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Fragaszy, D., & Visalberghi, E. (2004). Socially biased learning in monkeys. Learn Behav, 32(1), 24–35.
Abstract: We review socially biased learning about food and problem solving in monkeys, relying especially on studies with tufted capuchin monkeys (Cebus apella) and callitrichid monkeys. Capuchin monkeys most effectively learn to solve a new problem when they can act jointly with an experienced partner in a socially tolerant setting and when the problem can be solved by direct action on an object or substrate, but they do not learn by imitation. Capuchin monkeys are motivated to eat foods, whether familiar or novel, when they are with others that are eating, regardless of what the others are eating. Thus, social bias in learning about foods is indirect and mediated by facilitation of feeding. In most respects, social biases in learning are similar in capuchins and callitrichids, except that callitrichids provide more specific behavioral cues to others about the availability and palatability of foods. Callitrichids generally are more tolerant toward group members and coordinate their activity in space and time more closely than capuchins do. These characteristics support stronger social biases in learning in callitrichids than in capuchins in some situations. On the other hand, callitrichids' more limited range of manipulative behaviors, greater neophobia, and greater sensitivity to the risk of predation restricts what these monkeys learn in comparison with capuchins. We suggest that socially biased learning is always the collective outcome of interacting physical, social, and individual factors, and that differences across populations and species in social bias in learning reflect variations in all these dimensions. Progress in understanding socially biased learning in nonhuman species will be aided by the development of appropriately detailed models of the richly interconnected processes affecting learning.
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Dubois, F., Giraldeau, L. - A., Hamilton, I. M., Grant, J. W. A., & Lefebvre, L. (2004). Distraction sneakers decrease the expected level of aggression within groups: a game-theoretic model. Am Nat, 164(2), E32–45.
Abstract: Hawk-dove games have been extensively used to predict the conditions under which group-living animals should defend their resources against potential usurpers. Typically, game-theoretic models on aggression consider that resource defense may entail energetic and injury costs. However, intruders may also take advantage of owners who are busy fighting to sneak access to unguarded resources, imposing thereby an additional cost on the use of the escalated hawk strategy. In this article we modify the two-strategy hawk-dove game into a three-strategy hawk-dove-sneaker game that incorporates a distraction-sneaking tactic, allowing us to explore its consequences on the expected level of aggression within groups. Our model predicts a lower proportion of hawks and hence lower frequencies of aggressive interactions within groups than do previous two-strategy hawk-dove games. The extent to which distraction sneakers decrease the frequency of aggression within groups, however, depends on whether they search only for opportunities to join resources uncovered by other group members or for both unchallenged resources and opportunities to usurp.
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Bering, J. M. (2004). A critical review of the “enculturation hypothesis”: the effects of human rearing on great ape social cognition. Anim. Cogn., 7(4), 201–212.
Abstract: Numerous investigators have argued that early ontogenetic immersion in sociocultural environments facilitates cognitive developmental change in human-reared great apes more characteristic of Homo sapiens than of their own species. Such revamping of core, species-typical psychological systems might be manifest, according to this argument, in the emergence of mental representational competencies, a set of social cognitive skills theoretically consigned to humans alone. Human-reared great apes' capacity to engage in “true imitation,” in which both the means and ends of demonstrated actions are reproduced with fairly high rates of fidelity, and laboratory great apes' failure to do so, has frequently been interpreted as reflecting an emergent understanding of intentionality in the former. Although this epigenetic model of the effects of enculturation on social cognitive systems may be well-founded and theoretically justified in the biological literature, alternative models stressing behavioral as opposed to representational change have been largely overlooked. Here I review some of the controversy surrounding enculturation in great apes, and present an alternative nonmentalistic version of the enculturation hypothesis that can also account for enhanced imitative performance on object-oriented problem-solving tasks in human-reared animals.
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Nelson, D. M., Gardner, I. A., Chiles, R. F., Balasuriya, U. B., Eldridge, B. F., Scott, T. W., et al. (2004). Prevalence of antibodies against Saint Louis encephalitis and Jamestown Canyon viruses in California horses. Comp Immunol Microbiol Infect Dis, 27(3), 209–215.
Abstract: Jamestown Canyon (JC) and Saint Louis encephalitis (SLE) viruses are mosquito-transmitted viruses that have long been present in California. The objective of this study was to determine the seroprevalence of these two viruses in horses prior to the introduction of West Nile (WN) virus. Approximately 15% of serum samples collected in 1998 from 425 horses on 44 equine operations horses throughout California had serum antibodies to JC virus, whereas antibodies were not detected to SLE virus. The results indicate that horses in California were commonly infected prior to 1998 with mosquito-transmitted Bunyaviruses that are identical or closely related to JC virus, but not with SLE virus. The different seroprevalence of SLE and JC viruses in horses likely reflects the unique ecology of each virus, and it is predicted that WN virus will have a wider distribution in California than closely related SLE virus.
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Cerutti, D. T., & Staddon, J. E. R. (2004). Immediacy versus anticipated delay in the time-left experiment: a test of the cognitive hypothesis. J Exp Psychol Anim Behav Process, 30(1), 45–57.
Abstract: In the time-left experiment (J. Gibbon & R. M. Church, 1981), animals are said to compare an expectation of a fixed delay to food, for one choice, with a decreasing delay expectation for the other, mentally representing both upcoming time to food and the difference between current time and upcoming time (the cognitive hypothesis). The results of 2 experiments support a simpler view: that animals choose according to the immediacies of reinforcement for each response at a time signaled by available time markers (the temporal control hypothesis). It is not necessary to assume that animals can either represent or subtract representations of times to food to explain the results of the time-left experiment.
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Pickens, C. L., & Holland, P. C. (2004). Conditioning and cognition. Neurosci Biobehav Rev, 28(7), 651–661.
Abstract: Animals' abilities to use internal representations of absent objects to guide adaptive behavior and acquire new information, and to represent multiple spatial, temporal, and object properties of complex events and event sequences, may underlie many aspects of human perception, memory, and symbolic thought. In this review, two classes of simple associative learning tasks that address these core cognitive capacities are discussed. The first set, including reinforcer revaluation and mediated learning procedures, address the power of Pavlovian conditioned stimuli to gain access, through learning, to representations of upcoming events. The second set of investigations concern the construction of complex stimulus representations, as illustrated in studies of contextual learning, the conjunction of explicit stimulus elements in configural learning procedures, and recent studies of episodic-like memory. The importance of identifying both cognitive process and brain system bases of performance in animal models is emphasized.
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Rollot, Y., Lecuyer, E., Chateau, H., & Crevier-Denoix, N. (2004). Development of a 3D model of the equine distal forelimb and of a GRF shoe for noninvasive determination of in vivo tendon and ligament loads and strains. Equine Vet J, 36(8), 677–682.
Abstract: REASONS FOR PERFORMING STUDY: As critical locomotion events (e.g. high-speed and impacts during racing, jump landing) may contribute to tendinopathies, in vivo recording of gaits kinematic and dynamic parameters is essential for 3D reconstruction and analysis. OBJECTIVE: To propose a 3D model of the forelimb and a ground reaction force recording shoe (GRF-S) for noninvasively quantifying tendon and ligament loads and strains. METHODS: Bony segments trajectories of forelimbs placed under a power press were recorded using triads of ultrasonic kinematic markers linked to the bones. Compression cycles (from 500-6000 N) were applied for different hoof orientations. Locations of tendon and ligament insertions were recorded with regard to the triads. The GRF-S recorded GRF over the hoof wall and used four 3-axis force sensors sandwiched between a support shoe and the shoe to be tested. RESULTS: Validation of the model by comparing calculated and measured superficial digital flexor tendon strains, and evaluation of the role of proximal interphalangeal joint in straight sesamoidean ligament and oblique sesamoidean ligament strains, were successfully achieved. Objective comparisons of the 3 components of GRF over the hoof for soft and hard grounds could be recorded, where the s.d. of GRF norm was more important on hard ground at walk and trot. CONCLUSIONS: Soft grounds (sand and rubber) dissipate energy by lowering GRF amplitude and diminish bounces and vibrations at impact. At comparable speed, stance phase was longer on soft sand ground. POTENTIAL RELEVANCE: The conjugate use of the GRF-S and the numerical model would help to quantify and analyse ground/shoe combination on comfort, propulsion efficiency or lameness recovery.
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Santamaria, S., Bobbert, M. E., Back, W., Barneveld, A., & van Weeren, P. R. (2004). Variation in free jumping technique within and among horses with little experience in show jumping. Am J Vet Res, 65(7), 938–944.
Abstract: OBJECTIVE: To quantify variation in the jumping technique within and among young horses with little jumping experience, establish relationships between kinetic and kinematic variables, and identify a limited set of variables characteristic for detecting differences in jumping performance among horses. ANIMALS: Fifteen 4-year-old Dutch Warmblood horses. PROCEDURE: The horses were raised under standardized conditions and trained in accordance with a fixed protocol for a short period. Subsequently, horses were analyzed kinematically during free jumping over a fence with a height of 1.05 m. RESULTS: Within-horse variation in all variables that quantified jumping technique was smaller than variation among horses. However, some horses had less variation than others. Height of the center of gravity (CG) at the apex of the jump ranged from 1.80 to 2.01 m among horses; this variation could be explained by the variation in vertical velocity of the CG at takeoff (r, 0.78). Horses that had higher vertical velocity at takeoff left the ground and landed again farther from the fence, had shorter push-off phases for the forelimbs and hind limbs, and generated greater vertical acceleration of the CG primarily during the hind limb push-off. However, all horses cleared the fence successfully, independent of jumping technique. CONCLUSIONS AND CLINICAL RELEVANCE: Each horse had its own jumping technique. Differences among techniques were characterized by variations in the vertical velocity of the CG at takeoff. It must be determined whether jumping performance later in life can be predicted from observing free jumps of young horses.
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Touma, C., Palme, R., & Sachser, N. (2004). Analyzing corticosterone metabolites in fecal samples of mice: a noninvasive technique to monitor stress hormones. Horm Behav, 45(1), 10–22.
Abstract: In small animals like mice, the monitoring of endocrine functions over time is constrained seriously by the adverse effects of blood sampling. Therefore, noninvasive techniques to monitor, for example, stress hormones in these animals are highly demanded in laboratory as well as in field research. The aim of our study was to evaluate the biological relevance of a recently developed technique to monitor stress hormone metabolites in fecal samples of laboratory mice. In total, six experiments were performed using six male and six female mice each. Two adrenocorticotropic hormone (ACTH) challenge tests, two dexamethasone (Dex) suppression tests and two control experiments [investigating effects of the injection procedure itself and the diurnal variation (DV) of glucocorticoids (GCs), respectively] were conducted. The experiments clearly demonstrated that pharmacological stimulation and suppression of adrenocortical activity was reflected accurately by means of corticosterone metabolite (CM) measurements in the feces of males and females. Furthermore, the technique proved sensitive enough to detect dosage-dependent effects of the ACTH/Dex treatment and facilitated to reveal profound effects of the injection procedure itself. Even the naturally occurring DV of GCs could be monitored reliably. Thus, our results confirm that measurement of fecal CM with the recently established 5alpha-pregnane-3beta,11beta,21-triol-20-one enzyme immunoassay is a very powerful tool to monitor adrenocortical activity in laboratory mice. Since mice represent the vast majority of all rodents used for research worldwide and the number of transgenic and knockout mice utilized as animal models is still increasing, this noninvasive technique can open new perspectives in biomedical and behavioral science.
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Zhang, T. - Y., Parent, C., Weaver, I., & Meaney, M. J. (2004). Maternal programming of individual differences in defensive responses in the rat. Ann N Y Acad Sci, 1032, 85–103.
Abstract: This paper describes the results of a series of studies showing that variations in mother-pup interactions program the development of individual differences in behavioral and endocrine stress responses in the rat. These effects are associated with altered expression of genes in brain regions, such as the amygdala, hippocampus, and hypothalamus, that regulate the expression of stress responses. Studies from evolutionary biology suggest that such “maternal effects” are common and often associated with variations in the quality of the maternal environment. Together these findings suggest an epigenetic process whereby the experience of the mother alters the nature of the parent-offspring interactions and thus the phenotype of the offspring.
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