Robins, A., & Rogers, L. J. (2004). Lateralized prey-catching responses in the cane toad, Bufo marinus: analysis of complex visual stimuli. Anim. Behav., 68(4), 767–775.
Abstract: We tested the responses of Bufo marinus to prey stimuli of varying visual complexity that were moved around the toads in either a clockwise or anticlockwise direction at 1.7 revolutions/min. Predatory responses directed at prey resembling an insect were frequent when the model insect moved clockwise across the visual midline into the right visual hemifield. In contrast, the toads tended to ignore such stimuli when they moved anticlockwise across the midline into the left hemifield. No such lateralization was found when a rectangular strip moved along its longest axis was presented in a similar way. The toads also directed more responses towards the latter stimulus than towards the insect prey. Hence, the results suggest that lateralized predatory responses occur for considered decisions on whether or not to respond to complex insect-like stimuli, but not for decisions on comparatively simple stimuli. We discuss similarities between the lateralized feeding responses of B. marinus and those of avian species, as support for the hypothesis that lateralized brain function in tetrapods may have arisen from a common lateralized ancestor.
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Sullivan, R. M. (2004). Hemispheric Asymmetry in Stress Processing in Rat Prefrontal Cortex and the Role of Mesocortical Dopamine. Stress, 7(2), 131–143.
Abstract: The prefrontal cortex (PFC) is known to play an important role not only in the regulation of emotion,
but in the integration of affective states with appropriate modulation of autonomic and neuroendocrine
stress regulatory systems. The present review highlights findings in the rat which helps to elucidate the
complex nature of prefrontal involvement in emotion and stress regulation. The medial PFC is
particularly important in this regard and while dorsomedial regions appear to play a suppressive role in
such regulation, the ventromedial (particularly infralimbic) region appears to activate behavioral,
neuroendocrine and sympathetic autonomic systems in response to stressful situations. This may be
especially true of spontaneous stress-related behavior or physiological responses to relatively acute
stressors. The role of the medial PFC is somewhat more complex in conditions involving learned
adjustments to stressful situations, such as the extinction of conditioned fear responses, but it is clear
that the medial PFC is important in incorporating stressful experience for future adaptive behavior. It is
also suggested that mesocortical dopamine plays an important adaptive role in this region by preventing
excessive behavioral and physiological stress reactivity. The rat brain shows substantial hemispheric
specialization in many respects, and while the right PFC is normally dominant in the activation of
stress-related systems, the left may play a role in countering this activation through processes of
interhemispheric inhibition. This proposed basic template for the lateralization of stress regulatory
systems is suggested to be associated with efficient stress and emotional self-regulation, and also to be
shaped by both early postnatal experience and gender differences.
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da Costa, A. P., Leigh, A. E., Man, M. - S., & Kendrick, K. M. (2004). Face pictures reduce behavioural, autonomic, endocrine and neural indices of stress and fear in sheep. Proc. R. Soc. Lond. B., 271(1552), 2077–2084.
Abstract: Faces are highly emotive stimuli and we find smiling or familiar faces both attractive and comforting, even as young babies. Do other species with sophisticated face recognition skills, such as sheep, also respond to the emotional significance of familiar faces? We report that when sheep experience social isolation, the sight of familiar sheep face pictures compared with those of goats or inverted triangles significantly reduces behavioural (activity and protest vocalizations), autonomic (heart rate) and endocrine (cortisol and adrenaline) indices of stress. They also increase mRNA expression of activity–dependent genes (c–fos and zif/268) in brain regions specialized for processing faces (temporal and medial frontal cortices and basolateral amygdala) and for emotional control (orbitofrontal and cingulate cortex), and reduce their expression in regions associated with stress responses (hypothalamic paraventricular nucleus) and fear (central and lateral amygdala). Effects on face recognition, emotional control and fear centres are restricted to the right brain hemisphere. Results provide evidence that face pictures may be useful for relieving stress caused by unavoidable social isolation in sheep, and possibly other animal species, including humans. The finding that sheep, like humans, appear to have a right brain hemisphere involvement in the control of negative emotional experiences also suggests that functional lateralization of brain emotion systems may be a general feature in mammals.
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Ghirlanda, S., & Vallortigara, G. (2004). The evolution of brain lateralization: a game-theoretical analysis of population structure. Proceedings of the Royal Society of London. Series B: Biological Sciences, 271(1541), 853–857.
Abstract: In recent years, it has become apparent that behavioural and brain lateralization at the population level is the rule rather than the exception among vertebrates. The study of these phenomena has so far been the province of neurology and neuropsychology. Here, we show how such research can be integrated with evolutionary biology to understand lateralization more fully. In particular, we address the fact that, within a species, left– and right–type individuals often occur in proportions different from one–half (e.g. hand use in humans). The traditional explanations offered for lateralization of brain function (that it may avoid unnecessary duplication of neural circuitry and reduce interference between functions) cannot account for this fact, because increased individual efficiency is unrelated to the alignment of lateralization at the population level. A further puzzle is that such an alignment may even be disadvantageous, as it makes individual behaviour more predictable to other organisms. Here, we show that alignment of the direction of behavioural asymmetries in a population can arise as an evolutionarily stable strategy when individual asymmetrical organisms must coordinate their behaviour with that of other asymmetrical organisms. Brain and behavioural lateralization, as we know it in humans and other vertebrates, may have evolved under basically ‘social’ selection pressures.
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Monfort, S. (2004). Przewalski’s Horse (Equus przewalskii) Species Survival Plan. In PROCEEDINGS OF THE EAZA EQUID TAG MEETING FROM 5TH TO 9TH MAY 2004 AT HORTOBÁGY NATIONAL PARK, HUNGARY.
Abstract: A Master Planning meeting for the Asian wild horse, or Przewalski’s horse, was held 14th –15th April 2004 at the National Zoological Park’s Conservation and Research Center (CRC) in Front Royal, Virginia. The overall objectives of the meeting were to 1) develop a strategy to maximize genetic diversity and improve demographics, 2) make specific breeding recommendations, 3) establish ex situ research priorities, and 4) discuss strategies for ensuring that the North American herd contributes to the global managed population, as well as ongoing in situ conservation programs. Of particular importance were discussions focused on whether to continue managing the North American herd as two separate bloodlines — the A- and B-lines — or to manage the entire population using an M-line, or mixed-line strategy, designed to maximize founder representation and genetic diversity. The Equid Taxon Advisory Group has currently designated a target population of 150 specimens for this species. The current SSP population is 154 individuals distributed among 18 institutions (15 AZA, 3 non-AZA), of which San Diego Zoo, the Wilds, Minnesota Zoo, Calgary Zoo, the Wildlife Conservation Society/Bronx Zoo and the National Zoological Park were represented at the Master Planning meeting.
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Sands, J., & Creel, S. (2004). Social dominance, aggression and faecal glucocorticoid levels in a wild population of wolves, Canis lupus. Anim. Behav., 67(3), 387–396.
Abstract: Adrenal glucocorticoid (GC) secretion is an important component of the response to stress in vertebrates. A short-term increase in circulating GCs serves to redirect energy from processes that can be briefly curtailed without harm, allowing energy to be directed towards eliminating or avoiding the stressor. In contrast, prolonged elevation of GCs can cause a broad range of pathologies, including reproductive suppression. We examined whether social subordination in wolves leads to chronically elevated GC levels, and whether this [`]social stress' causes reproductive suppression of subordinates in cooperatively breeding species. Behavioural and endocrine data collected over 2 years from three packs of free-living wolves in Yellowstone National Park did not support this hypothesis. GC levels were significantly higher in dominant wolves than in subordinates, for both sexes, in all packs, in both years of study. Unlike other cooperatively breeding carnivores (e.g. dwarf mongooses, Helogale parvula, and African wild dogs, Lycaon pictus), high GCs in dominant wolves were not associated with high rates of aggression or agonistic interaction. Aggression increased for wolves of all ranks during mating periods, accompanied by a significant rise in GC levels. If chronic elevation of GCs carries fitness costs, then social stress in wolves (and many other social species) is a cost of dominance, not a consequence of subordination. The specific behavioural correlates of dominance that affect GC levels appear to vary among species, even those with similar social systems.
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Pongrácz, P., Miklósi, Á., Timár-Geng, K., & Csányi, V. (2004). Verbal Attention Getting as a Key Factor in Social Learning Between Dog (Canis familiaris) and Human. J. Comp. Psychol., 118(4), 375–383.
Abstract: Pet dogs (Canis familiaris) learn to detour a V-shaped fence effectively from an unfamiliar human demonstrator. In this article, 4 main features of the demonstrator's behavior are highlighted: (a) the manipulation of the target, (b) the familiarity of the demonstrator, (c) the role of verbal attention-getting behavior, and (d) whether a strange trained dog could also be an effective demonstrator. The results show that the main factor of a successful human demonstration is the continuous verbal communication with the dog during detouring. It was also found that an unfamiliar dog demonstrator was as efficient as the unfamiliar experimenter. The experiments provide evidence that in adult dogs, communicative context with humans is needed for effective interspecific social learning to take place. (PsycINFO Database Record (c) 2010 APA, all rights reserved)
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Hois, C. (2004). Feldstudie zur Gewichtsentwicklung und Gewichtsschätzung beim wachsenden Pferd. Ph.D. thesis, Tierärztlichen Fakultät der Ludwig-Maximilians-Universität München, .
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Eckardt, G., & Windhofer, A. (2004). Untersuchung der Beanspruchung von Pferden während Isolation und beim Verladen. Master's thesis, , .
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Aberle, K. S., Hamann, H., Drögemüller, C., & Distl, O. (2004). Genetic diversity in German draught horse breeds compared with a group of primitive, riding and wild horses by means of microsatellite DNA markers. Anim. Gen., 35(4), 270–277.
Abstract: Summary We compared the genetic diversity and distance among six German draught horse breeds to wild (Przewalski's Horse), primitive (Icelandic Horse, Sorraia Horse, Exmoor Pony) or riding horse breeds (Hanoverian Warmblood, Arabian) by means of genotypic information from 30 microsatellite loci. The draught horse breeds included the South German Coldblood, Rhenish German Draught Horse, Mecklenburg Coldblood, Saxon Thuringa Coldblood, Black Forest Horse and Schleswig Draught Horse. Despite large differences in population sizes, the average observed heterozygosity (Ho) differed little among the heavy horse breeds (0.64�0.71), but was considerably lower than in the Hanoverian Warmblood or Icelandic Horse population. The mean number of alleles (NA) decreased more markedly with declining population sizes of German draught horse breeds (5.2�6.3) but did not reach the values of Hanoverian Warmblood (NA = 6.7). The coefficient of differentiation among the heavy horse breeds showed 11.6% of the diversity between the heavy horse breeds, as opposed to 21.2% between the other horse populations. The differentiation test revealed highly significant genetic differences among all draught horse breeds except the Mecklenburg and Saxon Thuringa Coldbloods. The Schleswig Draught Horse was the most distinct draught horse breed. In conclusion, the study demonstrated a clear distinction among the German draught horse breeds and even among breeds with a very short history of divergence like Rhenish German Draught Horse and its East German subpopulations Mecklenburg and Saxon Thuringa Coldblood.
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