Records |
Author |
Cheung, C.; Akiyama, T.E.; Ward, J.M.; Nicol, C.J.; Feigenbaum, L.; Vinson, C.; Gonzalez, F.J. |
Title |
Diminished hepatocellular proliferation in mice humanized for the nuclear receptor peroxisome proliferator-activated receptor alpha |
Type |
Journal Article |
Year |
2004 |
Publication |
Cancer research |
Abbreviated Journal |
Cancer Res |
Volume |
64 |
Issue |
11 |
Pages |
3849-3854 |
Keywords |
Animals; Anticholesteremic Agents/pharmacology; Carcinogens/pharmacology; Cell Division; DNA Replication/drug effects; Fatty Acids/metabolism; Hepatocytes/cytology/drug effects/metabolism/*physiology; Humans; Mice; Mice, Transgenic; Oxidation-Reduction; Peroxisome Proliferators/pharmacology; Pyrimidines/pharmacology; Receptors, Cytoplasmic and Nuclear/genetics/*physiology; Species Specificity; Transcription Factors/genetics/*physiology |
Abstract |
Lipid-lowering fibrate drugs function as agonists for the nuclear receptor peroxisome proliferator-activated receptor alpha (PPARalpha). Sustained activation of PPARalpha leads to the development of liver tumors in rats and mice. However, humans appear to be resistant to the induction of peroxisome proliferation and the development of liver cancer by fibrate drugs. The molecular basis of this species difference is not known. To examine the mechanism determining species differences in peroxisome proliferator response between mice and humans, a PPARalpha-humanized mouse line was generated in which the human PPARalpha was expressed in liver under control of the tetracycline responsive regulatory system. The PPARalpha-humanized and wild-type mice responded to treatment with the potent PPARalpha ligand Wy-14643 as revealed by induction of genes encoding peroxisomal and mitochondrial fatty acid metabolizing enzymes and resultant decrease of serum triglycerides. However, surprisingly, only the wild-type mice and not the PPARalpha-humanized mice exhibited hepatocellular proliferation as revealed by elevation of cell cycle control genes, increased incorporation of 5-bromo-2'-deoxyuridine into hepatocyte nuclei, and hepatomegaly. These studies establish that following ligand activation, the PPARalpha-mediated pathways controlling lipid metabolism are independent from those controlling the cell proliferation pathways. These findings also suggest that structural differences between human and mouse PPARalpha are responsible for the differential susceptibility to the development of hepatocarcinomas observed after treatment with fibrates. The PPARalpha-humanized mice should serve as models for use in drug development and human risk assessment and to determine the mechanism of hepatocarcinogenesis of peroxisome proliferators. |
Address |
Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA |
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English |
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0008-5472 |
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PMID:15172993 |
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no |
Call Number |
refbase @ user @ |
Serial |
74 |
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Author |
Adler, L.L.; Adler, H.E. |
Title |
Ontogeny of observational learning in the dog (Canis familiaris) |
Type |
Journal Article |
Year |
1977 |
Publication |
Developmental Psychobiology |
Abbreviated Journal |
Dev Psychobiol |
Volume |
10 |
Issue |
3 |
Pages |
267-271 |
Keywords |
Animals; Dogs/*physiology; Female; Learning/*physiology; Male; Vision, Ocular/physiology |
Abstract |
A split-litter technique was used to test observational learning in 4 litters of Miniature Dachshund puppies, 21, 28, 38, and 60 days old at the beginning of the experiment. In one side of a duplicate cage, one puppy of a litter, the demonstrator, learned to pull in a food cart on a runner by means of a ribbon, while another puppy, the observer, watched from an adjacent compartment, separated by a wire screen. Observational learning was demonstrated by the saving in time for the 1st trial when the observer was given the same problem to solve. Maturation, particularly the development of visual function and motor coordination, set a lower age limit for the emergence of observational learning. |
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ISSN |
0012-1630 |
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Notes |
PMID:863122 |
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no |
Call Number |
Equine Behaviour @ team @ |
Serial |
5186 |
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Author |
Hall, C.A.; Cassaday, H.J.; Derrington, A.M. |
Title |
The effect of stimulus height on visual discrimination in horses |
Type |
Journal Article |
Year |
2003 |
Publication |
Journal of Animal Science |
Abbreviated Journal |
J. Anim Sci. |
Volume |
81 |
Issue |
7 |
Pages |
1715-1720 |
Keywords |
Animals; *Discrimination Learning/physiology; Female; Horses/physiology/*psychology; Male; Orientation; *Photic Stimulation; Vision/*physiology |
Abstract |
This study investigated the effect of stimulus height on the ability of horses to learn a simple visual discrimination task. Eight horses were trained to perform a two-choice, black/white discrimination with stimuli presented at one of two heights: ground level or at a height of 70 cm from the ground. The height at which the stimuli were presented was alternated from one session to the next. All trials within a single session were presented at the same height. The criterion for learning was four consecutive sessions of 70% correct responses. Performance was found to be better when stimuli were presented at ground level with respect to the number of trials taken to reach the criterion (P < 0.05), percentage of correct first choices (P < 0.01), and repeated errors made (P < 0.01). Thus, training horses to carry out tasks of visual discrimination could be enhanced by placing the stimuli on the ground. In addition, the results of the present study suggest that the visual appearance of ground surfaces is an important factor in both horse management and training. |
Address |
School of Land-based Studies, Nottingham Trent University, Brackenhurst College Campus, Southwell, Nottinghamshire, England NG25 0QF. carol.hall@ntu.ac.uk |
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0021-8812 |
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PMID:12854807 |
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no |
Call Number |
refbase @ user @ |
Serial |
835 |
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Author |
Wolfe, J.M. |
Title |
Hidden visual processes |
Type |
Journal Article |
Year |
1983 |
Publication |
Scientific American |
Abbreviated Journal |
Sci Am |
Volume |
248 |
Issue |
2 |
Pages |
94-103 |
Keywords |
Color Perception/*physiology; Humans; Motion Perception/physiology; Ocular Physiology; Vision; Visual Perception/*physiology |
Abstract |
Isoluminant stimulus is an image whose edges are defined only by a change in color, not by change in brightness. The stimulus here is imperfect: the blue parts and the green parts of the image are only as nearly equal in brightness as they can be on the printed page. Moreover, the change in brightness beyond the edge of the page is apparent, and so is the fact that the reader is holding the magazine at reading distance. When such cues are removed under laboratory conditions, subjects faced with an isoluminant stimulus prove unable to bring its edges into focus. This deficiency contributes to making a familiar face hard to recognize. The experiment indicates that the brain process underlying visual accommodation (the focusing of the eyes) cannot “see” color; it is a hidden process distinct from the processes that lead to perception. The image shows Groucho Marx as he appeared in the motion picture Horse Feathers. |
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ISSN |
0036-8733 |
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Notes |
PMID:6836258 |
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no |
Call Number |
Equine Behaviour @ team @ |
Serial |
4066 |
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Author |
Timney, B.; Keil, K. |
Title |
Local and global stereopsis in the horse |
Type |
Journal Article |
Year |
1999 |
Publication |
Vision Research |
Abbreviated Journal |
Vision Res |
Volume |
39 |
Issue |
10 |
Pages |
1861-1867 |
Keywords |
Animals; Depth Perception/*physiology; Female; Horses/*physiology; Pattern Recognition, Visual/physiology; Psychophysics; Sensory Thresholds/physiology; Vision, Binocular/physiology; Vision, Monocular/physiology |
Abstract |
Although horses have laterally-placed eyes, there is substantial binocular overlap, allowing for the possibility that these animals have stereopsis. In the first experiment of the present study we measured local stereopsis by obtaining monocular and binocular depth thresholds for renal depth stimuli. On all measures, the horses' binocular performance was superior to their monocular. When depth thresholds were obtained, binocular thresholds were several times superior to those obtained monocularly, suggesting that the animals could use stereoscopic information when it was available. The binocular thresholds averaged about 15 min arc. In the second experiment we obtained evidence for the presence of global stereopsis by testing the animals' ability to discriminate between random-dot stereograms with and without consistent disparity information. When presented with such stimuli they showed a strong preference for the cyclopean equivalent of the positive stimulus with the real depth. These results provide the first behavioral demonstration of a full range of stereoscopic skills in a lateral-eyed mammal. |
Address |
Department of Psychology, Faculty of Social Science, University of Western Ontario, London, Canada. timney@julian.uwo.ca |
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0042-6989 |
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Notes |
PMID:10343877 |
Approved |
yes |
Call Number |
Equine Behaviour @ team @ |
Serial |
3580 |
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Author |
Siniscalchi, M.; Sasso, R.; Pepe, A.M.; Vallortigara, G.; Quaranta, A. |
Title |
Dogs turn left to emotional stimuli |
Type |
Journal Article |
Year |
2010 |
Publication |
Behavioural Brain Research |
Abbreviated Journal |
Behav. Brain. Res. |
Volume |
208 |
Issue |
2 |
Pages |
516-521 |
Keywords |
Dog; Laterality; Vision; Behaviour; Physiology; Cognition; Emotion; Animal welfare |
Abstract |
During feeding behaviour, dogs were suddenly presented with 2D stimuli depicting the silhouette of a dog, a cat or a snake simultaneously into the left and right visual hemifields. A bias to turn the head towards the left rather than the right side was observed with the cat and snake stimulus but not with the dog stimulus. Latencies to react following stimulus presentation were lower for left than for right head turning, whereas times needed to resume feeding behaviour were higher after left rather than after right head turning. When stimuli were presented only to the left or right visual hemifields, dogs proved to be more responsive to left side presentation, irrespective of the type of stimulus. However, cat and snake stimuli produced shorter latencies to react and longer times to resume feeding following left rather than right monocular visual hemifield presentation. Results demonstrate striking lateralization in dogs, with the right side of the brain more responsive to threatening and alarming stimuli. Possible implications for animal welfare are discussed. |
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0166-4328 |
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no |
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Equine Behaviour @ team @ |
Serial |
5080 |
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Author |
Hirata, S. |
Title |
A note on the responses of chimpanzees (Pan troglodytes) to live self-images on television monitors |
Type |
Journal Article |
Year |
2007 |
Publication |
Behavioural Processes |
Abbreviated Journal |
Behav. Process. |
Volume |
75 |
Issue |
1 |
Pages |
85-90 |
Keywords |
Animals; *Discrimination Learning; Female; Male; Pan troglodytes/*psychology; *Self Concept; Self Psychology; Social Behavior; Television |
Abstract |
The majority of studies on self-recognition in animals have been conducted using a mirror as the test device; little is known, however, about the responses of non-human primates toward their own images in media other than mirrors. This study provides preliminary data on the reactions of 10 chimpanzees to live self-images projected on two television monitors, each connected to a different video camera. Chimpanzees could see live images of their own faces, which were approximately life-sized, on one monitor. On the other monitor, they could see live images of their whole body, which were approximately one-fifth life-size, viewed diagonally from behind. In addition, several objects were introduced into the test situation. Out of 10 chimpanzees tested, 2 individuals performed self-exploratory behaviors while watching their own images on the monitors. One of these two chimpanzees successively picked up two of the provided objects in front of a monitor, and watched the images of these objects on the monitor. The results indicate that these chimpanzees were able to immediately recognize live images of themselves or objects on the monitors, even though several features of these images differed from those of their previous experience with mirrors. |
Address |
Great Ape Research Institute, Hayashibara Biochemical Laboratories Inc., Okayama, Japan. hirata@gari.be.to |
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0376-6357 |
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PMID:17324534 |
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no |
Call Number |
Equine Behaviour @ team @ |
Serial |
4145 |
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Author |
Hanggi, E.B.; Ingersoll, J.F. |
Title |
Stimulus discrimination by horses under scotopic conditions |
Type |
Journal Article |
Year |
2009 |
Publication |
Behavioural Processes |
Abbreviated Journal |
Behav. Process. |
Volume |
82 |
Issue |
1 |
Pages |
45-50 |
Keywords |
Discrimination learning; Equine; Horse; Night vision; Scotopic vision |
Abstract |
Scotopic vision in horses (Equus caballus) was investigated using behavioral measurements for the first time. Four horses were tested for the ability to make simple visual discriminations of geometric figures (circles and triangles) under various brightness levels within an enclosed building. Measurements of brightness ranging from 10.37 to 24.12 magnitudes per square arcsecond (mag/arcsec2; in candelas per square meter--7.70 to 2.43E-05 cd/m2) were taken using a Sky Quality Meter. These values approximated outdoor conditions ranging from twilight in open country to a dark moonless night in dense forest. The horses were able to solve the discrimination problems in all brightness settings up to 23.77 mag/arcsec2 (3.35E-05 cd/m2). Moreover, they easily navigated their way around obstacles located within the testing area in extremely dim light (>23.50 mag/arcsec2; 4.30E-05 cd/m2), which were in conditions too dark for the human experimenters to see. These findings support physiological data that reveal a rod-dominated visual system as well as observations of equine activity at night. |
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0376-6357 |
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Equine Behaviour @ team @ |
Serial |
5051 |
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Author |
Blackmore, T.L.; Foster, T.M.; Sumpter, C.E.; Temple, W. |
Title |
An investigation of colour discrimination with horses (Equus caballus) |
Type |
Journal Article |
Year |
2008 |
Publication |
Behavioural Processes |
Abbreviated Journal |
Behav. Process. |
Volume |
78 |
Issue |
3 |
Pages |
387-396 |
Keywords |
Chromatic discrimination; Colour vision; Horse; Operant |
Abstract |
The ability of four horses (Equus caballus) to discriminate coloured (three shades of blue, green, red, and yellow) from grey (neutral density) stimuli, produced by back projected lighting filters, was investigated in a two response forced-choice procedure. Pushes of the lever in front of a coloured screen were occasionally reinforced, pushes of the lever in front of a grey screen were never reinforced. Each colour shade was randomly paired with a grey that was brighter, one that was dimmer, and one that approximately matched the colour in terms of brightness. Each horse experienced the colours in a different order, a new colour was started after 85% correct responses over five consecutive sessions or if accuracy showed no trend over sessions. All horses reached the 85% correct with blue versus grey, three horses did so with both yellow and green versus grey. All were above chance with red versus grey but none reached criterion. Further analysis showed the wavelengths of the green stimuli used overlapped with the yellow. The results are consistent with histological and behavioural studies that suggest that horses are dichromatic. They differ from some earlier data in that they indicate horses can discriminate yellow and blue, but that they may have deficiencies in discriminating red and green. |
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0376-6357 |
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Equine Behaviour @ team @ |
Serial |
5336 |
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Author |
Kilian, A.; Fersen, L. von; Güntürkün, O. |
Title |
Left hemispheric advantage for numerical abilities in the bottlenose dolphin |
Type |
Journal Article |
Year |
2005 |
Publication |
Behavioural Processes |
Abbreviated Journal |
Behav. Process. |
Volume |
68 |
Issue |
2 |
Pages |
179-184 |
Keywords |
Bottlenose dolphin; Hemispheric specialization; Monocular vision; Numerical ability |
Abstract |
In a two-choice discrimination paradigm, a bottlenose dolphin discriminated relational dimensions between visual numerosity stimuli under monocular viewing conditions. After prior binocular acquisition of the task, two monocular test series with different number stimuli were conducted. In accordance with recent studies on visual lateralization in the bottlenose dolphin, our results revealed an overall advantage of the right visual field. Due to the complete decussation of the optic nerve fibers, this suggests a specialization of the left hemisphere for analysing relational features between stimuli as required in tests for numerical abilities. These processes are typically right hemisphere-based in other mammals (including humans) and birds. The present data provide further evidence for a general right visual field advantage in bottlenose dolphins for visual information processing. It is thus assumed that dolphins possess a unique functional architecture of their cerebral asymmetries. |
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0376-6357 |
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Equine Behaviour @ team @ |
Serial |
5366 |
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