This study involved a new type of patterned string task in which a delay period was imposed between string presentation and opportunity to respond. In Experiments I and II, six squirrel monkeys were tested on parallel and crossed string problems in a Wisconsin General Test Apparatus. After the parallel or crossed string pattern was viewed by the subject for five seconds, one of three conditions was carried out: (a) a cover was placed over the ends of the strings thereby obscuring the food cup at the end of one string (far cover); (b) a cover was placed over the center portion of the strings allowing the subject to view the food cup but breaking the visual continuity of the strings (middle cover); (c) a cover was placed behind the string pattern thereby not obstructing the subject's view (no cover). After placing the cover according to one of three conditions, a Plexiglas screen was raised either immediately or after a five-second delay thus allowing the subject to respond. Results indicated that squirrel monkeys committed more errors under the far cover condition than under the no cover condition on parallel string patterns. On the crossed string pattern, squirrel monkeys manifested more position preference during the middle cover condition than during the no cover condition or during the far cover condition. In Experiment III, six capuchin monkeys were tested under 11 conditions on crossed string patterns. Eleven conditions were used to vary the lighting and the location of covering during the 12-second delay. Conditions 1 through 10 were conducted either in light or in dark when a cover was imposed during the beginning, middle, or end four seconds or during the beginning or end eight seconds. Regardless of light or dark conditions, capuchin monkeys manifested more correct responses when the full pattern was visible during the last four or the last eight seconds before the response. The result suggests that information received in the early part of the delay interval was used less efficiently than did that in the last part of the delay interval.

No description available.

Schizophrenia is characterized by positive and negative symptoms along with cognitive symptoms that include impairment in working memory (WM). WM is the storage of relevant information for short intervals of time to guide thoughts and actions. The neural correlate of WM is thought to be the persistent activity exhibited during the retention interval of WM tasks. Persistent activity is hypothesized to be mediated by the activation of NMDA receptors (NMDAR) within recurrent neuronal circuits. Consistent with this hypothesis, studies with healthy humans and monkeys have shown that the administration of the NMDAR antagonist ketamine induces memory-load dependent deficits in WM, along with increasing response time. In parallel to this, the pathophysiology of schizophrenia has been hypothesized to rest on the hypofunction of NMDAR. Previous studies in humans indicate that blockade of NMDAR induces schizophrenia-like symptoms. In addition, symptoms of schizophrenia patients are alleviated with sub-chronic treatments focusing on the activation of the NMDAR co-agonist site. Based on these observations, I tested the hypothesis that increasing the activation of NMDAR with co-agonist stimulation has beneficial effects on WM. D-serine (100mg/kg/day-6 weeks) was orally administered to two female macaque monkeys performing a visual sequential comparison task (VCST), which allows the manipulation of memory load. In this task, the monkeys had to identify the location of a colour change within an array of 2 to 5 coloured stimuli following a retention interval of 1 second. I hypothesized that sub-chronic treatment with D-serine produces a gradual improvement in the monkeys’ performance on the VSCT. Specifically, I predicted that the improvement would scale with memory load due to increased demands on WM resources at higher loads. Contrary to my hypothesis, D-serine produced minute changes in response accuracy, which were not memory load-dependent. Also, the response latency of the monkeys was found to increase, which is commonly observed following NMDAR antagonist treatments. These findings suggest that D-serine has a limited role in increasing the activation of NMDARs to improve WM per se. The beneficial effects reported by NMDAR co-agonists in schizophrenic patients could be a general reduction in cognitive symptoms, not specifically related to WM. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2013-10-01 17:45:20.643

The aim of this thesis was to provide a better understanding of the needs of spider monkeys (genus: Ateles) kept in zoological parks in order to provide an appropriate environment, which enhances the physical and emotional wellbeing of the individuals. This series of studies adopted primarily a physiological approach that entailed measuring cortisol in urine samples collected over a seven year period to assess the impact of a variety of social and environmental conditions. My studies also involved behavioural observations and a questionnaire study to collect information from other zoological parks that maintain groups of spider monkeys. In order to address the aims of my research I first validated an enzyme immunoassay for urinary cortisol which allowed for the activity of the HPA axis to be measured to assess the physiological stress responses in spider monkeys. The first study assessed the impact of visitors on spider monkeys by comparing levels of urinary cortisol collected with visitor numbers and I found an increase in visitor numbers was associated with an increase in cortisol. This was the first time the physiological impact of visitors was investigated and supports behavioural researcher that visitors adversely impact on primates in zoos. The second study I carried out involved a questionnaires to investigate frequency, direction and intensity of aggression in zoo-housed spider monkeys in 55 other zoos around the world. The pattern of aggressions reported indicated severe and lethal aggression was relatively frequent among captive spider monkeys. Adult males were the most frequent actors of aggression and sub adult males were the most frequent targets, contradicting reports from wild spider monkeys. This aggression could be a condition of the management of spider monkeys in the zoos whereby males and normally transferred between zoos contradicting reports from the wild spider monkeys in which females would emigrate on reaching maturity. Next I investigated aggression, reproductive and separation stressors in the spider monkeys housed at Chester Zoo over a seven year period and measured their effects via changes in urinary cortisol prior to, at and following each event. Aggression had the largest effect, with targets and bystanders having the highest levels of cortisol on the day of aggression for severe and lethal aggression, respectively. When examining the reproductive events, cortisol levels were significantly elevated in the mother the week prior to and the day or birth, but were highest for bystander females on the day of birth. In the case of separations, cortisol was elevated when an individual was separated for longer than 24 hours for separations and less than 24 hours for reintroductions. Finally I investigated the replacement of the breeding male in the spider monkeys at Chester Zoo. Although a significant behavioural effect was identified in the adult females, there was little evidence of an increase in urinary cortisol among them. In addition, there were no instances of aggression between the adult males and the juvenile male in the group. Overall conclusions from this study indicate that the group of spider monkeys did demonstrate a varying stress response to a variety of social and environmental stressors associated with elevated cortisol levels and behavioural changes. However, there was no evidence of long term chronic stressors which are normally associated with poor welfare. This indicated that the environmental provided for this particular group of zoo-housed spider monkeys generally allowed for the individuals within the group to cope and adapt. In light these findings the study also makes a number of recommendations regarding the enclosure design, relocated of individuals and the gradual introduction of spider monkeys in zoos. The findings of this study are important as it contributes to our understanding of the physiological responses to stressors in a zoo environment and therefore has implications for animal management. It also identifies potential species specific requirements for the spider monkey that should be considered.

Analisou-se pelves de 72 primatas neotropicais, adultos, 42 machos e 30 fêmeas não prenhes, da espécie Aotus azarai infulatus, para obtenção dos diâmetros pélvicos, in vivo, e compará-los com o dimorfismo sexual, correlacionando-os com a biometria corpórea e a origem dos animais. Mensurou-se nas radiografias em projeção ventro-dorsal, digitalizadas, os diâmetros biilíaco superior, biilíaco inferior, biilíaco médio, diagonal direito, diagonal esquerdo, sacro púbico e área da entrada da pelve. As médias verificadas foram: para o comprimento do corpo 30,94 cm; comprimento da cauda 35,63 cm; perímetro do tórax 18,97 cm; perímetro da pelve 17,11 cm e o peso 0,96 g. As médias verificadas para o DDD da pelve foram 2,61 cm; DDE 2,66 cm; DBIM 1,97 cm; DBIS 1,41 cm; DBII 1,58 cm; DSP 2,48 cm e a AEP 3,85 cm. Concluiu-se com o estudo que tendo sido verificados os diâmetros biilíaco médio menores do que os diâmetros sacro-púbico tanto nos machos quanto nas fêmeas, pode-se dizer a pelve de Aotus azarai infulatus é classificada como dolicopélvica e existe dimorfismo sexual em relação às pelves Aotus azarai infulatus adultos. / Related data to the diameters of the pelvis from 72 Neotropical primates, owl monkeys (Aotus azarai infulatus), 42 adult males and 30 adult non-pregnant females, were obtained in vivo by ventrodorsal projection radiographic exams, compared between sex and correlated with the measures of the body and their origin. The mean values of the body length (30.94 cm), tail length (35.63 cm), thoracic perimeter (18.97 cm), hip perimeter (17.11) and the weight (0.96 g) were verified. The radiographic images were digitalized and the superior biiliac (DBIS), inferior biiliac (DBII), medium biiliac (DBIM), right diagonal (DDD), left diagonal (DDE), sacrum-pubic diameters (DSP) and the inlet pelvic area (AEP) were measured. The mean values were DBIS 1.41 cm; DBII 1.58 cm; DBIM 1.97 cm; DDD 2.61 cm; DDE 2.66 cm; DSP 2.48 cm; AEP 3.85 cm. In conclusion, once medium biiliac diameters were minor than sacrum-pubic diameters in males and females, the pelvis from Aotus azarai infulatus can be classified as dolicopelvic and we also conclude there is pelvic sexual dimorphism in adult owl monkeys (Aotus azarai infulatus).

No description available.

Thesis (Ph. D. in Physics)--Vanderbilt University, Dec. 2007. / Title from title screen. Includes bibliographical references.

published_or_final_version / abstract / toc / Dentistry / Doctoral / Doctor of Philosophy

No description available.

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