bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of vitamin A excess administered during the mid‐fetal period on learning and development in rat offspring
Authors: Hutchings Donald E. , Gaston John
Published: January 2005

Pregnant rats were administered a teratogenic dose of vitamin A excess on Days 17 and 18 of gestation. Intubation controls received the vehicle alone and nontreated mothers were left undisturbed. All groups were fostered to other nontreated mothers at birth. During adulthood, offspring were lever‐trained to obtain a water reward on an intermittent reinforcement schedule and on an S+, S− auditory discrimination. Unlike animals treated with vitamin A excess on Days 14 and 15 of gestation, these animals revealed no retardation in growth and development nor in brain size. Throughout the VI‐40 sessions and the S+ trials of discrimination training, the vitamin A animals had consistently slower rates of response compared to the controls. However, they did not evidence any impaired learning ability; like the nontreated, they extinguished S− responding, acquired long S− latencies, and maintained short S+ latencies. Possibly, the treatment may have produced a subtle motor deficit affecting fine motor coordination.
Developmental changes in the rate of ultrasonic vocalization in the Mongolian gerbil
Authors: De Ghett V. J.
Published: January 2005

Developmental changes in the rate of ultrasonic vocalization were investigated in Mongolian gerbils from birth until 30 days of age. The rate of ultrasonic vocalization increased from birth until Day 4. Following Day 4, the rate declined rapidly until Day 10. A moderate decline in the rate occurred from Day 10 to Day 13. After Day 13, the decline in the rate of ultrasonic vocalization was very gradual. Vocalizations were not detected on Day 20 or thereafter. Developmental changes in the rate of ultrasonic vocalization corresponded to those changes reported for the laboratory mouse and laboratory rat. Furthermore, the daily changes in the rate of ultrasonic vocalization followed the pattern that would have been predicted from knowledge of the development of homoiothermy in this species.
Development of dustbathing in bobwhite quail. I. Effects of age, experience, texture of dust, strain, and social facilitation
Authors: Borchelt Peter L. , Overmann Stephen R.
Published: January 2005

Variables influencing the development of dustbathing in Bobwhite quail chicks were investigated in 3 studies. Study 1 showed the development to be a complex function of age of the chick, the amount of experience the chick has had with dust, and the texture of the dust. Chicks generally dustbathed at an earlier age in fine than in coarse dust. In Study 2, a different Age x Experience developmental pattern was found for dustbathing in chicks from a different strain of Bobwhite quail. In Study 3, chicks experienced in dustbathing were found to facilitate significantly the development of dustbathing in naive chicks. These studies indicate that the development of dustbathing is not simply age or maturation dependent, but is a function of a number of important variables, both genetic and experiential.
Genetic divergence in relatives of PKU's: Low IQ correlation among normal siblings
Authors: Fuller Renee N. , Shuman Joyce B.
Published: January 2005

The IQ frequency distribution of 78 unaffected siblings of patients with phenylketonuria (PKU) differed significantly from the normal population (X2 = 43.42, df = 5, p < .0001). The excessive number of superior IQ's of this distribution apparently was not a function of superior families. The low intersibling correlation, r = .13, suggests a difference between carriers and noncarriers of the disease PKU. Because the proportion of high IQ's approaches the expected percentage of homozygotes or noncarriers for the disease, heterozygotes for PKU may be suffering a functional disadvantage.

A theory is presented on the possible importance of genetic‐recessive diseases whose carriers are at an intellectual disadvantage, thereby requiring compensatory genetic mechanisms.
A cat's form‐experienced but visual‐motor deprived eye lacks focal vision
Authors: Robinson John S. , Fish Stephen E.
Published: January 2005

Cats were allowed to move about freely from birth to 18 months with one eye open; the other eye was open during daily 1‐hr periods of binocular exposure in a holder, but was deprived of all visual‐motor experience. Focal vision failed to develop in the deprived eye (DE): (1) the DE's guidance deficit was especially pronounced for targets in the central field and in the photopic light range (it was much smaller in the periphery and in the mesopic range); (2) conjugate eye control, required for binocular fixation of objects in focal viewing, was disrupted by strabismus (squint); and (3) focal vision's identification function was virtually absent in the DE—it showed only slight recognition of patterns learned by the experienced eye (EE) and little ability to learn to identify them itself.
Visual exploratory behavior as a function of early handling, sex, and level of auditory prestimulation
Authors: Wachs Theodore D.
Published: January 2005

Previous research has indicated that preexposing animals to intense stimulation leads to subsequent decrements in exploratory behavior. The present study was an attempt to determine if early handling could “buffer” animals against intense stimulation effects. At birth, rat pups were assigned to either a handling or a nonhandling condition. As adults, they received either intense, moderate, or no stimulation prior to being allowed 3 min of visual exploration. The predictions were: (1) handled animals will show significantly more exploration than nonhandled animals; (2) intensely stimulated animals will show significantly less exploration than animals receiving lower amounts of stimulation; (3) handled animals, under intense stimulation, will show significantly more exploration than nonhandled animals under intense stimulation. The results supported the 2nd and 3rd predictions. The first prediction was supported, but was complicated by a Sex x Handling interaction.
Effects of d‐amphetamine sulfate given to pregnant mice on activity and on catecholamines in the brains of offspring
Authors: Middaugh Lawrence D. , Blackwell L. Ann , Santos Carroll A. , Zemp John W.
Published: January 2005

Offspring of C57BL/6J mice injected with d‐amphetamine sulfate during the last third of pregnancy had slightly reduced body weight at birth, altered concentrations of catecholamines (CA's) in their brains during development, and increased activity after they had matured. Norepinephrine concentrations were depressed at birth, returned to control values by Day 3, and were elevated at 21 and 30 days after birth. Dopamine values were elevated at 30 days after birth. At 75 days of age, animals prenatally exposed to the drug had CA concentrations similar to controls, but had heightened activity levels compared to controls tested in the open field. The results of these experiments demonstrate that d‐amphetamine sulfate administered to mice during the last third of pregnancy produce transient alterations in CA concentrations and long‐lasting changes in behavior.
A comparison of live and videorecord viewing of infant behavior under sound stimulation. I. Neonates
Authors: Bench John , Hoffman Eric , Wilson Ian
Published: January 2005

Twelve clinically normal neonates were presented with a battery of sound stimuli while their behavior was assessed live by 2 sound‐masked observers and simultaneously videorecorded. This procedure was performed for the baby's whole body aspect and also for the head aspect only in a 31/2X “close‐up”. 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 usually 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 live and video assessments was slightly better than the level of interobserver agreement (Pearson's contingency coefficients). The use of videorecording caused, at most, slight losses of relevant information and, apparently, did not generally distort the findings.
Interaction of environment and injections on brain weight in rats
Authors: Eterović Vesna A. , Ferchmin Pedro A.
Published: January 2005

Rats exposed to environmental complexity (EC) for 4 days had heavier cerebra than controls maintained in an impoverished condition (IC). Such a difference did not occur when the EC‐IC pairs were given a subcutaneous injection of distilled water or an intracranial injection of saline on the 3rd day of treatment. Injecting animals in psycho‐biochemical experiments is therefore a procedure whose effects should be determined in every case.
Presurgical dietary history and the behavior of control and septal lesioned rats
Authors: Donovick Peter J. , Burright Richard G. , Bentsen Ellen O.
Published: January 2005

Rats reared under dietary enrichment or standard diet from 25 days of age underwent septal or control surgery 2 months later. Enrichment differentially altered septal or control behavior as measured by: exploration tests; fluid consumption of water, saccharin, and quinine; and the acquisition of an active avoidance task.
Developmental and genetic variables in mouse startle response habituation
Authors: Groswald Douglas E. , Luttges Marvin W.
Published: January 2005

A behavioral task insensitive to inherent sensory and motor limitations, specifically a startle response habituation technique, was used to investigate genetic (strains) and developmental (age) effects on behavior. All mice tested using two procedures exhibited evidence for habituation which was dependent on strain, age, and length of the testing process. Exploitation of this simple technique may permit clarification of more complex types of behavior.
Effects of differential rearing condition on heart rate conditioning and response suppression
Authors: Caul William F. , Freeman Betty Jo , Buchanan Denton C.
Published: January 2005

Rats were reared in either an enriched or isolated environment for 60 days following weaning. Neither rearing environment nor sex affected heart rate conditioning. However, when the CS used during conditioning was subsequently presented in a drinking situation, males reared in isolation showed a greater degree of response suppression than did similarly reared females. Males and females reared in the enriched environment did not differ in degree of response suppression.
Effect of atropine on behavioral arousal in the developing rat
Authors: Blozovski Denise , Bachevalier Jocelyne
Published: January 2005

A tropine‐induced changes in behavioral arousal were examined in the developing rat between 21 and 40 days of age using a single exploratory trial on an elevated T‐maze. Under atropine (10 mg/kg, i.p.) spontaneous activity as measured by numbers of errors, rearing responses, and stereotyped responses was significantly decreased in animals less than 25 days of age. It was significantly increased, however, between 26 and 30 days, with maximal action on the 28th day. After 30 days the effect of atropine was negligible. These results support the hypothesis of a cholinergic inhibitory mechanism controlling behavioral arousal and becoming efficient after the 25th day of life.
Comparative ontogenetic features of skeletal muscles in physiologically mature and immature mammals
Authors: Arshavsky I. A. , Darinsky N. V. , Li L. A. , Siryk L. A.
Published: January 2005

One series of experiments investigated the time required by such indices of the states of skeletal muscles as membrane potential (MP), action potential (AP), and content of total protein and dense residue to acquire values approximating those found in adults. We established that these indices acquire values approximating those found in adults at the beginning of sexual maturation in both rats and dogs. Chronologically, these values require one‐fifth the time to become established in rats as they do in dogs. Another series of experiments investigated the same indices in physiologically mature and immature organisms (rats and dogs). We established that they are much lower in immature than in mature organisms. We conclude that under conditions of natural development the main objects of elimination through natural selection in early developmental periods are physiologically immature organisms.
Neurological organization and visual fixation in infants at 40 weeks conceptional age
Authors: Kopp Claire B. , Sigman Marian , Parmelee Arthur H. , Jeffrey Wendell E.
Published: January 2005

Neurological organization and visual fixation were found to be unrelated in a group of premature infants tested at their term date. These results are discrepant with those obtained with a sample of full term infants. Separate comparisons made of the neurological and fixation data revealed one significant group difference from the fixation data; all other analyses were nonsignificant. The discrepant findings may have occurred because prematures are subject to developmental disparities in the regulation of arousal, neuromuscular, and visual systems due to differential impact of preterm extrauterine life.
Looking behavior in monkeys raised with mobile and stationary artificial mothers
Authors: Eastman Robert F. , Mason William A.
Published: January 2005

Rhesus monkeys raised with mechanically driven mobile artificial mothers for the first 10 months of life looked more at other animals and were more sensitive to stimulus differences than monkeys raised on stationary surrogates. Both groups looked less and were not as discriminating as wild‐born monkeys. The results are consistent with other evidence suggesting that one of the long‐range consequences of maternal mobility is to reduce emotional responsiveness to novel situations.
Acquisition and retention of an avoidance response by rats of different ages
Authors: McLaughlin Lynn J. , Eller Harold D. , Korol Bernard
Published: January 2005

Rats, 21, 120, and 480 days of age, were given acquisition training in a 1‐way avoidance task and tested for retention of the response 1 and 30 days later. Whereas the 480‐day‐old rats showed poorer performance during acquisition, the 21‐day‐old rats showed the greatest impairment of long term retention. The results suggest that age differences in performance are due to intrinsic maturational processes.
Variability of the effects of rearing in a large litter on the development of the rat
Authors: Galler Janina R. , Turkewitz Gerald
Published: January 2005

The variability in the effects of rearing rats in large litters was examined. Subjects reared in litters of 16 were stunted and delayed in the appearance of eye‐opening and fur‐eruption as compared with pups reared in litters of 8. However, the effects of the large‐litter treatment were not uniform; pups in this group exhibited markedly higher variability with regard to all measures than did pups from small litters. In fact, some pups from the large litters were heavier and some exhibited developmental landmarks earlier than did most pups reared in small litters.
Neonatal thyroxine administration, behavioral maturation, and brain growth in mice of different brain weight
Authors: Chen Chia‐Shong , Fuller John L.
Published: January 2005

L‐thyroxine in amounts of .5, 1, and 2 μg was injected daily from age 5 through 14 days in 3 lines of mice selected for high (H), medium (M), or low (L) brain weight. Controls (injected with vehicle only) of these lines differed in ages of eye‐opening, first auditory startle, and perfection of a surface‐righting response. Thyroxine at .5 μg/day accelerated the maturation of eye‐opening, auditory startle, and aerial‐righting response, but had no effect on a grasping response or open‐field activity. Brain weights were depressed significantly in all thyroxine treated groups except in the .5‐μg dosage in H mice.
Development of dustbathing in bobwhite quail. II. Effects of early pecking experiences
Authors: Borchelt Peter L. , Overmann Stephen R.
Published: January 2005

The development of dustbathing was facilitated among groups of Bobwhite chicks allowed to peck into dust as compared to chicks allowed to peck at dust or those inexperienced with dust. A 2nd study found a consistent, but nonsignificant, facilitation among chicks pecking into dust on Days 1–3 as compared to Days 4–6. In Study 3, groups of chicks pecked into dust on Days 2, 4, or 6. Dustbathing development was facilitated among chicks pecking on Day 2, and inhibited among chicks pecking on Day 4, as compared to those pecking on Day 6. The only difference, however, between each of these groups and chicks with no pecking experience in dust (Study 1) was an inhibition of dustbathing among chicks pecking on Day 4.
Enzymatic activities in mitochondria isolated from the rat brain during development
Authors: Mourek J. , Průžzková V. , Svobodové Z. , Kraml J.
Published: January 2005

In an attempt to discern whether mitochondrial changes during ontogeny are due to increases in number of mitochondria or to increases in number plus changes in their organization, we investigated the enzymatic markers of the inner and outer membranes of mitochondria from cerebral cortex and subcortical material in young and adult rats. We conclude from the data gathered that significant changes do occur in mitochondrial organization, that gradual maturation occurs in the inner membrane during development, especially in the cerebral cortex and considerably less so in the subcortical structures. We found no such changes in the structure of the outer membrane during the periods of development examined.
Excess neonatal thyroxine: Effects on learning in infant and adolescent rats
Authors: Stone James M. , Greenough William T.
Published: January 2005

Previous reports have suggested that neonatal thyroxine administration may enhance learning ability in rats as infants but the rats become deficient in learning as they grow older. This experiment compared neonatally thyroxine‐injected rats with injected and nonhandled controls on passive and active avoidance and a geotactic cold‐escape discrimination. Thyroxine‐injected infant rats were superior to controls on active avoidance, inferior on passive avoidance, and equal on discriminated escape. Adolescent rats which had received postnatal thyroxine were inferior to controls in Lashley III maze acquisition whether or not they had received supplementary thyroxine at the time of training. These data suggest that differences in locomotor activity, rather than in learning ability, account for early behavioral effects and that changes other than endocrine disturbances account for the adult deficits. The results are compatible with previous contentions that excess neonatal thyroxine disrupts the timing of brain development.
Maternal growth hormone and growth and function
Authors: Sara Vicki R. , Lazarus L.
Published: January 2005

Factors regulating somatic growth postnatally have been proposed to affect brain growth and subsequent function when applied prior to birth. This study pertains to the role of growth hormone administered to pregnant rats and the subsequent growth of the progeny. The results showed a significant increase in brain weight and cortical neurone number as determined by the incorporation of labelled thymidine into DNA and subsequent autoradiography. At maturity, learning performance on a series of conditional discrimination tasks was found to be enhanced.
The development of convulsive seizures in the grasshopper mouse (Onychomys torridus)
Authors: McCarty Richard , Southwick Charles H.
Published: January 2005

Open‐field tests were administered to 29 male and 50 female southern grasshopper mice (Onychomys torridus) at 10‐day intervals from 30–100 days of age. Convulsive seizures were observed to occur in 9 males and 23 females during at least 1 of the open‐field tests. No significant differences appeared in the seizure characteristics of male and female subjects. The potential of O. torridus as an animal model of human epilepsy is discussed.
Postnatal undernutrition: An alternative method
Authors: Lynch A.
Published: January 2005

Rat pups were undernourished from birth by placing them for 12 hr/day with a normal lactating mother and 12 hr/day with a nipple‐ligated mother each day for 25 days. The method resulted in a marked delay in the body growth of the undernourished pups, especially during the first 2 weeks of life. Observations of the behavior of the mothers towards the underfed pups were made at different times of the day and compared to the behavior of the mothers suckling well‐fed pups. The results show that (1) nipple‐ligated mothers are able to provide adequate maternal care for undernourished pups, and (2) both ligated and nonligated mothers caring for underfed pups spend more time with those pups than mothers caring for well‐fed pups.
Audiogenic priming in DBA/2J and C57 BL/6J mice: Interactions among age, prime‐to‐test interval, and index of seizure
Authors: Schreiber Robert A. , Graham John M.
Published: January 2005

C57BL/6J mice, not susceptible to audiogenic seizures (AGS) on the 1st exposure to an acoustic stimulus, were exposed to the acoustic stimulus for 1 min and then tested at some later date (acoustic priming). They were first exposed at either 8, 16, 19, 22, or 28 days of age, and then tested for AGS 2‐16 days after priming. DBA/2J mice, susceptible to AGS on the 1st exposure to intense noise, were exposed to the acoustic stimulus at 26 days of age, and then again 2‐14 days later. Data indicate that the incidence of AGS upon the 2nd exposure to the acoustic stimulus is a function of age at priming, the prime‐to‐test interval in days, and the index of seizures. In the case of DBA mice, later effects are also dependent on the initial level of seizure.
Food availability as a determinant of the rats' circadian rhythm in maternal behavior
Authors: Stern Judith M. , Levin Robert
Published: January 2005

The present study was designed to determine whether environmental factors other than light would alter the daily periodicity in the rat's maternal behavior and whether such a change in the dam's behavior pattern would in turn alter the pattern of her sucklings' milk intake. Experiment 1 determined the daily pattern of litter weight gain (which presumably reflects milk intake) displayed by young reared by dams fed and watered either ad lib (Group C), only during the day (Group D), or only at night (Group N). Experiment 2 compared nocturnal and diurnal frequency of maternal behavior in Groups C, D, and N. The pattern of both litter weight gain and maternal behavior was observed to be diurnal in Groups C and N and nocturnal in Group D.
Active avoidance and brain DNA after postnatal food deprivation in rats
Authors: Howard Evelyn , Olton David S. , Johnson Craig T.
Published: January 2005

Food deprivation was produced in infant rats, from 2 to 20 days of age, by a procedure designed to minimize reduction in maternal care. Body weights in the deprived animals were 60% of control weights at 7 days, 65% at 20 days, and, after ab lib feeding, 89% at 4 months. No change was observed in the rate of acquistion of a conditioned active avoidance response in the food‐deprived rats when compared with their littermate controls when tested as adults. No lasting reduction in cerebral desoxynucleic acid (DNA) was observed despite a 9% reduction in cerebellar DNA.
Position reversal deficit in young ferrets
Authors: Haddad R. , Rabe Ausma , Dumas R. , Lazar J. Wayne
Published: January 2005

Young ferrets (6 and 10 weeks old at the start of the experiments) werc compared to adult ferrets on learning (1 ) a Lashley III maze, (2) a left‐right discrimination in a T‐maze with identical choice arms, and (3) a reversal of the left‐right discrimination. The young were not inferior to the adults in Iearning either the Lashley III maze or the initial discrimination in the T‐maze. However, thc young were markedly (and significantly) inferior to the adults in learning to reverse.
The split‐brain neonate: A surgical method for corpus callosum section in newborn kittens
Authors: Sechzer Jeri A. , Folstein Susan E. , Geiger Eric H. , Mervis Ronald F.
Published: January 2005

One way to determine the importance of interhemispheric interaction in the development of adaptive and acquired behavior is to section completely the corpus callosum about the time of birth before myelination commences and before any significant hemispheric interaction takes place. Therefore, we developed a technique for commissurotomy in the neonatal kitten 36 to 72 hr of age. A specially designed “commissurotomy knife” was used which eliminated retraction of the hemispheres. Histology showed completeness of corpus callosum section as well as commissure of the fornix without any apparent damage to cortical or subcortical structures. This technique meets the following criteria: (1) reproducibility of lesions without additional nonspecific damage; (2) minimal exposure and manipulation of the delicate newborn brain; (3) brief operational procedure minimizing risk of infection; and (4) low mortality rate.
Protein deprivation in primates. VIII. Early behavior of progeny
Authors: Riopelle Arthur J. , Hale Penelope Anne , Hill Charles W.
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 tested on 13 behavioral tests during their first 60 days of life. (The diets had been shown to affect significantly the weights and blood protein concentrations of both pregnant and nonpregnant females)The tests sampled a wide range of behaviors, including visual and auditory perception, feeding reflexes, and locomotion. Despite the maternal dietary differences, the performances of infants on all tests were comparable in all groups. These data contrast with the finding of persistent deficit in rats born of protein‐deprived mothers.
Effects of cyclophosphamide treatment of newborn mice on the development of swimming and reflex behavior and on adult behavioral performance
Authors: Preache Maurline M. , Gibson James E.
Published: January 2005

Cyclophosphamide (CP), an antineoplastic agent, was administered subcutaneously to Swiss‐Webster mice on the day of birth and the mice were later tested for developmental or adult behavioral abnormalities. The CP dosages of 20, 30, or 45 mg/kg of body weight retarded maturation of swimming ability and 45 mg/kg retarded maturation of the righting reflex. At 7 weeks of age mice treated neonatally with 30 or 45 mg/kg of CP had reduced locomotor activity and were more emotionally reactive than controls in an open field. Mice treated with 30 but not 20 mg/kg of CP tended to avoid shock less often than controls and those treated with 20 mg/kg fell more frequently when crossing a rotating rod for food. Rotorod performance was improved by treatment with 45 but not 30 mg/kg of CP. All dosages examined decreased body weight gains but only 30 or 45 mg/kg resulted in gross body malformations. The results indicate that CP can functionally impair the development of mice and that some of these impairments are independent of gross body malformations.
The effects of tactile and kinesthetic stimulation on neonatal development in the premature infant
Authors: White Jerry L. , Labarba Richard C.
Published: January 2005

The effects of tactile and kinesthetic stimulation on the neonatal development of 12 premature infants were investigated. Experimental infants received four 15‐min periods of tactile and kinesthetic stimulation daily for 10 days. The control infants received only standard, routine nursery care. Data were collected daily on 8 dependent measures: weight, number of feedings, amount of formula intake, body temperature, respiration, heart rate, frequency of voiding, and frequency of stooling. The data analyses revealed significant differences in amount of formula intake and in weight at the end of the treatment period in favor of the experimental infants. Additionally, the experimental infants required significantly fewer feedings during the stimulation period. All other dependent measures were nonsignificant.
Effect of arousal conditions during reinstatement treatment upon learned fear in young rats
Authors: Haroutunian Vahram , Riccio David C.
Published: January 2005

The role of shock and epinephrine‐induced arousal in the reinstatement of learned fear was investigated in young rats. Groups of 21‐day‐old rats received classical fear conditioning to the black compartment of a black/white avoidance box. One week later each rat received one of a number of reinstatement conditions consisting of exposure to the apparatus cues, non‐contingent foot shock, or exogeneous epinephrine injections, alone or in combination. Subjects were tested for retention of spatial avoidance behavior 1 week following reinstatement. Reinstatement with epinephrine and exposure to the training contextual cues, non‐contingent foot shock followed by cue exposure, and non‐contingent foot shock alone were all found to be as effective as shock administered in conjunction with the cues (the same conditions as those prevailing during training). Cue exposure alone and epinephrine injections without the training cues were ineffective reinstating agents.
Effects of stimulus intensity and stimulus duration during acoustic priming on audiogenic seizures in C57BL/6J mice
Authors: Schreiber Robert A.
Published: January 2005

The effects of stimulus intensity and stimulus duration were examined in C57BL/6J mice not susceptible to audiogenic seizures (AGS) on the 1st exposure to an acoustic stimulus. Two experiments were performed. In the 1st, 16‐day‐old mice were exposed to 108, 112, 120, or 127 dB for 60 sec. Mice were then tested for susceptibility to AGS at varying ages thereafter. Increasing intensity of noise during priming resulted in heightened peak seizure risk, an extended duration of peak seizure risk, and a prolonged time of seizure risk. In the 2nd experiment, mice were exposed for 5, 15, 30, or 60 sec to 127 dB of noise. Five seconds of noise was barely sufficient to induce later susceptibility to AGS. Increasing stimulus duration from 15 to 30 to 60 sec resulted in increasing seizure risk and duration of peak risk period.
Early protein malnutrition in the rat: Behavioral changes during rehabilitation
Authors: Massaro Thomas F. , Levitsky David A. , Barnes Richard H.
Published: January 2005

Behavioral development was studied in 2 groups of rats during the postweaning period. Pups were selected from litters nursed by dams fed either a standard protein (25% casein by weight) or a low protein diet (12% casein) during lactation. Two pups from each litter were housed together and fed the control diet throughout rehabilitation Behavioral observations were made by repeated time‐lapse photography at 5‐day intervals. Differences in h ome cage behavior were observed at the onset of rehabilitation in the postnatally malnourished rats. Increased feeding behavior was observed during the 1st week of rehabilitation. Locomotor behavior was depressed during the rehabilitation period in the experimental animals. Climbing activity, however, was significantly greater. Self‐grooming activity was elevated throughout rehabilitation in post‐natally malnourished animals. During the course of rehabilitation, the behavioral differences between the 2 groups gradually disappeared.
Effect of maternal vitamin a excess on S‐100 in neonatal rat cerebellum: A preliminary study
Authors: Vacca Linda , Hutchings Donald E.
Published: January 2005

Pregnant rats were administered a teratogenic dose of vitamin A excess on Days 17 and 18 of gestation and intubation controls received the vehicle alone. Pups were sacrificed at birth or on postnatal Days 5 or 10; the cerebellum was removed, frozen, and fixed in preparation for immunohistochemical localization of the brain specific protein, S‐100. Vitamin A produced a transient delay in the appearance of S‐100 in the external granular layer which was no longer evident on Days 5 and 10. These findings corroborate autoradiographic evidence that vitamin A temporarily interferes with neurogenesis. However, the early damage results in permanent behavioral deficits in adulthood despite apparent cytochemical repair.
Response to auditory stimuli in 6‐and 9‐week‐old human infants
Authors: Brown James W. , Leavitt Lewis A. , Graham Frances K.
Published: January 2005

Response to 5‐sec, 75‐dB complex sounds was studied in groups of 24 infants each at 6 and 9 weeks of age. Under conditions appropriate for eliciting orienting, no significant cardiac response appeared at 6 weeks, but a significantly decelerative response did appear at 9 weeks. Measurement of noncardiac responses suggested that sucking suppression is also a component of orienting to sound, that the status of eye‐opening is equivocal, and that previously reported eye‐movement responses are probably a component of startle. We concluded that age changes in orienting may occur in young infants, even when state is controlled, and that the probability of orienting varies with the kind of stimuli employed.
Locomotor‐rotational movements in the ontogeny and play of the laboratory rat RATTUS norvegicus
Authors: Pellis Sergio M. , Pellis Vivien C.
Published: January 2005

During postnatal development, young laboratory rats, Rattus norvegicus, exhibit a variety of locomotor‐rotational movements, that is, runs and jerk‐jumps, in both playful and nonplayful contexts. The frequency of movement types differed between contexts. Some contexts, such as exploration and sleeping, contained spontaneously (i.e., possible eliciting stimuli were not observed) occurring jerk‐jumps which varied with increasing age. In some contexts, such as social play, in which locomotor‐rotational movements were elicited by observed stimuli, the frequency of jerk‐jumps remained similar throughout ontogeny. During social play some locomotor‐rotational movements were found to have immediate functions, such as achieving advantage over the partner during play‐fighting, and as a means of terminating sensory input from the partner at the end of social contact.
The response of young peking duklings to sibling distress calls
Authors: Gaioni Stephen J. , Applebaum Steven , Goldsmith Jane
Published: January 2005

Peking ducklings were tested at 1‐2 or 7‐8 days of age for their tendency to inhibit their own distress calling in response to the distress calls of siblings. At both ages the ducklings displayed a significant inhibitory response of the sibling calls, although the response of the older birds was greater. When the younger ducklings were subsequently tested with variety of acoustic stimuli that wee similar to the nonspecific calls, however, they showed the same degree of response specificity; displayed by older ducklings in previous research: in both cases the ducklings more strongly inhibited their vocalizing in response to the sibling calls than to most of these other stimuli. Finally, it was demonstrated that this differential responsiveness to sibling calls was not due merely to differences in pretest exposure to the sibling calls vs these other stimuli. This sensitivity of 1–2‐day‐old ducklings to sibling distress calls is of interest because (1) this age period is of great importance for the formation of social attachments, including sibling bonds, (2) distress calls are known to play an important role in maintaining family cohesion, and (3) it stands in contrast to the common view that young precocial birds do not respond to sibling distress calls.
Alleviation of infantile amnesia in rats by means of a pharmacological contextual state
Authors: Richardson Rick , Riccio David C. , Jonke Theresa
Published: January 2005

Although a number of studies have demonstrated that the relatively rapid rate of forgetting in young rats (i.e., infantile amnesia) can be alleviated by various reminder treatments, the possibility of enhancing retention by other procedures seems largely unexplored. Given the putative importance of contextual cues as sources of memory retrieval, this experiment examined whether the presence of a distinctive pharmacological state at training and testing could override infantile amnesia. Weanling rats were given pentobarbital or saline prior to Pavlovian fear‐conditioning. When tested 1 week later, subjects in the same‐state drug condition showed better retention than the same‐state saline group. This finding extends previous work on memory recovery in young animals by demonstrating alleviation of infantile amnesia without a re‐exposure to the CS or UCS during the retention interval.
Correlations among measures of playfulness and skillfulness in captive common marmosets (Callithrix jacchus jacchus)
Authors: Chalmers N. R. , Locke‐Haydon J.
Published: January 2005

Infant sensorimotor and social skills, playfulness, and nonplayful behaviors were measured in common marmosets from 6 to 22 weeks old. Different measures of skill showed a low concordance, implying that skill is a multiple rather than unitary attribute. Significant correlations were found between the amount of social play infants performed from 11 to 13 weeks of age and their performance at 14 weeks in (1) competitive food tests with their mothers, and in (2) their ability to negotiate an obstacle for a food reward. Significant correlations were also found between these skills and nonplayful behaviors, however comparable analyses at other ages revealed few significant correlations, suggesting that the association between social play and skills is restricted to the age when infants are rapidly becoming independent of their caregivers both for locomotion and food. Age‐specific correlations occurred between changes in levels of skills and both playful and nonplayful behavious. Our results are consistent with the hypothesis that social play promotes the development of skills, but alternative explanations are possible.
Differential rearing experience, gender, and radial maze performance
Authors: Juraska Janice M. , Henderson Constance , Müller Jutta
Published: January 2005

Since both differential rearing and gender have been known to affect maze abilities, the present study examines the performance of male and female hooded rats raised from weaning in either a complex environment (EC) or isolated environment (IC) on the 17‐arm radial maze. In two separate replications, EC rats learned the maze more quickly and accurately than IC rats, as assessed by total errors, the number of correct choices to the first error, and the number correct in the first 17 choices. However, EC rats were more likely than IC rats to employ an adjacent‐arm strategy which may have contributed to their superior performance. There were no gender differences or environment by gender interaction effects on any measure of accuracy or adjacent arm strategy in either replication. It appears that the performance of both male and female rats on the 17‐arm radial maze is similarly influenced by the rearing environment.
Contribution of self‐grooming to onset of puberty in male rats
Authors: Moore Celia L. , Rogers Sigrid A.
Published: January 2005

Self‐grooming was observed to increase during the prepubertal period of Long‐Evans rats. Males were significantly more likely than females to engage in genital grooming during this period. To determine whether self‐grooming contributes to the onset of puberty, males were fitted with collars that either prevented or allowed self‐grooming of hindquarters or were left uncollared from 27 to 48 or 55 days of age when autopsied to determine weight of accessory organs. Ventral, dorsal, and lateral prostrates and seminal vesicles were significantly lighter in those rats wearing collars that prevented self‐grooming. It was concluded that self‐grooming, probably of the genitals, contributes to accessory organ growth in males of this species.
Ontogenesis of learning. II. Variation in the rat's reflexive and learned responses to acoustic stimulation
Authors: Hyson Richard L. , Rudy Jerry W.
Published: January 2005

The onotogenesis of the rat's reflexive and simple learned reactions to acoustic stimulation was investigated in five experiments. The pattern of restults suggests that (a)reflexive reactions to tonal stimulation emerge earleir in ontogenesis that the capacity to learn about thses stimuli, and (b)the age at which simple Pavlovian conditioning is first obsrved depedens on the nature of the acoustic conditioned stimulus (CS). Specifically, these data suggest that pups are not capable of simple Pavlovian conditioning to a 2000hyphen;Hz tone (CS) paired with an oral infusion of sucrose (US) until they are 14–15 days old. The same acoustic stimulus will, however, evoke reflexive reactions (startle inspiration) in pups as young as 10–12 days old. Additionally when a different auditory stimulus (an intermittent trains of clicks) serves as the CS, there is evidence of conditioning in pups only 12–13 days old. It is suggested that these age‐related dissociations in the emergence of reflexive and simple learned responses to sound reflect a caudal‐to‐rostral maturational sequence of the components of the ascending auditory system.
Effects of maturation and priming on audiogenic seizure thresholds in mice
Authors: Fuller John L.
Published: January 2005

The rise and fall of audiogenic seizure vulnerability were followed in three lines of mice selected for brain/body weight ratio and in the heterogeneous stock from which they were derived. Over a period of 12 to 24 days, susceptibility increased and then declined. Subjects retested after a 2‐day interval were more susceptible, but this priming effect declined steadily. Differences in seizure threshold varied unsystematically among the lines. No sex differences in susceptibility were found. Mice who seized were heavier on the average than nonseizers of the same age and line. It is proposed that mice with a slower development rate are less susceptible to the stimulus used to evoke seizures. If so, rapid development may tend to lower the threshold of audiogenic seizures in mice.
Development of locomotor activity of rat pups in figure‐eight mazes
Authors: Ruppert Patricia H. , Dean Karen F. , Reiter Lawrence W.
Published: January 2005

In a series of four experiments, social and experiential factors that influence the development of motor activity in rat pups were examined. Motor activity was monitored from postnatal Days 13 to 21 as photocell interruptions in figure‐eight mazes and comparisons were made between (1) pups maintained in a nest box containing a dam and siblings and allowed access to the maze for 23 hr/day, (2) pups tested daily for 1 hr/day vs pups tested only on postnatal Days 15, 18, or 21, (3) pups tested daily for either 5 min, 30 min, or 1 hr/day, and (4) pups tested daily for 30 min/day either singly in a maze, paired with a littermate, or paired with an anesthetized pup of the same age. A monotonic increase in activity was seen for nest‐box testing, minimal developmental change was seen for pups tested on only a single day or for pups tested with an anesthetized pup, whereas all other groups showed an inverted U‐shaped profile of activity which was influenced by the duration of testing and/or the presence of a littermate. These data emphasize the relevance of environmental factors as determinants of preweaning behavior.
Development of maternal behaviors in prepubertal rats at three ages: Age‐characteristic patterns of responses
Authors: Brunelli Susan A. , Shindledecker Richard D. , Hofer Myron A.
Published: January 2005

Individual 18‐, 24‐, or 30‐day‐old male and female Wistar prepubertal rats (juveniles) were continuously exposed to 3–8‐day old pups in order to determine developmental differences in the expression of maternal and other behaviors during the process of sensitization. The results that emerged from this study are as follows: (a) Maternal behaviors are neither consistent nor integrated in their expression prepubertally; (b) exposure to pups facilitates the emergence of some maternal behaviors in juveniles more easily than others, e.g., retrieving and anogenital licking more than ventral crouching or nestbuilding; (c) there are age‐related differences in the expression of different maternal behaviors, e.g., 24‐day‐olds retrieve more than at other ages; (d) in our strain, few, if any, gender differences are apparent in the expression of maternal behaviors prepubertally; (e) juvenile play behaviors (charge, pounce) are related to retrieving behavior in the context of exposure to pups. Overall, the results suggest that maternal behaviors are distinct developmentally and probably involve different mechanisms in prepubertal animals.
Social facilitation of eclosion in the fire ant, Solenopsis invicta
Authors: Lamon Brent , Topoff Howard
Published: January 2005

In colonies of the fire ant, Solenopsis invicta, eclosion is facilitated by adult workers which strip away and consume the pupal cuticle. This stage‐specific social interaction involves chemical stimuli which are present at the onset of eclosion, concurrent with the initiation of gross movements and separation of the pupal cuticle. Fire ant workers retrieved inanimate objects treated with an extract of eclosing pupae and placed them in the colony brood chamber with the appropriate age group where they were tended by several workers. The facilitation of eclosion by adult colony members appears to be an obligatory process in the development of this species; pupae denied the aid of adult workers during eclosion are unable to remove the pupal cuticle and rapidly succumb.
Associative factors and the development of pecking in the ring dove
Authors: Graf Joan S. , Balsam Peter D. , Silver Rae
Published: January 2005

In these studies, descriptive information on the diet and feeding behavior of ring dove squab is considered in the context of an analysis of the mechanisms underlying the development of eating. Experiment I shows that squab begin to peck at grain around Day 13 and both the rate and efficiency of pecking increase through Day 21 when the squab are weaned. Experiment II shows that squab reared without seed in their home cage do not develop normal levels of pecking unless exposure to seed is followed in close temporal proximity by interaction with parents. It is concluded that an association between some aspect of squab's interaction with seed and a parentally provided unconditioned stimulus is sufficient for normal pecking ot develop. The nature of these associations and their contribution to the ontogeny of independent feeding are discussed.
Deficits in response inhibition and attention in rats rendered mentally retarded by early subcortical brain damage
Authors: Thompson Robert , Harmon David , Yu Jen
Published: January 2005

Young rats with lesions to either the globus pallidus, substantia nigra, median raphe, or pontine reticular formation have previously been reported to be deficient in learning a wide variety of laboratory tasks. In the current study, weanling rats subjected to one of these lesions were rested for three weeks, then examined for acquisition and extinction of a water‐motivated straight alley task, and finally tested on luminous flux discriminations of increasing difficulty. All brain‐damaged groups were slower than the controls in extinguishing the alley task and only the median raphe group failed to show an impairment on the discrimination problems. These results and others suggest that the foregoing lesions produce deficits in inhibitory and attentional processes. The possibility is discussed that young rats bearing these lesions might serve as a model for the investigation of the neurobiological and cognitive disturbances underlying certain classes of mental retardation in children.