bluuebunny/crossref_metadata_2025 huggingface dataset:
Age‐related differences in avoidance behavior in rats following CS preexposure
Authors: Wilson Linda M. , Phinney Richard L. , Brennan James F.
Published: January 2005

Weanling and adult rats were exposed to either 0 or 10 conditioned stimulus (CS) presentations prior to 1‐way active‐avoidance (AA) training. Although CS exposure retarded avoidance acquisition in the adults, it produced no effect in the pups during avoidance learning. Neither adult nor young rats demonstrated preexposure effects in extinction. A general extinction analysis showed that pups had less resistance to extinction than the adults, despite a comparable avoidance learning criterion between age groups. The lack of preexposure influences on performance by the pups was compared to previous findings of response inhibitory deficits in immature rats. The results were considered in light of selective attention interpretations of latent inhibition.
Influence of age and sex on the behavior of rats deprived of the rearing response
Authors: Syme Lesley A.
Published: January 2005

Rearing on the hind legs, one component of “general activity,” was restricted in male and female rats both before (25 days) and after (50 days) the development of this response. In contrast to previous restriction studies the animals were kept in groups and allowed free locomotor activity in the cage environment. After 8 weeks, open‐field testing showed that selective restriction decreased the frequency of rearing behavior, particularly unsupported rearing which requires physical coordination and balance. Effects were greater for females (which usually rear more than males) and for animals restricted at weaning (25 days).
Effect of mother on the development of aggressive behavior in rats
Authors: Flandera V. , Nováková V.
Published: January 2005

Young rats 23 days of age (Wistar strain) that are offspring of aggressive parents will attack mice. They kill them, however, only if the mother has already killed mice in their presence. Rats 30 days of age will kill mice spontaneously without any previous exposure to killing. The occurrence of muricide activity in young rats of this age is the same as in the adult population. If offspring of aggressive parents are reared by nonaggressive foster mothers from birth, they will not exhibit the muricide reaction at 30 days. In adulthood, however, the reaction appears to the same extent as in the offspring of aggressive parents reared by aggressive mothers. If the descendants of nonaggressive parents are reared by aggressive foster mothers from birth, 64.7% of them will kill mice at the age of 30 days. This aggression is retained in equal intensity during adulthood and cannot be attributed to specific learning in that the mothers have never encountered a mouse in the presence of their foster young.
Olfactory, thermal, and tactual influences on infantile ultrasonic vocalization in rats
Authors: Oswalt Gaylon L. , Meier Gilbert W.
Published: January 2005

The amount of time infant rats 3–13 days old spent emitting ultrasounds was greater when pups were placed in an empty dish than when placed in a dish containing clean bedding or soiled bedding from the nest. Pups from 5–13 days of age vocalized more when on the clean bedding than when on the soiled bedding. When placed on cloth covered dishes, pups vocalized most to the empty dish and least to the dish containing soiled bedding. The odor of clean bedding elicited less ultrasonic vocalization than the odor of the empty dish only when pups were less than 7 days old. Pups vocalized more to room temperature than to heated conditions. The results indicate that olfactory, tactual, and thermal nest cues influence infantile ultrasonic vocalization in the rat.
Early life undernutrition and aggression in two mouse strains
Authors: Randt Clark T. , Blizard David A. , Friedman Eitan
Published: January 2005

Early undernutrition was shown to be correlated with increased aggression in adult mice after isolation. This was significant in numbers of fights and shorter latency to fight in the DBA/2J strain. Lower 5HIAA in the brain after pretreatment with a monoamine oxidase inhibitor was found in the undernourished group.
Duration of early visual experience and visual cliff behavior of chicks
Authors: Kaufman Lynn W.
Published: January 2005

Visual cliff behavior was studied in 120 chicks as a function of 22, 46, 70, 94, or 118 hr of rearing in a deep or shallow environment. Preference for the deep side of the visual cliff increased directly with duration of depth‐rearing but was uninfluenced at any duration of shallow‐rearing. Although qualitative differences existed in the behaviors of those shallow‐ and deep‐reared chicks which crossed the cliff, the loss of depth avoidance by the latter group appeared to be specific to the rearing and testing apparatus.
The development of passive and active avoidance learning in the cat
Authors: Davis Joel L. , Jensen Robert A.
Published: January 2005

Kittens of 25 and 50 days of age were tested on a passive avoidance task in a 2‐compartment black‐white shuttle box. Latency t o enter the dark side of the box was the same for both groups on Day 1, but the latency to enter the dark side on Day 2 was much shorter for the younger kittens. Other kittens were trained in a step‐up active avoidance task also at 25 and 50 days of age. No differences were found in active avoidance performance between the younger and older animals, indicating that active and passive avoidance tasks may possibly reflcct separate devclopmcntal proccsses that mature at different rates in the cat.
Effects of early experience on the metabolism and production of corticosterone in rats
Authors: Grota Lee J.
Published: January 2005

Rats were handled for 3 min daily for 3 weeks before or after weaning or were left totally undisturbed. At 80 days of age, animals from each group were selected for corticosterone half‐life determination. Adrenal tissue from the remaining animals was incubated in vitro in the presence or absence of ACTH. Handled and unmanipulated animals did not differ in half‐life or in adrenocortical output. These data do not support the hypothesis that the reduced adrenocortical reactivity that results from manipulating animals is due to either the metabolism of corticosterone or the response of the adrenal cortex to ACTH.
The effects of prenatal psychological stress on the sexual behavior and reactivity of male rats
Authors: Masterpasqua Frank , Chapman Robert H. , Lore Richard K.
Published: January 2005

Male offspring of prenatally stressed rats showed low levels of copulatory behavior during a series of brief tests with estrous females but successfully impregnated female cagemates during long term tests of breeding effectiveness. Sexual performance on the short term tests was inversely related to open field activity with the offspring of prenatally handled mothers exhibiting more sexual behavior and less open field activity. These results support the notion that prenatal stress influences both the sexual behavior and emotional reactivity of male offspring. Deficits observed during short term tests of breeding effectiveness appear to be reversible under optimal conditions.
The development of the EEG in the rat
Authors: Gramsbergen Albert
Published: January 2005

The development of the electroencephalogram EEG and, especially, behavioral state‐specific EEG patterns was studied in white and black hooded rats of the Lister strain, aged 9‐30 days. Movements of the rat were recorded and the behavioral state was monitored by means of a push‐button device. The EEG was collected when the rat was in State 1 (regular respiration, absense of movements, and, after the 14th day when the rat eye opens, eyes closed, State 2 irregular respiration, continual occurrence of twitches, and, after the 14th day, eyes closed, and in State 4 irregular respiration, presence of gross body movements, and, after the 14th day, eyes opened).

The EEG of rats on the 9th and 10th day did not reveal behavioral state‐specific patterns. The amplitudes of the EEG were low and only low frequencies occurred. Between the 10th and 13th day an EEG pattern specific for State 1 containing high amplitudes developed. From the 14th day onwards, spindles frequencies from 14‐18 Hz occurred in the EEG during State 1. From the 14th day onwards, the EEG from the visual cortex during State 2 showed a regular and continually occurring 5‐Hz rhythm. Bursts with 5‐Hz waves were recorded from the visual cortex only intermittently during State 4. The EEG frequencies during the bursts varied between 5 and 7 Hz from the 17th day onwards. Computer analysis of the amplitude distributions showed a considerable increase in the power after the 10th day. The analysis of the frequency spectra indicated that the power increase occurs especially in the higher frequencies of the EEG signal. Visual analysis as well as computer analysis of the EEG did not reveal systematic changes in the EEG after the 18th day when the EEG was similar to that recorded at older ages.
Female perception of cowbird song: A closed developmental program
Authors: King Andrew P. , West Meredith J.
Published: January 2005

To investigate the modifiability of the brown‐headed female cowbird's (Molothrus ater ater) response to male song, we reared M.a. ater females with either M.a. ater or M.a. obscurus males, whose songs differ in geographic origin. The females were later tested for their responsiveness to playbacks of M.a. ater and M.a. obscurus song. Rearing with M.a. obscurus males had no effect on the female's preference for her native song variant, suggesting a closed program for receptive development. The data on song perception are contrasted with those previously obtained for male production and indicate different constraints on song perception as opposed to song production.
Olfaction mediates developmental transition in the altricial newborn of selected species of mammals
Authors: Rosenblatt Jay S.
Published: January 2005

“We should compare the manner in which orientation develops, first to the mother and later to an expanding environment. It would be interesting to carry out detailed comparisons of the ontogeny of such adjustments in blind‐born mammals such as the dog in comparison with mammals that have vision at birth–ungulates, for example. Important changes occur in the orientation of blind‐born mammals in the presight period, which we do not as yet have the techniques to investigate adequately.”

T.C. Schneirla (1954)
Acoustic correlates of individuality in the cries of human infants
Authors: Gustafson Gwene E. , Green James A. , Tomic Tamara
Published: January 2005

The acoustic features that differentiate the cries of individual human infants were examined in this study. A recognition task, performed by 400 nonparent adults, was used to classify twenty 30‐day‐old infants as easy or difficult to recognize on the sole basis of their tape recorded cries. The cries of easy‐ vs difficult‐to‐recognize infants were then compared on measures of duration, fundamental frequency, peak frequency in the spectrum, signal‐to‐noise ratios, and energy in selected frequency bands. The results indicated that each of these measures differentiated the cries of easy‐ vs difficult‐to‐recognize infants. Such redundancy should make the cry robust to degradations of selected acoustic parameters, thus enhancing its ability to carry information about individual identity across distances.
Appetitive conditioning in neonatal rats: Conditioned ingestive responding to stimuli paired with oral infusions of milk
Authors: Johanson Ingrid B. , Hall W. G. , Polefrone Joanna M.
Published: January 2005

Components of rat pups' ingestive responses to orally infused milk came to be elicited by a novel odor conditioned stimulus (cedar) that had been repeatedly paired with milk infusions (Experiment I). Pups responded specifically to one odor, and they did not generalize their conditioned responding to either another odor or an unscented airstream (Experiment II). Ingestive responses could also be conditioned to a vibrotactile CS paired with milk, although levels of conditioned responding were lower than were obtained with an odor CS (Experiment III). Pups' internal state determined the effectiveness of training, in that pups that were removed from their dam for 24 hr showed reliable conditioned responding, while nondeprived pups and dehydrated pups did not (Experiment IV). Finally, pups showed retention of conditioned responding for at least several days after training (Experiment V).
Haloperidol differentially potentiates tonic immobility, the dorsal immobility response, and catalepsy in the developing rat
Authors: Meyer Merle E. , Smith Ronald L. , Van Hartesveldt Carol
Published: January 2005

The effects of a single subcutaneous injection of haloperidol (1 or 10 mg/kg) or the vehicle solution on three kinds of behavioral inhibition were investigated in rats of 10, 15, and 20 days of age. The behaviors measured were tonic immobility, a response induced by lacing an animal on its back supported by a V‐shaped trough; the dorsal immobility response, which can be elicited in young rodents by grasping the skin of the dorsal surface of the neck and lifting the animal into the air; and catalepsy, a form of immobility in which animals remain in unusual postures but are capable of righting themselves, and which can be elicited by drugs which block dopamine receptors. Haloperidol (10 mg/kg) significantly potentiated the duration of tonic immobility only at 10 days of age; potentiated catalepsy at all age levels, but significantly less in the 15‐day‐old rats than in the 10‐ or 20‐day‐old rats; and potentiated the duration of the dorsal immobility response in the 10‐ and 20‐day‐old animals but not in the 15‐day‐olds. These results are discussed with respect to the development of neurotransmitter systems in the brain.
Familiar contextual odors promote discrimination learning in preweanling but not in older rats
Authors: Wigal Tim , Kucharski David , Spear Norman E.
Published: January 2005

For rats 16‐ or 28‐days‐old postnatal, we tested the source of the facilitation in instrumental learning provided by odors from home nest materials. Three experiments confirmed that acquisition of a spatial discrimination (to escape footshock) was facilitated not only by the presence of typical nest odors in the training context, but also by the presence of a non‐rat odor (banana) to which the animals had been familiarized for 4 hr/day for 7 days. There was a borderline tendency for a similar facilitation after familiarization to the latter odor for only 10 min. These effects occurred for a similar facilition after familiarization to the latter odor for only 10 min. These effects occurred for rats 16 days postnatal but not for those 28 days old. The experiments also confirmed that the prior exposure to non‐rat odors did not in itself, in the absence of that odor during learning, affect discriminated escape learning, and that enhanced affinity for a contextual odor is not a sufficent condition for enhancement of learning in its presence. There was some indication that the 16‐day‐old rat was more likely to select a discriminative odor to guide their choice of spatial locations if a familiar contextual odor was present.
Techniques for observing fetal behavior in Utero: A comparison of chemomyelotomy and spinal transection
Authors: Smotherman William P. , Richards Laura S. , Robinson Scott R.
Published: January 2005

Two procedures–chemomyelotomy and spinal transection–have been utilized to chemically block or phsycially sever the spinal cord of pregnant rats, enabling direct observation of fetal behavior without the use of anesthesia. The effect of each procedure on fetal behavior was studied at four gestatoinal ages (Days 17, 18, 19, and 20). Substantial differneces in fetal activity were found between chemomyelotomy and spinal transection groups, including differnces in the overall level of activity as well as the pattern of developmental change of behavior. Such differntial effects indicate that chemomyelotomy and spinal transection are not equivalent maternal preparations in the study of fetal behavior.
Effects of 6‐hydroxydopamine‐induced catecholamine depletion on shock‐precipitated wall climbing of infant rat pups
Authors: Emerich Dwaine F. , Scalzo Frank M. , Enters E. Karl , Spear Norman E. , Spear Linda Patia
Published: January 2005

Sprague‐Dawley rat pups were intracisternally injected with 6‐hydroxydopamine (6OHDA) or vehicle on postnatal Day 3 and tested for footshock‐precipitated wall climbing behavior every 48 hr from postnatal Days 5 through 17. The 6OHDA treatment was observed to lower brain catecholamine levels, particularly in forebrain, and to decrease the incidence of wall climbing. This attenuation in the amount of wall climbing did not appear to be related to any neurotoxin‐induced alterations in general motor activity, body weight, or body temperature. It also did not appear that the depression in wall climbing seen in 6OHDA‐treated animals was related to an observed neurotoxin‐induced increase in shock sensitivity, given that amount of wall climbing was observed to be positively correlated with footshock intensity. These results provide further support that catecholaminergic systems are involved in the elicitation of wall climbing behavior. The 6OHDA treatment did not alter the ontogenetic time course of disappearance of this behavior pattern, suggesting that maturational changes occurring in forebrain catecholaminergic terminals may not be critical for the dissipation of wall climbing following the second postnatal week.
Control of suckling and feeding by methysergide in weaning albino rats: A determination of Y‐maze preferences
Authors: Stoloff Michael L. , Supinski Deborah M.
Published: January 2005

To assess the effects of serotonergic receptor blockade on the weaning process, 20‐, 25‐, and 30‐day‐old albino rat pups were injected with methysergide and were permitted to choose between suckling and feeding in a Y maze. At every age, progressively larger doses of methysergide (1) enhanced pup preferences for the suckling goal, (2) increased the frequency of suckling when in the suckling goal, and (3) decreased the frequency of feeding when in the feeding goal. These results, with the support of other findings, suggest that the weaning process may be, in part, the result of emerging or changing serotonergic neurological mechanisms.
Reproductive development in male deer mice exposed to aggressive behavior
Authors: Whitsett J. Mal , Miller Linda L.
Published: January 2005

Male deer mice (Peromyscus maniculatus bairdii) were reared in a long photoperiod and housed individually from 3 weeks of age until they were killed 2, 4, or 6 weeks later. Males that were exposed to aggressive females for 2 min, three times per week, were of normal body weight and healthy, but had smaller reproductive organs than did males exposed to a control treatment. Reproductive development in male deer mice is responsive to at least two classes of social stimuli: pheromones and aggressive behavior.
The effects of rearing environment on pup development
Authors: Jans James E. , de Villers Sophie , Woodside Barbara
Published: January 2005

Norway rats were reared either in a standard laboratory cage or in a nest constructed by the dam from newspaper strips. Growth, thermoregulatory ability, and adrenal, gonad, adipose tissue, and brian weights were measured at weaning on Day 21 postpartum. While there was no difference in growth, nest‐reared animals had lower body temperatures, but could thermoregulate as well as cage‐reared animals. Nest‐reared animals also had relatively smaller adrenals and less brown adipose tissue. Gonad and brain weights were similar. An interesting finding was that males and females were differentially affected by the nest‐rearing. Differences between cage‐ and nest‐reared animals were more evident in females, and thermoregulatory ability was more closely associated with the quality of the nest during the first 10 days than body weight in females. For males, body weight was more important. These latter data are discussed in relation to differential interaction between the dam and male and female pups.
Adrenalectomy in the developing rat: Does it cause reduced or increased brain myelination?
Authors: Meyer Jerrold S. , Fairman Kenneth R.
Published: January 2005

We have previously demonstrated increased myelination in adult rats that were adrenalectomized (ADX) neonatally. However, Preston and McMorris (1984) recently reported reduced myelination at Day 21 or 22 in day 14 ADX animals. The present experiment attempted to replicate Preston and McMorris' study to determine whether early adrenalectomy might be producing a transient hypomyelination prior to the hypermyelination observed at later time points. We were unable to duplicate the exact protocol of Preston and McMorris (which involved weaning at Day 18 with administration of saline and glucose drinking solutions) because of 100% mortality of our ADX rats by Day 20. However, using our standard mineralocorticoid replacement therapy which allowed the animals to remain with their mothers, all of the ADX rats survived, and we were able to assess myelination in these animals by means of standard biochemical methods. All measures showed absolutely no reduction in myelination in ADX rats compared with sham‐operated controls. The discrepancy between the present results and those of Preston and McMorris are attributed, at least in part, to the early weaning procedure used by these investigators.
Mediation of passive avoidance learning by nicotinic hippocampo‐entorhinal components in young rats
Authors: Blozovski Denise
Published: January 2005

Young rats, 11, 16, and 20 days of age, received bilateral injections of three antinicotinic agents into the posteroventral hippocampo‐subiculo‐entorhinal area, and were trained to learn a cool‐draft‐stimulus, passiveavoidance task shortly after (17 min). Gallamine triethiodide had no action at low doses and provoked convulsions at higher concentrations. Pempidine tartrate produced ageq and dose‐dependent impairments of the passive avoidance, and was much more effective in younger groups (11 and 16 days) than at 20 days. α‐bungarotoxin also induced dose‐dependent deficits. These results, together with the mecamylamine‐induced deficits already reported, suggest that nicotinic cholinergic synapses located in the posteroventral part of the hippocampal complex play a role in passive‐avoidance learning in the young rat as soon as this type of conditioning is possible, but become relatively less important at older ages, when muscarinic mechanisms also become involved.
Cochlear function and audiogenic seizures: Developmental covariance in the LP/J mouse
Authors: Henry Kenneth R.
Published: January 2005

Innate susceptibility to audiogenic seizures develops and declines at varying rates and ages, depending upon genotype and environmental conditions. Auditory dysfunctions have been experimentally produced which induce susceptibility in otherwise nonsusceptible mouse strains. In order to more closely correlate cochlear functions and audiogenic seizures in genetically susceptible mice, both measures were obtained from LP/J mice, at ages ranging from 8 to 120 days. Susceptibility to sound‐produced convulsions was first noted at 12 days, was maximal from 18 to 32 days, declined rapidly by 40 days, and disappeared by 120 days of age. Cochlear nerve‐evoked potential thresholds were very high at 12 days, were lowest between 18 and 32 days and increased thereafter. The correlation between susceptibility and cochlear thresholds was greatest for high frequencies (r = −.93), intermediate for midfrequency (r = −.77), and poorest for low frequencies (r = −.56). It was concluded that either genetic or environmental factors which produce an intermediate level of high frequency cochlear damage in the young mouse will produce susceptibility to audiogenic seizures.
Neonatal hemidecortication and bilateral cutaneous stimulation in rats
Authors: Schallert Timothy , Whishaw Ian Q.
Published: January 2005

In humans, a dominant somatosensory consequence of extensive unilateral neocortex damage is “simultaneous extinction,” which is an interhemispheric perceptual interaction that is operationally distinguishable from neglect. A tactile stimulus presented on the contralateral side of the body is detected when presented singly, but is completely masked during bilateral stimulation. Analogous tests designed to calibrate somatosensory asymmetries in rats were used to determine the long‐term effects of hemidecortication sustained on postnatal Day 1. These data were compared with that observed in adult operated rats at a comparable postoperative period. In one respect the neonatal brain was more vulnerable than the adult brain. That is, unlike adult operated rats which were tested at 3 postoperative months, a sensory asymmetry appeared to be permanent in the neonatally operated rats, at least for the duration of testing (3–9 months). Further analysis suggested that in another way the neonates were more resistant to the effects of hemidecortication than were the adults. Neonatally operated rats appeared to be capable of processing input from both sides of the body simultaneously, even during markedly asymmetrical input. In other words, the early occurrence of brain damage may have spared them from a condition reminiscent of “simultaneous extinction.” Finally, the adult operated and neonatally operated rats both displayed a subtle motor abnormality. Thus, depending on the test used, the neonatal operation yielded more severe, less severe, or comparable behavior deficits.
Early ontogeny of face grooming in mice
Authors: Golani Ilan , Fentress John C.
Published: January 2005

A U‐shaped function of behavioral growth characterizes the early ontogeny of face grooming in mice. In the first few postnatal days (0–100 hr), mice groom their face by using temporally isolated strokes, or bouts of strokes, which vary in amplitude and symmetry. Later on (100–200 hr), bouts disappear, asymmetry is eliminated, and the amplitude of strokes is gradually restricted; the infants engage in stereotyped, double‐handed, temporally isolated strokes. Finally (200–300 hr), bouts reappear, including both short and long, symmetrical and asymmetrical, strokes. These changes, are accompanied by unidirectional changes such as an increasing participation of the trunk, the neck, and the head in grooming, which lead to the flexible organization of face grooming seen in adults. Instead of describing development in terms of emerging unitary “acts,” we have recorded from high‐speed films three simultaneous aspects of movement: the movements of the separate limb and body segments, the resultant paths which are traced by the forepaws, and the paths of contact which are traced on the face. This method of description disclosed (a) reversible changes, and (b) a change in the relative stability of each of these aspects of face grooming, in the course of early ontogeny.
Spatial cue utilization in chronically malnourished rats: Task‐specific learning deficits
Authors: Goodlett Charles R. , Valentino M. Lisa , Morgane Peter J. , Resnick Oscar
Published: January 2005

Rats whose mothers were maintained on either a 25% casein diet or an 8% casein diet and who were provided the same diet after weaning were tested on delayed spatial alternation or on one of a series of spatial localization problems using the Morris maze (Morris, 1981). Malnourished rats demonstrated perseverative deficits in the form of strings of consecutive errors on the delayed spatial alternation. Performance in the Morris maze indicated spatial localization ability and spatial memory processes were not impaired by chronic malnutrition in rats. The data suggest that complex processing of spatial information that includes flexible use of place cues over short intervals is impaired by malnutrition, while spatial localization per se and spatial mapping are not affected.
Developmental changes in salt acceptability in human infants
Authors: Beauchamp Gary K. , Cowart Beverly J. , Moran Marianne
Published: January 2005

Human infants less than 4 months of age ingested water and moderate concentrations of sodium chloride solution (0.10–0.20 M) in equal amounts. In contrast, infants 4–24 months of age exhibited heightened acceptance of saline solution relative to water. Such a developmental change in salt acceptability is consistent with a hypothesis of postnatal maturation of peripheral and/or central structures underlying this response. Children 31–60 months of age tended to reject saline solution relative to water. This change may in part reflect the effects of experience.
The effect of home cage stimuli on acquisition and retention of an active avoidance response in previsual rats
Authors: Misanin James R. , Lariviere Nancy A. , Turns Alan E. , Turns Laurie E. , Hinderliter Charles F.
Published: January 2005

The effect of home cage environmental stimuli on learning and the effects on retention of the presence or absence of these familiar contextual training stimuli during the retention test (Experiment 1) or during the retention interval (Experiment 2) were examined using 10‐day‐old rats, a multidirectional active avoidance task, and a 30‐min retention intrval. Home cage environmental stimuli were found to improve learning. A change in stimuli immediately after training, during the 30‐min retention interval, was found to have a greater impact on retention performance than stimulus change introduced at the time of the retention test. The implications of these findings are discussed in relation to ontogenetic differences in retention performance and theories of forgetting.
Ontogenetic comparison of memory for pavlovian conditioned aversions to temperature, vibration, odor, or brightness
Authors: Markiewicz Barbara , Kucharski David , Spear Norman E.
Published: January 2005

Ontogenetic differences in forgetting of Pavlovian conditioning were tested in four experiments with 550 rats of ages 12, 18, or 60 days postpartum. The experiments had in common the same unconditioned stimulus (US; footshock) and procedures for conditioning and testing, but the conditioned stimulus (CS) differed. The CS was a particular vibrotactile stimulus (Experiment 1), ambient temperature (Experiment 2), odorant (Experiments 3), or brightness (Experiment 4). The intent of this study was to assess, in more comparable circumstances than previously tested, the possibility of substantial differences in infantile amnesia for different sensory modalities. Particular attention was given those modalities that mature early and had not been tested in previous studies of infantile amnesia. The results verified some degree of infantile amnesia for even those sensory modalities used adaptively from birth.
Spatiotemporal linkage in infant interlimb coordination
Authors: Goldfield Eugene C. , Michel George F.
Published: January 2005

Timing and direction of movement of the arms and hands of 7‐ and 11‐month‐old infants were examined during bimanual reaching for a transparent cube. Videotape analysis of frames from release of the hands to initial contact of one hand with the cube revealed that hand movement was more often temporally linked for 7‐month infants than for 11‐month infants. Also, at 7 months, the hands moved toward the cube in the same direction, whereas at 11 months, they moved in opposite (complementary) directions. Thus, although both 7‐ and 11‐month infants perform bimanual reaching, at 7 months the 2 hands are linked both in timing and direction of movement in a fashion different than at 11 months.
Opioid‐mediation of separation distress in 10‐day‐old rats: Reversal of stress with maternal stimuli
Authors: Kehoe Priscilla , Blass Elliott M.
Published: January 2005

A relationship between distress vocalizations, response to nociception and their opioid mediation in 10‐day‐old maternally isolated rat pups was established. The comforting effects of several classes of biological stimuli were examined. Short‐term (5 min) isolation from mother, siblings and nest caused a significant analagesic repsonse to heat (48°C) relative to nonisolated siblings. Morphine administration markedly increased heat escape latencies and decreased distress vocalizations during isolation. Naltrexone, and opioid antagonist, had the opposite effect; escape latencies were halved and distress vocalizations doubled. Contact with an anesthetized female, dam or virgin, immediately reduced both analgesia and vocalizations. Home‐bedding was only effective after 5 min exposure, whereas clean bedding did not reduce isolation‐induced behaviors. These results are discussed in terms of infant learning and motivation under natural circumstances.
Developmental changes in chickens' masked thresholds
Authors: Gray Lincoln
Published: January 2005

Masked thresholds were estimated at four frequencies (.25, .5, 1, and 2 kHz) in three levels of broadband noise (approximately 0, 10, and 20 dB/Hz) in over 100 chickens at 0 and 4 days of age. An adaptive procedure was based on delays in ongoing peeps that occurred when chicks heard the tones over the background noise. Masked thresholds decreased an average of 1 dB per day immediately after birth. This increasing sensitivity is more likely due to nonsensory factors, similar to distraction masking reported in human neonates, than to improving frequency resolution. Masked thresholds in these neonates are otherwise affected by spectrum level and frequency in the same way as the responses of mature subjects: thresholds increase by nearly 1 dB for each dB of increase in the spectrum level of the masker, and by approximately 3 dB for each octave of frequency. Thus, although elevated by some nonsensory effect, masked thresholds in newborn chicks are similar to those in humans. © 1993 John Wiley & Sons Inc.
The effect of an intensive care unit sound environment on the development of habituation in healthy avian neonates
Authors: Kathleen Philbin M. , Ballweg Diane D. , Gray Lincoln
Published: January 2005

There is increasing concern that environmental stimuli in the Neonatal Intensive Care Unit (NICU) may be detrimental to the preterm infants hospitalized there. Separately, there is longstanding recognition that preterm infants at 40 weeks postconceptional age habituate less reliably than full‐term infants. This study uses a relevant animal model to test whether exposure to NICU sounds, as a single departure from normal neonatal experience, can alter habituation. Chicks were incubated, hatched, and reared in either a quiet or a NICU‐sound environment. Habituation was measured by the length of time that chicks delay their ongoing peeping upon hearing a white noise stimulus. NICU‐sound‐reared 4‐day‐olds failed to habituate, showing as much responsiveness at the end of repeated stimulation as at the beginning. This is, to our knowledge, the first demonstration that atypical sound exposure alone can alter this fundamental aspect of neurosensory competence in an otherwise healty neonate.© 1994 John Wiley & Sons, Inc.
Functional analysis of spontaneous movements in preterm infants
Authors: Hayes Marie J. , Plante Lonnie S. , Fielding Brenda A. , Kumar Savitri P. , Delivoria‐Papadopolos Maria
Published: January 2005

Spontaneous movements of premature infants between 25 and 34 weeks conceptional age were observed for 1 hr on two or three occasions. Subjects had low‐risk prognoses and were clinically stable at the time of testing. Behavioral acts were scored using a 0/1 time sampling technique in 60 continuous, 1‐min time blocks. Temporal associations between individual movements were found using chi‐square analyses. Some associated behaviors contained combinations consistent with neonatal action patterns, for example, single and bilateral leg kicking, head turning, and mouthing. Features of state organization were also evident in that general motor activity (GM), which has been used as a marker of active sleep (AS) in neonates, was found to cluster temporally with startle, facial, and head movements but not eye movements. Behavioral quiescence (≥5 s) was dissociated from AS‐related behaviors (GM, facial, head, and eye movements). Combinations of state‐segregated behaviors were more likely to exhibit co‐occurrence within 1‐min intervals in infant 30 weeks conceptional age and older.
Behavioral and hormonal responses to stress in the newborn mouse: Effects of maternal deprivation and chlordiazepoxide
Authors: Cirulli Francesca , Santucci Daniela , Laviola Giovanni , Alleva Enrico , Levine Seymour
Published: January 2005

These studies investigated behavioral and hormonal responses to stress in developing mice. Experiment 1 examined the effects of 24‐hr maternal deprivation on corticosterone (CORT) secretion and ultrasonic vocalization (UVZ) rate in 4‐, 8‐, and 12‐day‐old mice. At these ages, exposure to a novel environment resulted in minimal changes in CORT secretion. Maternal deprivation increased pups′ CORT secretion in an age‐dependent fashion but did not affect their UVZ rate.

The aim of experiment 2 was to test the effects of cholordiazepoxide (CDP), an anxyolytic compound, on CORT secretion and UVZ in both normally reared and in maternally deprived 8‐day‐old mice. CDP administration elevated CORT increases in deprived (DEP) animals. CDP affected UVZ only in nondcprived (NDEP) animals: UVZ ratewas decreased by high CDP doses

Overall, these findings demonstrate that the infant mouse shows a period of stress hyp9oresponsiveness similar to the rat and that maternal presence contributes to inhibit adrenocorticalactivity. CDP administration, butnot novelty exposure, increased CORT secretion in 8‐day‐ old normally reared mice suggesting that during the stress hyporesponsive period, the HPA axis is capable of responding only to specific stimuli. Changes in HPA axis activity and UVZ rateresulting from maternal deprivation and/or CDP challenge do not seem to be directly related. ©1994 John Wiley & Sons, Inc.
Response to maternal separation in infant guinea pigs exposed to intrapartum meperidine
Authors: Golub Mari S. , Kaaekuahiwi Margaret A.
Published: January 2005

We investigated whether opiate analgesics as commonly administered to women during labor would affect later response to maternal separation in infant guinea pigs. Meperidine hydrochloride (10–15 mg/kg i.m.) was administered to late‐pregnant guinea pigs 5 min prior to labor induction with oxytocin. On Day 11 or 12 postnatal, pup distress vocalizations, locomotor activity, and plasma cortisol were measured under one of two conditions: alone (alone in a novel environment for 30 min) or mother (with the dam in the novel environment). Female pups exposed to intrapartum meperidine emitted fewer vocalizations than controls in the alone condition. Plasma cortisol was higher in meperidine females in the alone condition than in controls at the end of the separation period, but the difference was not significant. There was no drug effect on vocalizations or cortisol in males. Neither test condition nor drug affected activity level. The data suggest that intrapartum opiates may alter separation‐induced distress in female guinea pig infants. © 1995 John Wiley & Sons, Inc.
Systematic changes in gaping during the ontogeny of pecking in ring doves (Streptopelia risoria)
Authors: Deich James D. , Tankoos Jenine , Balsam Peter D.
Published: January 2005

Food pecking in the ring dove is a skilled prehensile response that is similar to, but simpler than, many other prehensile responses. Previous work has shown that this response is initially poorly executed and requires experience for its accurate direction and coordination. The response involves two components: the thrusting of the bird's head toward food, and the opening and closure of the beak around food. Here, this second component, called gape, is followed through development with a precise measurement system. Four squabs moved through a similar sequence of three gape topographies, each of which is more efficient in picking up seed, during development. The present outcome, together with other work, argues for a substantial contribution of experience with pecking to the development of food pecking. We discuss the implications of these findings for understanding the ontogeny of motor control and for understanding how experience affects behavioral development. © 1995 John Wiley & Sons, Inc.
The influence of flavor and color on drink identification by children and adults
Authors: Oram Nicholas , Laing David G. , Hutchinson Ian , Owen Joanne , Rose Grenville , Freeman Melanie , Newell Graeme
Published: January 2005

This study investigated how color and flavor influences drink identification by children and adults. The children ranged in age from 2 to 18 years of age. Each subject tasted four drinks that differed in color and flavor. Each drink had an atypical color–flavor pairing (e.g., brown–pineapple) or a typical pairing (e.g., brown–chocolate). After tasting each drink, the subject chose which of four flavor names identified the drink. For the atypical drinks, the selection of color‐associated names (e.g., chocolate for a brown drink) decreased, and the selection of flavor‐associated names increased with age from the preschoolers to the adults. For the typical drinks, the selection of the correct name was greater than 80% for all ages. These results suggest that drink identification becomes more influenced by flavor as children get older because of an increase in the ability of children to focus on flavor as their perceptual‐attentional skills mature. © 1995 John Wiley & Sons, Inc.
Neonatal medial prefrontal lesions and recovery of spatial delayed alternation in the Rat: Effects of delay interval
Authors: Carter Christy S. , Freeman John H. , Stanton Mark E.
Published: January 2005

We have previously shown that rats given medial prefrontal lesions on postnatal Day 10 show a performance deficit on spatial delayed alternation (2‐s delay) when tested between Days 19 and 23, but show recovery of function by Days 27–33 (Freeman & Stanton, 1992). The present study attempted to (a) examine the effects of extending the delay interval from 2 s to 15 or 45 s on the ontogeny of spatial delayed alternation; and (b) determine whether these longer delays would alter the ontogenetic profile of recovery from medial prefrontal damage. Animals were given medial prefrontal lesions (mPFC) or sham surgery on Day 10. They received acquisition training on delayed alternation with a 2‐s delay on Day 21 or Day 28, followed by “probe” tests at delays of 15 and 45 s on the following day (Day 22 or Day 29). On Days 21–22 there was an overall effect of lesion at the 2‐, 15‐, and 45‐s delay intervals indicating and early deficit. However, on Days 28–29 there was no effect of lesion at the end of acquisition or at the 15‐ or 45‐s delay intervals. Recovery of memory function by mPFC animals on this task appears to occur during the weanling period regardless of delay interval. © 1995 Johnv Wiley & Sons, Inc.
Auditory brainstem response in sheep. Part I: Fetal development
Authors: Pierson Linda L. , Gerhardt Kenneth J. , Griffiths Scott K. , Abrams Robert M.
Published: January 2005

The Auditory Brainstem Response (ABR) was recorded from fetal sheep in utero between gestational ages of 111 days and 136 days (Normal gestation is 145 days). The ABR was detected at 111 days gestation (dGA) and morphology of the waveform improved rapidly from 116 to 123 dGA. At 123 dGA, the four vertex‐positive peaks were similar to those observed in adult ewes. Thresholds of the ABR to clicks and tone bursts improved rapidly between 111 and 123 dGA. From 123 to 136 dGA, ABR thresholds continued to improve, but at a much slower rate. Latencies for the peaks also decreased during development from 111 to 136 days, with latencies for Waves III and IV showing a greater decrease than latencies for Waves I and II. © 1995 John Wiley & Sons, Inc.
The surface evoked potential and parvalbumin‐immunoreactivity in the somatosensory cortex of the developing rat
Authors: Seo‐Hiraiwa Misako L. , Seto‐Ohshima Akiko , Kato Kanefusa
Published: January 2005

The development of the rat somatosensory system was followed electrophysiologically and immunohistochemically. In the surface evoked potential elicited in the primary somatosensory cortex by electrical stimulation of the whisker C3 follicle, a short‐latency positive wave was first recorded on postnatal Day 2. A longlatency positive wave was recorded in some pups on postnatal Day 7 and in most pups on postnatal Day 8. On postnatal Day 10, a P/N complex appeared between the short‐ and long‐latency positive waves. Parvalbumin, believed to appear with functional maturation, appeared mainly after postnatal Day 7 in Layer V in the underlying area, although a few weakly stained cells appeared on postnatal Day 5. On postnatal Day 10, weakly stained cells appeared in the area containing barrels; their staining increased with time. In this system, electrophysiological and immunohistochemical parameters changed by the 3rd postnatal week with the most marked changes occurring within 2 postnatal weeks. © 1995 John Wiley & Sons, Inc.
Responses of infant Titi monkeys, Callicebus moloch, to removal of one or both parents: Evidence for paternal attachment
Authors: Hoffman Kurt A. , Mendoza Sally P. , Hennessy Michael B. , Mason William A.
Published: January 2005

The response to parental separation in infant titi monkeys was evaluated. Separation from the mother for 1 hr did not elicit an adrenocortical response from the infant unless the father was also removed. Separation from the father elicited a significant elevation in adrenocortical activity even when the mother remained with the infant during the separation period. Infants showed the highest cortisol levels and vocalization rates when both parents were removed and the infant remained alone in the living cage for 1 hr. As in previous research, infants maintained higher levels of contact with the father than with the mother. The results indicate that in this monogamous New World primate, the father is the primary attachment figure for the developing infant. © 1995 Johnv Wiley & Sons, Inc.
Asymmetry of finger temperature and early behavior
Authors: Kagan Jerome , Arcus Doreen , Snidman Nancy , Peterson Eric , Steinberg Donna , Rimm‐Kaufman Sara
Published: January 2005

Measures of the temperature of the fingertips of eighty‐three 4‐year‐old children revealed an unexpected asymmetry in which the index finger of the left hand but the ring finger of the right hand were the coolest digits. In addition, a subset of 20 children who had the coolest right compared with the left ring finger were more fearful to unfamiliar events and also had a cooler right than left forehead at 21 months of age. © 1995 John Wiley & Sons, Inc.
The C4H4CO potential surface. Reactions involving bicyclo[2.1.0]pentenone
Authors: Schweig Armin , Thiel Walter
Published: January 2005

MNDO and MINDO/3 calculations were used to study the photochemical formation, thermal rearrangements, and dissociation of bicyclo[2.1.0]pentenone. The “forbidden” thermal conversion to cyclopentadienone requires little activation, which accounts for the low kinetic stability of bicyclo[2.1.0]pentenone. The theoretical results seem to be compatible with the available experimental evidence for the tri‐tert‐butyl‐substituted systems and suggest an explanation for observed differences in reactivity.