after birth, but in the undernourished animal this rate was markedly lower. The biochemical maturation of the brain, followed in terms of the age‐dependent increase in the glutamine/glutamate specific radioactivity ratio, was severly retarded in the undernourished animals, mainly as a result of a marked depression in the conversion of leucine carbon into glutamine. However these biochemical effects of undernutrition were reversible: on rehabilitation from Day 21–35 the rate of conversion of leucine carbon, both into proteins and glutamate and glutamine, was restored to normal.
Development of visually evoked responses and visually guided behavior in kittens: Effects of superior colliculus and lateral geniculate lesions
Authors: Atwell Constance W. , Lindsley Donald B.
Published: January 2005

The development of visually evoked responses (VER's) and visually guided behavior was studied in kittens for 3 months after unilateral lesions of the superior colliculus (SC) or lateral geniculate nucleus (LGN) made at an early age. Of 37 kittens studied, data are presented for 6 which met 3 criteria: survival to at least 90 days of age; adequate lesion size and location; and technically satisfactory VER's and behavioral observations at appropriate intervals. The SC and LGN lesions markedly reduced or eliminated different VER components in infancy, but only the effects of LGN lesions persisted to 3 months of age. Visual field behavior deficits occurred following both types of lesions, but only those following SC lesions persisted to 3 months of age. These results are interpreted in terms of the functional status of the structures mediating the VER's and behavior at the time the lesions were made.
The effect of chronic protein malnutrition on trans‐callosal evoked responses in the rat
Authors: Forbes William B. , Resnick Oscar , Stern Warren C. , Bronzino Joseph D. , Morgane Peter J.
Published: January 2005

Studies were carried out on the trans‐callosal evoked response in rats born of dams fed either a low (8%) or normal (25%) protein diet beginning 5 weeks prior to mating and throughout gestation and lactation. After weaning, pups were fed the same diets as their mothers. Bipolar (surface vs depth) stainless steel stimulating and recording electrodes were positioned at corresponding loci in the right and left sensorimotor cortices. Trans‐callosal evoked responses were measured under urethane anesthesia using twice‐threshold bipolar pulses of .1 msec duration at ages 13, 21, and 60–66 days. Evoked response latency was significantly greater in malnourished animals at 13 days of age, whereas at adulthood no latency differences were seen. Poststimulation excitability (15–100 msec range) was not significantly affected by the dietary treatment. These results are interpreted as corroborating previous reports on rats undernourished during development using sensory evoked potentials. By avoiding the use of extrinsic sensory stimulation, the present study demonstrates a dietary effect upon ontogeny of cortical evoked potentials independent of any possible effect on sensory receptor mechanisms.
Effects of testing age and fostering experience on seizure susceptibility of rats treated prenatally with chlorpromazine
Authors: Golub Mari , Kornetsky Conan
Published: January 2005

Offspring of rats treated with 2 mg/kg body weight chlorpromazine (CPZ) on Days 5–8 of gestation had lower seizure thresholds than offspring of saline‐treated controls at 30, 60, 90, and 120 days of age. The CPZ‐treated offspring were also heavier than controls prior to weaning. Further analysis using cross‐fostered litters indicated that at least part of the drug effect on seizure thresholds took place before birth, although a postnatal component was also demonstrated. A striking effect of the fostering experience itself on the seizure threshold prevented conclusions about the relative importance of prenatal and postnatal influences.
Perinatal hypothyroidism in rats: Persistent motivational and metabolic effects
Authors: Davenport John W. , Hennies Richard S.
Published: January 2005

Five groups of female rats which were exposed to thiouracil for varying periods around the time of birth were compared with a 6th group of untreated controls in motivational, metabolic, and hormonal test situations during adolescence and adulthood. The thiouracil‐treated rats displayed reduced fearfulness in lever‐touching and lever‐pressing tasks in operant conditioning chambers and in their initial adaptation to activity‐wheel and maze apparatuses. These rats also showed hyperactivity in asymptotic running‐wheel performance, increased spontaneous recovery of extinguished lever‐pressing, and elevated responding in lever‐pressing for variable‐interval food reinforcement. A supplemental study revealed significantly greater ad libitum food and water intake and oxygen consumption in male thiouracil‐treated rats and elevated serum thyroxine levels in thioracil‐treated females. In general the results indicate that perinatal thyroid deficiency engenders a chronic hypermetabolic state in both sexes which may be associated with a persistent, mild hyperthyroid condition in the case of female rats.
Selective responding by recently separated juvenile rhesus monkeys to the calls of their mothers
Authors: Hansen Ernst W.
Published: January 2005

Four juvenile rhesus monkeys responded to the coo‐type vocalization of their respective mothers by increasing dramatically their own vocalization rate and their locomotor activities. The juveniles appeared quite disturbed when they heard their mothers voices and this disturbance was, with one exception, apparently specific to their own mothers.
Early behavioral differences: Gender or circumcision?
Authors: Richards M. P. M. , Bernal J. F. , Brackbill Yvonne
Published: January 2005

In human studies, the possible long‐term effects on behavior of early physical insult or pharmacological agents have received little attention. We present both circumstantial and direct evidence that circumcision of male infants leads to behavioral changes. In some American studies using circumcised infants, reported gender differences may instead be the result of the altered behavior of circumcised males. We suggest that circumcision requires more study in its own right, and that it requires description if not control in all neonatal and infancy studies.
Acquisition and retention of habituation in the preweanling rat
Authors: File Sandra E. , Scott Elizabeth M.
Published: January 2005

The acquisition and retention of habituation to air‐puff was studied in rats on Days 1‐19 postpartum. Animals of all ages demonstrated habituation but the rate of habituation varied with age: slower on each successive day from Day 1 to Day 8, but thereafter more rapid on each successive day. This peak of elicited responding is discussed in relation to the peak of spontaneous activity at Day 16 and to the pattern of neural development, including changes in acetylcholinesterase, norepinephrine, and serotonin, measured during the preweaning period. All ages showed 30‐min retention of habituation, with 60‐min retention developing after the 1st week. No evidence of 24‐hr retention appeared at any age.
Modality differences in the habituation and dishabituation of cardiac responsiveness in the human newborn
Authors: Moreau Tina
Published: January 2005

The relative efficacy of (1) repeated auditory and somesthetic stimulation for the habituation of cardiac acceleration responses and (2) intramodal and cross‐modal stimulation for the dishabituation of cardiac responses was studied in 45 full‐term 2‐day‐old infants. Although the 2 stimuli were equally effective initially, repeated presentation of the somesthetic stimulus had a greater decremental effect than repeated presentation of the auditory stimulus. The stimuli were equally effective in producing dishabituation when in a different modality from that of the habituating stimulus (cross‐modal) but not when in the same modality (intramodal). Changes in the locus of stimulation without a change in modality were ineffective for producing dishabituation. The findings indicate the human newborn discriminates auditory and somesthetic inputs effectively and equally but does not discriminate contralateral from ipsilateral stimulation in either modality.
Puberal status and sex differences: Activity and maze behavior in rats
Authors: Krasnoff Alan , Weston Louise M.
Published: January 2005

This study assessed sex differences in spontaneous wheel running and maze performance in relation to puberal status in rats. No sex differences were found prepuberally in either task whereas, postpuberally, females exceeded males in wheel running and males made fewer maze errors than females. Postpuberal males and females were less active than independent groups of prepuberal males and females, respectively. Although mature females made more errors than prepuberal females, no differences were found between independent groups of pre‐ and postpuberal males.
The effects of prenatal and postnatal protein malnutrition on physical and motor development of the rat
Authors: Sykes S. E. , Cheyne J. A.
Published: January 2005

The effects of protein malnutrition in the early stages of mammalian life have been found to be pervasive and frequently very persistent. We conducted this experiment to investigate the relative effects of protein deficiency during prenatal and/or postnatal (preweaning) stages of development in order to evaluate the effects of the timing of protein malnutrition and its duration and found significant deficits on a variety of measures of physical and motor development. Animals maintained on low protein diets both prenatally and postnatally showed the greatest developmental deficits whereas animals maintained on low protein diets either prenatally or postnatally were developmentally intermediate relative to animals maintained on normals diets.
The stability and interrelationships of newborn sucking and heart rate
Authors: Lipsitt Lewis P. , Reilly Bernice M. , Butcher Marian J. , Greenwood Martha M.
Published: January 2005

The sucking behavior of 44 newborns was recorded along with heart rate (HR) and respiration. These 3 systems showed stability over a 24‐hr period. Sucking parameters varied markedly depending upon whether the infant was sucking for sucrose or under a no‐fluid condition. Moreover, HR was strikingly affected by sweetness. The direction of HR change was toward increasing rates when sucking for sweet, even though sucking for sweet substances occurs more slowly than for no fluid.
Behavioral development in three hamster species
Authors: Daly Martin
Published: January 2005

The preweaning behavioral development was compared in 3 hamster species: the golden (Mesocricetus auratus), Chinese (Cricetulus griseus), and Djungarian (Phodopus sungorus). Differences in the age of appearance of action patterns could not be summarized by simply ranking species on either precocity or developmental speed, nor were they eliminated by measuring age from conception. Problems in the interpretation of species differences in the age of appearance of action patterns are discussed.
Escape learning in infant mice as a function of drive level and drive shifts during acquisition
Authors: Nagy Z. Michael
Published: January 2005

Separate groups of 9‐day‐old Swiss‐Webster mice began straight‐alley escape training at .1 or .4 mA. After 12 trials, half of the mice in each group were shifted to .4 or .1 mA, respectively, whereas the remaining half continued at their orginal level for an additional 12 trials. Twenty‐four hours later, half of each of the 4 shock‐level groups were retested at .1 mA, half at .4 mA. The result indicated that those groups which made a large number of competing responses during early trials and showed a gradual reduction over training trials (.1‐.1 and .1‐.4) emitted the fewest number during retest at either shock level. In contrast, those groups with either limited (.4‐.1) or no (.4‐.4) opportunity to decrease competing responses during training showed evidence of poor (.4‐.1) and no (.4‐.4) retention of learned inhibition of that response. Running speed was clearly a performance measure, as it only reflected existing shock levels during both training and retention trials.
Effect of postnatal dietary protein and energy restriction on exploratory behavior in young pigs
Authors: Barnes Richard H. , Levitsky David A. , Pond Wilson G. , Moore Ulric
Published: January 2005

Three‐week‐old pigs were subjected to dietary energy or protein restriction so as to prevent weight gain over a period of 8 weeks. During the last week of restriction their responses to a novel object introduced into an exploratory test situation were measured. The malnourished pigs exhibited indifference to the object, taking longer to make contact with it, spending less time playing with it, but not showing evidence of fear or avoidance of the object or the area in which it was located. Following 6 weeks of nutritional rehabilitation, the previously malnourished pigs again displayed less approach behavior to the novel object than controls, but the effect was substantially reduced. These observations are interpreted to support our hypothesis that a major mechanism through which early malnutrition produces long‐term effects on behavior is by disturbing those behaviors required for gathering information from the environment.
Hypothermia causes adult‐like retention deficits of prior learning in infant mice
Authors: Nagy Z. Michael , Anderson James A. , Mazzaferri Timothy A.
Published: January 2005

Nine‐day‐old S‐W mice receiving deep body hypothermia or hyperthermia immediately after escape training were retested 1 or 24 hr later. Results indicated that hypothermia impaired 24‐hr retention but had no effect upon 1‐hr memory. Hyperthermia had no effect, with the mice demonstrating retention of the escape response at both retest intervals. In Experiment 2, administration of hypothermia or hyperthermia 23 hr after original training had no effect upon memory nor did either treatment produce motoric deficits upon retest 1 hr following thermal exposure. Experiment 3 indicated that hypothermia administered immediately after training produced retention deficits directly related to amount of body temperature reduction following hypothermia. These data are similar to those obtained with adult mice and suggest that memory processess occurring in 9‐day‐old mice may represent the onset of functioning of processes underlying adult long‐term memory.
Growth in the hubbard broiler: Increased size following early handling
Authors: Thompson Carl I.
Published: January 2005

Hubbard cockerels, 1 day of age (n=91) were divided into 3 handling groups: (1) chicks from the 5‐Day group were removed from the brooder and isolated at 22°C for 3 min on each of the first 5 days; (2) chicks from the 15‐Day group received this treatment for 15 days; and (3) Control chicks were not handled. Within each group half were fed broiler starter for 5 weeks, and half were fed layer starter which produces slower growth. On Days 28, 35, 42, and 49 the average weight of 5‐Day birds was significantly higher than that of Controls; 15‐Day birds weighed slightly less than birds in the 5‐Day group. The weight advantage of the 5‐Day birds occurred with both starter rations, at all weighing periods, and did not appear to reflect increased food consumption. Similarities between these findings and results obtained with rodents were noted.
Visual evoked response (VER) changes during maturation in the weddell seal
Authors: Gruenau Steven P. , Shurley Jay T.
Published: January 2005

Visual evoked responses (VER's) were recorded from the cortex of immature Weddell seals, 3‐365 days of age. Results indicated a high degree of maturity at birth evident from the multiphasic array of waveforms and the comparatively short onset latency of the VER. At low flash intensities, single flashes evoked an immature secondary response. Topographical distribution of VER's were confined largely to the gyrus immediately adjacent to midline, from the posterior aspect near lambda to the vertex. Recordings from CI‐744 dosed seals displayed a well‐demarcated developmental sequence of VER's, contrary to VER's recorded in flaxedilized seals. Onset latency and waveform configuration changed concomitantly as a function of age. During the postnatal period from birth to weaning, VER changes were related to major behavioral events such as the seal's first encounter with swimming and diving at 2 weeks of age and weaning at 6 weeks of age.
Exploration and play with objects in domestic kittens
Authors: West Meredith J.
Published: January 2005

The responses of 12 kittens to unfamiliar and familiar objects was tested. Four categories of behavior were measured: exploration, play‐exploration, play, and non‐manipulatory contact. The results indicated that exploration and play‐exploration were used for longer durations with unfamiliar objects and play was used for longer durations with familiar objects. Rank‐order correlations between the measures showed that objects explored were not correlated with objects played with or play‐explored. Analysis of the ranking revealed that small size and mobility were important object properties of play. The results suggest that exploration involves learning about stimulus properties, play‐exploration involves learning about perceptual‐motor properties, and play involves learning to coordinate movements with those of moving objects.
Development of dustbathing components in Bobwhite and Japanese quail
Authors: Borchelt Peter L.
Published: January 2005

The development of dustbathing components was investigated in Bobwhite and Japanese quail. The incidence and frequencies of components for both species increased with age, but dustbathing occurred earlier in Japanese quail. The dust toss, head rub, and side rub components invariably developed in the same order they occur during an adult bout. The topographies of many components changed systematically with a „rudimentary”︁ form preceding the typical adult form. Large individual differences were observed in the development of the temporal relations among components, but these differences were unrelated to the relative frequencies of components.
A critical period for social isolation in the rat
Authors: Einon Dorothy F. , Morgan M. J.
Published: January 2005

Rats housed in social isolation show heightened levels of object‐contact in an open‐field and are slower than socially‐housed controls to emerge from a small enclosure into an unfamiliar environment. Isolation between 25 and 45 days of age produced an irreversible effect upon object contact but had no lasting effect if between 16 and 25 days or after 45 days. In contrast to object contact, emergence was affected by isolation at any age and the effect was reversed by subsequent social housing. Thus the effects of isolation upon object contact and upon emergence apparently do not depend upon a single underlying variable.
Visual stimulation and wake‐sleep behavior in human neonates
Authors: Boismier James D.
Published: January 2005

Sixteen male and 16 female infants were exposed to 1 of 4 visual stimulus conditions during pre‐ and postprandial wakefulness. Whereas a nonpatterned gray stimulus minimized the amount of alert inactivity and maximized the amount of subsequent rapid eye movement (REM) sleep, black‐and‐white checkerboard patterned stimuli produced greater amounts of alert inactivity and correspondingly lesser amounts of subsequent REM sleep. Amounts of alert inactivity and of subsequent REM sleep produced by the checkerboard patterns depended upon pattern size, infant gender, and stimulus presentation strategy. Inversely correlated stimulus control of wakefulness and subsequent REM sleep was proposed as the functional basis of the inversely correlated ontogenesis of wakefulness and REM sleep.