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Mole rat bone marrow cells and peritoneal eosinophils are used to study granule morphological maturation by quantitative microscopy. The bulk eosinophil granule content is pre-stored in unique granular structures known as crystalloid or secondary granules. Mole rat eosinophil granules exhibit the basic structure of an electron-dense crystalloid core surrounded by a lighter, homogeneous matrix. Morphometric analysis demonstrated that bone marrow-derived eosinophil sphere-like granules display a periodic, multimodal granule volume distribution. In contrast, peritoneal eosinophils display cigar-shaped granules, whose crystalloid cores are more variable in size and shape as compared to bone marrow eosinophil granules. Using a morphometric approach, we deduced that the basic granule volume quantum is similar in both cases, suggesting that the sphere-like young eosinophil granules turn into dense ellipsoidal ones by intragranular processes in which both volume and membrane surface are conserved. Crystalloid granule mediators are known to be widely associated with allergic inflammatory events, which may damage the host tissue following secretion to the extracellular environment. Based on mathematical modeling, we suggest that this deviation from sphere-like to ellipsoidal shape reflects an adaptive response of the mole rat to its unique solitary life.
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Gránulos Citoplasmáticos/fisiología , Eosinófilos/fisiología , Microscopía/métodos , Animales , Ratas Topo , RatasRESUMEN
Habituation to human observers is an essential tool in animal behaviour research. Habituation occurs when repeated and inconsequential exposure to a human observer gradually reduces an animal's natural aversive response. Despite the importance of habituation, little is known about the psychological mechanisms facilitating it in wild animals. Although animal learning theory offers some account, the patterns are more complex in natural than in laboratory settings, especially in large social groups in which individual experiences vary and individuals influence each other. Here, we investigate the role of social learning during the habituation process of a wild chimpanzee group, the Waibira community of Budongo Forest, Uganda. Through post hoc hypothesis testing, we found that the immigration of two well-habituated, young females from the neighbouring Sonso community had a significant effect on the behaviour of non-habituated Waibira individuals towards human observers, suggesting that habituation is partially acquired via social learning.
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Animales Salvajes/psicología , Habituación Psicofisiológica , Pan troglodytes/psicología , Conducta Social , Animales , Femenino , Humanos , Masculino , Factores SexualesRESUMEN
Abnormal stereotypic behaviour is widespread among captive non-human primates and is generally associated with jeopardized well-being. However, attributing the same significance to all of these repetitive, unvarying and apparently functionless behaviours may be misleading, as some behaviours may be better indicators of stress than others. Previous studies have demonstrated that the affective state of the individual can be inferred from its bias in appraising neutral stimuli in its environment. Therefore, in the present study, in order to assess the emotional state of stereotyping individuals, 16 captive tufted capuchins (Cebus apella) were tested on a judgment bias paradigm and their faecal corticoid levels were measured in order to assess the intensity of the emotional state. Capuchins with higher levels of stereotypic head twirls exhibited a negative bias while judging ambiguous stimuli and had higher levels of faecal corticoids compared to subjects with lower levels of head twirls. Levels of stereotypic pacing, however, were not correlated with the monkeys' emotional state. This study is the first to reveal a positive correlation between levels of stereotypic behaviour and a 'pessimistic'-like judgment bias in a non-human primate by employing a recently developed cognitive approach. Combining cognitive tests that evaluate the animals' affective valence (positive or negative) with hormonal measurements that provide information on the strength of the emotional state conduces to a better understanding of the animals' affective state and therefore to their well-being.
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Cebus/psicología , Juicio , Conducta Estereotipada , Afecto/fisiología , Animales , Conducta Animal , Cebus/fisiología , Corticosterona/análisis , Heces/química , Femenino , Movimientos de la Cabeza , Juicio/fisiología , Aprendizaje , Masculino , Movimiento , Conducta Estereotipada/fisiologíaRESUMEN
Glycogen synthase kinase-3 (GSK-3) is a highly conserved serine/threonine protein kinase that plays a central role in a wide variety of cellular processes, cognition and behaviour. In a previous study we showed that its α and ß isozymes are highly conserved in vertebrates, however the α gene is missing in birds. This selective loss offers a unique opportunity to study the role of GSK-3ß independently. Accordingly, in the present study we aimed to investigate the role of GSK-3ß in social behaviour, motivation, and motor activity in zebra finches (Taeniopygia guttata). We did that by selective inhibition of GSK-3ß and by using tests that were specifically designed in our laboratory. Our results show that GSK-3ß inhibition: 1) Affected social recognition, because the treated birds tended to move closer towards a stranger, unlike the control birds that stood closer to a familiar bird. 2) Caused the treated birds to spend more time in the more middle parts of the cage compared to controls, a behaviour that might indicate anxiety. 3) As the experiment progressed, the treated birds took less time to make a decision where to stand in the cage compared to controls, suggesting an effect on decision-making. 4) Increased in the motor activity of the treated birds compared to the controls, which can be regarded as hyperactivity. 5) Caused the treated birds to pass through a barrier in order to join their flock members faster compared to controls, and regardless of the increase in the level of difficulty, possibly suggesting increased motivation. Our study calls for further investigation, because GSK-3 is well acknowledged as a central player in regulating mood behaviour, cognitive functions, and neuronal viability. Therefore, studying its impact on normal behaviour as we did in the current study, unlike most studies that were done in diseases models, can advance our understanding regarding GSK-3 various roles and can contribute to the discovery and development of effective treatments to repair cognition and behaviour.
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OBJECTIVE: To examine behavioral differences during a 1-year observational period between urban feeding groups of neutered and sexually intact free-roaming cats following a trap-neuter-return procedure. DESIGN: Natural-setting trial. Animals-Free-roaming cats (n = 184) living in 4 feeding groups in an urban region of Israel. PROCEDURES: Trap-neuter-return procedures were applied to 2 cat feeding groups (A and B). Their social and feeding behaviors and frequency of appearance at feeding time were compared with those of 2 unneutered cat groups (C and D). Behavioral data were obtained from weekly observations before and during feeding over a 1-year period. Results-A lower rate of agonistic interactions was observed in the neutered groups than in the unneutered groups. Sexually intact male cats participated in more agonistic male-male encounters than did neutered male cats. Of 199 such encounters in the feeding groups, only 1 occurred between 2 neutered males. Neutered cats in group A appeared earlier and had higher frequencies of feeding and appearance at the feeding site, compared with unneutered cats. CONCLUSIONS AND CLINICAL RELEVANCE: Less aggression was observed in the neutered groups, specifically, fewer agonistic neutered-neutered male encounters occurred. This reduced agonistic behavior of neutered males resulted in reduced fighting and vocalizations, potentially leading to fewer injuries and reduced transmission of fight-related infectious diseases and reduced noise disturbance from a human perspective. Regarding food delivery, the feeding groups were time-and-place dependent, exhibiting context-related social interactions. When competing for food resources, as neutered cats time their arrival in accordance with food delivery, they thereby gain access to the choicest items.
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Conducta Animal/fisiología , Gatos/cirugía , Orquiectomía/veterinaria , Ovariectomía/veterinaria , Conducta Social , Bienestar del Animal , Animales , Femenino , Masculino , Regulación de la Población/métodos , Dinámica Poblacional , Factores de TiempoRESUMEN
OBJECTIVE: To examine demographic differences during a 1-year observational period between urban feeding groups of neutered and unneutered free-roaming cats following a trap-neuter-return procedure. DESIGN: Natural-setting trial. Animals-Free-roaming adult cats (n = 184) and kittens (76) living in 4 feeding groups in an urban region of Israel. PROCEDURES: Cats in 2 feeding groups were subjected to a trap-neuter-return (TNR) procedure. Cats in 2 other feeding groups were untreated. Data were collected on a weekly basis before and during feeding time over a 1-year period. Following individual cat identification, presence of adults and kittens was recorded throughout the year. Rates of immigration, emigration, and kitten survival were compared between neutered and unneutered groups. RESULTS: The number of adult cats in the 2 neutered groups increased significantly during the study period because of higher immigration and lower emigration rates than in the unneutered groups, in which the number decreased. In the neutered groups, annual presence of neutered cats was significantly higher than that of sexually intact cats. Kitten survival in the neutered groups was significantly higher than in the unneutered groups. CONCLUSIONS AND CLINICAL RELEVANCE: Targeting the TNR method mainly at feeding groups in urban residential neighbourhoods may result in increased group size, as a consequence of 2 major changes in group dynamics: sexually intact cats immigrate into the neutered groups more readily and neutered cats reduce their emigration rates, possibly because of a reduction in reproductive and competitive pressures. To maintain a high proportion of neutered cats in such cat groups, persistent TNR campaigns are therefore necessary.
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Gatos/cirugía , Conducta Alimentaria/fisiología , Orquiectomía/veterinaria , Ovariectomía/veterinaria , Bienestar del Animal , Animales , Femenino , Masculino , Regulación de la Población/métodos , Dinámica Poblacional , Factores de TiempoRESUMEN
The ability to extract reliable segments from the sensory data-stream is necessary for learning and for creating a reliable representation of the environment. Here we focused on segmentation in visual learning associated with foraging. Fifty-one pigeons (Columba livia) were trained to recognize two food-predicting signals, one presented against fixed background elements and the other against varying backgrounds. The pigeons were divided into two groups: 32 pigeons were trained with short intervals of 3-5 min between sessions and 19 with long intervals of 60 min between sessions. When tested on the signal with a plain background, 24 pigeons trained with the short time intervals preferred the signal presented against a varying background during training and eight preferred the signal presented against a fixed background during training. Nine pigeons trained with the long intervals preferred the signal presented against a varying background during training and ten the signal presented against a fixed background during training. Our findings indicate that pigeons possess an ability to use variation-set structure to segment visual data. To date, the effect of variation-set structure has been demonstrated only in the context of human language acquisition. Our current findings suggest that variation sets structure may be linked to other learning abilities too.
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Columbidae , Aprendizaje , Animales , Aprendizaje Discriminativo , HumanosRESUMEN
Captive environments encompass various factors that can elevate stress levels and jeopardize the wellbeing of the captive animals. The use of positive reinforcement training (PRT) techniques enables researchers and caretakers to reduce tension directly associated with potentially stressful procedures and states. The current study tested the general effect of PRT on the wellbeing of zoo-housed chimpanzees (Pan troglodytes) by measuring behaviors that reflect poor and good welfare and that were not directly connected to the specific aim of the training session. The behavior of a group of twelve chimpanzees was measured throughout the day from the exhibition yard, at baseline (12 weeks) and during the PRT period (10 weeks). The results show a significant decrease in abnormal and stress-related behaviors and a significant rise in prosocial affiliative behaviors following implementation of the training program. The training was shown to have a greater positive effect on low-ranking individuals compared with high-ranking ones. This research shows for the first time that PRT offers an enrichment effect whose general influence lasts throughout the day, irrespective of any direct link to a specific trained behavior. Consequently, it can be claimed that PRT presents an effective enrichment tool that can be implemented with captive animals. Because of the above-noted differential effect between high- and low-ranking chimpanzees, however, this should be taken into consideration when combining PRT with the non-human primates' daily routine.
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Animales de Zoológico/psicología , Pan troglodytes/psicología , Refuerzo en Psicología , Agresión , Animales , Conducta Animal , Femenino , Promoción de la Salud , Masculino , Estrés Psicológico/prevención & controlRESUMEN
Recent studies revealed that although subterranean mammals inhabit a dark underground environment, they can still perceive light stimuli and use this to entrain their circadian activity rhythm. Regarding spatial orientation, olfactory and tactile cues are employed for short-distance; whereas for long-distance, subterranean mammals employ the earth's magnetic field and self-generated (vestibular and kinestatic) cues. We suggest that seismic signals, utilized for long-distance communication, might also be used as an echolocation mechanism to determine digging depth and presence of obstacles ahead. Taken together, these mechanisms provide an equally efficient means of overall orientation and communication as those found in sighted mammals.
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Orientación/fisiología , Percepción Espacial/fisiología , Percepción Visual/fisiología , Animales , Ritmo Circadiano/fisiología , Señales (Psicología) , Oscuridad , Percepción de Distancia/fisiología , Luz , Magnetismo , Mamíferos , Olfato , Tacto , Visión Ocular/fisiologíaRESUMEN
We compared the role of tactile perception in maze learning in the blind mole rat and in the laboratory rat. Both species were tested in each of two mazes that were identical in complexity but differed in tunnel width and height: the first was only slightly wider than the animal's body width (narrow maze) while the second was about twice the animal's body width (wide maze). We found that the performances of rats tested in the narrow maze were significantly lower than those tested in the wide maze, as measured by time and number of errors to reach the end of the maze (food reward). The mole rats, in contrast, performed significantly better in the narrow maze than in the wide maze. Further, in contrast to the rats, the mole rats' locomotion in the wide maze was much less continuous than in the narrow maze, reflected in longer and more frequent stops at maze junctions, where they pressed the side of their body tightly against the tunnel walls. Two main conclusions are derived from this experiment. First, subterranean mammals, such as the blind mole rat, appear to rely more on tactile stimuli while exploring and learning a complex maze than do sighted surface-dwelling rodents, such as rat. The extensive use of this somatosensory channel may compensate for the mole rats' visual deficiency, and thus substantially contribute to their excellent spatial orientation ability, previously demonstrated in field and laboratory conditions. Second, poor performance of surface-dwelling rodents, such as the rats, in spatial-maze learning tasks might not be a consequence of impaired cognitive learning ability, but rather due to testing the animal in a physical situation that does not provide the necessary somatosensory stimuli found in their natural habitat.
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Aprendizaje por Laberinto/fisiología , Orientación/fisiología , Propiocepción/fisiología , Privación Sensorial/fisiología , Tacto/fisiología , Percepción Visual/fisiología , Animales , Femenino , Mecanorreceptores/fisiología , Ratas , Ratas Wistar , Tiempo de Reacción/fisiología , Spalax , Especificidad de la EspecieRESUMEN
Stereotypic behavior often indicates poor welfare. It may develop when the animal's ability to carry out appropriate behavioral responses is limited, despite a high motivation to express them. Behavioral motivations vary across species. Consequently, under similar captive conditions, the sustained inability of animals to express certain behaviors is likely to affect some species more than others. We used a phylogenetic comparative approach to evaluate the socio-ecological factors affecting the manifestation of stereotypic behavior in 24 species of zoo-housed primates. We examined the relationship between two stereotypic behaviors: hair-pulling and pacing, and the species' natural socio-ecological factors and captivity conditions. The degree of stereotypic behaviors was unaffected by phylogenetic relatedness between species. Stereotypic hair-pulling behavior levels were positively correlated with natural group size. Stereotypic pacing levels were positively correlated with the animals' natural day journey length. These findings suggest large-group and wide-ranging primate species are more prone to suffer in captivity. Our findings facilitate the detection of species that are more susceptible to behaving stereotypically in captivity. We suggest that providing appropriate social stimuli, and increasing the complexity of the captive environment rather than enlarging it, are both attainable and expected to improve the animals' welfare.
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Bienestar del Animal , Animales de Zoológico , Vivienda para Animales , Primates , Conducta Estereotipada , Crianza de Animales Domésticos , Animales , Filogenia , Especificidad de la EspecieRESUMEN
The attitudes and behaviours of cat owners in regard to treatment of cats may have a cumulative effect on the food availability, reproduction, density and welfare of the free-roaming cat population and thus also on the extent of cat overpopulation. Understanding this is thus a vital step in the a priori planning of cat management programs on any scale, as well as in developing public education programs on this issue. Although recent years have seen an accumulation of knowledge in regard to cat owners' attitudes and behaviours, the findings vary among countries and locations and in Israel this has never been investigated systematically. Using a questionnaire provided to cat owners in veterinary clinics, this study aimed at identifying those attitudes and behaviours that may be contributing to cat overpopulation in Tel Aviv, Israel, and at exploring the socio-economic factors that influence this problem. The findings show that the influential factors can be predicted from the cat owners' socio-economic status, mainly education and income, as well as gender and age. A consistency in those cat owner behaviours that contribute to cat overpopulation was also uncovered, revealing a sub-population of individuals who persist in the undesirable behaviours. Finally, a strong relationship between attitude and consequent behaviour was demonstrated, indicating the importance of education and targeted publicity as a means to influence attitudes and thereby change behaviours in this respect. We propose several measures by which to reduce the current extent of cat owners' contribution to the cat overpopulation: discouraging unwanted owner behaviours such as abandonment of their cats and allowing them to breed; promoting awareness of the neutering option among cat caretakers; and increasing pre-adoption neutering rates in shelters. Regional and national laws promoting responsible pet ownership need to be enacted. By improving the current level of knowledge and awareness among cat owners regarding cat overpopulation issues, and encouraging a more responsible attitude, cat owners' bond with their cats could be strengthened, as well as their bond with and contribution to their environment.
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Crianza de Animales Domésticos , Actitud Frente a la Salud , Propiedad , Adolescente , Adulto , Animales , Animales Salvajes , Castración/veterinaria , Gatos , Demografía , Femenino , Humanos , Israel/epidemiología , Masculino , Persona de Mediana Edad , Regulación de la Población , Encuestas y Cuestionarios , Población Urbana , Adulto JovenRESUMEN
This article describes the theoretical-conceptual frame of equine-facilitated psychotherapy (EFP) for adolescents at-risk, the unique components of this intervention, and its implementation in an evaluation study. The study was conducted at a residential treatment facility for adolescents at-risk. We examined the outcomes of EFP on self-image, self-control, trust and general life satisfaction. Fourteen resident adolescents comprised the treatment group, and were compared with a matched group of 15 residents who did not receive EFP (control). The treatment comprised a weekly individual EFP session over a period of seven months. The study found a trend of positive change in all four research parameters within the treatment group. Additional indications of the intervention's positive influence were also found and are discussed.
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Terapía Asistida por Caballos/métodos , Satisfacción Personal , Autoimagen , Confianza/psicología , Adolescente , Femenino , Humanos , Masculino , Trastornos Mentales/rehabilitación , Instituciones Residenciales , Riesgo , Resultado del TratamientoRESUMEN
The most prevalent sub-group of abnormal repetitive behaviors among captive animals is that of stereotypies. Previous studies have demonstrated some resemblance between stereotypy in captive animals and in humans, including the involvement of neurological malfunctions that lead to the expression of stereotypies. This malfunction can be evaluated through the use of neuropsychological tasks that assess perseveration as implying a failure of the basal ganglia (BG) to operate properly. Other studies, in contrast, have suggested that stereotypies are the product of neurologically intact individuals reacting to the abnormal nature of their surroundings, and are possibly characterized by an adaptive feature that enables the subject to cope with such adversity. Employing neuropsychological tests and also measuring the levels of fecal corticoids in captive rhesus macaques, we tested the hypothesis that stereotypies are related both to brain pathology and to a coping mechanism with stress, resembling accounts by autistic individuals exhibiting basal ganglia malfunction, and who report a sense of relief when performing stereotypies. Self-directed and fine-motor stereotypies exhibited by the monkeys were positively correlated with perseveration, suggesting BG malfunction; while self-directed stereotypies were also negatively correlated with an increase in fecal corticoids following a stress challenge, suggesting a related coping mechanism. We therefore suggest that not all repetitive, unvarying, and apparently functionless behaviors should be regarded as one homogeneous group of stereotypic behaviors; and that, reflecting reports from autistic individuals, self-directed stereotypies in captive rhesus monkeys are related both to brain pathology, and to an adaptive mechanism that allows those that express them to better cope with acute stressors.
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Adaptación Psicológica , Macaca mulatta/fisiología , Macaca mulatta/psicología , Conducta Estereotipada/fisiología , Estrés Psicológico/fisiopatología , Corticoesteroides/metabolismo , Análisis de Varianza , Animales , Conducta de Elección/fisiología , Extinción Psicológica , Heces/química , Femenino , Modelos Lineales , Masculino , Pruebas NeuropsicológicasRESUMEN
Previously, we found that new neurons recruited into the nidopallium caudale in isolated birds were less labeled than those of communally housed birds, suggesting that different types of neurons may survive best under different conditions. Repetition of the experiment revealed no differences between groups, indicating that the new neurons were of the same generation. Hence, social environment does not appear to affect the type of newly recruited nidopallium caudale neurons.
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Globo Pálido/citología , Plasticidad Neuronal/fisiología , Neuronas/fisiología , Medio Social , Factores de Edad , Análisis de Varianza , Animales , Pinzones , Timidina/metabolismo , Tritio/metabolismoRESUMEN
This study examined the duration of the effect of early olfactory experience in rats by determining the ease of conditioning and then reconditioning to an early-experienced odor. Rat pups (experimental group) were exposed to aniseed odor sprayed on the mother's belly from day 1 to 20 after birth. A control group was exposed only to water. At the ages of 21 and 40 days all the rats (experimental and control) were tested for preference for the odor of aniseed. Starting from day 41 after birth they were conditioned in a Y-maze to approach the odor of aniseed for a reward. We then divided both groups into five subgroups each. Each subgroup was retrained to approach aniseed after 5, 6, 7, 8 or 9 months, and their speeds of reconditioning to the odor were compared. The results showed that all rats in the early exposed group had remembered the odor and did not require reconditioning, unlike those in the group that had not had the early olfactory conditioning. The effect of the early experience was still detectable at least 5 months after last exposure to the odor.
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Condicionamiento Clásico , Aprendizaje por Laberinto , Recuerdo Mental , Odorantes , Animales , Animales Recién Nacidos , Animales Lactantes , Femenino , Masculino , Pimpinella , Ratas , Ratas Sprague-DawleyRESUMEN
Subterranean mammals like the blind mole-rat (Rodentia: Spalax ehrenbergi) are functionally blind and possess poor auditory sensitivity, limited to low-frequency sounds. Nevertheless, the mole-rat demonstrates extremely efficient ability to orient spatially. A previous field study has revealed that the mole-rat can assess the location, size and density of an underground obstacle, and accordingly excavates the most efficient bypass tunnel to detour around the obstacles. In the present study we used a multidisciplinary approach to examine the possibility that the mole-rat estimates the location and physical properties of underground obstacles using reflected self-generated seismic waves (seismic 'echolocation'). Our field observations revealed that all the monitored mole-rats produced low-frequency seismic waves (250-300 Hz) at intervals of 8+/-5 s (range: 1-13 s) between head drums while digging a bypass to detour an obstacle. Using a computerized simulation model we demonstrated that it is possible for the mole-rat to determine its distance from an obstacle boundary (open ditch or stone) by evaluating the amplitude (intensity) of the seismic wave reflected back to it from the obstacle interface. By evaluating the polarity of the reflected wave the mole-rat could distinguish between air space and solid obstacles. Further, the model showed that the diffracted waves from the obstacle's corners could give the mole-rat precise information on the obstacle size and its relative spatial position. In a behavioural experiment using a special T-maze setup, we tested whether the mole-rat can perceive seismic waves through the somatosensory system and localize the source. The results revealed that the mole-rat is able to detect low frequency seismic waves using only its paws, and in most cases the mole-rats determined accurately the direction of the vibratory source. In a histological examination of the glabrous skin of the mole-rat's paws we identified lamellate corpuscle mechanoreceptors that might be used to detect low frequency seismic waves. The combined findings from these different approaches lead us to suggest that a specialized seismic 'echolocation' system could be used by subterranean mammals to determine the most energy-conserving strategy with which to bypass an obstacle, as well as to estimate their distance from the surface, keeping their tunnels at the optimal depth.
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Adaptación Fisiológica , Mecanorreceptores/fisiología , Modelos Biológicos , Ratas Topo/fisiología , Orientación , Vibración , Animales , Simulación por Computador , Mecanorreceptores/anatomía & histología , Estimulación FísicaRESUMEN
Various experiments revealed that if an animal learns a stimulus-response-reinforcer relationship in one context and is then tested in another context there is usually a lessening of stimulus control, and the same discriminative stimuli that reliably controlled the behavior in the first context will have less effect in the new context. This reduction in performance is known as the "context shift effect." The effect of changing context on the probability of detecting explosives was investigated in seven highly trained explosives detection dogs (EDDs). In experiment 1 the dogs were trained alternately on path A, which always had five hidden explosives, and on a very similar path B, which never had any explosives. Within a few sessions the dogs showed a significant decrease in search behavior on path B, but not on path A. In experiment 2 the same dogs were trained only on path B with a target density of one explosive hidden every 4th day. The probability of the dogs now detecting the explosive was found to be significantly lower than in experiment 1. In experiment 3 the effect of the low target density as used in experiment 2 was investigated on a new but very similar path C. Both the detection probability for the one explosive every 4th day on the new path and the motivation to search were significantly higher than found in experiment 2. Finally, in experiment 4, an attempt was made to recondition the dogs to search on path B. Although trained for 12 daily sessions with one explosive hidden every session, the dogs failed to regain the normal levels of motivation they had shown on both new paths and on the paths that they knew usually contained explosives. The findings reveal that even a very intensively trained EDD will rapidly learn that a specific stretch of path does not contain explosives. The dog will then be less motivated to search and will miss newly placed targets. This learning is specific to the formerly always-clean path and is to some extent irreversible. However, the dog will search and detect normally on new paths even if they are very similar to the always-clean path. The data are discussed in terms of variables affecting renewal. The results suggest that following training designed to make a behavior "context independent," any extinction training will not generalize beyond that specific context used during the extinction training. In addition, if the behavior is extinguished in a specific context, it will be very difficult to restore that behavior in that context. These conclusions should be considered by anyone attempting to extinguish well-established trans-context behaviors.
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Aprendizaje por Asociación , Aprendizaje Discriminativo , Ambiente , Generalización del Estimulo , Olfato , Animales , Condicionamiento Clásico , PerrosRESUMEN
Studies dealing with spatial orientation in mammals have mostly dealt with surface-dwelling species. We studied the ability of a subterranean rodent to orient in space and compared it with two species of rodents that spend most of their lives above ground. The solitary blind mole-rat, Spalax ehrenbergi, inhabits an extensive, branching tunnel system that it digs itself and in which it spends its entire life. We examined its ability to learn and remember a winding path towards a goal in a multiple labyrinth and compared it with Levant voles, Microtus guentheri, and laboratory rats, Rattus norvegicus. The mole-rats learned significantly faster than the rats and voles. Furthermore, their ability to remember the maze was significantly better than that of the rats after 2, 7, 30 and 60 days from the end of the learning experiment and significantly better than the voles after 120 days. The mole-rats still retained ca. 45% of their optimal performance at the end of the learning experiment after 4 months compared with 20% for the voles after 4 months and less than 20% for the rats after 2 months. Despite having lost its vision, the mole-rat was thus more able to orient in a complex maze than the surface-dwelling vole and laboratory rat. We suggest that the mole-rat compensates for the sensory limitations imposed by the subterranean niche and for its loss of vision by relying on the Earth's magnetic field and internal cues to steer its course efficiently. We discuss the possible mechanisms of orientation. Copyright 2001 The Association for the Study of Animal Behaviour.
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Mole rats inhabit extensive individual tunnel systems. Since the energetic cost of burrowing far exceeds that of surface locomotion, excellent orientation ability is crucial. Here we examined whether mole rats can bypass an obstacle (ditch) intersecting an existing tunnel in order to rejoin the two tunnel sections. The mole rats dug two bypass types, depending on the size of the obstacle confronting them: a bypass around the small ditches, parallel and close to the ditch walls; or a bypass beneath the floor of the large ditches. These results demonstrate that the mole rat has the ability to avoid obstacles by digging accurate and energy-conserving bypass tunnels. In order to utilize such a capacity, the mole rat must possess both the means to evaluate the size of the obstacle as well as the ability to perceive its exact position relative to the original tunnel that it will rejoin. Possible mechanisms of orientation that could explain such ability are briefly discussed.