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Pickens, C. L., & Holland, P. C. (2004). Conditioning and cognition. Neurosci Biobehav Rev, 28(7), 651–661.
Abstract: Animals' abilities to use internal representations of absent objects to guide adaptive behavior and acquire new information, and to represent multiple spatial, temporal, and object properties of complex events and event sequences, may underlie many aspects of human perception, memory, and symbolic thought. In this review, two classes of simple associative learning tasks that address these core cognitive capacities are discussed. The first set, including reinforcer revaluation and mediated learning procedures, address the power of Pavlovian conditioned stimuli to gain access, through learning, to representations of upcoming events. The second set of investigations concern the construction of complex stimulus representations, as illustrated in studies of contextual learning, the conjunction of explicit stimulus elements in configural learning procedures, and recent studies of episodic-like memory. The importance of identifying both cognitive process and brain system bases of performance in animal models is emphasized.
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Cook, M., Mineka, S., Wolkenstein, B., & Laitsch, K. (1985). Observational conditioning of snake fear in unrelated rhesus monkeys. J Abnorm Psychol, 94(4), 591–610.
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Matzke, S. M., Oubre, J. L., Caranto, G. R., Gentry, M. K., & Galbicka, G. (1999). Behavioral and immunological effects of exogenous butyrylcholinesterase in rhesus monkeys. Pharmacol Biochem Behav, 62(3), 523–530.
Abstract: Although conventional therapies prevent organophosphate (OP) lethality, laboratory animals exposed to such treatments typically display behavioral incapacitation. Pretreatment with purified exogenous human or equine serum butyrylcholinesterase (Eq-BuChE), conversely, has effectively prevented OP lethality in rats and rhesus monkeys, without producing the adverse side effects associated with conventional treatments. In monkeys, however, using a commercial preparation of Eq-BuChE has been reported to incapacitate responding. In the present study, repeated administration of commercially prepared Eq-BuChE had no systematic effect on behavior in rhesus monkeys as measured by a six-item serial probe recognition task, despite 7- to 18-fold increases in baseline BuChE levels in blood. Antibody production induced by the enzyme was slight after the first injection and more pronounced following the second injection. The lack of behavioral effects, the relatively long in vivo half-life, and the previously demonstrated efficacy of BuChE as a biological scavenger for highly toxic OPs make BuChE potentially more effective than current treatment regimens for OP toxicity.
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Roper, K. L., & Zentall, T. R. (1993). Directed forgetting in animals. Psychol Bull, 113(3), 513–532.
Abstract: Directed-forgetting research with animals suggests that animals show disrupted test performance only under certain conditions. Important variables are (a) whether during training, the cue to forget (F cue) signals nonreward (i.e., that the trial is over) versus reward (i.e., that reinforcement can be obtained) and (b) given that reinforcement can be obtained on F-cue trials, whether the post-F-cue response pattern is compatible with the baseline memory task. It is proposed that some findings of directed forgetting can be attributed to trained response biases, whereas others may be attributable perhaps to frustration-produced interference. It is suggested that directed forgetting in animals should be studied using procedures similar to those used to study directed forgetting in humans. This can be accomplished by presenting, within a trial, both to-be-remembered and to-be-forgotten material.
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Parkin, T. D. H., Clegg, P. D., French, N. P., Proudman, C. J., Riggs, C. M., Singer, E. R., et al. (2004). Horse-level risk factors for fatal distal limb fracture in racing Thoroughbreds in the UK. Equine Vet J, 36(6), 513–519.
Abstract: REASONS FOR PERFORMING STUDY: Fractures below the level of the radius or tibia (distal limb fractures) are the most common cause of equine fatality on UK racecourses; however, little is known about their epidemiology or aetiology. Identification of risk factors could enable intervention strategies to be designed to reduce the number of fatalities. OBJECTIVES: To identify horse-level risk factors for fatal distal limb fracture in Thoroughbreds on UK racecourses. METHODS: A case-control study design was used. Fractures in case horses were confirmed by post mortem examination and 3 matched uninjured controls were selected from the race in which the case horse was running. One hundred and nine cases were included and information was collected about previous racing history, horse characteristics and training schedules. Conditional logistic regression was used to identify the relationship between a number of independent variables and the likelihood of fracture. RESULTS: Horses doing no gallop work during training and those in their first year of racing were at significantly increased risk of fracture on the racecourse. Case horses were also more likely to have trained on a sand gallop, i.e. a gallop described by trainers as being primarily composed of sand. CONCLUSIONS: Modifications to training schedules, specifically within the first year of racing, may have a large impact on the risk of fatal distal limb fracture on the racecourse. Horses should do some gallop work in training and our results suggest that the minimum distance galloped should be between 805-2012 m (4-10 furlongs)/week. POTENTIAL RELEVANCE: The information from this study can be used to alter training schedules in an attempt to reduce the incidence of fatal distal limb fracture in Thoroughbred racehorses. Training should include some gallop work, and further studies, recording the exact level of work, will help to identify an optimum range of training speeds and distances which will reduce the liklihood of catastrophic fracture on the racecourse.
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Gerber, V., Robinson, N. E., Luethi, S., Marti, E., Wampfler, B., & Straub, R. (2003). Airway inflammation and mucus in two age groups of asymptomatic well-performing sport horses. Equine Vet J, 35(5), 491–495.
Abstract: REASONS FOR PERFORMING STUDY: Horses housed in conventional stable environments are exposed to high dust loads. Long-term exposure to inhaled dust may lead to subclinical airway disease. HYPOTHESES: Airway inflammation and mucus accumulation are 1) common in asymptomatic well-performing sport horses, 2) increased in older compared to younger individuals and 3) correlated. METHODS: Mucus quantity and quality (endoscopic scoring) and BALF differential cytology were assessed in 13 younger horses (mean age 5 years) and 13 older horses (mean age 15 years), which had no historical or clinical evidence of lower airway disease, were performing well and were housed permanently in a conventional stable environment. RESULTS: 1) Airway inflammation and/or mucus accumulation were very common. All sport horses showed evidence of subclinical inflammatory airway disease (IAD). 2) Older horses, having been exposed for 10 more years to a conventional stable environment, did not show increased subclinical airway inflammation or mucus accumulation. The only differences between the age groups were increased BALF total and lymphocyte cell counts in the younger horses. 3) Mucus quantity and quality scores were not significantly correlated with each other or with BALF neutrophil percentages and absolute numbers. CONCLUSIONS: Although clinically healthy and performing well, all of the examined horses housed in a conventional stable environment showed evidence of IAD. The degree of IAD was not increased in older horses that had not developed clinical signs. POTENTIAL RELEVANCE: The effect of subclinical degrees of IAD on performance in dressage and show jumping should be investigated further to better understand the clinical significance of IAD in sport horses.
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Robert, C., Valette, J. P., & Denoix, J. M. (2006). Correlation between routine radiographic findings and early racing career in French trotters. Equine Vet J Suppl, (36), 473–478.
Abstract: REASONS FOR PERFORMING STUDY: The relationship between the presence of radiological abnormalities and subsequent racing performance is controversial. However, as training is expensive and time consuming, it would save time and money to identify subjects with osteo-articular lesions not compatible with a normal racing career on the basis of routine radiographic screenings at yearling age. OBJECTIVES: To evaluate the impact of osteo-articular lesions on racing ability in French Trotters and identify radiographic changes associated with failure in 'qualification', in order to provide objective criteria for selection of horses based on their osteo-articular status. HYPOTHESIS: The influence of radiographic findings (RF) on racing ability depends on their nature, location, clinical relevance and number. METHODS: The limbs of 202 French Trotters were radiographed just before they started training. All the RF were graded according to a standardised protocol depending on their severity. The success in 'qualification' (first race in career of French Trotters) was the criteria used to assess racing ability. Breeders and trainers were questioned about the causes for horses not racing. RESULTS: Overall 113 (55.9%) horses qualified. Osteoarticular lesions were directly responsible for nonqualification in 31% of the horses. Subjects with more than one abnormal RF, with abnormal RF on the fore-, hind-fetlock or proximal tarsus were less likely to qualify. Dorsal modelling in the front fetlock and osteochondrosis of the lateral trochlear ridge of the femur also significantly reduced the qualification rate. CONCLUSIONS: Most RF are compatible with beginning a racing career, but severe RF or multiple abnormal RF significantly compromise future racing career. POTENTIAL RELEVANCE: This study supports the use of routine radiographic programmes for detection of osteoarticular lesions in yearlings. A synthetic radiographic score, based on both the severity and the number of lesions, could be useful for breeders and trainers as complementary information to select their horses.
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Zentall, T. R. (1999). Support for a theory of memory for event duration must distinguish between test-trial ambiguity and actual memory loss. J Exp Anal Behav, 72(3), 467–472.
Abstract: Staddon and Higa's (1999) trace-strength theory of timing and memory for event duration can account for pigeons' bias to “choose short” when retention intervals are introduced and to “choose long” when, following training with a fixed retention interval, retention intervals are shortened. However, it does not account for the failure of pigeons to choose short when the intertrial interval is distinct from the retention interval. That finding suggests that stimulus generalization (or ambiguity) between the intertrial interval and the retention interval may result in an effect that has been attributed to memory loss. Such artifacts must be eliminated before a theory of memory for event duration can be adequately tested.
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Robert, C., Valette, J. P., & Denoix, J. M. (2001). The effects of treadmill inclination and speed on the activity of three trunk muscles in the trotting horse. Equine Vet J, 33(5), 466–472.
Abstract: The purpose of this study was to evaluate the effects of speed and slope on the activity of trunk muscles. The electromyographic (EMG) activity of the splenius (Sp), longissimus dorsi (LD) and rectus abdominis (RA) muscles was recorded with surface electrodes during treadmill locomotion at trot for different combinations of speed (3.5 to 6 m/s) and slope (0 to 6%). Raw EMG signals were processed to determine activity duration, onset and end and integrated EMG (IEMG). For the 3 muscles investigated, onset and end of activity were obtained earlier in the stride cycle when speed increased. A longer duration of activity for the LD, a shorter duration for the RA and an unchanged duration for the Sp were also observed. The IEMG of the latter was poorly affected by speed, whereas it increased linearly with speed for the 2 other muscles. When treadmill inclination changed from 0 to 6%, EMG activity of the LD and RA began and ended later; a longer activity duration was noted. Temporal parameters for Sp did not change with slope. A significant and progressive increase in the IEMG of the 3 muscles was observed with increasing slope. This evaluation of the activity of trunk muscles provides objective data for the use of speed or slope in training programmes.
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Dreier, S., van Zweden, J. S., & D'Ettorre, P. (2007). Long-term memory of individual identity in ant queens. Biol Lett, 3(5), 459–462.
Abstract: Remembering individual identities is part of our own everyday social life. Surprisingly, this ability has recently been shown in two social insects. While paper wasps recognize each other individually through their facial markings, the ant, Pachycondyla villosa, uses chemical cues. In both species, individual recognition is adaptive since it facilitates the maintenance of stable dominance hierarchies among individuals, and thus reduces the cost of conflict within these small societies. Here, we investigated individual recognition in Pachycondyla ants by quantifying the level of aggression between pairs of familiar or unfamiliar queens over time. We show that unrelated founding queens of P. villosa and Pachycondyla inversa store information on the individual identity of other queens and can retrieve it from memory after 24h of separation. Thus, we have documented for the first time that long-term memory of individual identity is present and functional in ants. This novel finding represents an advance in our understanding of the mechanism determining the evolution of cooperation among unrelated individuals.
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