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Experiments
Kinds of Experiments Terms modified by Experiments Selected AbstractsTesting Usability of Butylated Hydroxytoluene in Conservation of Goat SemenREPRODUCTION IN DOMESTIC ANIMALS, Issue 5 2008TAA Khalifa Contents The objective of this study was to investigate whether butylated hydroxytoluene (BHT) could be used as a suitable supporter or alternative of egg yolk during preservation of goat spermatozoa. Three in vitro experiments and a fertility test were conducted to evaluate the effect of BHT on viability of chilled-stored semen as well as motility and kidding rate of frozen-thawed spermatozoa. In the first two experiments, ejaculates (n = 30/experiment) were collected from 10 bucks, split, diluted with egg yolk-based and egg yolk-free extenders supplemented with or without 0.3, 0.6, 2, 5 and 8 mm BHT and stored at 5°C for 168 h. In the third experiment, 30 ejaculates were collected from the above-mentioned bucks, split and diluted with egg yolk-free extenders supplemented with or without 0.3, 0.6 and 0.9 mm BHT and egg yolk-based extenders supplemented with or without 5 mm BHT. Diluted semen was cooled to 5°C over a period of 4 h, frozen and thawed in the form of 0.3-ml pellets. In the fertility test, 75 ejaculates were collected from two proven fertile bucks, split, diluted with egg yolk-free extenders containing 0.6 mm BHT and egg yolk-based extenders supplemented with or without 5 mm BHT, frozen and thawed as described above. An insemination volume of 0.6 ml containing 120,140 × 106 progressively motile spermatozoa was used for a single cervical insemination of cloprostenol-synchronized does (n = 230). The results showed that addition of 5 mm BHT to egg yolk-deficient (2.5%) extenders significantly improved viability of chilled-stored semen together with motility (48.5%) and fertility (62.5%) of frozen-thawed spermatozoa. Replacement of egg yolk in semen extenders by 0.6 mm BHT could sustain not only viability of chilled-stored semen but also post-thaw motility (47.5%) and fertility (53.75%) of frozen-thawed spermatozoa. In conclusion, supplementation of semen diluents with BHT can ameliorate preservability of goat sperm. [source] UNITED STATES V. BOOKER AS A NATURAL EXPERIMENT: USING EMPIRICAL RESEARCH TO INFORM THE FEDERAL SENTENCING POLICY DEBATE,CRIMINOLOGY AND PUBLIC POLICY, Issue 3 2007PAUL J. HOFER Research Summary: In United States v. Booker, the U.S. Supreme Court held that the federal sentencing guidelines must be considered advisory, rather than mandatory, if they are to remain constitutional under the Sixth Amendment. Since the decision, the U.S. Sentencing Commission has provided policy makers with accurate and current data on changes and continuity in federal sentencing practices. Unlike previous changes in legal doctrine, Booker immediately increased the rates of upward and downward departures from the guideline range. Government-sponsored downward departures remain the leading category of outside,the-range sentences. The rate of within-range sentences, although lower than in the period immediately preceding Booker, remains near rates observed earlier in the guidelines era. Despite the increase in departures, average sentence lengths for the overall caseload remain stable, because of offsetting increases in the seriousness of the crimes being sentenced and in the severity of penalties for those crimes. Analyses of the reasons that judges reported for downward departures suggest that treatment of criminal history and offender characteristics are the two leading areas of dissatisfaction with the guidelines. Policy Implications: Assessment of changes in sentencing practices following Booker by different observers depends partly on competing institutional perspectives and on different degrees of trust in the judgment of judges, prosecutors, the Sentencing Commission, and Congress. No agreement on whether Booker has bettered or worsened the system can be achieved until agreement exists on priorities among the purposes of sentencing and the goals of sentencing reform. Both this lack of agreement and an absence of needed data make consensus on Booker's effects on important sentencing goals, such as reduction of unwarranted disparity, unlikely in the near future. Similarly, lack of baseline data before Booker on the effectiveness of federal sentencing at crime control makes before-after comparisons impossible. Despite these limitations, research provides a sounder framework for policy making than do anecdotes or speculation and sets valuable empirical parameters for the federal sentencing policy debate. [source] TESTING THE QUALITY OF A CARRIER: A FIELD EXPERIMENT ON LIZARD SIGNALERSEVOLUTION, Issue 3 2009Mats Olsson In the Australian painted dragon lizard (Ctenophorus pictus), males occur in two different morphs with respect to gular color, with or without a yellow bib. Males without a bib lost within-clutch paternity significantly more often to rivals than bibbed males. Thus, it appears that bibs identify some phenotypic advantage linked to competitive ability. To test whether this could be related to whole-organism capacity to withstand an increased workload (due to better health and vigor, or evolved differences in self-maintenance), we implanted males with a lead pellet (loaded), Styrofoam pellet (controls), or sham-operated males without implants (shams), and compared male categories with respect to how they maintained body mass during the mating season. Somewhat unexpectedly, bibbed males consistently lost more body weight across all treatments and controls, although we could not verify that this translated into higher mortality in this short-lived animal (about 80% survive for one year only). However, bibbed males may invest more into "mating success" than nonbibbed males, which agrees with our experimental results and paternity data. [source] THE FISH POND EXPERIMENT: CHAPTER TWOJOURNAL OF PHYCOLOGY, Issue 2000A.W. Coleman Forty years ago, after 1 1/2 years of weekly surveys, a Baltimore fishpond was inoculated with three identifiable clones of Pandorina morum. The results of subsequent recollection attempts are published in Amer. Naturalist 118:761 (1981). More recently, molecular analyses have permitted characterization of the P. morum population that was endemic to the pond. The results, and their comparison with those from other P. morum sites, challenge some longstanding assumptions concerning the importance of various lifehistory stages to the introduction and maintenance of algal populations in temperate freshwater locales. [source] FIELD STUDY OF ALGAL RECRUITMENT BY CLEARING EXPERIMENT IN PING CHAU, HONG KONG SAR, CHINAJOURNAL OF PHYCOLOGY, Issue 2000S. L. Kong Recruitment, the entry of new individuals into a population, was investigated by a clearing experiment along the shore of A Ma Wan (AMW) in Ping Chau, Hong Kong SAR, China. Two types of clearing, with all the existing vegetation removed (cleared) and with the top 2 to three mm of the rock surface removed (hammered), were carried out monthly in AMW from November 1997 to June 1999. Observations were made one month after clearing and on a monthly basis thereafter. The number of algal species present on the cleared areas and their percentage cover were recorded. The experimental results showed that more algal species were recruited during March and April in 1998 (n=10) but in 1999, the number of species was found higher in February and March (n=8). Species richness dropped after May (more obvious in 1998), indicating that recruitment greatly declined in summer. A tuft complex composed of several filamentous algal species dominated over the others in all clearing areas (coverage mostly over 90%) but recruits of Caulerpa peltata, Colpomenia sinuosa, Enteromorpha sp., Hypnea charoides, Padina spp., Sargassum sp., Spyridia filamentosa, Ulva sp., etc. also were observed during the study period. Generally, there were no significant differences in terms of species richness and composition of the recruits between the two treatments (cleared vs. hammered) as well as with the controls. This implied that algae in AMW were more likely to be recruited de novo from elsewhere rather than regenerated from remnants of the previous year's growth. [source] INDEPENDENCE DAY FOR THE ,OLD LADY': A NATURAL EXPERIMENT ON THE IMPLICATIONS OF CENTRAL BANK INDEPENDENCE,THE MANCHESTER SCHOOL, Issue 3 2007JAGJIT S. CHADHA Central bank independence is widely thought be a sine qua non of a credible commitment to price stability. The surprise decision by the UK government to grant operational independence to the Bank of England in 1997 affords us a natural experiment with which to gauge the impact on the yield curve from the adoption of central bank independence. We document the extent to which the decision to grant independence was ,news' and illustrate that the reduction in medium- and long-term nominal interest rates was some 50 basis points, which we show to be consistent with a sharp increase in policy-maker's aversion to inflation deviations from target. We therefore suggest that central bank independence represents one of the clearest signals available to elected politicians about their preferences on the control of inflation. [source] THE TRAVELING SEMINAR: AN EXPERIMENT IN CROSS-CULTURAL TOURISM AND EDUCATION IN TAIWANANNALS OF ANTHROPOLOGICAL PRACTICE, Issue 1 2005DAVID BLUNDELL This article explores the anthropologist's role in facilitating and guiding international educational traveling seminars through interaction with local people, based on my experiences with such seminars in Taiwan. Since the late 1980s, the Taiwanese authorities have reviewed restricted space, converting it into scenic areas and national parks. Martial law was lifted, allowing for changes in the society and introducing a "green" consciousness concerned with examining local roots. In 1992, a method of tourism was developed in which the participants of traveling seminars visited places in Taiwan or other world locations expecting to (1) explore, (2) learn, (3) interact, (4) respect, (5) share qualitative feedback with one another, and (6) enjoy the process. When addressing a topic for discussion, such as cultural heritage or the environment, each member of such traveling seminars speaks in his or her own language to share with the group. That is to say, participants explore through travel as a learning process, interacting with others with concern and respect for differences, sharing experiences, and conversing in their mother tongues with translation assistance. [source] INLINE RADIOFREQUENCY ABLATION-ASSISTED LAPAROSCOPIC LIVER RESECTION: FIRST EXPERIMENT WITH STAPLING DEVICEANZ JOURNAL OF SURGERY, Issue 6 2007Peng Yao Background: In liver surgery, the increase in advancement of laparoscopic equipment has allowed the feasibility and safety of complex laparoscopic liver resection. However, blood loss and the potential risk of gas embolism seem to be the main obstacles. In this study, we successfully used the InLine radiofrquency ablation (RFA) device to carry out laparoscopic hand-assisted liver resection in pigs. Methods: Under general anaesthesia with tracheal intubation, pigs underwent InLine RFA-assisted laparoscopic liver resection. After installation of Hand Port and trocars, the InLine RFA device was introduced through Hand Port system and inserted into the premarked resection line. Then the generator was turned on and the power was applied according to the power setting. The resection was finally carried out using diathermy or stapler. For the control group, resection was simply carried out by diathermy or stapler. Results: Eight Landrace pigs underwent 23 liver resections. Blood loss was reduced significantly in the InLine group (P < 0.001) when compared with control group in both surgical methods (diathermy and stapler). Conclusion: In this study, we successfully carried out InLine RFA-assisted laparoscopic liver resection in both stapled and diathermy group. We showed that there was a highly significant difference between InLine and other liver resection techniques laparoscopically. [source] PRECISION OF HERBIVORE TOLERANCE EXPERIMENTS WITH IMPOSED AND NATURAL DAMAGEEVOLUTION, Issue 3 2003Kari Lehtilä Abstract Tiffin and Inouye (2000) discussed the use of natural and imposed (controlled) damage in experiments of herbivore tolerance. They constructed a statistical model of the effect of herbivory on plant fitness, including damage level and an environmental factor as the independent factors, in which tolerance is defined as a slope of the regression line when damage level is regressed with plant fitness. They claim that while experiments with imposed damage are more accurate (i.e., they give a more correct estimate of tolerance), experiments with natural damage are more precise under a wide range of parameter values (i.e., tolerance estimates explain a larger part of variation in fitness). I show, however, that experiments with imposed damage are less precise only when an experimenter uses an experimental design that has weaker statistical power than in experiments with natural herbivory. The experimenter can nevertheless control the damage levels to optimize the experimental designs. For instance, when half of the experimental plants are left undamaged and the other half treated with maximal relevant damage level, experiments with imposed damage are almost always much more precise than experiments with natural damage. [source] OF UNDERWATER EXPLOSION EXPERIMENTS ON PLANE PLATESEXPERIMENTAL TECHNIQUES, Issue 1 2007R. Rajendran First page of article [source] A COST-EFFECTIVE EDUCATIONAL PENDULUM FOR IMPACT EXPERIMENTSEXPERIMENTAL TECHNIQUES, Issue 2 2002D. Carter No abstract is available for this article. [source] IN BETWEEN CURING AND COUNTING: PERFORMATIVE EFFECTS OF EXPERIMENTS WITH HEALTHCARE INFORMATION INFRASTRUCTUREFINANCIAL ACCOUNTABILITY & MANAGEMENT, Issue 3 2007Signe Vikkelsř Performance standards and accountability pervade modern healthcare. According to Michael Power, this may signify a new rationality of governance characterized by control of controls, which affects practices not by direct intervention, but through the processes by which practices are made auditable. The paper addresses this thesis by exploring the construction of a Danish standard for electronic patient records. It is shown that making healthcare auditable activates deep tensions between programs of clinical practice, quality control, evidence based medicine, and casemix funding, resulting in an ambiguous and unstable standard. During this process, however, particular notions of patients, diseases, and diagnoses emerge as undisputed innovations, which may come to survive the subsequent career of the standard. The paper discusses the performative effects of these innovations and argues that information infrastructure has become an analytically important site for exploring the substantial effects of new rationalities of governance in healthcare. [source] FIELD EXPERIMENTS SHOW THAT ACOUSTIC PINGERS REDUCE MARINE MAMMAL BYCATCH IN THE CALIFORNIA DRIFT GILL NET FISHERYMARINE MAMMAL SCIENCE, Issue 2 2003Jay Barlow Abstract A controlled experiment was carried out in 1996,1997 to determine whether acoustic deterrent devices (pingers) reduce marine mammal bycatch in the California drift gill net fishery for swordfish and sharks. Using Fisher's exact test, bycatch rates with pingers were significantly less for all cetacean species combined (P < 0.001) and for all pinniped species combined (P= 0.003). For species tested separately with this test, bycatch reduction was statistically significant for short-beaked common dolphins (P= 0.001) and California sea lions (P= 0.02). Bycatch reduction is not statistically significant for the other species tested separately, but sample sizes and statistical power were low, and bycatch rates were lower in pingered nets for six of the eight other cetacean and pinniped species. A log-linear model relating the mean rate of entanglement to the number of pingers deployed was fit to the data for three groups: short-beaked common dolphins, other cetaceans, and pinnipeds. For a net with 40 pingers, the models predict approximately a 12-fold decrease in entanglement for short-beaked common dolphins, a 4-fold decrease for other cetaceans, and a 3-fold decrease for pinnipeds. No other variables were found that could explain this effect. The pinger experiment ended when regulations were enacted to make pingers mandatory in this fishery. [source] TOOLS TO QUALIFY EXPERIMENTS WITH BLOOMERY FURNACES*ARCHAEOMETRY, Issue 1 2010M. SENN Five experimental bloomery iron ore smelts were carried out in a reconstruction of an early medieval furnace of the Boécourt type (Switzerland). A part of the bloom from the most successful experiment was forged to a billet. Starting materials and products were weighed, described and chemically characterized (ICP-MS, LA-ICP-MS and WD-XRF). The calculation of the yield and mass balance based on the chemical analyses from the ore (optimum) and from the ore, furnace lining, slag and ash (applied) allow the determination and quantification of the materials involved in the process. This permits the interpretation of the quality of the experiments. The chemical characterization of metal produced from hematite ore from the Gonzen Mountains in Switzerland gives archaeologists the possibility to compare the metal of iron artefacts to metal from this mine. Finally a good agreement between experiments and archaeological reality can be shown. [source] Eulerian backtracking of atmospheric tracers.THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 615 2006II: Numerical aspects Abstract In Part I of this paper, a mathematical equivalence was established between Eulerian backtracking or retro- transport, on the one hand, and adjoint transport with respect to an air-mass-weighted scalar product, on the other. The time symmetry which lies at the basis of this mathematical equivalence can however be lost through discretization. That question is studied, and conditions are explicitly identified under which discretization schemes possess the property of time symmetry. Particular consideration is given to the case of the LMDZ model. The linear schemes used for turbulent diffusion and subgrid-scale convection are symmetric. For the Van Leer advection scheme used in LMDZ, which is nonlinear, the question of time symmetry does not even make sense. Those facts are illustrated by numerical simulations performed in the conditions of the European Transport EXperiment (ETEX). For a model that is not time-symmetric, the question arises as to whether it is preferable, in practical applications, to use the exact numerical adjoint, or the retro-transport model. Numerical results obtained in the context of one-dimensional advection show that the presence of slope limiters in the Van Leer advection scheme can produce in some circumstances unrealistic (in particular, negative) adjoint sensitivities. The retro-transport equation, on the other hand, generally produces robust and realistic results, and always preserves the positivity of sensitivities. Retro-transport may therefore be preferable in sensitivity computations, even in the context of variational assimilation. Copyright © 2006 Royal Meteorological Society [source] FASTEX IOP 18: A very deep tropopause fold.THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 577 2001I: Synoptic description, modelling Abstract The life cycle of a very deep tropopause fold (820 hPa) is documented with aircraft and ship observations during the Intensive Observing Period 18 of the Fronts and Atlantic Storm-Track EXperiment (FASTEX). The initial setting involves a coherent tropopause disturbance and an associated Arctic tropopause fold. The confluence episode that results from the phasing up of the tropopause disturbance and a southern ridge, ends in the formation of an intense jet streak, the dynamics of which are associated with the development of a polar tropopause fold. A diagnostic analysis suggests that the final dramatic stratospheric intrusion is the consequence of the vertical superposition of the Arctic and polar tropopause folds. The Mesoscale Non-Hydrostatic (Meso-NH) model is used to discuss this hypothesis. Mixing of the passive stratospheric tracer within the marine boundary layer is investigated with sensitivity tests which unplug, in turn, the model physical parametrizations. Finally, upper-level forcings associated with the development of the tropopause fold are investigated in detail in a companion paper. [source] Analytical Models for the Design of the LAPLAS ExperimentCONTRIBUTIONS TO PLASMA PHYSICS, Issue 4-5 2007A. R. Piriz Abstract We review the theoretical activity at the University of Castilla-LaMancha directed to the design of the LAPLAS (Laboratory of Planetary Sciences) experiment in the framework of the HEDgeHOB international collaboration. We have developed analytical models for the different phases of LAPLAS, including models for the implosion of the cylindrical shell target, for the generation of an annular focal spot by means of a high-frequency wobbler system and for the hydrodynamic instabilities that could affect the performance of the target implosion. These models have been complemented with one and two-dimensional numerical simulations and such a combination have allowed us to have a powerful tool available for the design of the experiments as well as for the interpretation of their results. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A strategy to communicate corporate social responsibility: cause related marketing and its dark sideCORPORATE SOCIAL RESPONSIBILITY AND ENVIRONMENTAL MANAGEMENT, Issue 1 2009Ilaria Baghi Abstract Cause related marketing (CRM) is a strategy that aims to communicate a company's striving for corporate social responsibility and to improve brand image. A strategy to increase consumers' emotional involvement toward a product,cause association is to describe the cause in vivid terms. In two experiments we investigated how vivid messages might increase the effectiveness of CRM strategy. We sought to demonstrate that a vivid description of the cause could influence consumers' preferences and trust in the effective use of money collected by selling the product. Experiment 1 results showed that individuals prefer products associated with a vivid message of the social cause rather than products associated with a pallid message. Experiment 2 results suggested that vivid messages induce more positive affective reactions and a higher trust in the effective use of money than pallid ones. In the final section, the implications of CRM for corporate social responsibility are discussed. Copyright © 2008 John Wiley & Sons, Ltd and ERP Environment. [source] Dopamine receptors modulate ethanol's locomotor-activating effects in preweanling ratsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 1 2010Carlos Arias Abstract Near the end of the second postnatal week motor activity is increased soon after ethanol administration (2.5,g/kg) while sedation-like effects prevail when blood ethanol levels reach peak values. This time course coincides with biphasic reinforcement (appetitive and aversive) effects of ethanol determined at the same age. The present experiments tested the hypothesis that ethanol-induced activity during early development in the rat depends on the dopamine system, which is functional in modulating motor activity early in ontogeny. Experiments 1a and 1b tested ethanol-induced activity (0 or 2.5,g/kg) after a D1-like (SCH23390; 0, .015, .030, or .060,mg/kg) or a D2-like (sulpiride; 0, 5, 10, or 20,mg/kg) receptor antagonist, respectively. Ethanol-induced stimulation was suppressed by SCH23390 or sulpiride. The dopaminergic antagonists had no effect on blood ethanol concentration (Experiments 2a and 2b). In Experiment 3, 2.5,g/kg ethanol increased dopamine concentration in striatal tissue as well as locomotor activity in infant Wistar rats. Adding to our previous results showing a reduction in ethanol induced activity by a GABA B agonist or a nonspecific opioid antagonist, the present experiments implicate both D1-like and D2-like dopamine receptors in ethanol-induced locomotor stimulation during early development. According to these results, the same mechanisms that modulate ethanol-mediated locomotor stimulation in adult rodents seem to regulate this particular ethanol effect in the infant rat. © 2009 Wiley Periodicals, Inc. Dev Psychobiol 52: 13,23, 2010 [source] Olfactory learning in the rat immediately after birth: Unique salience of first odorsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 6 2009Stacie S. Miller Abstract An infant rat's chance of survival is increased when it remains close to the nest. Early olfactory learning supports such adaptive behavior. Previous experiments indicated that non-associative odor exposure immediately after birth promoted later attachment to a similarly scented artificial nipple. The goal of the current experiments was to extend these findings on olfactory learning in the hours after birth by: exposing pups to more than one odor exposure (Experiment 1), dissecting the role of timing versus order of odor exposure (Experiment 2), testing the odor specificity of these effects (Experiments 3 and 4), and evaluating associative odor conditioning soon after birth (Experiment 5). Without explicit prior odor experience, pups only hours old do not respond much to a novel odor. Prior non-associative odor experience increases later motor activity to that same odor and to novel odors. Furthermore, these findings may be specific to certain amodal dimensions of the (in our case) lemon odor exposure. Single odor non-associative and associative conditioning was equally effective immediately after birth and during the third postnatal hour. Nevertheless, pups given two mere odor exposures responded to the first one more than the second at test, regardless of whether the exposures began immediately or 2,hr after birth. Possible mechanisms for these findings concerning early olfactory learning are discussed. © 2009 Wiley Periodicals, Inc. Dev Psychobiol 51: 488,504, 2009 [source] Maternal care affects the development of maternal behavior in inbred miceDEVELOPMENTAL PSYCHOBIOLOGY, Issue 4 2009Hirotaka Shoji Abstract The present study investigated the effects of variations in maternal behavior on the development of maternal behavior of female offspring in BALB/c and CBA/Ca inbred mice. In Experiment 1, we conducted fostering within or between the two strains and observed the maternal behaviors of mothers and female offspring for 2 weeks postpartum. Although fostering changed the maternal behavior of mothers in both strains, CBA mothers generally showed greater frequency of nursing posture and pup licking than BALB mothers. BALB female offspring reared by CBA mothers showed more body licking than those reared by BALB mothers, whereas fostering did not affect the maternal behavior of CBA female offspring. In Experiment 2, we examined the maternal behavior of females of F1 hybrids derived from reciprocal crosses between the two strains to confirm the maternal effect demonstrated in Experiment 1. Female F1 hybrids from CBA mothers showed more arched-back nursing, body licking, and nest building than those from BALB mothers. These results suggested that maternal care affect the development of maternal behavior in inbred mice, though the contributions of genetic and prenatal factors cannot be ignored. © 2009 Wiley Periodicals, Inc. Dev. Psychobiol 51: 345,357, 2009. [source] Therapeutic effects of complex rearing or bFGF after perinatal frontal lesionsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 2 2008Wendy Comeau Abstract We investigated the effects of an enriched environment and/or basic fibroblast growth factor (bFGF) on recovery from neonatal frontal injury in rats. Rats received medial frontal lesions, or sham surgery, on postnatal day (P) 2/3. In the first set of experiments (Experiments 1 and 2), rats were housed in enriched environments that consisted of a large enclosure with multiple objects (or standard housing) for 90 days beginning at weaning (P22) or in adulthood (P110). In Experiment 3, the rats either received 7 days of subcutaneous bFGF beginning on the day after surgery or bFGF plus enriched housing beginning at weaning. After the 90-day housing period, the animals were tested on a spatial navigation task and a skilled reaching task. Early lesions of the medial frontal cortex caused severe impairments in spatial learning but this deficit was markedly reduced with enriched housing, bFGF, or a combination of both, with the latter being most effective. The housing effects varied with age, however: the earlier the experience began, the better the outcome. Enriched housing increased dendritic length in cortical pyramidal neurons, an effect that was greater in the lesion than the control animals, and enriched housing reversed the lesion-induced decrease in spine density. Enriched environment increased the thickness of the cortical mantle in both lesion and controls whereas bFGF had no effect. Experience thus can affect functional and anatomical outcome after early brain injury but the effects vary with age at experience and may be facilitated by treatment with bFGF. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 50: 134,146, 2008. [source] Rapid acquisition of operant conditioning in 5-day-old rat pups: A new technique articulating suckling-related motor activity and milk reinforcementDEVELOPMENTAL PSYCHOBIOLOGY, Issue 6 2007Carlos Arias Abstract Newborn rats are capable of obtaining milk by attaching to a surrogate nipple. During this procedure pups show a gradual increase in head and forelimb movements oriented towards the artificial device that are similar to those observed during nipple attachment. In the present study the probability of execution of these behaviors was analyzed as a function of their contingency with intraoral milk infusion using brief training procedures (15 min). Five-day-old pups were positioned in a smooth surface having access to a touch-sensitive sensor. Physical contact with the sensor activated an infusion pump which served to deliver intraoral milk reinforcement (Paired group). Yoked controls received the reinforcer when Paired neonates touched the sensor. Paired pups trained under a continuous reinforcement schedule emitted significantly more responses than Yoked controls following two (Experiment 1) or one training session (Experiment 2). These differences were also observed during an extinction session conducted immediately after training. The level of maternal deprivation before training (3 or 6 hr) or the volume of milk delivered (1.0 or 1.5 µl per pulse) did not affect acquisition or extinction performances. In addition, it was observed that the rate of responding of Paired pups during the early phase of the extinction session significantly predicted subsequent levels of acceptance of the reinforcer. These results indicate that the frequency of suckling-related behaviors can be rapidly modified by means of associative operant processes. The operant procedure here described represents an alternative tool for the ontogenetic analysis of self-administration or behavior processes of seeking. © 2007 Wiley Periodicals, Inc. Dev Psychobiol 49: 576-588, 2007. [source] Brief exposure to the biological mother "potentiates" the isolation behavior of precocial Guinea pig pupsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 8 2006Michael B. Hennessy Abstract When isolated rat pups are briefly reunited with a lactating female, her subsequent removal leads to a dramatic increase in the emission of ultrasonic vocalizations, but not other behaviors. Whether this socially induced augmentation of isolation behavior (i.e., "potentiation") is characteristic only of altricial rodents is not known. Therefore, we examined precocial guinea pig pups in a potentiation paradigm. Ten-day-old guinea pigs were isolated in a test cage for 10 min, at which time they were then placed into a second cage for 5 min that either contained a companion or, for controls, was empty. Pups were then isolated again in the test cage for a second 10-min period. Control pups showed a significant reduction in vocalizing and locomotor activity from the first to second isolation period. Exposure to the biological mother prevented the decline in both behaviors (Experiment 1), whereas exposure to a familiar littermate (Experiment 2) had no effect, and exposure to an unfamiliar lactating female (Experiment 3) had only a minimal effect on locomotor activity. The results show that potentiation of isolation behaviors is not limited to altricial rodents, and suggest that specific characteristics of the effect (i.e., its magnitude, the specific behaviors affected, and the selectivity of the response to particular social partners) varies with the abilities and requirements of the young, as well as the behavioral ecology of the species in question. © 2006 Wiley Periodicals, Inc. Dev Psychobiol 48: 653,659, 2006. [source] Perception of audiovisual rhythm and its invariance in 4- to 10-month-old infantsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 4 2006David J. Lewkowicz Abstract This study investigated the perception of complex audiovisual rhythmic patterns in 4-, 6-, 8-, and 10-month-old human infants. In Experiment 1, we first habituated infants to an event in which an object could be seen and heard bouncing in a rhythmic fashion. We then tested them to determine if they would detect a relative temporal pattern change produced by rearranging the intrapattern intervals. Regardless of age, infants successfully detected the pattern change. In Experiment 2, we asked whether infants also can extract rhythmic pattern invariance amid tempo variations. Thus, we first habituated infants to a particular rhythmic pattern but this time varying in its tempo of presentation across trials. We then administered one test trial in which a novel rhythm was presented at a familiar tempo and another test trial in which a familiar rhythm was presented at a novel tempo. Infants detected both types of changes indicating that they perceived the invariant rhythm and that they did so despite the fact that they also detected the varying tempo. Overall, the findings demonstrate that infants between 4 and 10 months of age can perceive and discriminate complex audiovisual temporal patterns on the basis of relative temporal differences and that they also can learn the invariant nature of such patterns. © 2006 Wiley Periodicals, Inc. Dev Psyshobiol 48: 288,300, 2006. [source] Nonnutritive sucking: One of the major determinants of filial loveDEVELOPMENTAL PSYCHOBIOLOGY, Issue 3 2006David Val-Laillet Abstract The present study investigated the rewarding effects of nonnutritive sucking on the development of a filial preference. Two experiments were conducted to test whether nonnutritive visceral and oral stimuli have reinforcing properties independent from each other or act in synergy. Lambs could interact freely with their dam but were deprived of suckling by covering the udder for the first 12 hr. In Experiment 1, suckling was prevented and replaced by human giving, in the presence of the mother, either a bottle of water (B5 and B2.5: 5% or 2.5% birth weight, BW, divided into seven portions over 12 hr) or water via tube-feeding (I5 and I2.5: 5% or 2.5% BW, also divided into seven portions over 12 hr). During a two-choice test performed at 12 hr after birth, only B5 and I5 lambs preferred their mother to an alien ewe however, B5 were faster at choosing their mother at the beginning of the test. B2.5 and I2.5 lambs made a random choice. In Experiment 2, suckling was prevented and replaced by human giving, in the presence of the mother, either a bottle of water (B2.5: 2.5% BW, divided into seven portions over 12 hr) or water via tube-feeding (I10 and I2.5: 10% or 2.5% BW, also divided into seven portions over 12 hr). During a two-choice test at 12 hr, tube-fed lambs (I10 and I2.5) preferred their mother to a human. B2.5 lambs were equally attracted to both partners and spent more time near the human than lambs from the other groups. In a test of reactivity to a human performed on neonates isolated from their mother, B2.5 lambs explored the human much more than the other lambs. The presence of the human had soothing properties in B2.5 lambs and once the human left, they were the only lambs displaying enhanced vocal and locomotor activity. In these experiments, nonnutritive gastrointestinal stimuli induced a preference for the mother whereas nonnutritive sucking led to a strong positive relationship with the human. These results suggest that when lambs suckle their dam, the development of filial bonding is facilitated through the combined effects of oral and gastrointestinal stimuli. © 2006 Wiley Periodicals, Inc. Dev Psyshobiol 48: 220,232, 2006. [source] Spatial conditional discrimination learning in developing ratsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 2 2005Kevin L. Brown Abstract The present study established an effective procedure for studying spatial conditional discrimination learning in juvenile rats using a T-maze. Wire mesh located on the floor of the maze as well as a second, identical T-maze apparatus served as conditional cues which signaled whether a left or a right response would be rewarded. In Experiment 1, conditional discrimination was evident on Postnatal Day (PND) 30 when mesh,+,maze or maze-alone were the conditional cues, but not when mesh-alone was the cue. Experiment 2 confirmed that mesh-alone was sufficiently salient to support learning of a simple (nonconditional) discrimination. Its failure to serve as a conditional cue in Experiment 1 does not reflect its general ineffectiveness as a stimulus. Experiment 3 confirmed that the learning shown in Experiment 1 was indeed conditional in nature by comparing performance on conditional versus nonconditional versions of the task. Experiment 4 showed that PND19 and PND23 pups also were capable of performing the task when maze,+,mesh was the cue; however, the findings indicate that PND19 subjects do not use a conditional strategy to learn this task. The findings suggest postnatal ontogeny of conditional discrimination learning and underscore the importance of conditional cue salience, and of identifying task strategies, in developmental studies of conditional discrimination learning. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 46: 97,110, 2005. [source] Correlated attributes and categorization in the first half-year of lifeDEVELOPMENTAL PSYCHOBIOLOGY, Issue 2 2004Ramesh S. Bhatt Abstract In two experiments with 36 human infants, we asked whether 3- and 6-month-olds could use correlations between attributes of individual objects to categorize. Infants learned to kick to move block mobiles that simultaneously displayed two categories defined by the figures displayed on them: the colors of the figures and the colors of the blocks. Two features were correlated, and the third varied across categories. Only 6-month-olds categorized novel category exemplars that preserved the original feature correlations (Experiment 1A), but both 3- and 6-month-olds discriminated feature recombinations that broke the original correlations (Experiment 1B). When category exemplars were presented successively, 6-month-olds also learned the feature correlations and used them to categorize (Experiment 2), but their performance was less robust. Infants' superior learning when stimuli were presented simultaneously may reflect "unitization," a learning disposition unique to immature infants. These experiments reveal that infants' ability to use correlated attributes to categorize emerges months earlier than previously thought. © 2004 Wiley Periodicals, Inc. Dev Psychobiol 44: 103,115, 2004. [source] Transnatal olfactory continuity in the rabbit: Behavioral evidence and short-term consequence of its disruptionDEVELOPMENTAL PSYCHOBIOLOGY, Issue 4 2002Gérard Coureaud Abstract This study investigates the role of prenatal odor learning on postnatal adaptive orientation responses in the newborn rabbit. Preference tests revealed that pups are equally attracted to the odors of placentae and colostrum (Experiments 1,4), suggesting that an odor continuity may exist between the fetal and neonatal environments. To test some predictions derived from this hypothesis, we manipulated the odor of the diet of pregnant-lactating does to control the chemical niches of their perinates. Fetuses exposed in this way to the odor of cumin (C) were selectively attracted as neonates to the odor of pure C (Experiment 6). Prenatal exposure to C also was followed, to a certain extent, by enhanced attraction to C odor in the placenta or colostrum from females which had consumed it (Experiments 5 & 7). Finally, the functional implications of perinatal odor continuity were tested by disrupting it. The odor component of the feto,neonatal transitional environment revealed indeed to affect the ability of certain pups to gain colostrum and milk at the very first sucking opportunities (Experiment 8). © 2002 Wiley Periodicals, Inc. Dev Psychobiol 40: 372,390, 2002. Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/dev.10038 [source] Classical conditioning in the rat fetus: Involvement of mu and kappa opioid systems in the conditioned responseDEVELOPMENTAL PSYCHOBIOLOGY, Issue 2 2002William P. Smotherman Abstract When the Embryonic Day 20 (E20) rat fetus is given a conditioning trial involving a paired presentation of an artificial nipple (the conditioned stimulus; CS) with an intraoral infusion of milk (the unconditioned stimulus; US), it shows evidence of classical conditioning when again exposed to the CS during a test trial. Specifically, the fetus shows fewer oral grasp responses (the conditioned response; CR) when continuously presented with the artificial nipple. The present study further investigated this classically conditioned reduction in oral grasping. Separate experiments (a) examined the time course of the reduction in oral grasping (Experiment 1), (b) characterized the time course of mu opioid (Experiment 2) and kappa opioid (Experiment 3) involvement in the CR, and (c) described changes in fetal behavior (Experiment 4) associated with mu and kappa opioid effects on responding to the artificial nipple. The results are discussed in terms of opioid involvement in establishing and maintaining early suckling behavior. © 2002 Wiley Periodicals, Inc. Dev Psychobiol 40: 104,115, 2002. DOI 10.1002/dev.10016 [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||