Branchi, I., Bichler, Z., Berger-Sweeney, J., & Ricceri, L. (2003). Animal models of mental retardation: from gene to cognitive function. Neurosci Biobehav Rev, 27(1-2), 141–153.
Abstract: About 2-3% of all children are affected by mental retardation, and genetic conditions rank among the leading causes of mental retardation. Alterations in the information encoded by genes that regulate critical steps of brain development can disrupt the normal course of development, and have profound consequences on mental processes. Genetically modified mouse models have helped to elucidate the contribution of specific gene alterations and gene-environment interactions to the phenotype of several forms of mental retardation. Mouse models of several neurodevelopmental pathologies, such as Down and Rett syndromes and X-linked forms of mental retardation, have been developed. Because behavior is the ultimate output of brain, behavioral phenotyping of these models provides functional information that may not be detectable using molecular, cellular or histological evaluations. In particular, the study of ontogeny of behavior is recommended in mouse models of disorders having a developmental onset. Identifying the role of specific genes in neuropathologies provides a framework in which to understand key stages of human brain development, and provides a target for potential therapeutic intervention.
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Matsushima, T., Izawa, E. - I., Aoki, N., & Yanagihara, S. (2003). The mind through chick eyes: memory, cognition and anticipation. Zoolog Sci, 20(4), 395–408.
Abstract: To understand the animal mind, we have to reconstruct how animals recognize the external world through their own eyes. For the reconstruction to be realistic, explanations must be made both in their proximate causes (brain mechanisms) as well as ultimate causes (evolutionary backgrounds). Here, we review recent advances in the behavioral, psychological, and system-neuroscience studies accomplished using the domestic chick as subjects. Diverse behavioral paradigms are compared (such as filial imprinting, sexual imprinting, one-trial passive avoidance learning, and reinforcement operant conditioning) in their behavioral characterizations (development, sensory and motor aspects of functions, fitness gains) and relevant brain mechanisms. We will stress that common brain regions are shared by these distinct paradigms, particularly those in the ventral telencephalic structures such as AIv (in the archistriatum) and LPO (in the medial striatum). Neuronal ensembles in these regions could code the chick's anticipation for forthcoming events, particularly the quality/quantity and the temporal proximity of rewards. Without the internal representation of the anticipated proximity in LPO, behavioral tolerance will be lost, and the chick makes impulsive choice for a less optimized option. Functional roles of these regions proved compatible with their anatomical counterparts in the mammalian brain, thus suggesting that the neural systems linking between the memorized past and the anticipated future have remained highly conservative through the evolution of the amniotic vertebrates during the last 300 million years. With the conservative nature in mind, research efforts should be oriented toward a unifying theory, which could explain behavioral deviations from optimized foraging, such as “naive curiosity,” “contra-freeloading,” “Concorde fallacy,” and “altruism.”
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McKinley, S., & Young, R. J. (2003). The efficacy of the model-rival method when compared with operant conditioning for training domestic dogs to perform a retrieval-selection task. Appl. Anim. Behav. Sci., 81(4), 357–365.
Abstract: Traditionally, dogs have been trained by operant conditioning techniques; that is, dogs make a desired behavioural response and this response is reinforced by a reward such as food. This type of training is very effective in training dogs to perform basic obedience behaviours (e.g. `stay'). However, dogs are social animals and should be predisposed to learn from social stimuli. In the present study, we used a modified version of the model-rival technique that has been extensively used in experiments investigating the cognitive ability of parrots. In this technique, social stimuli are used to create in the animal an interest in the object without the use of food or other rewards. Therefore, the animal learns the name of the object (intrinsic reward) and not that the object's name means food. In this experiment we compared the learning ability of nine pet dogs to solve the same retrieval-selection task having been previously trained using operant conditioning or model-rival techniques. The retrieval-selection task was the dogs had to correctly select the commanded object to bring to the experimenter from a group of three similar objects. The results show no difference in the speeds with which the dogs solved the test--demonstrating the efficacy of the model-rival method. This is the first time that the effectiveness of the model-rival technique has been experimentally demonstrated with dogs. Furthermore, we believe that the methodology reported in this paper has applications in dog training and in experiments into dog cognition.
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Milgram, N. W. (2003). Cognitive Experience and Its Effect on Age-Dependent Cognitive Decline in Beagle Dogs. Neurochemical Research, 28(11), 1677–1682.
Abstract: Test-sophisticated beagle dogs show marked age sensitivity in a size discrimination learning task, with old and senior dogs performing significantly more poorly than young dogs. By contrast, age differences in learning were not seen in dogs naive with respect to neuropsychological test experience. These results indicate that old animals benefit less from prior cognitive experience than young animals, which is an example of an age-dependent loss in plasticity. This finding also suggests that behaviorally experienced animals are a more useful model of human cognitive aging than behaviorally naive animals. We also looked at the effect of a program of behavioral enrichment in aged dogs. One year of enrichment did not lead to significant differences, but after 2 years the behaviorally enriched group performed significantly better than the control group. The effect after 2 years indicates that a prolonged program of cognitive enrichment can serve as an effective intervention in aged dogs. These findings demonstrate that cognitive abilities in aged animals can be modified by providing behavioral experience, indicating that cognitive abilities remain moderately plastic, even in very old animals.
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Sluyter F., Arseneault L., Moffitt T.E., Veenema A.H., de Boer S., & Koolhaas J.M. (2003). Toward an Animal Model for Antisocial Behavior: Parallels Between Mice and Humans: Aggression. Behavior Genetics, 33, 563–574.
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Bekoff M. (2003). Minding Animals, Minding Earth: Old Brains, New Bottlenecks. Zygon, 38, 911–941.
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Bekoff M. (2003). Consciousness and Self in Animals: Some Reflections. Zygon, 38, 229–245.
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Tomasello M., Call J., & Hare B. (2003). Chimpanzees understand psychological states – the question is which ones and to what extent. Trends. Cognit. Sci., 7, 153–156.
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McGuigan, M. P., & Wilson, A. M. (2003). The effect of gait and digital flexor muscle activation on limb compliance in the forelimb of the horse Equus caballus. J Exp Biol, 206(Pt 8), 1325–1336.
Abstract: A horse's legs are compressed during the stance phase, storing and then returning elastic strain energy in spring-like muscle-tendon units. The arrangement of the muscle-tendon units around the lever-like joints means that as the leg shortens the muscle-tendon units are stretched. The forelimb anatomy means that the leg can be conceptually divided into two springs: the proximal spring, from the scapula to the elbow, and the distal spring, from the elbow to the foot. In this paper we report the results of a series of experiments testing the hypothesis that there is minimal scope for muscle contraction in either spring to adjust limb compliance. Firstly, we demonstrate that the distal, passive leg spring changes length by 127 mm (range 106-128 mm) at gallop and the proximal spring by 12 mm (9-15 mm). Secondly, we demonstrate that there is a linear relationship between limb force and metacarpo-phalangeal (MCP) joint angle that is minimally influenced by digital flexor muscle activation in vitro or as a function of gait in vivo. Finally, we determined the relationship between MCP joint angle and vertical ground-reaction force at trot and then predicted the forelimb peak vertical ground-reaction force during a 12 m s(-1) gallop on a treadmill. These were 12.79 N kg(-1) body mass (BM) (range 12.07-13.73 N kg(-1) BM) for the lead forelimb and 15.23 N kg(-1) BM (13.51-17.10 N kg(-1) BM) for the non-lead forelimb.
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Singer, E. R., Saxby, F., & French, N. P. (2003). A retrospective case-control study of horse falls in the sport of horse trials and three-day eventing. Equine Vet J, 35(2), 139–145.
Abstract: REASONS FOR PERFORMING STUDY: Serious injuries to horses and riders in horse trials (HT) and three-day events (3DE) are usually associated with falls of horses, which invariably involve falls of the riders. Many potential causes for these falls have been discussed. OBJECTIVES: The aim of this case-control study was to investigate the risk factors for horse falls on the cross-country phase of horse trials and three-day events. METHODS: Using retrospective data, significant risk factors identified with unvariable analysis (P value <0.2) were entered into a multivariable logistic regression model. Significant risk factors (P value <0.05) were included in the final model. RESULTS: It was revealed that a number of course, obstacle and rider variables were significantly and independently associated with the risk of falling. Falling was associated with obstacles sited downhill (Odds ratio [OR] 8.41) and with obstacles with ditches in front (OR = 5.77). CONCLUSIONS: The relationship between course variables and the risk of falling was characterised and showed a significantly increased risk with increasing numbers of jumps on the course and for jumping efforts later in the course. In contrast, after allowing for the total number of obstacles on the course, an increase in the total number of jumping efforts appeared to have a protective effect. A later cross-country start time was associated with a decreased risk of a horse fall. Amateur event riders were approximately 20 times more likely to fall than professional riders. POTENTIAL CLINICAL RELEVANCE: This study has identified a number of risk factors associated with horse falls and highlights areas that can be altered to improve safety in cross-country competitions.
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