bluuebunny/crossref_metadata_2025 huggingface dataset:
Strain, sex, and environment effects on appetitively and aversively motivated learning tasks
Authors: Freeman Betty Jo , Ray Oakley S.
Published: January 2005

Two strains of rats (Zivic‐Millers and F‐344s) were reared in either an enriched or isolated environment for 60 days (experiment I) or 27 days (experiment II). At maturity, independent groups of subjects were tested on both appetitively and aversively motivated learning tasks. The results indicated that the effects of early rearing conditions on later behavior were both task and strain specific. Passive avoidance and appetitively motivated tasks were more sensitive to the early experience variable whereas active avoidance tasks were more sensitive to the genetic variable.
Behavioral and neuroendocrine effects in rats of postnatal exposure to low dietary levels of maneb
Authors: Sobotka Thomas J. , Brodie Robert E. , Cook Michelle P.
Published: January 2005

Several behavioral and neurochemical consequences of neonatal and/or postneonatal exposure to maneb (ethylenebisdithiocarbamate manganese), a popularly used fungicide, were investigated in male rats at dietary levels of 0, .5, 1.0, or 10 ppm. Three different periods of exposure were employed: (1) during the 28‐day neonatal period; (2) during the 5 months postweaning; and (3) during both the neonatal and postweaning periods of life. Behaviorally, neonatal exposure to maneb depressed exploratory activity of the 30‐day old wealings. As adults, neonatally treated rats demonstrated enhanced learning ability in an operant conditioning procedure. However, no facilitation of learning was found in animals whose exposure to maneb was restricted to only their postweaning period of life. Although unrelated to the behavioral changes, neuroendocrine effects were also found. Regional brain cholinesterase (ChE) activity was reduced in rats exposed to maneb during either the neonatal period alone or during the 5 month postweaning period alone, but continuous exposure to maneb during both the neonatal and postweaning periods did not appreciably affect brain ChE activity. Adult plasma corticosterone levels were elevated by exposure to maneb only postweaning. No such change was found in the neonatally exposed rats.
Visual discrimination learning of the young chick: Key‐peck conditioning with heat‐light reinforcement
Authors: Zolman James F. , Chandler Sharon D. , Black Diane
Published: January 2005

Heat‐light reinforcement procedures are described which were developed for key‐peck conditioning of 1‐day‐old chicks. 24 Vantress x Arbor Acre and 24 White Leghorn chicks were randomly assigned to two preference conditions in a successive discrimination problem: bright yellow as S+ and dim blue as S−, or the reverse. During 7 sessions of 48 discrete conditioning trials each, the chicks learned quickly to peck the key when the S+ was presented and to inhibit pecks when the S− was presented. This differential responding to S+ and S− was evident when the chicks were 1 day old (sessions 1 and 2) and became more evident with further training when the chicks were 2 days old (sessions 3–7). There were no significant preference or breed differences. Contrary to previous results, this experiment demonstrated that neural mechanisms involved in inhibition of responses are well developed in the young chick.
Effects of prenatal maternal handling and rearing with aunts on behavior, brain weight, and whole‐brain serotonin levels
Authors: Plaut S. Michael , Graham Charles W. , Leiner Katharine Y.
Published: January 2005

Rats were handled daily throughtout gestation. Their litters and those of nonhandled rats were fostered to nonhandled mothers, half of whom were then housed with a virgin female (aunt). Prenatal handling decreased serotonin levels in 21‐day‐old offspring tested at the trough of the 24‐hr serotonin rhythm. Rearing with aunts resulted in lower brain weights among males, but had no effect on the serotonin levels of weanling rats. Both prenatal handling and rearing with aunts affected scores of female offspring in a reaction‐to‐handling test administered at age 56 days, but an open‐field test yielded only sex differences. Rearing with aunts differentially affected trough serotonin levels at that age, males showing a signficant decrease, whereas female values increased.
Latency of EEG attenuation (“blocking”) in relation to age and reaction time in normal children
Authors: Surwillo Walter W.
Published: January 2005

Blocking latency of the EEG (BL) and reaction time (RT) were investigated in 53 normal boys aged 88–207 months. The purpose was to discover whether changes in BL which have been reported to occur during growth in children parallel the well known decrease in RT that accompanies development. EEGs were recorded (1) during an experiment in which the tracings were attenuated by short, high intensity flashes of white light, and, (2) while the subjects performed an auditory reaction task in which they responded to a tone that occurred without warning by closing a switch as quickly as possible.

As expected, findings showed an inverse relationship between RT and age of substantial magnitude (r= −.822). By contrast, no relationship was apparent between BL and age in the group tested. This finding, together with the fact that the correlation between BL and RT was not significantly different from zero, suggested that BL and RT follow different developmental courses and may be measures of essentially independent systems in children 7 years and older.
The effects of saline or blank injections during development on maze learning at maturity
Authors: Stein Donald G.
Published: January 2005

Rats were given daily isotonic saline or blank injections intraperitoneally during one of three postnatal periods (1–25 days, 25–50 days, 50–75 days) and were then subjected to 18 Hebb‐Williams maze problems beginning at 92 days of age. The rats receiving the blank injections from 25–50 days of age were impaired on later maze performance. Weight differences did not correspond to the effects of the control injections.
Age effects in the acquisition and retention of active and passive avoidance learning by rats
Authors: Egger Garry J. , Livesey Peter J.
Published: January 2005

Three groups of 8 male albino rats within each of the age ranges 24, 50, and 100 days were trained on an active avoidance task to a criterion of 10 successive avoidances. The number of trials to criterion was found to be a monotonic function of age. One group at each age was tested immediately thereafter for passive avoidance of the conditioning chamber, another group was tested for passive avoidance after 25 days, and the third was tested for retention of active avoidance after 25 days. Groups at 50, 75, and 125 days were used as controls for the active avoidance retention groups. All animals took significantly fewer trials to relearn the active avoidance after 25 days than did controls on the acquisition of the original learning task. On passive avoidance 24‐day olds performed less efficiently than the older groups and failed to show any retention after 25 days.
Ultrasounds and maternal behavior in small rodents
Authors: Noirot Eliane
Published: January 2005

Rodent pups in distress emit 2 different types of ultrasonic calls. One is given in response to cold; the other in response to unusual tactile stimulation. The effects of these calls on adult behavior can also be classified into 2 categories. Some exert positive effects attracting the adult to the pup in distress and stimulating searching, retrieving, and nest‐building. Others cause withdrawal of the adult from the pup thereby causing cesation of rough handling or aggression. The ultrasounds elicited by cold could exert the positive effects whereas those elicited by tactile stimulation produce the withdrawal effects.
Mice reared with rats: Effects of prenatal and postnatal maternal environments upon hybrid offspring of C57BL/10J and Swiss Albino mice
Authors: Denenberg Victor H. , Paschke Richard E. , Zarrow M. X.
Published: January 2005

The hybrid offspring of reciprocal crosses between C57BL/10J and Swiss Albino mice were fostered at birth to Swiss Albino mouse mothers or to Purdue‐Wistar rat mothers.

Measures were taken of incidence of survival, body weight, open‐field performance, passive avoidance learning, and fighting. As compared to mice reared by mouse mothers after birth, mice reared by rat mothers (a) had a lower incidence of survival at weaning; (b) weighed more; (c) were less active in the open field, defecated less in the field, and had a greater latency to initiate movement in the field; and (d) had poorer passive learning scores. The findings indicate that the postnatal maternal environment has pervasive effects upon a number of behavioral and morphological characters, but reveal a minimal effect of the prenatal environment. Moreover, they indicate that the absence of differences in fighting scores among the 4 groups may be caused by dominant genes.
The effects of infantile stimulation and intermittent fasting and feeding on life span in the black‐hooded rat
Authors: Kendrick Don C.
Published: January 2005

The effects of accelerating development by 2 kinds of infantile stimulation (handling or faradic stimulation) interacting with a postweaning intermittent fasting and feeding regime have been assessed in relation to changes in life span. The results indicate that the fasting regime significantly increases life span in those animals subjected to infantile stimulation. Some of the claims made concerning the secondary effects of intermittent fasting on excitability levels of the central nervous system were not supported.
The interaction of genotype and exogenous neonatal androgen and estrogen: Sex behavior in female mice
Authors: Vale Jack R. , Ray Donald , Vale Carol A.
Published: January 2005

Female neonates of the A, BALB/c, and C57BL/6 mouse strains were injected with androgen, estrogen, or oil and the effects upon their sex behavior studied. Genotype and treatment combined interactively on a substantial number of variables, indicating that the effects of perinatally administered sex hormones and genotype cannot be considered separately. Effects of the 2 hormones were often in different directions. The lordosis response of one genotype appeared relatively insensitive to neonatal treatment, particularly with androgen.
Behavioral development in mice selected for differences in brain weight
Authors: Fuller John L. , Geils Helen D.
Published: January 2005

Mouse pups from the SEL‐16 lines which have been selected for high or low brain weight differed from unselected controls in body size and intensity of some behaviors, particularly between 4 and 10 days of age. The differences were not related in a simple manner to brain size nor to brain growth patterns previously described by the authors. A hypothesis of pleiotropic effects of “brain weight genes” upon behavior is not supported by the data.
Transient and enduring effects of handling on infant and maternal behavior in mice
Authors: Sherrod Kathryn B. , Connor William H. , Meier Gilbert W.
Published: January 2005

Effects of handling on both maternal and infant behavior were observed daily on laboratory mice from birth to weaning. Pups were cross‐fostered after 7 days in order to assess enduring effects of handling on mothers and infants separately. The handling manipulation resulted in increases in maternal behavior which were stimulating to pups during the first 7 postpartum days. However these effects dissipated sometime during the 24‐hr period between observations, as handled litters observed prior to the handling manipulation did not differ from unhandled litters, and neither maternal nor infant effects of handling were significant, following cross‐fostering.
Sexual behavior of male rats following removal of the glans penis at weaning
Authors: Spaulding William D. , Peck Carol K.
Published: January 2005

Male rats in which the glans penis was removed at 20 days of age showed all of the sexual behavior patterns of normal rats, including ejaculation, when tested as adults. However, the distribution of the behaviors within the patterns was statistically different from normal: the experimental males required a greater number of mounts and a longer time for ejaculation than did control males.
The development and behavioral characteristics of the startle response in the zebra fish
Authors: Kimmel Charles B. , Patterson Jill , Kimmel Richard O.
Published: January 2005

The behavioral responses of developing larvae of the zebra fish (Brachydanio rerio) to vibratory stimulation are described. Larvae begin to respond after 4‐5 days from the time of fertilization (the approximate time of hatching). Once this response appears, the characteristic movement, the latency of the response, and the sensitivity of the larva to sound do not change for a period of several days. A number of related behavioral changes are observed at the same time the response to sound appears.

The larval startle response is a characteristic pronounced tail flip. It is very similar to the adult startle response which is believed to be mediated via Mauthner's neuron. The data suggest that the usual response may be due to a wave of muscular contractions along one side of the larva, as would be expected to result from an action potential in a Mauthner cell. More complex responses were also observed and are described.
Effects of maternal undernutrition on offspring behavior: Incentive value of a food reward and ability to escape from water
Authors: Cravens Richard W.
Published: January 2005

Two experiments were performed to evaluate the effects of maternal undernutrition during gestation and lactation upon the incentive value of a food reward and upon performance and reversal learning in an escape‐from‐water task. The results of the present experiments suggest that offspring of underfed mothers have lower incentive values for food rewards than control offspring, although they are able to perform comparably in an escape‐from‐water task. The implication is that the results of hunger‐motivated tests of problem solving or learning in maternally undernourished and control offspring are suspect.
Early experience, emotionality, and exploration in the rat: A critique of Whimbey and Denenberg's hypothesis
Authors: Aitken P. P.
Published: January 2005

Whimbey and Denenberg have suggested that emotionality and exploration are orthogonal or independent dimensions of behavior which can be affected to different degrees by stimulation during infancy. This paper suggests that the factorial structure of the data on which they based this hypothesis supports the viewpoint that the relationship between measures of fearfulness and exploration is inverse.
Some aspects of the behavior of young and adult rats treated with p‐chlorophenylalanine in infancy
Authors: Adlard B. P. F. , Smart J. L.
Published: January 2005

Suckling rats were treated with p‐chlorophenylalanine (PCP; 300 mg/kg, 5–15 days of age or 150 mg/kg, 5–21 days) in order to selectively deplete brain 5‐hydroxytryptamine (5HT). Some bodily growth retardation occurred during treatment. Although a normal body weight was achieved in adulthood, some stunting of cerebellar growth had occurred.

During PCP treatment a reduction in State 2 (paradoxical) sleep occurred at 10 and 14 days of age, without alteration in total sleeping time. Compared with controls, locomotor activity in the open field was reduced only at 22 days of age after prolonged treatment. A marked reduction in turning frequency was evident at 12 and 18 days.

Passive‐avoidance behavior was facilitated when tested 4–6 days after cessation of PCP. This may represent increased reactivity to a noxious stimulus and is probably dependent on concomitant cerebral 5HT depletion.

In adults who received PCP in infancy, brain 5HT concentraton was normal. Learning ability as assessed in the Hebb‐Williams maze and passive avoidance in adulthood were not affected. However, a significant degree of hyperactivity was observed in open‐field tests.
The effects of lifelong isolation on species identification in zebra fish (Brachydanio rerio)
Authors: Mc Cann Lee I. , Matthews James J.
Published: January 2005

Virtually no information is currently available regarding the relative effects of innate and experiential factors on the development of species identification in fish. Those studies which have approached the problem through schooling behavior have confounded species identification with attraction to a single available school of species‐mates. In this study, isolated Brachydanio rerio spent significantly less time in nonpolarized schools with species‐mates than controls when animals of a related species were available as an alternative. This difference suggests the involvement of experiential factors in species identification and questions the assumption that species identification is entirely innate.
Learning and retention of a discriminated escape response in infant mice
Authors: Nagy Z. Michael , Murphy James M.
Published: January 2005

Separate groups of mice received 25 training trials in a shock‐escape T‐maze at 7,9,11, or 13 days of age, followed by retention trials 24 hr later. During original training, all mice were trained to the goal opposite their 1st‐trial choice‐point turn. During the retraining sessions, half of the mice in each age group received an additional 25 trials to the same goal as original training, while the other half was trained to the goal opposite that of original training. All age groups demonstrated improved performance during training in reaching the choice point, although only mice 9 days of age and older indicated an increase in correct choice‐point turns. During retraining, only the groups trained at 11 and 13 days of age showed significant effects of prior training.
Activity and exploratory behavior of adult offspring of undernourished mother rats
Authors: Smart J. L.
Published: January 2005

Mother rats were either adequately fed or were undernourished during much of pregnancy and throughout lactation. Both control (C) and undernourished (UN) offspring had free access to food from weaning. Rats were tested between 15 and 27 weeks of age. During repeated exposures on the same day in a rectangular observation box, UN rats moved about more and reared on their hind legs more often than controls, but defecated less frequently. Two measures of exploratory behavior, tendency to emerge from a familiar to an unfamiliar area and responsiveness to a novel object, did not differentiate the 2 groups, nor did control and UN rats differ in the rate at which they pressed a lever to produce a light stimulus in a dark Skinner box. These and other long‐term, activity studies indicate that previously undernourished rats are more active than controls in familiar, nonstressful situations.
Effect of a hand sock on prehension in infancy
Authors: Umansky Richard
Published: January 2005

In 4‐12 month human infants a briefly applied hand sock frequently resulted in marked prehensile disuse of the socked arm (SA) in excess of the sock's mechanical restriction. Most infants failed to reach with the SA for midline objects on a majority of trials while continuing to use the unsocked arm (UA). The SA grasp and manipulation efforts were also reduced. The onset of disuse was rapid, as was resumption of use after sock removal. The SA disuse was attributed to the effect of excess contactual input from the SA. The character of the disuse differed with age. Whereas younger infants often appeared not to recognize the option to attempt prehension with the SA, older ones were capable at times of deliberate disuse of the arm and could reverse existing patterns of SA disuse. Older infants also displayed: (1) better awareness of the handicapping effects of the sock in the framework of an improved concept of arm structure and function, and (2) better adaptive and compensatory responses including substitute use of the UA. These data were interpreted to suggest a general transition from peripheral to central control of prehensile intention during the 2nd half of the 1st year.
Indolethylamine‐N‐methyltransferase in developing rabbit lung
Authors: Lin R‐L. , Sargeant S. , Narasimhachari N.
Published: January 2005

The activity of indolethylamine‐N‐methyltransferase (INMT) from the rabbit lung is relatively high in the newborn and increases rapidly after birth, attaining its maximum level at 15 days of age. Between the 15th and 19th postnatal days, INMT activity declines to the mature level and remains fairly constant thereafter. The decrease in the activity of the enzyme may be due to the presence of dialyzable endogenous inhibitor(s). The inhibition of the enzyme from lungs of rabbits of varying ages by S‐adenosylhomocysteine (SAH), N, Ndimethyltryptamine (DMT), and chlorpromazine (CPZ) is reported.
The development of heart rate responses to weak and strong shock in the preweaning rat
Authors: Chalmers Donald V. , Levine Seymour
Published: January 2005

Heart rate (HR) responses to 2 intensities (.2 and 2.0 mA) of electric shock were studied in preweaning rats at 5, 7, 9, 11, 13, 15, 17, 19, and 21 days. Both weak and strong shock elicited at least some HR acceleration at all ages. Beginning on Day 13, a deceleratory component was added to the response to weak shock. HR acceleration was significantly greater in response to strong shock on Days 5 and 7 and then again from Days 15‐21. Strong shock also elicited a relatively long‐latency bradycardia beginning with Day 11. Results are discussed in terms of the emergence of 3 response tendencies: (1) the orienting reflex; (2) the defensive reflex; and (3) a change in the state of the organism, and their possible implications for the study of preweaning shock on subsequent behavior.
Protein malnutrition in the rat: Its effects on maternal behavior and pup development
Authors: Massaro Thomas F. , Levitsky David A. , Barnes Richard H.
Published: January 2005

Repeated time‐lapse photographic observations were used to examine the maternal behavior and pup development of female Holtzman rats maintained on either a low‐protein (12% casein by weight) or a high‐protein (25% casein) diet throughout the period of lactation. Dams fed the low‐protein diet were observed to spend more time in the nesting area with their pups than dams fed the high‐protein diet. Locomotor activity of the dams did not differ between the 2 groups. The behavioral development of the pups suckling the dams receiving the low‐protein diet was markedly depressed as compared with the controls. Included in this latter observation were pup behaviors such as movement from the nesting area, feeding and drinking from available supplies, and rearing and climbing activity. The results indicate that feeding a low‐protein diet to a lactating dam results in behavioral changes in both the dam and pups that tend to minimize the exposure of the pups to the immediate environment.
Arousal and temporal factors in imprinting in mallards
Authors: Martin James T. , Schutz Friedrich
Published: January 2005

A number of factors affecting the learning processes in laboratory imprinting were examined. Two factors alone explain the degree to which young ducklings learn the characteristics of a given model: the length of exposure to the model, and the endogenous arousal state of the duckling. A third, the effect of muscular exertion is not warranted.

The characteristics of some models are more rapidly learned than others, and the significance of this fact for biochemical studies of learning is discussed. In this study ease of learning coincided with innate preference; this suggests the presence of a neural filtering mechanism in the duckling which alters the assimilation of information into the CNS and hence controls both innate preference and learnability.
Preliminary evidence for the effects of environmental complexity on hybridization of rat brain RNA to rat unique DNA
Authors: Uphouse Lynda L. , Bonner James
Published: January 2005

Hybridization to unique DNA by RNA from brain or liver of rats given varying degrees of experience was investigated. RNA from brain of environmentally enriched rats hybridized to more unique DNA than did brain RNA from nonenriched controls. No significant differences were observed with liver RNA. This provides preliminary evidence for an increased transcription of the unique sequences of DNA in the enriched animals. The technique used has great promise for the investigation of experientially‐induced alterations in gene expression.
Effect of postnatal litter size on adult aggression in the laboratory mouse
Authors: Ryan Virginia , Wehmer Francine
Published: January 2005

Growth, emotionality, food competition, and aggression were examined in mice nursed in litters of 3 or 9 and reared in isolation until testing. Animals from large litters were lighter at weaning and in adulthood and were more emotional in the open field than subjects from small litters. They did not win more food competition tests than subjects from small litters although their consummatory behavior during food competition tests was greater. Subjects from large litters were more aggressive in initial encounters, but over repeated encounters became more submissive. In a 2nd open‐field test, emotionality of large‐litter subjects was reduced more than that of subjects from small litters. When later placed in group‐living cages, subjects from small litters sustained less long term physical assault than subjects from large litters. High correlations were found between the 4 measures of brief aggression.
Taste‐aversion learning in infant guinea pigs
Authors: Kalat James W.
Published: January 2005

Infant guinea pigs were hand‐fed a 10% sucrose solution and poisoned after delays of 0 min, 30 min, or 24+ hr. Subjects in the first 2 groups showed significant sucrose aversions when tested more than a month later. No significant difference existed between the 0‐ and 30‐min groups; no deficiency in this type of learning was evident even in neonates. All 3 groups showed a lower sucrose preference if first exposed to sucrose at ages 0–6 days than at 7–11 days. Evidently exposure to sucrose at the earlier ages was less effective in reducing later neophobia to sucrose; although the youngest animals had no evident deficiency in learning aversions, they may have been deficient in learning “safety.”
Effects on offspring of chronic maternal methamphetamine exposure
Authors: Martin Joan C.
Published: January 2005

Twenty‐five Sprague‐Dawley derived rats were administered 1.0, 3.0, or 5.0 mg/kg of methamphetamine HCl or saline twice daily throughout gestation beginning on Day 1 of pregnancy. Rats were allowed to deliver normally; offspring were culled to 8 and sexed on Day 7, and weaned on Day 21. All females had viable litters except at the 5.0 mg/kg dose where 4 of 7 failed to deliver. The rats given methamphetamine delivered earlier than did controls. Weight gian over gestation decreased as a function of increasing drug dose. No gross anomalies were visible in the offspring. Litter size decreased as a function of increased dose and eye opening was delayed in the drug groups; the 5.0 mg/kg offspring made more conditioned avoidance responses than did the 3.0 mg/kg and saline offspring.
Aggressive behavior of juvenile mice: Influence of androgen and olfactory stimuli
Authors: Svare Bruce , Gandelman Ronald
Published: January 2005

Testosterone propionate (TP) administered from Day 21 through Day 50 of life enhanced the aggressiveness of castrated and neonatally TP‐treated juvenile male and female mice and, to a lesser extent, enhanced the aggressiveness of nonneonatally androgenized females. In addition, the enhanced aggressive behavior of juvenile male and female mice was directed principally toward juvenile male but not female opponents and was inhibited by the application of urine from juvenile females to the fur of juvenile male opponents. These experiments indicate that androgen and olfactory stimuli modulate the aggressive behavior of juvenile mice in a manner similar to that of adult animals.
The development of response to continuous auditory stimulation in rats treated neonatally with 6‐hydroxydopamine
Authors: Brackbill Yvonne , Douthitt Thomas C.
Published: January 2005

This study investigated biochemical substrates of the continuous stimulation effect, i.e., the developmental phenomenon whereby continuous stimulation depresses arousal level. Neonatal rats were injected intracisternally with 6‐hydroxydopamine. Motility, heart rate, and brain amines were measured in these animals, as well as in injected and noninjected control animals, at 14 and 28 days of age in an own‐control design with and without continuous auditory stimulation. Brain norepinephrine was significantly and inversely related to the magnitude of the continuous stimulation effect and experimental‐control differences increased with age. These results indicate that an intact catecholaminergic system is necessary for the mediation of increased arousal during stimulation.
The influence of incubatory photic stimuli on chicks' visual intensity preference for approach behavior
Authors: Metcalfe John
Published: January 2005

Incubating chicks were presented with a high‐intensity or low‐intensity photic flicker stimulus, or with no photic stimulation. The chicks were tested at 16 hr posthatching for approach behavior, or at 96 hr for imprinting performance to the 2 visual flicker stimuli. The data were analyzed in accord with the arguments of whether those stimuli that effectively elicit approach behavior are determined by interaction between maturation and experience or by a genetic program. The results show that prehatch exposure to photic flicker stimuli affects initial approach behavior and imprinting performance, supporting the interaction position in opposition to the genetically programmed position.
Weak inhibitory behavioral effects of postnatal/preweaning taurine injections in rats
Authors: Persinger Michael A. , Valliant Paul M. , Falter Herman
Published: January 2005

The behavior of rats injected once every 2 days between Postnatal Days 4 and 20 with 62.5 m̈g/g or 125 m̈g/g body weight of taurine was compared with saline‐ or .5 M NaCl‐injected litter‐mate controls. Taurine‐injected rats ran significantly less in the running wheel test anddisplayed lower response/reinforcement ratios following step‐like changes in DRL reinforcement schedules. The quicker adjustments to the changes in DRL schedules did not occur immediately but during sessions following the change. We concluded that taurine administration during early juvenile development could weakly influence adult inhibitory behavior.
Maternal hyperphenylalaninemia: An experimental model in rats
Authors: Andersen Arnold
Published: January 2005

Experimental maternal hyperphenylalaninemia produced in pregnant F344 rats by the combined use of p‐Chloro‐DL‐phenylalanine and L‐phenylalanine reduced fetal birth weight in comparison to saline‐injected controls. Offspring who experienced hyperphenylalaninemia in utero died within 5 days after birth. Fetal plasma phenylalanine levels were several times higher than maternal plasma phenylalanine levels, indicating that the placenta actively concentrates maternal phenylalanine. Fetal brain phenylalanine levels rose in direct proportion to elevations in fetal plasma phenylanaline, whereas maternal brain phenylalanine levels remained low during maternal plasma phenylalanine elevation; the contrast suggests that the maternal brain is better able than the fetal brain to screen itself against high circulating plasma phenylalanine levels.
Visual sensitivity to orientation of rectangles in mice with retinal degeneration
Authors: Schnitzer Samuel B. , Beane Millard E. N.
Published: January 2005

C3H/HeJ male mice, an inbred strain showing retinal degeneration (rd), and normal‐eyed DBA/1J male mice were studied in a task requiring discrimination of horizontally and vertically oriented rectangles. The apparatus was a modified Yerkes discrimination apparatus. The mice were given 30 days of discrimination training, 10 trials/day, after which 10 more trials were given on the 31st day with positive and negative cues reversed. Both strains showed a highly significant decrease in errors during acquisition, the rd strain making significantly fewer errors than the DBA/1J animals. Reversal of the cues brought about a sharp increase in percentage of errors.
Depth perception after infant and adult visual neocortical lesions in light‐ and dark‐reared rats
Authors: Tees Richard C.
Published: January 2005

In 2 experiments the behavior of light‐ and dark‐reared infant‐ and adult‐operated striate rats were compared at 20‐160 days of age on a visual cliff apparatus in which the depth of the deep side could be varied. Differential depth thresholds revealed that depth discriminative ability did not develop normally following removal of the striate cortex in infancy. Further, infant‐operates who were reared in darkness following their operations performed less well than their light‐reared, infant‐operated counterparts. The infant‐operated animals, regardless of their postoperative rearing condition, performed significantly better than did adult‐operated animals after comparable post‐operative recovery periods and testing. The results are discussed in terms of further specification of the role played by age of operation and by the interaction between visual experience and age of operation.
Scopolamine's effect on passive avoidance behavior in immature rats
Authors: Wilson Linda M. , Riccio David C.
Published: January 2005

Male albino rats ranging in age from 15‐‐30 days were injected with either scopolamine hydrobromide or saline, prior to training and retention testing on a black‐white passive avoidance (PA) task. Pretraining administration of a 1.0‐mg/kg dose of scopolamine significantly increased the median number of trials to criterion for 18‐, 21‐, and 30‐day‐old rat pups when compared with their saline controls. Fifteen‐day‐olds showed drug‐related PA deficits when a 2.0‐mg/kg dose was given. Retention data reflect characteristic age‐dependent memory loss over the 1‐week acquisitionretention period with no apparent state‐dependent effects. The data suggest the presence of cholinergic inhibitory mediation of PA responding in preweanling and postweanling pups.
The influence of early auditory experience on later auditory and tactual variation seeking in the rat
Authors: Hennessy Michael B. , Hershberger Wayne A. , Bell Robert W. , Zachman Thomas A.
Published: January 2005

Albino rats were raised under 1 of 4 conditions of auditory stimulation from 22‐‐35 days of age. At 40 days, preferences for auditory and tactual variation were assessed in separate runway tests. Results were analyzed in a split‐plot design for each of 2 measures of variation seeking. Subjects experiencing more‐variable early stimulation scored higher than subjects receiving lessvariable stimulation on 1 measure of variation‐seeking and lower on the 2nd measure. The effect was intermodal since these results were obtained for tactual as well as auditory variation seeking.
The effect of reinstatement stimulus conditions on the maintenance of long‐term memory
Authors: Campbell Byron A. , Randall Patrick K.
Published: January 2005

Weanling rats trained on an appetitive SDSΔ discrimination were subsequently exposed to different components of the training stimulus for 15 min each week for 10 successive weeks. On the week following the final stimulus exposure retention was measured by a 2‐hr relearning test. Those subjects exposed to all acquisition cues (SDSΔ with reinforcement), as well as those exposed to SΔ conditions alone, demonstrated enhanced retention relative to a control group receiving no reinstatement experience. All other exposure conditions including presentation of SD with reinforcement were either ineffective or impaired retention.
Stability of motor OR and heart rate habituation rates of infancy
Authors: Sostek Anita Miller , Brackbill Yvonne
Published: January 2005

The stability of the OR habituation rate as an individual difference trait was investigated in 2 studies. The 1st focused on motor OR's to auditory stimuli at 3 ages within the 1st month of life, and the 2nd examined the HR responses to auditory stimuli at 4 and 8 months. The results indicate that motor OR's did not differ significantly with age and were moderately stable across ages. The stability decreased with age across consecutive days but increased across consecutive weeks. The cross‐age correlation for HR responses was moderate. The results were compared with similar findings on other parameters of the OR.
The effects of neonatal vestibular stimulation on adult growth and emotional reactivity in BALB/c mice
Authors: Labarba Richard C. , Stewart Allan
Published: January 2005

Two experiments were conducted to determine the effects of neonatal vestibular stimulation on the subsequent development and behavior in BALB/c mice. No evidence appeared to suggest that neonatal vestibular stimulation alters either the growth pattern or the ontogenesis of emotional reactivity.
Effects of pre‐ and postnatal litter size reduction on development and behavior of rat offspring
Authors: Milković Karmela , Paunović Jasenka , Joffe Justin M.
Published: January 2005

Litter size was reduced to 2‐5 rat pups either prenatally by unilateral maternal oviduct ligation (Group PRN) or postnatally by removing pups (Group PST). Normal size litters (8‐10 pups) of sham ligated (SHM) and intact (CON) mothers served as controls. Weights at 30 days were increased by prenatal or postnatal reduction and reduced by prenatal stress (SHM); the sex difference in weight was most pronounced in PRN rats. At 75 days PRN rats were heaviest, with no differences between the other groups. Relative ovarian weights were reduced in PRN females and absolute testes weights increased in PST males. The PRN and SHM females had smaller relative adrenal weights than CON and PST females. Open‐field activity was generally increased by prior avoidance conditioning and effects of treatments were found only in groups tested after avoidance‐conditioning: PRN and SHM rats were more active than PST and CON rats, particularly on Days 1 (SHM) and 4 (SHM and PRN) of testing. Passive‐avoidance behavior of PRN rats was also more susceptible to previous test experience: they emerged more slowly if they had prior open‐field experience. The PST animals, in contrast, emerged more rapidly after prior test experience. Plasma corticosterone levels and shuttlebox conditioning and extinction were unaffected by treatments.
Effects of neonatal thyroid hormone stimulation and differential preweaning rearing on open‐field behavior in adult rats
Authors: Sjödén Per‐Olow , Söderberg Ulf
Published: January 2005

In 2 experiments, rats were given a mixture containing high doses of 1‐tri‐iodothyronine and 1‐thyroxine‐sodium on Day 4 after birth (Group T)Controls (C) received equivalent amounts of saline. During the preweaning period, half of the litters in the T and C groups were raised in an impoverished (I) condition, and half in an enriched (E) condition. Open‐field ambulation, rearing, defecation, and, in Experiment 2, grooming behavior were recorded during a 4‐day period at 210 days (Experiment 1) and at 90 days of age (Experiment 2). A consistent augmenting action of neonatal hormone stimulation on ambulation and rearing was found for both males and females. Hormone‐treated animals did not habituate their rate of general motor activity with repeated testings in the open‐field. An over‐all pattern of a larger effect of hormone‐treatment in the I condition than in the E condition was noted, particularly among the females. Thus, the experience of preweaning enrichment partly “normalized” the open‐field behavior of the T groups. The results are discussed in relation to an hypothesis concerning the interaction of rate of development of the central nervous system and environmental stimulation in determining later behavior.
Genetic and ontogenetic variations in locomotor activity following treatment with scopolamine or d‐amphetamine
Authors: Remington Gary , Anisman Hymie
Published: January 2005

Highly inbred mice of 3 strains A/J, DBA/2J, and C57 BL/6J were tested in an open field at 14, 21, or 28 days of age. Ten minutes prior to testing, mice received treatment of saline, scopolamine .5 or 1.0 mg/kg of body weight, or d‐amphetamine (.5, 1.0, or 5.0 mg/kg). The d‐amphetamine 5.0 mg/kg increased activity in all strains at 14 days and 28 days of age, and at 21 days significantly increased activity in all except the C57BL/6. In contrast, increased activity with the scopolamine treatment was seen in DBA/2 at 21 days, but not in A and C57BL/6 until 28 days postnatally. The data support a caudal‐rostral gradient of brain development with the inhibitory cholinergic system developing more slowly than the excitatory catecholamine system. In addition, strain‐specific differences in activity levels are discussed in relation to the differential rates of cholinergic maturation.
The role of auditory stimulation in responsiveness in young chicks
Authors: Brown Cathryn P.
Published: January 2005

The mechanism of action of the auditory signal in increasing responsiveness to a visual‐auditory stimulus in chicks of 14–48 hr was examined. Stimulus effectiveness of an auditory signal dissociated from the visual stimulus was less than proximate auditory signal presentation but greater than a silent visual stimulus. Familiarity with the auditory signal increased and decreased responding under proximate and dissociated presentation, respectively. These data were interpreted as confirming the influence of auditory stimulation via increased arousal, and as indicating the possibility of selective responding to specific features of the auditory stimulus when its localization at the visual stimulus is possible.
Development of learning and memory in mice genetically selected for differences in brain weight
Authors: Herman Barbara H. , Nagy Z. Michael
Published: January 2005

Mice selected for high (H), medium (M), and low (L) brain weight were trained to the goal arm opposite their preference in a shock‐escape T‐maze at 7, 9, 11, or 13 days of age. Twenty‐four hours later, half of the trained groups at each age received additional training to the original goal, whereas the other half was trained to the opposite goal. Maturational control groups without prior training were trained on the selected retest days for the previously trained groups. Improvement in correct choice‐point turns during training was suggested for the H‐line by 9 days of age and by 11 days of age for the M‐ and L‐lines. During retraining, H‐line mice demonstrated 24‐hr retention effects by 10 days of age, whereas 24‐hr memory was not indicated for M‐ and L‐lines at any of the ages investigated. These results indicate that the onsets of learning and memory were influenced by genes affecting brain weight, in that H‐line mice demonstrated more rapid brain growth as well as heavier brain weights at every age studied as compared with M‐ and L‐line mice which showed similar brain growth functions.
Maternal pituitary‐adrenal responsiveness as a function of differential treatment of rat pups
Authors: Smotherman William P. , Wiener Sandra G. , Mendoza Sally P. , Levine Seymour
Published: January 2005

The effects of litter separation and pup treatment on the maternal pituitary‐adrenal system were investigated in 3 experiments. Lactating females did not show a pituitary‐adrenal response to separation from their pups. However, the lactating females showed an increase in plasma corticosterone when their pups had been briefly removed and then returned. If, in addition, the pups were subjected to a noxious stimulus (electric shock) during the 2‐min separation, mothers showed a further increase in corticosterone. When pups were returned after 3 hr of separation, mothers again showed a differential pattern of corticoid responsiveness. The magnitude of the mother's pituitary adrenocortical response depended upon the intensity of treatment given to the pups. These data lend physiological support to behavioral studies which have shown that maternal behavior is differentially influenced by pup‐produced stimuli.
Early handling influences on behavioral and physiological responses during active avoidance
Authors: Weinberg Joanne , Levine Seymour
Published: January 2005

The effects of early handling on behavioral and physiological responses of the rat during active avoidance learning were investigated. Handled and nonhandled males and females were run in a 2‐way shuttlebox task with an unconditioned stimulus of either .5 mA or .8 mA. Animals exposed to .8 mA showed a higher corticosterone response, a shorter response latency, and increased defecation. Early handling did not affect performance of the task, however handling did alter the patterns of the plasma corticosterone response over the course of avoidance training. Handled females showed less elevation of plasma corticosterone than nonhandled females, but all females showed a decrease in corticosterone over the course of avoidance learning. All males showed the drop in corticoids if run at .5 mA shock, but only handled males showed this change at .8 mA shock.
Interaction‐induced reduction in differential maternal responsiveness: An effect of cue‐reduction or behavior?
Authors: Brown C. P. , Smotherman William P. , Levine S.
Published: January 2005

Litters from donor mothers received differential treatments (handling or shocking) and were then placed in wire‐mesh baskets affixed to the cage tops of test mothers. Pup‐produced cues from donor litters elicited different patterns of maternal behavior from test mothers that interacted with their own litters. In addition to these differences in maternal behavior, cues from the donor litters elicited a differential pattern of pituitary‐adrenal activity. Shocked pups elicited larger corticosterone elevations than handled pups. These data suggest that the elimination of differential pituitary‐adrenal responsiveness evidenced when mothers interact directly with pups subsequent to pup treatment results from the termination of pup‐produced cues that normally accompany active mother‐infant interactions.
Interactive effects of genotype and early life undernutrition on the development of behavior in rats
Authors: Tonkiss John , Smart James L.
Published: January 2005

Developing rats of 2 outbred stocks were either well‐nourished or undernourished by underfeeding their mothers throughout pregnancy and lactation. All rats were well‐fed from 25 days of age. Starting at 110 days male rats were observed first in an open field and then in a social situation; finally their motor performance was tested on a revolving drum. The social behavior test comprised pairing male rats of the same stock, 1 well‐fed control with 1 previously undernourished rat.

Analysis of variance of the results of the open‐field and social behavior tests revealed main effects of Nutrition and of Stock for several measures of behavior in each test. There were also Nutrition X Stock interactions for 2 measures from the open field and 1 from the social situation. Motor performance was not impaired by early life undernutrition. The evidence of Nutrition X Stock interactions, together with that from analyses of the effects of nutrition performed separately for the 2 stocks, as if each stock had been investigated in a separate study, indicates that genotypic differences may be one of the reasons for the discordance often found between the conclusions of different early life malnutrition studies.