bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ontogeny of an endogenous, nonopioid and hormonally mediated analgesic system
Authors: Hamm Robert J. , Knisely Janet S. 
Published: January 2005

AbstractRats of different ages (10‐day, 28‐day, and 3‐month‐old) were exposed to cold‐water stress in order to activte an endogenous analgesic system. The effects of naltrexone (7 mg/kg) and dexamethasone (.4 mg/kg) were also studied to examine the role of the opioid and hormonal systems in cold‐water‐induced analgesia. Following cold‐water exposure, nociception was measured with the tail‐flick procedure for 2 hr. Results revealed that cold water produced a significant level of analgesia in the 10‐day, 28‐day, and 3‐month‐old age groups with no differences between age groups. In addition, in each age group naltrexone did not block the analgesia while dexamethasone attenuated the analgesia produced by cold water. The effects of naltrexone and dexamethasone confirm that cold‐water immersion activates a nonopioid, hormonally mediated analgesic system in each age group. Thus, this experiment found that the endogenous, nonopioid, and hormonally mediated analgesic system activated by cold water is functional early in the development of the rat. The early development of this hormonally mediated analgesic system is in contrast to the slower development of endogenous analgesia systems that are mediated by the central nervous system.
Pregnancy‐induced autogrooming in mice: The effects of nipple removal
Authors: Harvey Pamela J. , Mann Martha A. 
Published: January 2005

AbstractAs pregnancy advances, Rockland‐Swiss albino mice spend increasingly more time engaged in autogrooming. By gestation day 18 (the day prior to parturition), the total duration of autogrooming (a composite measure) as well as the duration of nipple line grooming is significantly longer than that displayed by virgin and early pregnant females. Nipple excision (i.e., thelectomy) performed prior to pregnancy reduces the time GD 18 dams spend licking nipple line regions without producing a concomitant decrease in the duration of grooming all regions. It is unlikely, therefore, that peripheral stimulation of the nipple line regions via self‐licking contributes to the heightened display of grooming by pregnant mice.
Hormonal and behavioral attachment responses in infant guinea pigs
Authors: Hennessy Michael B. , Ritchey Robyn L. 
Published: January 2005

AbstractInfant guinea pigs, 11/12 and 18/19 days of age, exhibited high rates of vocalizing and increases in plasma concentrations of cortisol when separated from their mothers for 30 min in a novel environment (unfamiliar cage in an unfamiliar room). Levels of vocalizations and plasma cortisol were significantly reduced when the pup was exposed to the novel environment with its own conscious or anesthetized mother, but not when it was exposed with an unfamiliar anesthetized lactating female. Pups spent equivalent amounts of time in physical contact with their own conscious mother, their own anesthetized mother and an unfamiliar anesthetized lactating female. Unexpectedly, when the unfamiliar cage was placed in an environmental chamber during separation, pups showed negligible increases in vocalizations and plasma cortisol levels, even when administered footsck just prior to exposure. These findings demonstrate that guinea pig pups exhibit adrenocorticoid as well as behavioral responses to maternal separation, provide further evidence for the existence of filial attachment in this species, and document an unexpected role of the test environment in determining responses during maternal separation. The guinea pig may afford a rodent model for examining the effects of attachment‐object separation on the activity of the pituitary‐adrenal system.
Pre‐ and postnatal choline supplementation produces long‐term facilitation of spatial memory
Authors: Meck Warren H. , Smith Rebecca A. , Williams Christinal L. 
Published: January 2005

AbstractAlthough research has demonstrated that short‐term improvement in memory function of adult rats can occur when the availability of precursors for the neurotransmitter acetylcholine is increased, little is known about whether memory function of adult rats can be permanently altered by precursor supplementation during early development. In the present study, male albino rats were exposed to choline chloride supplementation both prenatally (through the diet of pregnant rats) and postnatally (subcutaneous injections). At 60 days of age rats were tested on a 12‐ and 18‐arm radial maze task. Results indicated that compared to control littermates, perinatal choline‐treated rats showed more accurate performance on both working and reference memory components of the task. Theis performance difference was apparent on the first block of sessions and continued throughout training. Further analysis revealed that the difference between choline and control rats is not due to use of differntaial response or cue‐use strategies. Instead, it appears that choline induced performance differences are due to long‐term enhancement of spatial memory capactiy and precision.
Sibling inhibition of hoarding in postweaning hamster pups (Mesocricetus auratus)
Authors: Turpin Barbara , Johnston Timothy D. , Fulk Keith R. 
Published: January 2005

AbstractIf hamster pups are placed in individual cages at weaning (21 days of age) they begin to hoard food immediately; within 2–6 days, they hoard 90% of the food they take from their food dish in the course of a 1‐hr test, consuming only 10% of it. Pups that remain with their littermates after weaning in large group cages do not hoard food until they are placed in individual cages, when hoarding starts immediately. The inhibitory effect of littermates is just as pronounced in hamsters that have been allowed to hoard food in individual cages for 14 days after weaning and are then regrouped into litters. If litters are housed in divided cages that prevent physical interactions among littermates, but allow the interchange of olfactory, auditory, and some visual cues, hoarding is suppressed to an intermediate level. These results show that the presence of siblings inhibits the expression of hoarding, partly as a result of direct physical interactions and partly through the agency of sensory cues. The onset of hoarding following the dispersal of young from the nest cannot be explained as a motivational consequence of the young no longer having access to the mother's food hoard.
Unfamiliar environments impair information processing as measured by behavioral and cardiac orienting responses to auditory stimuli in preweanling and adult rats
Authors: Richardson Rick , Siegel Michael A. , Campbell Byron A. 
Published: January 2005

AbstractPlacing animals in an unfamiliar environment triggers at least two major reactions: (1) a heightened state of arousal, fear, or distress and (2) a sharp increase in information processing as the animal attempts to learn about its new environment. These changes could have a profound effect on the way in which the animal reacts to the types of extraneous innocuous stimuli typically used to study learning and memory. For example, an increase in arousal or fear could either (1) make the animal more “attentive” to stimulus change resulting in a larger orienting response, or (2) produce a shift from orienting to defensive responding. Conversely, processing of the new stimuli present in the unfamiliar environment may make the animal less responsive to additional extrinsic stimulation. These possibilities were examined experimentally using both autonomic and behavioral measures of orienting and defensive responses. The results demonstrated that animals fail to exhibit either an orienting response or a defensive response to a novel auditory stimulus when they are first placed in an unfamiliar environment. With continued exposure to the test environment the orienting response appears and then shows a time‐dependent increase in magnitude. This pattern of results was obtained in both preweanling and young adult rats. On the basis of additional research and analysis, it was concluded that a limitation in information processing capacity was the primary reason for the failure of the orienting response to occur when an animal is first placed in an unfamiliar test chamber.
Drinking behavior and motor function in rat pups depleted of brain dopamine during development
Authors: Weihmuller Fredric B. , Bruno John P. 
Published: January 2005

AbstractThe ability of rat pups depleted of brain dopamine (DA) at either 3 or 15 days of age to increase fluid intake in response to intracellular dehydration was studied. Despite near‐total depletions of striatal DA, animals depleted at either age ingested normal amounts of fluid even as soon as 3–7 days after incurring the brain damage. The effects of DA receptor blockade on ingestion and motor function were also studied. Haloperidol had markedly different effects as a function of the age at which the depletions were sustained. Weanlings that were depleted of DA at 3 days of age failed to exhibit the drug‐induced adipsia, akinesia, and catalepsy seen in controls and animals that were depleted at 15 days of age. These findings suggest that the DA depletions were performed at different periods of brain organization. The resultant neural controls of ingestion and motor function are qualitatively different in the two groups of depleted animals. Rats depleted at 3 days of age utilize nondopaminergic mechanisms, whereas animals lesioned at 15 days of age continue to rely upon residual DA neurons for both behaviors.
Effects of hand‐rearing on the behavioral development of infant and juvenile gorillas (Gorilla g. gorilla)
Authors: Meder Angela 
Published: January 2005

AbstractNineteen hand‐reared and seven mother‐reared infant and juvenile gorillas were observed for a period of 3 years. Almost all hand‐reared individuals developed stereotyped behaviors during the first months. In most cases these behaviors disappeared in the first or second year. Social behaviors, solitary play, nest building and grooming developed at about the same age in hand‐reared and mother‐reared infants. Hand‐reared immatures showed significantly more solitary play, more aggression and less social play than mother‐reared ones, especially when raised in pairs. When young gorillas were kept in groups, the frequencies of these behaviors came nearer to those of mother‐reared immatures. No significant differences were noted in social play. When introduced to conspecifics, hand‐reared infants sometimes reacted with indiscriminant aggression. Gorillas should thus preferably be reared in peer groups and be introduced to adults not later than one year of age.
Gender differnces in visual habit formation in 3‐month‐old rhesus monkeys1
Authors: Bachevalier Jocelyne , Hagger Corinne , Bercu Barry B. 
Published: January 2005

AbstractThe rate of learning concurrent visual discriminations with 24‐hr intertrial intervals, a measure of habit formation, was assessed in infant monkeys of both sexes and compared with the rate of learning in adults. In two separate series of animals, 3‐month‐old male monkeys learned an initial set of discriminations (but not later sets) more slowly than 3‐month‐old females. This gender difference was absent in 6‐month‐old monkeys and in adults, both of which learned the initial set at the same rate. Determination of plasma gonadal hormone levels at the time of testing revealed a significant correlation (rs = 0.95) between testosterone levels and learning scores on the initial set in the 3‐month‐old male monkeys (i.e., the higher the level the poorer the score). No such correlation was found in the 3‐month‐old female monkeys or in the 6‐month‐olds of either sex. These results suggest that high testosterone levels found perinatally in male monkeys temporarily slows maturation of the neutral system underlying visual habit formation.
Ontogenetic differences in the expresion of odor‐aversion learning in 4‐ and 8‐day‐old rats
Authors: Miller James S. , Molina Juan C. , Spear Norman E. 
Published: January 2005

AbstractTwo experiments investigated the ability of preweanling rats, 4 or 8 days of age, to form an odor‐LiCl association across various CS‐US delays. The results of the odor preference test indicated that 8‐day‐old subjects acquired an aversion to the CS+ odor when trained with either a 0 or 15 min CS‐US delay, while 4‐day‐old subjects did not exhibit a reduction in preference for the CS+ at any of the CS‐US delays tested. The absence of a reduction in preference for the CS+ by 4‐day‐old rats could not be attributed to their failure to acquire the odor aversion, however; they avoided a texture with which the CS+ odor was paired in a second order conditioning paradigm. The results suggest that outcomes appearing to represent age‐related differences in associative learning may in some instances be more appropriately viewed as representing ontogenetic differences in the way in which acquired associations are manifested in behavior.
Morphine treatment and reproductive condition alter olfactory preferences for pup and adult male odors in female rats
Authors: Kinsley Craig Howard , Bridges Robert S. 
Published: January 2005

AbstractAdministration of morphine sulfate (MS) to pregnancy‐terminated and postpartum lactating female rats disrupts both maternal behavior and postpartum aggression. Since the display of these behaviors may be heavily dependent on olfactory cues provided by the stimulus animals (rat pups and adult male rats, respectively), we examined whether MS was affecting the perception of the olfactory stimuli, and whether olfactory perception was modified by reproductive condition. In Experiment 1, lactating rats had their pups removed and were injected with MS (5.0 mg/kg, sc.) or saline. 60 min later they were placed into a two‐choice apparatus, one side of which contained bedding soiled by neonates and the other clean bedding. Time spent on each side was recorded for a total of 5 min (300 s; chance = 150 s). Saline‐treated mothers spent significantly more time on the pup‐odor side, whereas MS‐treated females spent significantly less. In Experiment 2, lactating females were treated with MS or saline and exposed to male odors (soiled bedding). MS significantly increased time spent on the side with male odors; when treated with saline, time spent was significantly reduced. Thus, in lactating rats, MS creates an aversion for pup odors while reducing the female's normal aversion toward male odors. In Experiment 3, ovariectomized (ovx) virgin females expressed neither an aversion nor a preference for the odor of pups following saline administration. After MS treatment, however, the virgins showed a distinct preference for pup odors. When exposed to male odors in Experiment 4 ovx virgins showed a marked preference for male odors after MS treatment, and neither a preference nor an aversion after saline. Experiment 5 examined pup odor preferences in intact virgins, early (Day 7), middle (Day 14), late‐pregnant (Day 21), and prepartum (Day 22) rats. The pup odor preferences of virgin, Day 7, Day 14, and Day 21 pregnant rats were not different and generally were at chance levels. Day 22 pregnant females exhibited a marked preference for pup odors compared to chance levels, as well as compared to the other four groups. These findings suggest that opiates and endogenous opioids may regulate olfactory preferences and that alterations in this system may underlie normal behavioral changes toward conspecifics prepartum as well as during lactation.
Striking absence of long‐lasting effects of early color deprivation on monkey vision
Authors: Brenner Eli , Cornelissen Frans , Nuboer Wim 
Published: January 2005

AbstractA monkey (Macaca fascicularis) spent its first three months under far red illumination that made color vision impossible. It developed normal spectral sensitivity. In the present study we examined two aspects of color vision that presumably reflect cortical connectivity. In the first part of this article we show that chromatic induction was also unaffected: a blue surrounding made a gray target appear to be yellow to the monkey.At five months of age, the deprived monkey did not readily use color to recognize objects, although it was able to do so if necessary. In the second part of this article we show that, as an adult, the monkey was quite willing to use color to categorize objects. We conclude that early color deprivation does not result in long lasting deficits in color vision.
Multiple contexts and memory retrieval at three months
Authors: Rovee‐Collier Carolyn , Dufault Debra 
Published: January 2005

AbstractStudies of adults have shown that the contextual dependence of memory retrieval can be alleviated by training in multiple contexts. In the present studies with 3‐month‐old infants, retention was disrupted when infants were trained in one context and tested in another, but not when they were trained in multiple contexts prior to testing in a novel context. The retention advantage of multiple learning contexts was observed after 3 days in a simple forgetting paradigm (Exp. 1) and after 14 days in a reactivation paradigm (Exp. 2). These findings demonstrate that although the setting in which an event occurs is an important determinant of memory retrieval at 3 months, its protective function can be overridden by common experiences in varied settings.
The effects of rate and forward masking on human adult and newborn auditory evoked brainstem response thresholds
Authors: Lasky Robert E. 
Published: January 2005

AbstractSeveral investigators have reported that human newborn auditory brainstem evoked response (ABR) thresholds to clicks are about 10‐20 dB higher than human adult thresholds to the same stimuli (Galambos amp; Hecox, 1978; Shulman‐Galambos amp; Galambos, 1979; Lasky, Rupert, amp; Waller, 1987). The present study replicated these results, but, in addition, addressed developmental differences in ABR thresholds due to forward masking and changes in stimulus repetition rate. Eight human newborns and seven human adults served as subjects. Newborn ABR thresholds to a 100 μs click which followed a 82 db (A) SPL 50 ms broadband forward masker by 10 ms were significantly more elevated relative to their unmasked ABR thresholds than were those of the adults. Relatively loud sounds seem to have a greater effect on the newborn's ability to process subsequently presented soft sounds than they do on adult processing. In contrast, changes in repetition rate of 100μs clicks from 10/s to 50/s had no greater effect on newborn than adult ABR thresholds. At near threshold stimulus levels, rate effects on the ABR are not apparent in newborns nor adults.
Restriction of early exploratory forays effects specific aspects of spatial processing in weanling hamsters
Authors: Tomlinson W. Thomas 
Published: January 2005

AbstractNormally reared hamsters, but not hamsters reared on a liquid diet, demonstrated spatial memory for the location of odor cues in an allocentric task (Experiment 1). In Experiment 2, an egocentric task, liquid‐reared hamsters detected a change in the spatial location of odor cues. In Experiment 3 liquidreared hamsters detected a change in the spatial location of two visual cues under allocentric task conditions. Female hamsters on a liquid diet retrieved their pups more often than dams on solid food, resulting in reduced exploratory opportunities for their pups during the period when olfaction mediates behavior. Hamsters in Experiment 4 experienced a direct restriction of early forays. The restricted‐rearing group failed to detect a change in the spatial location of odor cues in an allocentric task. These findings suggest that restriction of early exploratory experience during a narrow period of development results in specific spatial processing deficits.
Age‐related differences in sensory conditioning in rats
Authors: Chen Wei‐Jung , Lariviere Nancy A. , Heyser Charles J. , Spear Linda P. , Spear Norman E. 
Published: January 2005

AbstractFour experiments tested rats 8, 12, or 21 days postnatal for sensory conditioning in terms of the association acquired between two odors presented simultaneously or sequentially. The sensory conditioning of 8‐ and 12‐day‐old rats exceeded that of rats 21 days of age when the odors were presented simultaneously. When one odor was presented immediately followed by another, however, 21‐day‐old rats conditioned as effectively as the younger animals, and with a sufficiently long interval between odors (20 min), the sensory conditioning of the 21‐day‐old rats surpassed that of the rats 12 days of age. Although consistent across a variety of procedures, in previous experiments and within the present study, the age‐related differences in sensory conditioning after simultaneous presentation of two odors are difficult to understand. Increasing knowledge of the ontogeny of orienting may lead to an explanation in terms of Thompson's (1972) theory linking sensory conditioning with orienting and sensitization.
The amniotic sac as scaffolding: Prenatal ontogeny of an action pattern
Authors: Robinson Scott R. , Smotherman William P. 
Published: January 2005

AbstractIntraoral lemon infusion elicits facial wiping behavior in fetal rats on Days 20 and 21 of gestation. On Day 19, fetuses tested in a warm saline bath respond to infusion but do not express the wiping response. In contrast, fetuses tested within the amniotic sac exhibit wiping. Fetal movements after infusion were analyzed on Days 19 and 20 in both the bath and amnion environments. Facial wiping is assembled from simpler components in both real time (during the 15 s after infusion) and developmental time (over Days 19–20 of gestation). In real time, the wiping response occurs following a brief period of fetal activity comprising head and forelimb movements. After the wiping bout is initiated, strokes by left and right forelimbs increase in duration and become synchronized. In developmental time, components of the wiping response (forelimb strokes) are consistently expressed on Day 19, but other components (head stabilization) are lacking when fetuses are tested in bath. The amniotic sac appears to provide scaffolding that reduces head movement and promotes paw‐face contact, thus facilitating facial wiping.
The development of exploration and spontaneous alternation in hooded rat pups: Effects of unusually early eyelid opening
Authors: Foreman Nigel , Altaha Mohammad 
Published: January 2005

AbstractChanges in exploratory activity and spontaneous alternation were examined across postnatal Days 8–31 in Lister hooded rat pups whose eyelids were surgically opened at 6–8 postnatal days. Compared with controls, whose eyes open naturally at 14–16 days, the treated animals showed accelerated behavioral development. Open‐field activity increased more rapidly in the week following surgery, but only when all pups in the litter had their eyelids opened, and not when only half of the litter was treated. Rearing on the hind paws emerged earlier in treated animals, but grooming was unaffected. Pups having unilateral early eyelid opening made pivotal circling movements contraversive to the opened eye in an open‐field arena in the early neonatal period. When tested in a T‐maze, treated pups showed earlier spontaneous alternation than controls. Possible physiological systems underlying such changes are discussed. Our results show that unusually early visual stimulation has behavioral consequences, producing a brief speeding of some attentional and investigatory behaviors, though such changes may also depend upon environmental factors.