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Author Benhamou, S.
Title Place navigation in mammals: a configuration-based model Type Journal Article
Year 1998 Publication Animal Cognition Abbreviated Journal Anim. Cogn.
Volume 1 Issue 1 Pages 55-63
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Abstract Recent water maze experiments suggest that rats performing place navigation primarily use the geometric information provided by a set of landmarks, and neglect the featural information provided by the identities of the landmarks. Here, I develop a model that explains how an animal may perform place navigation by relying only on geometric information. The core of the model is the representation of places as panoramas defined by circular bar-codes embodying the relative bearings and apparent sizes of the landmarks, irrespective of their identities. There are two stages in the model. During the first stage, the animal freely explores its environment in order to acquire spatial information at the local level. During the second stage, the animal uses the information previously memorized to perform place navigation towards the goal it intends to reach. The possible role of two brain areas in place navigation is discussed within this framework. Beyond their primary role in landmark-based representations of places, hippocampal place cells may be involved in computing the current distances to the landmarks. Beyond their primary role in landmark-based representations of headings, post-subicular head-direction cells may be involved in computing the “compass bearings” of the landmarks.
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Call Number Equine Behaviour @ team @ Serial 3344
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Author Vallortigara, G.; Regolin, L.; Rigoni, M.; Zanforlin, M.
Title Delayed search for a concealed imprinted object in the domestic chick Type Journal Article
Year 1998 Publication Animal Cognition Abbreviated Journal Anim. Cogn.
Volume 1 Issue 1 Pages 17-24
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Abstract Five-day-old chicks were accustomed to follow an imprinted object (a small red ball with which they had been reared) that was moving slowly in a large arena, until it disappeared behind an opaque screen. In experiments, each chick was initially confined in a transparent cage, from where it could see and track the ball while it moved towards, and then beyond, one of two screens. The screens could be either identical or differ in colour and pattern. Either immediately after the disappearance of the ball, or with a certain delay, the chick was released and allowed to search for its imprinted object behind either screen. The results showed that chicks took into account the directional cue provided by the ball movement and its concealment, up to a delay period of about 180 s, independently of the perceptual characteristics of the two screens. If an opaque partition was positioned in front of the transparent cage immediately after the ball had disappeared, so that, throughout the delay, neither the goal-object nor the two screens were visible, chicks were still capable of remembering and choosing the correct screen, though over a much shorter period of about 60 s. The results suggest that, at least in this precocial bird species, very young chicks can maintain some form of representation of the location where a social partner was last seen, and are also capable of continuously updating this representation so as to take into account successive displacements of the goal-object.
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Call Number Equine Behaviour @ team @ Serial 3347
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Author Shuster, G.; Sherman, P.W.
Title Tool use by naked mole-rats Type Journal Article
Year 1998 Publication Animal Cognition Abbreviated Journal Anim. Cogn.
Volume 1 Issue 1 Pages 71-74
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Abstract Naked mole-rats (Heterocephalus glaber, Rodentia: Bathyergidae) excavate extensive subterranean burrows with their procumbent incisors. Captive individuals often place a wood shaving or tuber husk behind their incisor teeth and in front of their lips and molar teeth while gnawing on substrates that yield fine particulate debris. This oral barrier may prevent choking or aspiration of foreign material. Consistent use of tools has rarely been reported in rodents.
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Call Number Equine Behaviour @ team @ Serial 3367
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Author McNelis, N.L.; Boatright-Horowitz, S.L.
Title Social monitoring in a primate group: the relationship between visual attention and hierarchical ranks Type Journal Article
Year 1998 Publication Animal Cognition Abbreviated Journal Anim. Cogn.
Volume 1 Issue 1 Pages 65-69
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Abstract Social monitoring has been hypothesized to be an important component of primate social behavior. If the gaze direction of one animal can redirect the gaze of another, visual scanning of conspecifics can provide a more efficient means of locating food or predators than directly scanning the entire nonsocial environment. Social monitoring also allows distance regulation between members of a group, reducing the likelihood of agonistic encounters. Although assessment of gaze direction in freely moving primates is problematic, we were successful in assessing amounts of visual scanning among adult females of a captive, socially housed group of patas monkeys (Erythrocebus patas) using a focal sampling technique with on-the-dot recording (5-s sampling intervals). In study 1, relative amounts of scanning were assessed as subjects gazed at any other member of the group. Percentages of agreement between observers ranged from 80% to 92%, with corresponding &#115 values ranging from 0.74 to 0.92. In study 2, relative amounts of visual scanning were assessed so that specific targets of gaze were identified. The resultant data supported a long-standing prediction about the role of social monitoring in primate group dynamics. Lower-ranking animals gazed toward higher-ranking animals more often than vice versa. Although the specific cues eliciting social monitoring remain to be determined, visual attention in this social primate group appeared to be systematically related to hierarchical ranks, assessed by displacements. Minimally, these results suggest that patas monkeys structure their visual attention based on previous encounters with other members of their social group. While simple discrimination learning could account for these results, the demonstration of a systematic relationship between visual attention and primate social dynamics is relevant to current discussions of a primate's understanding of conspecific gaze direction.
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Call Number Equine Behaviour @ team @ Serial 3377
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Author McLaren I.P.L.
Title Animal Learning and Cognition: A neural network approach Type Journal Article
Year 1998 Publication Trends in Cognitive Sciences Abbreviated Journal Trends. Cognit. Sci.
Volume 2 Issue Pages 236-236
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Call Number refbase @ user @ Serial 3464
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Author Vallortigara G.
Title Minds of Their Own Type Journal Article
Year 1998 Publication Trends in Cognitive Sciences Abbreviated Journal Trends. Cognit. Sci.
Volume 2 Issue Pages 118-118
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Notes Approved no
Call Number refbase @ user @ Serial 3466
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Author Mesulam, M.-M.
Title Review article. From sensation to cognition Type Journal Article
Year 1998 Publication Brain Abbreviated Journal
Volume 121 Issue Pages 1013-1052
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Call Number refbase @ user @ Serial 3467
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Author Morales, J.L.; Manchado, M.; Vivo, J.; Galisteo, A.M.; Aguera, E.; Miro, F.
Title Angular kinematic patterns of limbs in elite and riding horses at trot Type Journal Article
Year 1998 Publication Equine Veterinary Journal Abbreviated Journal Equine Vet J
Volume 30 Issue 6 Pages 528-533
Keywords Animals; Biomechanics; Breeding; Extremities/*physiology; Gait/*physiology; Horses/*physiology; Image Processing, Computer-Assisted; Joints/*physiology; Male; Video Recording
Abstract Normal speed videography was used to determine the angular parameters of 28 Spanish Thoroughbreds at trot. Horses were divided into 3 groups: Group UT, comprising 9 animals (provided by the VII National Stud, Cordoba, Spain) which had undergone no specific training programme and which were hand led at the trot; Group T, formed by 19 horses considered to be highly bred and trained, and which were also hand led; and Group RT, comprising the same horses as the latter group but this time trotted by a rider. Each animal was filmed 6 times from the right-hand side, using a Hi8 (25 Hz) video camera. Angular parameters for fore- and hindlimb joints were measured in each stride from computer-grabbed frames and entered into a spreadsheet for calculation; parameters included maximum and minimum angles, range of motion, and angles at landing, lift off and maximum hoof height; the times at which maximum angle, minimum angle, lift off and maximum hoof height occurred were calculated as percentages of total stride duration. Stride velocity (mean [s.d.]) was 4.01 (0.62), 3.60 (0.34) and 3.07 (0.36) m/s for Groups UT, T and RT, respectively. Data were then compared between Groups UT-T and Groups T-RT. Compared with Group UT, horses from Group T featured a shorter stance percentage (P<0.001) in both fore- and hindlimbs. The range of motion in forelimbs was smaller (P<0.05), due to lower retraction (P<0.001); moreover, maximum retraction appeared earlier (P<0.05). Greater scapular inclination was in evidence (P<0.05) and the shoulder joint extended further (P<0.05). Fore- and hind fetlock joints revealed a relatively shorter hyperextension period during the stance phase (P<0.01). Compared with Group T, horses from Group RT had a longer stance percentage, with belated maximum retraction of the fore- and hindlimbs. The range of movement in scapular inclination was greater (P<0.05), due to a smaller minimum angle (P<0.01), and the shoulder joint flexed more (P<0.05). The elbow joint extended more and for longer during the stance phase. Initial extension of the hip joint (P<0.05) and tarsus (P<0.001) lasted longer. The carpal and fore and hind fetlock joints recorded relatively longer hyperextension times, in addition to greater hyperextension during the stance phase. The results from the present study suggest that rider-effect must be taken in consideration when well gaited horses are selected for dressage purposes.
Address Department of Compared Anatomy and Pathology, University of Cordoba, Veterinary Faculty, Spain
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ISSN 0425-1644 ISBN Medium
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Notes PMID:9844972 Approved no
Call Number Equine Behaviour @ team @ Serial 3734
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Author Heitkamp, H.C.; Horstmann, T.; Hillgeris, D.
Title [Riding injuries and injuries due to handling horses in experienced riders] Type Journal Article
Year 1998 Publication Der Unfallchirurg Abbreviated Journal Unfallchirurg
Volume 101 Issue 2 Pages 122-128
Keywords Adult; Animals; Athletic Injuries/*epidemiology/etiology/surgery; Cross-Sectional Studies; Female; Fractures, Bone/epidemiology/etiology/surgery; Germany/epidemiology; *Horses; Humans; Incidence; Male; Multiple Trauma/epidemiology/etiology/surgery; Risk Factors
Abstract A group of experienced riders who qualified for the German riding badge 9.5 years ago answered a questionnaire pertaining to injuries during jumping, dressage and cross-country riding, as well as handling the horse. During riding 69% of the persons had had 187 injuries and while handling the horse 52% had had 124 injuries. Fractures and contusions were the most-frequent injuries; most riding injuries were located in the upper extremities and shoulder while handling mainly in the hands and feet. The number of injuries was comparable in jumping, dressage or cross-country riding. The time engaged in jumping was about one-third of the other types of riding, but the injuries were more severe. While handling the horse the number of injuries relative to the time spent during the activity were higher but less complicated. No change in safety precautions had been implemented by 67% of the persons injured. The injury rate for equestrians is relatively low both in handling the horse and during riding. The frequent fractures and contusions may be reduced by following the required safety regulations.
Address Abteilung Sportmedizin, Universitat Tubingen
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Publisher Place of Publication (up) Editor
Language German Summary Language Original Title Reitverletzungen und Verletzungen beim Umgang mit Pferden bei erfahrenen Reitern
Series Editor Series Title Abbreviated Series Title
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ISSN 0177-5537 ISBN Medium
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Notes PMID:9553480 Approved no
Call Number Equine Behaviour @ team @ Serial 3735
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Author Birch, H.L.; Bailey, A.J.; Goodship, A.E.
Title Macroscopic 'degeneration' of equine superficial digital flexor tendon is accompanied by a change in extracellular matrix composition Type Journal Article
Year 1998 Publication Equine Veterinary Journal Abbreviated Journal Equine Vet J
Volume 30 Issue 6 Pages 534-539
Keywords Animals; Collagen/analysis; DNA/analysis; Extracellular Matrix/*chemistry; Glycosaminoglycans/analysis; Horses/injuries/*physiology; Immunohistochemistry; Rupture/veterinary; Tendon Injuries/metabolism/pathology/veterinary; Tendons/chemistry/*pathology; Water/analysis
Abstract Injuries to the superficial digital flexor tendon are common in horses required to gallop and jump at speed. Partial rupture of this tendon usually occurs in the central core of the midmetacarpal region and may be preceded by localised degenerative changes. Post mortem examination of apparently normal equine flexor tendons has revealed an abnormal macroscopic appearance in the central core, characterised by a reddish discolouration. We have previously shown that there is also physical damage to the collagen fibres. In the present study we tested the hypothesis that the abnormal appearance is accompanied by changes in the composition of the extracellular matrix of the tendon. Biochemical analysis of the extracellular matrix demonstrated an increase in total sulphated glycosaminoglycan content, increase in the proportion of type III collagen and decrease in collagen linked fluorescence in the central core of 'degenerated' tendons relative to tissue from the peripheral region of the same tendon. Dry matter content and total collagen content were not significantly different between tendon zones or normal and 'degenerated' tendons. These changes suggest a change in cell metabolism and matrix turnover in the central core of the tendon and are likely to contribute to a decrease in mechanical properties in this part of the tendon, predisposing to the characteristic partial rupture of the tendon.
Address Veterinary Basic Sciences, Royal Veterinary College, North Mymms, Hatfield, UK
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Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
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ISSN 0425-1644 ISBN Medium
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Notes PMID:9844973 Approved no
Call Number Equine Behaviour @ team @ Serial 3794
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