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Lea, S. E. G., Goto, K., Osthaus, B., & Ryan, C. M. E. (2006). The logic of the stimulus. Anim. Cogn., 9(4), 247–256.
Abstract: This paper examines the contribution of stimulus processing to animal logics. In the classic functionalist S-O-R view of learning (and cognition), stimuli provide the raw material to which the organism applies its cognitive processes-its logic, which may be taxon-specific. Stimuli may contribute to the logic of the organism's response, and may do so in taxon-specific ways. Firstly, any non-trivial stimulus has an internal organization that may constrain or bias the way that the organism addresses it; since stimuli can only be defined relative to the organism's perceptual apparatus, and this apparatus is taxon-specific, such constraints or biases will often be taxon-specific. Secondly, the representation of a stimulus that the perceptual system builds, and the analysis it makes of this representation, may provide a model for the synthesis and analysis done at a more cognitive level. Such a model is plausible for evolutionary reasons: perceptual analysis was probably perfected before cognitive analysis in the evolutionary history of the vertebrates. Like stimulus-driven analysis, such perceptually modelled cognition may be taxon-specific because of the taxon-specificity of the perceptual apparatus. However, it may also be the case that different taxa are able to free themselves from the stimulus logic, and therefore apply a more abstract logic, to different extents. This thesis is defended with reference to two examples of cases where animals' cognitive logic seems to be isomorphic with perceptual logic, specifically in the case of pigeons' attention to global and local information in visual stimuli, and dogs' failure to comprehend means-end relationships in string-pulling tasks.
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Lee, J., & Paik, M. (2006). Sex preferences and fertility in South Korea during the year of the Horse. Demography, 43(2), 269–292.
Abstract: Since antiquity, people in several East Asian countries, such as China, Japan, and South Korea, have believed that a person is destined to possess specific characteristics according to the sign of the zodiac under which he or she was born. South Koreans, in particular, have traditionally considered that the year of the Horse bears inauspicious implications for the birth of daughters. Using monthly longitudinal data at the region level in South Korea between 1970 and 2003, we found that in the year of the Horse, the sex ratio at birth significantly increased while fertility decreased.
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Lehmann, K., Kallweit, E., & Ellendorff, F. (2006). Social hierarchy in exercised and untrained group-housed horses--A brief report. Appl. Anim. Behav. Sci., 96(3-4), 343–347.
Abstract: Changes in social hierarchy were evaluated in a herd of 3-year-old Hanoverian geldings. One group (n = 5) was exposed to a training programme, the other (n = 5) remained untrained. After 6 months, the groups were reversed. Hierarchical positions were evaluated by field observations and/or paired-feeding tests at the beginning, the middle, the end of the first and at the end of the second training period. Both methods yielded identical results. Almost all horses changed position in only one direction: either up or down. Neither increase in aggression nor mutual injuries were recorded during the whole experiment. No statistically verified differences in dominance ranking occurred between trained and untrained groups, but apparent differences were consistent. Thus, if horses are kept in the same group for a longer period of time, exercise induced changes in hierarchy are probably of minor importance and are unlikely to increase the incidence of injuries. This may have implications for the promotion of group-housing for sport horses.
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Leiner, L. (2006). Vergleich verschiedener Methoden zur Angstextinktion bei Pferden. Diploma thesis, , .
Abstract: Pferde sind Fluchttiere. Ihr Fluchtinstinkt bewirkt, dass sie sich leicht erschrecken und auch in
diversen Situationen mit Flucht reagieren. Diese Tatsache ist den meisten Reitern bekannt,
nur ist es für den Menschen teilweise schwer, mit dieser Eigenschaft auszukommen und sie zu
verstehen oder gar nachzuvollziehen. So kommt es häufig zu Unfällen, die aus der Angst der
Pferde resultieren, jedoch vermeidbar gewesen wären, hätte man ankündigende Signale früher
erkannt. Des Weiteren kann die Angst eines Pferdes auch durch eine (Ver-) Weigerung,
bestimmte Dinge zu tun, sichtbar werden. Diese Weigerung wird in der Reiterei gerne als
„Bockigkeit“ und „Ungehorsam“ des Pferdes interpretiert und führt nicht selten zu einer
Bestrafung. Insgesamt kann man sagen, dass angstauslösende Reize und die Reaktionen des
Pferdes darauf oft falsch eingeschätzt oder falsch interpretiert werden und in der Folge auch
falsch damit umgegangen wird. Ein Grund dafür ist sicher das fehlende Wissen über das
Verhalten des Pferdes. Mit der vorliegenden Diplomarbeit soll ein Beitrag geleistet werden,
das Pferd in seinem Angstverhalten besser zu verstehen. Ziel der Arbeit war es, das Verhalten
des Pferdes bei verschiedenen Intensitäten von Angst zu untersuchen. Des Weiteren wurden
Methoden untersucht, mit denen man die Angst von Pferden vor bestimmten Reizen und
Situationen potentiell lindern kann, was letztendlich auch der Unfallvorbeugung dient.
Die vorliegende Diplomarbeit wurde am Haupt- und Landesgestüt Marbach durchgeführt; 24
Junghengste standen hierfür zur Verfügung. Darunter waren 18 Deutsche Warmblüter, 3
Vollblutaraber und 3 Schwarzwälder Füchse (Kaltblüter), somit war auch ein Rassenvergleich
möglich.
In einem ersten Teil der Arbeit wurde untersucht, wie sich Angst bei Pferden äußert. Hierfür
wurde ausgenutzt, dass Pferde ganz generell vor unbekannten, neuen Gegenständen Angst
haben (= Neophobie). Zur Angstauslösung dienten als Konfrontationsgegenstände ein
Sonnenschirm und eine Plastikplane. Beide Gegenstände waren für die Testpferde unbekannt.
Das Verhalten sowie die Herzrate der Tiere wurden während aller Versuche beobachtet und
quantifiziert. Nacheiner ersten Konfrontation wurden die Pferde an die Objekte gewöhnt
(Extinktionstraining = Angstlöschung) und beobachtet welche Verhaltensymptome sich
während dieser Gewöhnung (= Verlust der Neophobie) verändern. Die Hypothese war, dass
tatsächliche Angstsymptome während der Gewöhnung immer seltener zu beobachten sind.
Zusammenfassung III
Als Verhaltensweisen für Angst konnten Ausweichbewegungen und Flucht, Lautäußerungen
(Prusten und Schnauben), das Anspannen der Halsmuskulatur sowie das Vordrücken der
Oberlippe identifiziert werden. Darüber hinaus wurde gezeigt, dass Abstufungen im
Angstverhalten möglich sind: Bei sehr hohem Angstlevel sind Fluchtreaktionen zu
beobachten. Bei mittlerem Angstlevel treten Ausweichbewegungen im Schritt und
Lautäußerungen (Prusten und Schnauben) auf, bei geringem Angstlevel wird die
Halsmuskulatur angespannt und die Oberlippe vorgedrückt.
Im Zweiten Teil der Arbeit sollten verschiedene Methoden zur Angst-Extinktionauf ihre
Wirksamkeit hin untersucht werden. Verwendet wurde in verschiedenen Testgruppen die
Methode der Desensibilisierung (d.h. leichte, schrittweise stärker werdende Exposition
gegenüber dem angstauslösenden Reiz), die Desensibilisierung mit Gegenkonditionierung
(positive Verstärkung) durch Streicheln bzw. Reiben des Halses und die Desensibilisierung
mit Gegenkonditionierung durch Futterbelohnung. Als Kontrollgruppe dienten Pferde, die
ohne eine Konfrontation mit dem angstauslösenden Reiz nur über den Versuchplatz geführt
wurden.
Während des Extinktionstrainings konnte beobachtet werden, dass die Desensibilisierung mit
Gegenkonditionierung zu einer schnelleren Extinktion führt als ohne Gegenkonditionierung.
Allerdings zeigte ein Vergleich mit der Kontrollgruppe, die das Extinktionstraining nicht
erfahren hatte, den gleichen Verlust an Angstverhalten wie die Gruppen mit Extinktionstraining.
Dieses Ergebnis wurde so interpretiert, dass die wiederholte Exposition gegenüber
angstauslösenden Reizen bei den durchgeführten Verhaltenstests zwar eine Rolle spielt, doch
dass auch allein die Beschäftigung mit den Tieren zu einem Verlust von Angstverhalten führt
(wahrscheinlich auch aufgrund eines wachsenden Vertrauens zur Führperson, die über das
komplette Experiment hin die Gleiche blieb).
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Leleu, C., & Cotrel, C. (2006). Body composition in young standardbreds in training: relationships to body condition score, physiological and locomotor variables during exercise. Equine Vet J Suppl, (36), 98–101.
Abstract: REASONS FOR PERFORMING STUDY: Body composition is an essential factor in athletic performance of human sprinters and long distance runners. However, in horses, many questions remain concerning relationships between body composition and performance in the different equine activities. OBJECTIVES: To determine relationships between body composition, body score, physiological and locomotor variables in a population of young Standardbreds in training. METHODS: Twenty-four 2-year-old Standardbreds were studied, body condition on a scale 0-5 and bodyweight recorded, and height at withers measured. Percentage of fat (%F), fat mass (FM) and fat free mass (FFM) were estimated echographically. During a standardised exercise test on the track, velocity, heart rate, respiratory frequency and blood lactate concentrations were measured. V4 and V200 (velocity for a blood lactate concentration of 4 mmol/l and velocity of 200 beats/min) calculated. Basic gait variables were measured at 3 different speeds with an accelerometric device. RESULTS: Body composition variables: %F and FM were significantly related to body condition score and physiological variables. Body score was highly correlated to %F (r = 0.64) and FM (r = 0.71). V4 was negatively correlated to %F (r = -0.59) and FM (r = -0.60), P<0.05. V200 was also negatively related to %F and FM, (r = -0.39 and r = -0.37, respectively, P<0.1). No relationships were found between body composition and gait characteristics. CONCLUSIONS: Body composition was closely related to indirect measurements of aerobic capacity, which is a major factor of athletic performance in middle distance running horses. POTENTIAL RELEVANCE: As in human athletes, trainers should take special note to evaluate optimal bodyweight and body composition of race horses to optimise performance.
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Lensink, J., Veissier, I., & Boissy, A. (2006). Enhancement of performances in a learning task in suckler calves after weaning and relocation: Motivational versus cognitive control?: A pilot study. Appl. Anim. Behav. Sci., 100(3-4), 171–181.
Abstract: Weaning in suckler calves influences performance in a learning task. The aim of the present study was to investigate whether the improved performance after weaning, including relocation, is due to differences in motivation for the reward or in learning abilities. Forty Aubrac calves were used; half of them were weaned from their dams at around eight months, the other half were weaned one month later. After weaning, calves were housed in groups of four in a new setting. From the day after weaning of the last group of calves, the animals were subjected to two tests: (1) an arena test, (2) a T-maze test where one arm led to either a social or a food reward. The T-maze test consisted of three sessions: in Session 1, trials were conducted until the animal acquired the task (i.e. did not take the unrewarded arm on three consecutive trials); in Session 2, the motivation for the reward was assessed via the walking time of the animal to reach the reward; in Session 3, the place of reward was reversed and the animals were trained until they acquired the new task. Calves weaned for one day explored more (P < 0.05) and had lower heart rates during the arena test (P < 0.05) compared to the ones weaned for one month. During the T-maze test, calves weaned for one month versus one day did not differ in their capacities to learn the initial route (Session 1) or in their motivation for either the social or food reward (Session 2). Calves weaned for one day learned significantly faster (P < 0.05) the reversed route (Session 3) than calves weaned for one month. Hence, the better performances at reversal in the T-maze by calves that have just been weaned cannot be accounted for by a higher motivation for the reward. A better cognitive control of their behaviour due to a lower stress state is suggested by our results.
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Lewczuk, D., Sloniewski, K., & Reklewski, Z. (2006). Repeatability of the horse's jumping parameters with and without the rider. Livestock Science, 99(2-3), 125–130.
Abstract: The total number of 4323 jumps with and without the rider of 141 young stallions were filmed and measured using video image analysis. Horses were filmed on the doublebarre fence (100, 110 and 120 cm) with the same width of 90 cm. The style of jump was characterised by measurements of taking off and landing distances, as well as some measurements of the silhouette of the horse over the obstacle. The repeatability was 0.40-0.58 for distances of the jump's length, 0.37-0.56 for bascule's measurements and about 0.20 for legs' lifting above the fence. Traits measured under the rider and on the highest fences were more repeatable.
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Ligout, S., & Porter, R. - H. (2006). Social recognition in mammals: Mechanisms and sensorial bases. Prod. Anim., 19(2), 119–133.
Abstract: Social recognition plays a major role in the mediation of interactions between individuals and the organisation of societies. During the last 20 years, numerous studies have investigated the adaptive significance, underlying mechanisms and sensory basis of individual recognition of kin as well as non-kin. The results indicate that the recognition of conspecifics involves complex, flexible processes that are widespread throughout the vertebrate kingdom. Such recognition can be based upon different mechanisms and sensory modalities, and influenced by diverse factors. Learned phenotypic traits of conspecifics through familiarisation, including oneself, is the fundamental mechanism implicated in recognition. Animals become directly familiar with others with which they interact. Moreover, kin of familiar conspecifics may be discriminated because of their resemblance to the known individuals. An animal's genotype and environmental variables may both contribute to its recognisable individual signatures (e.g. distinctive olfactory, visual, or auditory characteristics). In general, the study of social recognition enhances our understanding of the cognitive world of animals.
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Lim, M. M., & Young, L. J. (2006). Neuropeptidergic regulation of affiliative behavior and social bonding in animals. Hormon. Behav., 50(4), 506–517.
Abstract: Social relationships are essential for maintaining human mental health, yet little is known about the brain mechanisms involved in the development and maintenance of social bonds. Animal models are powerful tools for investigating the neurobiological mechanisms regulating the cognitive processes leading to the development of social relationships and for potentially extending our understanding of the human condition. In this review, we discuss the roles of the neuropeptides oxytocin and vasopressin in the regulation of social bonding as well as related social behaviors which culminate in the formation of social relationships in animal models. The formation of social bonds is a hierarchical process involving social motivation and approach, the processing of social stimuli and formation of social memories, and the social attachment itself. Oxytocin and vasopressin have been implicated in each of these processes. Specifically, these peptides facilitate social affiliation and parental nurturing behavior, are essential for social recognition in rodents, and are involved in the formation of selective mother-infant bonds in sheep and pair bonds in monogamous voles. The convergence of evidence from these animal studies makes oxytocin and vasopressin attractive candidates for the neural modulation of human social relationships as well as potential therapeutic targets for the treatment of psychiatric disorders associated with disruptions in social behavior, including autism.
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Lin, Y. - L., Moolenaar, H., van Weeren, P. R., & van de Lest, C. H. A. (2006). Effect of microcurrent electrical tissue stimulation on equine tenocytes in culture. Am J Vet Res, 67(2), 271–276.
Abstract: OBJECTIVE: To determine effects of microcurrent electrical tissue stimulation (METS) on equine tenocytes cultured from the superficial digital flexor tendon (SDFT). SAMPLE POPULATION: SDFTs were collected from 20 horses at slaughter. PROCEDURE: Tenocytes were isolated following outgrowth from explants and grown in 48-well plates. Four methods of delivering current to the tenocytes with a METS device were tested. Once the optimal method was selected, current consisting of 0 (negative control), 0.05, 0.1, 0.5, 1.0, or 1.5 mA was applied to cells (8 wells/current intensity) once daily for 8 minutes. Cells were treated for 1, 2, or 3 days. Cell proliferation, DNA content, protein content, and apoptosis rate were determined. RESULTS: Application of microcurrent of moderate intensity increased cell proliferation and DNA content, with greater increases with multiple versus single application. Application of microcurrent of moderate intensity once or twice increased protein content, but application 3 times decreased protein content. Application of current a single time did not significantly alter apoptosis rate; however, application twice or 3 times resulted in significant increases in apoptosis rate, and there were significant linear (second order) correlations between current intensity and apoptosis rate when current was applied twice or 3 times. CONCLUSIONS AND CLINICAL RELEVANCE: Results of the present study indicate that microcurrent affects the behavior of equine tenocytes in culture, but that effects may be negative or positive depending on current intensity and number of applications. Therefore, results are far from conclusive with respect to the suitability of using METS to promote tendon healing in horses.
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