bluuebunny/crossref_metadata_2025 huggingface dataset:
The development of Na+‐dependent binding of γ‐aminobutyric acid to particles of rat brain
Authors: Defeudis F. V.
Published: January 2005

The Na+‐dependent binding of γ‐aminobutyric acid (GABA) in rat cerebral hemispheres was studied by subcellular fractionation and double‐labelling procedures. The distributions of tracer amounts of [2,3‐3H] GABA and [U‐14C] surcrose acquired by P1 (crude nuclear) and P2 (synaptosomal, mitochondrial) particles during homogenization at O° C were compared in the presence of 40 mM Na+ and in the absence of added Na+. Results indicated that addition of Na+ to the homogenizing fluid promotes extra binding of GABA to both P1 and P2 particles and that these processes are age‐dependent, but different. GABA binding to P1 particles increased with age until 21‐22 days after which it remained rather constant. On the other hand, a more dramatic developmental change occurred in the binding of GABA to P2 fractions (which contain the majority of the nerve endings) which was maximal in the brains of rats 11 and 15 days old and which declined in older rats.
Effects of preweaning stimulation on the GABA production in rat cortex
Authors: Fulker D. W. , Rick J. T.
Published: January 2005

The effects of infantile Stimulation × Genotype interaction on GABA production in rat cortex were investigated using an 8 × 8 diallel cross. Stimulation reversed the direction of dominance and epistasis typical of unstimulated controls, suggesting that a homeostatic genetic system has evolved in the rat ensuring an intermediate, optimal level of GABA production.
The development of visual flicker rate preference in the newly hatched chick
Authors: Simner Marvin L.
Published: January 2005

The approach‐generating properties associated with intermittent white light favoring 4 flashes/sec over adjacent rates of flicker, become evident between 512 and 530 hr after the onset of incubation independent of hatch time. The appearance of these properties can be attributed largely to the decline in approach elicited by nonflashing white light during this period rather than to a change in attractiveness associated with the 4 flash/sec rate itself.
Protein deficiency and performance of pigeons on a multiple schedule of reinforcement
Authors: Brown William G. , Mostofsky David I. , Warren Sue Allen
Published: January 2005

Pigeons reared from 2 pairs of healthy pigeons were fed on diets of either adequate (18%), medium (11%), or low (8%) protein for the first 30 days of life. The subjects were then placed on the 18% diet from 30 days of age until training and testing which was begun at 60 ± 3 days of age. Performance on a MULT FR30 FI60 was evaluated and the differences in the time necessary for the medium and low groups to stabilize were found to be statistically significant. Massed extinction trials to the FI were then begun followed by a schedule of MULT FR EXT. Differences between the adequate and inadequate protein groups were again found in both conditions. Other qualitative differences were found among the goups which suggested an analog of emotional lability and retardation.
Ultrasounds in small rodents: Arousal‐produced and arousal‐producing
Authors: Bell Robert W.
Published: January 2005

Recent interpretations of ultrasonic signaling by infant and adult rodents have emphasized the quality of the eliciting stimuli and acoustical parameters of the vocalizations. Infant calls have been hypothesized as being of 2 types: coldelicited and tactually elicited. Adult calls have been hypothesized as reflecting 2 distinct messages: aggressiveness and submission. These interpretations lack an adequate empirical foundation. Further, they suppose a capability of encoding and decoding vocal information by rodents for which no empirically established basis exists. An alternative explanation of both infantile and adult ultrasounds is offered. The proposed model hypothesizes that these vocalizations reflect a state of arousal and that they produce a similar state in nearby animals.
Developmental changes in tonic immobility in young chicks (Gallus gallus)
Authors: Rovee Carolyn Kent , Kleinman Joel M.
Published: January 2005

Tonic immobility (TI) was induced by means of ventral restraint in White Leghorn chicks within 12‐hr posthatch (Day 0) and, in independent groups, on succeeding days through Day 10. Durations of immobility and eye closure increased and incidence of immobility termination and vocalization decreased significantly with age. Marked qualitative changes in immobility reactions were also apparent over the first few posthatch days.
Effects of early handling on avoidance performance of Maudsley MR and MNR strains
Authors: Powell Barbara J. , North‐Jones Margaret
Published: January 2005

This study investigated the effect of infantile handling on the emotionality and avoidance performance of the Maudsley reactive (MR) and nonreactive (MNR) strains of rats. The expected difference in emotionality was found (MR's had higher defecation scores than MNR's); however, this difference was unaffected by early handling. The avoidance behavior of the 2 strains was different in that MR's had shorter escape latencies; however, they did not differ with respect to CAR's. Handling had a significant effect on avoidance behavior, but this was not greater in one strain than another. The interaction of genetic differences and infantile stimulation on avoidance performance does not appear to be supported in females from these 2 strains.
Sexual maturation of female house mice: Social inhibition
Authors: Drickamer Lee C.
Published: January 2005

Young female laboratory mice reared in the presence of an adult male mouse or male bedding containing a pheromone reach sexual maturity earlier than control females. A pheromone produced by grouped female mice leads to long, irregular estrous cycles or anestrus. The present study demonstrated that a female‐produced pheromone delays sexual maturation when females are grouped and that free social interaction and tactile contact among the grouped females are necessary for the production of this inhibitory pheromone. Both young and adult females caged in groups produced the inhibitory pheromone. This study provided additional support for the hypothesis that in female mice morphological and sexual development are under separate control mechanisms. Two pheromones may be active in reproductive processes of female mice: one exhibiting inhibitory effects and the other acceleratory effects.
Protein deprivation in primates. II. Effects of fondling on feeding behavior of discomforted infant rhesus monkeys
Authors: Hillman Nancy M. , Fuselier Penelope H. , Riopelle Arthur J.
Published: January 2005

Infant rhesus monkeys whose mothers were fed diets providing 1, 2, or 4 g protein/kg body weight/day during pregnancy were fondled for 5 min before their noon and 1600 hour feedings on 2‐3 weekdays weekly. Fourteen were caressed between 10 and 30 days of age; 18 between 41 and 95 days of age. The intake at meals following handling was compared to that for meals when handling was not given. The younger animals' intake was specific to the diet group and treatment. The older animals ate more at the 1600 hour meal than at the noon meal and more at weekday, nonhandled feedings than at weekday, handled or weekend feedings. Differences due to maternal nutritional history were not significant. Infant monkeys subjected to a variety of laboratory anxiety‐producing tests during weekdays drank more formula on test days than on tranquil weekends. This effect was ameliorated by preprandial comforting.
Development of adult‐young identification in Richardson's ground squirrel
Authors: Michener Gail R.
Published: January 2005

Adult female Richardson's ground squirrels were paired in an observation box with their own young and with unrelated young aged 20‐24 days through 40‐44 days. Social discrimination was characterized by a predominance of cohesive over agonistic contacts between related pairs, and a predominance of agonistic over cohesive contacts between unrelated pairs. Both adults and young were capable of identifying the other animal as familiar or unfamiliar. Adults did not pick up or carry young aged over 29 days. Young that were not carried could identify adults at 20‐24 days of age when the eyes were still closed. They responded cohesively with the mother and submissively with the unrelated adult. This pattern of behavior was maintained after the eyes opened. Adults initiated fewer contacts than young; the majority of their responses involved nasal investigation of the young.
The effects of neonatal tactile stimulation on adult emotional reactivity in BALB/c mice
Authors: LaBarba Richard C. , Fernandez Betty , White Jerry L. , Stewart Allan
Published: January 2005

The authors attempted to isolate tactile stimulation as a major independent variable treatment and to investigate the effects of 2 levels of neonatal tactile stimulation on the ontogenesis of emotional reactivity in BALB/c mice. The findings of this study strongly indicate differential reactivity as a function of intensity of tactile stimulation, with moderate levels of intensity producing the lowest levels of emotionality and the highest levels producing the highest emotionality.
Prepartum suckling reduces survival of newborn in the rat
Authors: Sachs Benjamin D. , Rosenblatt Jay S.
Published: January 2005

Pregnant female rats were induced to show maternal behavior by continuous exposure to 5‐10 day old pups. Prepartum suckling continuing into the immediate postpartum period (when the new litter was present) resulted in a high rate of mortality among the newborn. Preventing suckling by the older pups by sealing their mouths with collodion or removing them within 17 hr before parturition restored the normal low rate of pup mortality. Examination showed that pre‐ and early postpartum suckling by the older pups had damaged the mother's nipples preventing the delivery of milk to the newborn. Presumably, the mother's nipples are hormonally conditioned to respond to the sucking of newborn at parturition and become gradually adapted to the increased suckling strength of older pups as nursing proceeds.
Spatial and tactile discrimination learning in infant rats motivated by homing
Authors: Bulut Fatma G. , Altman Joseph
Published: January 2005

Rats 6, 10, and 15 days of age were tested on acquisition and reversal of position and tactile discrimination tasks in a 2‐choice situation using access to the home cage as reinforcement. In the early trials the 6‐day group often failed to respond due to locomotor immaturity. But, despite the missed opportunities, they mastered the position habit in about the same number of choice trials as the 10‐day group. However, the 15‐day group was superior to the 2 younger groups. In tactile discrimination these subgroups differed significantly in learning to select the rough or smooth surfaces both in acquisition and reversal. On both the spatial and the tactile discrimination tasks the animals older than 2 weeks showed improvement in learning ability.
EEG's of prematures: 3–8 year follow‐up study
Authors: Ellingson Robert J. , Dutch Stephen J. , McIntire Matilda S.
Published: January 2005

A classification of apparently normal neonatal EEG's into 4 classes (A‐D) on the basis of progressive maturity was devised and applied to 273 EEG's of 117 apparently normal newborns recorded between 24 and 50 weeks conceptional age (CA). Both the order in which the 4 classes of EEG's occurred for subjects upon whom more than 1 EEG was obtained, and the distributions of the ages over which the 4 classes were observed confirmed that the classes do indeed represent a maturational sequence of EEG pattern changes. Of the 81 original premature subjects, 46 underwent comprehensive clinical evaluation between 3 yr 9 months and 8 yr 7 months of age. Various features of their neonatal EEG's were evaluated in the light of clinical outcome. The results do not demonstrate the usefulness of the routine EEG as a prognostic indicator in neonates not displaying specific pathology at birth. They do offer some evidence of a relationship between immaturity of the EEG relative to CA in the neonatal period and the later manifestation of congenital disorders involving the brain, but the tendency, even if confirmed, may not prove strong enough to warrant prognostic decisions in individuals.
Protein composition in developing human brain myelin
Authors: Banik N. L. , Davison A. N. , Ramsey R. B. , Scott T.
Published: January 2005

Accumulation of protein and adenosine 2',3'‐cyclic phosphohydrolase activity have been found to increase with age in myelin isolated from human subjects. Notable alterations in the quantitative distribution of myelin proteins separated by disc polyacrylamide gel electrophoresis were seen in development. Proteolipid protein was found in myelin before the appearance of basic encephalitogenic protein. A myelin‐like fraction was also isolated from developing human brain. These chemical observations were correlated with ultrastructural changes in the isolated myelin during development.
Long term changes in nest condition and pup grouping following handling of rat litters
Authors: Lee M. H. S. , Williams D. I.
Published: January 2005

Observation of rat litters over the entire preweaning period revealed long term changes to result from handling pups. Handled litters had fewer good nests and were less likely to be found in a single group than control litters. These differences are not attributable to the disturbance per se, as litters where the mother was removed did not differ significantly from undisturbed controls. The differences occurred predominantly in the daytime when maternal activity was at its lowest.
Discrepancy from rearing conditions affects chicks' behavior in a novel situation
Authors: Brown Robert T.
Published: January 2005

Chicks raised in small or large cages were exposed to a relatively large novel situation at 12 or 24 hr of age. At both ages, chicks from small cages had longer latencies to begin moving and lower activity scores. Age itself had no effect. Apparently, chicks learn the characteristics of their home cage shortly after hatching, and discrepancy from the home affects their response to novel situations.
Effects of maternal mobility on the development of rocking and other behaviors in rhesus monkeys: A study with artificial mothers
Authors: Mason William A. , Berkson Gershon
Published: January 2005

Mechanically driven mobile artificial mothers effectively prevented the development of stereotyped body‐rocking in rhesus monkeys. Monkeys were maternally separated at birth and assigned to 2 groups. Both groups were placed with surrogates, identical in construction except that for 1 group the surrogate was in motion 50% of the time from 0500 hours to 2400 hours each day, and for the other group the surrogate was stationary. All but 1 of the 10 monkeys raised with stationary artificial mothers developed rocking as an habitual pattern whereas none of the 9 monkeys raised with mobile mothers did so. The data also suggest that emotional responsiveness was reduced in monkeys raised with mobile mothers, compared to monkeys raised with stationary devices.
Neonatal locomotor and long‐term behavioral effects of d‐amphetamine in the rat
Authors: Sobrian Sonya K. , Weltman Mardi , Pappas Bruce A.
Published: January 2005

Locomotor activity in the neonatal rat was found to increase from birth until the beginning of the 3rd week of life, at which time it peaked and then subsequently declined. Subcutaneous injections of both .25 and 2.0 mg/kg of d‐amphetamine increased activity in rats 1–21 days of age, with the maximum effect observed at 4 days of age. No tolerance to d‐amphetamine was observed after 6 daily injections beginning at 1, 7, or 14 days of age. The decline in the excitatory effects of the drug thus reflected maturational changes in response to it. Consistent with other observations from this laboratory, no persisting effects of the neonatal drug treatment was observed on adult 2‐way avoidance learning.
Responses of human‐reared monkeys to strange simian calls
Authors: Waldrop Marjorie K.
Published: January 2005

The responses of 16 young (10–12 month and 19–20 month) hand‐reared rhesus monkeys to rhesus vocalizations heard for the first time were recorded. The vocal stimuli were: (1) a “clear call” of a noncolony adult; (2) a “bark” of a noncolony adult; (3) a “bark” of a noncolony juvenile; and (4) a “bark” of a colony juvenile. Behavior was video‐tape recorded for 5‐min periods preceding and following the calls and scored according to standard categories. The characteristic response to the stimuli was a sharp reduction in overt behavior. Reaction to the adult sounds was greater than to the juvenile sounds.
Effects of phenobarbital given to pregnant mice on behavior of mature offspring
Authors: Middaugh Lawrence D. , Santos Carroll A. , Zemp John W.
Published: January 2005

Mature offspring of C57BL/6J mice (Mus musculus) injected daily with phenobarbital (40 mg/kg) for the last third of pregnancy differed from saline and untreated control animals on 3 measures of behavior. Offspring of phenobarbital treated animals had higher locomotor scores than controls during an open field activity test at 75 days of age. Male offspring were also tested on a 1‐trial passive avoidance task and treated animals were found to be deficient. Finally, female offspring responded less than controls on fixed ratio schedules of reinforcement. The behavioral changes suggest that offspring of mice injected with phenobarbital during pregnancy are less responsive to the stimuli in their environment which maintain behavior.
A comparison of live and videorecord viewing of infant behavior under sound stimulation. II. Six‐week‐old infants
Authors: Bench John , Wilson Ian
Published: January 2005

Ten clinically normal 6‐week old infants were presented with a series of sound stimuli while their behavior was assessed live by 2 sound‐masked observers and simultaneously videorecorded. Two weeks later the same observers assessed the behavior from the videorecords. In both situations, observers were permitted to see the babies for 10 sec at each trial. The first 5 sec was a prestimulus observation period, and the second 5 sec might have contained a sound stimulus. Between trials the observers were allowed 20 sec in which to not (1) prestimulus activity, (2) confidence in response, and (3) facial, digit, and limb movements, and “wholistic” impressions (e.g., “stilling”). The agreement between the live and video situations was fair for prestimulus activity, modest for confidence in response, and fair to good for movement items. The use of videorecorded material for 6‐week old infants generally caused rather small losses of relevant information and apparently will not overly distort the findings of experimental or clinical work. This outcome was rather similar to that of our earlier study of neonates.
Genetic variation in the development of mouse brain and behavior: Evidence from the middle postnatal period
Authors: Wahlsten Douglas
Published: January 2005

Six inbred strains and 3 F2 hybrid crosses of mice were assesed for developmental status at 32 days after conception (about 13 days after birth). Phenotypes measured included body weight, brain weight, maturity of 14 reflexive behaviors, myelination of 80 fiber tracts, and thickness of the external granular layer of the cerebellum. All measures of brain and behavior showed a similar pattern of results: hybrids were generally more advanced than either of their inbred parent strains; differences among inbred strains were large, but differences among hybrid crosses were quite small. Acceleration of F2 mice compared to their homozygous relatives ranged from .5 to 2.4 days mean difference. Developmental ages of inbred litters ranged from 28.7 to 32.2 days, whereas hybrid litters ranged from 31.5 to 32.7 days.
Alterations in consummatory behavior of mice produced by dietary exposure to inorganic lead
Authors: Morrison John H. , Olton David S. , Goldberg Alan M. , Silbergeld Ellen K.
Published: January 2005

Mice suckled by mothers given tap water and by mothers given a 5 mg/ml lead acetate solution during lactation were given a choice between tap water and a lead acetate solution after lactation. All offspring demonstrated an immediate aversion to the lead acetate solution. The offspring from the mothers receiving lead acetate during lactation demonstrated a greater aversion to the lead acetate solution than did the offspring from mothers receiving tap water. In addition, the lead acetate offspring drank more total fluid (tap water plus lead acetate solution) after weaning than the control offspring. The results indicate both learned and unlearned changes in motivation for fluid following ingestion of lead via the mother's milk in infancy.
Light‐dark discrimination and reversal learning in early postnatal kittens
Authors: Rose Guenter H. , Collins Jeremiah P.
Published: January 2005

During the early postnatal period kittens were trained in a visual discrimination task involving light‐dark stimuli in order to determine the age of onset of visual control of learned behavior. A Y water maze was used with escape from water as the reinforcer. The results indicate that kittens are able to master the discrimination within the 5th week of life. The relevance of this result to electro physiological measures of maturation is discussed.
Prehatch color stimulation effects on color pecking preferences and color discrimination learning in white leghorn chicks
Authors: Fischer Gloria J. , Davis Stephen J. , Nord John A.
Published: January 2005

Four experiments assessed the effects of stimulating chick embryos with colored light at 2 intensity levels. Both posthatch color pecking preferences (Experiments 1 and 2) and color discrimination learning (Experiments 3 and 4) were unaffected. These results affirm and extend a prior finding of no pre‐ and posthatch colored light stimulation effect on posthatch color preferences in ducklings. The color pecking preferences found replicated prior findings with chicks. However, they differed from the approach color preferences observed in color discrimination learning.
The use of habituation in the study of the effects of infantile malnutrition
Authors: Lester Barry M. , Klein Robert E. , Martinez Sonia J.
Published: January 2005

Habituation of the orienting response (OR) was used to assess possible attentional deficits associated with infantile malnutrition. The procedure involved the presentation of 40 trials of a pure tone stimulus to 8 marginally nourished and 8 malnourished 13 1/2‐month‐old male infants. The results showed that the initial OR to stimulus onset, as measured by the magnitude of cardiac deceleration, was significantly larger in marginally nourished than in malnourished infants. Within‐group comparisons revealed that marginally nourished infants showed significant increases in OR magnitude to changes in tonal frequency whereas the malnourished infants did not. The results were taken as evidence of an attentional deficit associated with infantile malnutrition that is likely to interfere with subsequent learning.
The development of intersession habituation and emergence in socially reared and isolated rats
Authors: Einon Dorothy , Morgan M. J. , Sahakian B. J.
Published: January 2005

Male and female hooded rats were weaned at 17 days and then reared in isolation or in social groups. Intersession habituation of locomotor activity in the open field was tested at 15, 25, and 45 days. Contrary to some previous reports, the 15‐day‐old animals showed significant habituation. At 45 days, however, the isolates showed very little habituation compared to the social animals. The isolates showed a similar pattern of development in their emergence into the open field. Apparently, isolation does not result in an arresting of development, but rather in the formation of behavior patterns otherwise absent in normally reared rats.
Anatomical and behavioral effects of colchicine administration to rats late in utero
Authors: Petit Ted L. , Isaacson Robert L.
Published: January 2005

Offspring from pregnant rats injected with 4mg/kg body weight colchicine on Embryonic Days 18, 19, and 20 were found to have isocortical and hippocampal structures greatly reduced in mass when examined at birth. Cells with pyknotic nuclei were found in Layers 5, 4, and 3 of the cerebral isocortex, the habenula, and anterior medial nuclei of the thalamus. Brains taken at Postnatal Days 22 and 132 were reduced in overall size, and had a 20‐30% reduction of cells at the vertex of the neocortex with up to 50% reduction in the thickness of the corpus callosum. A decrease in activity, an increase in fearfulness and/or decreased tendency to explore, reduced error scores on the Hebb‐Williams maze, poor performance on the Maier elevated maze, and a lessened sensitivity to sound‐induced seizures were correlated with these anatomical changes.
Effects of differential cue availability in an active avoidance CS for young and adult rats
Authors: Brennan James F. , Barone Raymond J.
Published: January 2005

In Experiment I, groups of 22‐ and 140+ ‐day‐old rats were trained in acquisition and extinction of 1‐way avoidance with a CS that consisted of the opening of a guillotine door 5 sec before US onset or a combination of door‐opening plus a tonal signal that remained on until the occurrence of the motor response. Under both CS conditions, avoidance acquisition was similar at each age level. The extinction data indicated comparable performance for the young subjects but differential performance and greater resistance to extinction for the adult subjects. Adults trained with the door‐opening CS persisted in responding for an entire series of 100 extinction trials, whereas the adults trained with the compound CS extinguished well within the 100‐trial limit. A 2nd experiment included 10 pre‐exposures of the simple or compound CS's prior to avoidance training. Although the pups were insensitive to pre‐exposure effects, the adults that were pre‐exposed and trained with identical CS'5 showed evidence of pre‐exposure effects. Results of both experiments were interpreted as indicative of differential cue saliency between ages.
Individual consistency in behavioral states in neonates
Authors: Thoman Evelyn B. , Korner Anneliese F. , Kraemer Helena C.
Published: January 2005

In this study we identified consistent characteristics of the sleep‐wake state of newborn infants. Forty‐one normal, full‐term infants were observed in a warmer–skin temperature maintained at 36.1°C–located in a sound‐attenuated room for 1 hr during 2 successive mid‐feeding periods. The infant's state was recorded on a check‐list every 10 sec using the following categories for sleep and wakefulness: Quiet Sleep A, Quiet Sleep B, Active Sleep Without REM, Active Sleep With REM, Active Sleep With Dense REM, Drowsy, Alert Inactivity, Waking Activity, Fussing, Crying, and Indefinite State. Immediately following the completion of each observation, the 2 observers made independent judgments of the degree of organization shown by the infant, using a 6‐point scale.

Over the two 1‐hr observations, only Quiet Sleep A, Quiet Sleep B, and Crying showed any consistency. Active Sleep as typically defined showed no consistency whatsoever. However, 2 of the 3 components of Active Sleep were significantly reliable measures for the 2 observations; in sleeping infants all 3 components of active sleep showed high reliability. These results indicate that Active Sleep may be a composite of at least 3 meaningful categories.

To look at overall state organization in the neonate, including both sleep and wake states, we considered Active Sleep as 3 separate states and then combined the resulting 11 behavioral states into derived clusters such that each combination of states showed a test‐retest reliability above .52. With these 5 state clusters we viewed each infant's state behaviors in terms of a profile depicting the percent of time spent in each state cluster. We found a close association between these profiles and the subjective judgments of sleep‐wake state organization made by the observers.

The results clearly indicate that a 1‐hr observation provides reliable information on individual sleep‐wake states in the newborn.
A comparison of live and videorecord viewing of infant behavior under sound stimulation. III. Six‐month‐old babies
Authors: Bench John , Wilson Ian
Published: January 2005

Ten clinically normal 6‐month‐old infants were presented with a series of sound stimuli while their behavior was simultaneously videorecorded and assessed live by 2 sound‐masked observers. Two weeks later the same observers assessed the behavior from the videorecords. In both situations observers were permitted to see the babies for 13 sec at each trial. The first 5 sec formed a prestimulus observation period and the following 8 sec possibly contained a sound stimulus. Between trials the observers were allowed 20 sec in which to note (1) prestimulus activity, (2) confidence in response, and (3) facial, digit, and limb movements and “wholistic” impressions (e.g., “stilling”). The agreement between the live and video situations was modest for prestimulus activity and confidence in response, and fair to good for movement items. The outcome was rather similar to that of our earlier work on neonates and 6‐week infants, although it did suggest a small loss of information with the videorecording of 6‐month infants.
A longitudinal analysis of maternal aggression in Rockland‐Swiss albino mice
Authors: Svare Bruce , Gandelman Ronald
Published: January 2005

Female Rockland‐Swiss albino mice were tested for aggression during 6 successive pregnancies and lactation periods or until they ceased to re‐mate. Fighting behavior was limited only to the lactation phase of each reproductive cycle. Although most animals exhibited fighting during every lactation period they completed, some exhibited fighting in some lactation periods but not in others. The intensity of aggression, as measured by the time spent fighting, was highest during the beginning of each lactation period and declined by the end of each period. Moreover, the intensity of aggression increased across the first 3 lactation periods and then declined on later lactation periods to a point below initial levels. Finally, the fighting behavior exhibited by multiparous animals was not due simply to previous fighting experience in that some multiparous mice exhibited postpartum aggression on the 6th lactation period in the absence of fighting experience during earlier lactation periods.
Undernutrition in early life: Lasting effects on activity and social behavior of male and female rats
Authors: Whatson T. S. , Smart J. L. , Dobbing John
Published: January 2005

The growth‐retarded offspring of mother rats undernourished throughout pregnancy and lactation were fed ad libitum from weaning. Males were tested at 100 days of age, and ovariectomized females at 150 days. After 2 weeks of isolation, pairs of males consisting of 1 control C and 1 previously undernourished PU rat were observed for 10 min on each of 9 consecutive days. Similarly paired and treated female rats were tested a total of 8 times, the first 3 tests being separated from the last 5 by a 10‐day interval. The PU rats, whether male or female, performed more rearing responses and PU male rats ambulated more in the social situation than C rats. The PU males also performed more of the social responses allogroom, walk over, and mount than C males. Similarly, PU females performed more allogroom and crawl under than C females. In general, PU rats were more active than C rats and more socially responsive.
A longitudinal study of bioelectric activity in the pre‐ and post‐hatch chick
Authors: Speciale S. G. , Nowaczyk T. , Jouvet M.
Published: January 2005

A technique for embryonic implantation and the subsequent recording of electrocortical, neck muscle, and ocular activity continously from the 20th day of incubation through hatching and the first few days thereafter is demonstrated. The embryonic maturation of the EEG, with a characteristic muscle burst pattern heralding hatching was found, supporting previous reports obtained with acute preparations. The technique for injection into the chorioallantoic membrane CAM vessels or direct deposition onto the CAM is also described. The usefulness of the embryonic neurophysiological implantation coupled with the injection at specific stages of development is discussed as an approach to the understanding of the parameters of the maturation of the sleep‐wakefulness cycle, neurochemistry, and behavior.
Short exposures to enriched environments can increase genetic variability of behavior in mice
Authors: Henderson Norman D.
Published: January 2005

Previous work indicates that mice of different genotypes reared in enriched environments show differential increases in performance on a food‐seeking task. In this study 2 experiments examined the effects in selected mice strains of short exposures to such enrichment. Experiment 1 indicated that 48 hr of exposure to enriched cages was sufficient to produce results found previously when subjects were reared from birth in enriched cages. Experiment 2 indicated that as little as 6 hr of exposure to an enriched cage was sufficient to produce almost maximal enrichment effects in C57BL/10J mice.
Neonatal and adult brain parameters in mice selected for adult brain weight
Authors: Zamenhof Stephen , Van Marthens Edith
Published: January 2005

Several neonatal and adult parameters were determined in the Roderick‐Wimer lines of mice selected for low (L) or for high (Hb and Hg) adult brain weight, and in the unselected control line (C). Neonatal cerebral weight, DNA (index of cell number), and protein were significantly higher in the H and C lines than in the L line. The ratios of cerebral DNA/weight (index of cell density), cerebral protein/weight, and cerebral protein/DNA (index of protein content per cell or cell size) were at birth practically the same in all lines. In the adult animals all the differences were amplified and, in addition, some of the differences in the above ratios were significant, for the cerebral cortex as well as for the cerebellum. These findings may be causally related to the reported superiority in behavioral performance of the H line.
Increase of the corticosterone level in ducklings during the sensitive period of the following response
Authors: Weiss J. , Köhler W. , Landsberg J.‐W.
Published: January 2005

Increased fear may be one of the factors limiting the sensitive imprinting period. Thus, we analyzed corticosterone levels in 121 Peking ducklings during and after this sensitive period using the method of competitive protein binding. The data pointed to a corticosterone increase within a period of 12–28 hr after hatching as well as to the presence of a circadian rythm. The low coefficient of determination of post‐hatch age and corticosterone level (8%) pleads for a multi‐dimensional system. However, the corticosterone increase may be the basis for an increase in fear and a decrease in the likelihood of imprinting.
Acquisition and extinction of an operant response in differentially reared rats
Authors: Gluck John P. , Pearce Harold E.
Published: January 2005

Rats reared in either socially isolated or control environments were trained to bar press for food on a variable interval schedule of reinforcement, beginning at 125 days of age for 37 consecutive days. Following this phase the subjects were tested for response persistence during an extinction test. Next, the subjects were compared on measures of spontaneous recovery and the rate of response reacquisition when the reinforcement contingencies were once again reinstated. Though no differences were discerned between the groups on measures of acquisition, maintenance, and reacquisition, isolated rats emitted many more responses than the controls during extinction testing.
The cardiac self‐stimulation hypothesis and the chick's differential attraction toward intermittent sound
Authors: Simner Marvin L. , Kaplan Wendy
Published: January 2005

Two experiments were conducted to determine whether the chick's attraction toward specific rates of intermittent sound stems from long‐term prehatch exposure by the chick to its own fetal heart beat. Contrary to prediction, Experiment I showed stronger attraction toward an intermittent square wave white noise signal matched for pulse rate, overall pulse duration, and mean intensity, than the sound of the actual fetal heart beat from which this attraction is said to derive. Experiment II demonstrated that long‐term prehatch exposure to an intermittent auditory signal having a normally non‐preferred rate will not establish an attraction for that same rate after hatching unless it contains a frequency component having latent appetitive properties. Alternatives to the cardiac self‐stimulation hypothesis are discussed and, in the context of related evidence, the fetus' general capacity for exposure learning is reconsidered.
Open‐field behavior of prenatally irradiated and/or postnatally handled C57BL/6 mice
Authors: Sherrod Kathryn B. , Meier Gilbert W. , Connor William H.
Published: January 2005

Mice (C57BL/6) were prenatally irradiated with 60Co and/or handled on postnatal Days 1‐10, and subsequently tested in an open field on Days 21, 42, and 63, and in a shuttle box on Days 30 and 60. Another group of mice was treated and tested similarly, but the shuttle box testing was omitted. All animals were cross‐fostered at birth. Handling increased open‐field activity and decreased defecation whereas irradiation decreased activity and had inconsistent effects on defecation. A comparison of the data from both groups of mice indicated that the shuttle box experience decreased open‐field activity, particularly for the irradiated and unhandled animals. Direct and indirect irradiation effects‐revealed by the cross‐fostering procedure‐were both significant and about equal in magnitude, underling the importance of attending to irradiation effects on maternal as well as on offspring behavior.
Alternations in the maternal behavior of rats rearing malnourished offspring
Authors: Wiener Sandra G. , Fitzpatrick Kathleen M. , Levin Robert , Smotherman William P. , Levine Seymour
Published: January 2005

Investigations of maternal behavior of mothers fed a low‐protein diet indicated deficits in retrieval and in the rate of nest‐building. In addition, they indicated a concomitant increase in time spent with young when assessed during periods not associated with the retrieval/nest‐building test session. The adrenalectomized mother, another case that produces growth‐stunted progeny, was compared with both low‐protein and control mothers for maternal behavior. Unlike the low‐protein mother, the adrenalectomized mother did not exhibit retrieval or nest‐building deficits; however, the adrenalectomized mother did display an increase in time spent with young. These data suggest that although deficits in retrieval and nest‐building can be attributed to the nutritional condition of the mother, the stimulus characteristics of the malnourished pup are important in eliciting the increased time spent with the litter.
Ontogeny of observational learning in the dog (Canis familiaris)
Authors: Adler Leonore Loeb , Adler Helmut E.
Published: January 2005

A split‐litter technique was used to test observational learning in 4 litters of Miniature Dachshund puppies, 21, 28, 38, and 60 days old at the beginning of the experiment. In one side of a duplicate cage, one puppy of a litter, the demonstrator, learned to pull in a food cart on a runner by means of a ribbon, while another puppy, the observer, watched from an adjacent compartment, separated by a wire screen. Observational learning was demonstrated by the saving in time for the 1st trial when the observer was given the same problem to solve. Maturation, particularly the development of visual function and motor coordination, set a lower age limit for the emergence of observational learning.
Absence of self‐recognition in a monkey (Macaca fascicularis) following prolonged exposure to a mirror
Authors: Gallup Gordon G.
Published: January 2005

To date only chimpanzees, orangutans, and humans have been found capable of recognizing themselves in mirrors. In an attempt to provide a more definitive test of the capacity for self‐recognition in monkeys, I gave a preadolescent crab‐eating macaque 2400 hr of mirror exposure. However, patterns of self‐directed behavior never developed and a more explicit test of self‐recognition yielded negative results. The data indicate possible differences between great apes and monkeys in self‐awareness.
Timing of dispersal in juvenile jewel fish during development is unaffected by available space
Authors: Chen Michael J. , Coss Richard G. , Godthwaite Ronald O.
Published: January 2005

The spatial distributions of 2 groups of sibling juvenile jewel fish were examined between 58 and 99 days of age to determine the effects of spatial experience on the timing of dispersal from a more aggregative behavioral mode. One group was provided a seminatural 1000‐liter aquarium, the other with 70% less space per fish, but both groups were able to observe the same number of fish. Using a computer and digitizing tablet, distances between 1st–6th nearest neighbors were measured from time‐sampled video recordings of spatial distributions in either overhead or underneath plan views. Both groups exhibited changes in aggregative behavior that were remarkably similar. Between 65 and 92 days of age, both groups showed gradual dispersal, which accelerated abruptly at 93–99 days of age. These results suggest that the timing of dispersal is regulated by developmental processes operating independently of spatial experience.
Changes in appetitive behavior in weanling‐age rats: Transitions from suckling to feeding behavior
Authors: Stoloff Michael L. , Blass Elliott M.
Published: January 2005

To help identify determinants of rat appetitive behavior during the weanling period, rat pups 17–32 day of age were studied in a Y‐maze. One arm of the maze provided pups with the opportunity to suckle a lactating or nonlactating anesthetized female. The other arm always contained a familiar food, either liquid diet or ground laboratory chow. In some experiments the dam was separated from the food compartment by a thin gauze screen. In other tests maternal contact could be maintained in the feeding goal but suckling in that compartment was prevented by nipple involution. Age was the major determinant of choice, with more older animals choosing the food arm. Availability of maternal contact in the feeding compartment increased the percentage of rats that chose to feed by about 20% at all ages studied. Food quality, but not quantity, affected choice at each age, as did lactational status. Prior food, water, and maternal deprivation (2 or 24 hr) did not affect choice behavior at any age but did influence behavior in the goal box. These findings are discussed within the context of the changing demands faced by the rats during the weaning period.
Developmental changes in head‐circumference and mental‐performance growth rates: A test of epstein's phrenoblysis hypothesis
Authors: McCall Robert B. , Meyers Edmund D. , Hartman John , Roche Alex F.
Published: January 2005

Epstein's phrenoblysis states that brain growth and mental growth occur in correlated spurts at 3–10 months and 2–4, 6–8, 10–12 or 13, and 14–16 or 17 years of age. The present study was the first to test statistically such spurts in head‐circumference and mental‐age growth rates and to assess any correspondence in individual differences between spurts in the two variables in a single sample of children measured serially between 2.5 and 17 years of age. While the statistically significant spurts observed in each variable did fall within the hypothesized age periods, the chance rate for such theoretical concordance was high and several hypothesized spurts were not supported. Moreover, no relationship existed within individuals between head‐circumference and mental‐age growth‐rate patterns.
Dietary effects on rhesus social behavior: Altered amino acid diets
Authors: Chamove A. S.
Published: January 2005

Twenty‐one monkeys continuously fed one of five diets high in tyrosine, histidine, alanine, glycine, or tryptophan between the ages of 1 and 12 months were compared with 20 controls. Social behavior either (a) while on the diet and tested in familiar groups of four or (b) while on a normal diet and paired with unfamiliar monkeys showed no effects of the high amino acid diets, confirming a previous analysis of learning ability.
Parabrachial nuclei damage in infant rats produces residual deficits in gustatory preferences/aversions and sodium appetite
Authors: Hill David L. , Almli C. Robert
Published: January 2005

Ten‐day‐old rats sustained bilateral electrolytic lesions of the parabrachial nuclei in the pons (PBN). Growth measures and tests of sensorimotor, feeding and drinking behaviors, sodium appetite, and gustatory capacities were made between age 1 and 150 days. PBN rats displayed a transient period of attentuated suckling, as evidenced by body weight loss. When tested soon after weaning, PBN rats were hyperdipsic in response to cellular dehydration and during food deprivation. This effect, however, was temporary. When tested as adults, PBN rats were hypodipsic in response to extracellular fluid volume depletion, they displayed alterations in sodium appetite, showed “exaggerated” preferences and aversions to saccharin and NaCl solutions, and they displayed attentuated quinine aversions. These results are generally similar to the behaviors of rats sustaining more central gustatory pathway lesions as adults. The functional significance of the PBN in the developing rat for preference/aversion and sodium appetite behaviors are discussed.
Sex and strain differences in the developmental activity profile of the rat tested over clean vs home cage bedding
Authors: Buelke‐Sam J. , Sullivan P. A. , Kimmel C. A. , Nelson C. J.
Published: January 2005

In the first of two experiments, CD rat litters were used to characterize activity patterns obtained in a size‐adjustable, single photodetector chamber. Beginning on postnatal Day 10 or 12, pups were tested repeatedly over clean bedding (C) or over bedding removed from each pup's home cage (HC). In C rats of both sexes and in HC females, short‐term activity levels peaked on Day 16. However, HC males displayed and earlier and even greater elevation in activity from Day 12 to 16. This overall pattern was found in rats tested either every second or every fourth day. In the second experiment, Long‐Evans pups were assigned to each testing condition (C vs HC) and activity measured beginning on Day 12. Peak levels were seen in all Long‐Evans rats on Day 16 and only females showed significant alterations as a function of bedding condition. When overall activity levels of the two strains were compared, significant differences were found on Days 12, 24, 30, and 120 in males, and 12, 24, and 30 in females. Significant differences between strains in activity as a function of bedding condition were found in males on Days 12, 20, 24, and 120 and in females on Days 12, 30, and 60. These data confirm the generality of a developmental hyperactivity phase in isolated juvenile rats. However, different patterns of hyperactivity were found in male vs female rats across strains. CD males were more active in the presence of HC olfactory cues, while in Long‐Evans rats, female activity was affected more by bedding condition.