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Does an extended washout period of six weeks following the end of chronic stress continue the benefits on spatial learning and memory?

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Chronic stress often leads to cognitive deficits, especially within the spatial memory domain mediated by the hippocampus. When chronic stress ends and a no-stress period ensues (i.e., washout, WO), spatial ability improves, which can be better than non-stressed controls (CON).

Chronic stress often leads to cognitive deficits, especially within the spatial memory domain mediated by the hippocampus. When chronic stress ends and a no-stress period ensues (i.e., washout, WO), spatial ability improves, which can be better than non-stressed controls (CON). The WO period is often the same duration as the chronic stress paradigm. Given the potential benefit of a post-stress WO period on cognition, it is important to investigate whether this potential benefit of a post-stress WO period has long-lasting effects. In this project, chronic restraint (6hr/d/21d) in Sprague-Dawley rats was used, as it is the minimum duration necessary to observe spatial memory deficits. Two durations of post-stress WO were used following the end of chronic restraint, 3 weeks (STR-WO3) and 6 weeks (STR-WO6). Immediately after chronic stress (STR-IMM) or the WO periods, rats were tested on various cognitive tests. We corroborated past studies that chronic stress impaired spatial memory (STR-IMM vs CON). Interestingly, STR-WO3 and STR-WO6 failed to demonstrate improved spatial memory on a radial arm water maze task, performing similarly as STR-IMM. Performance outcomes were unlikely from differences in anxiety or motivation because rats from all conditions performed similarly on an open field task and on a simple object recognition paradigm, respectively. However, performance on object placement was unusual in that very few rats explored, suggesting some degree of anxiety or fear in all groups. One possible interpretation of the unusual results of the 3 week washout group may be attributed to the different spatial memory tasks used across studies or external factors from the study. Further exploration of these other factors led to the conclusion that they did not play a role and the STR-WO3 RAWM data were anomalous to other studies. This suggests that a washout period following chronic stress may not be fully understood.

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2017-05

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Development of Brief Memory Tests for Use with Pet Dogs

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Brief memory tasks for use with pet dogs were developed using radial arm maze performance as a standard comparison measurement of memory capacity. Healthy pet dogs were first tested in a radial arm maze, where more errors made in completing

Brief memory tasks for use with pet dogs were developed using radial arm maze performance as a standard comparison measurement of memory capacity. Healthy pet dogs were first tested in a radial arm maze, where more errors made in completing the maze indicated poorer memory. These dogs were later tested with five novel memory tests, three of which utilized a treat placed behind a box with an identical distracter nearby. The treat placement was shown to each dog, and a 35 second delay, a 15 second delay with occluder, or a 15 second delay with room exit was observed before the dog could approach and find the treat. It was found that errors on the delayed match to sample (35 second delay) and occluder/object permanence (15 second delay with occluder) tasks were significantly positively correlated with the average number of errors made in the 8th trial of the radial arm maze (r =.58, p<.01** and r =.49, p<.05*, respectively) indicating that these new brief tests can reliably be used to assess memory in pet dogs.

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2015-05

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Dogs and Cognitive Dysfunction

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Alzheimer's disease affects a large number of Americans every year, and research on the causes and possible prevention continues to increase. Alzheimer's disease is a form of dementia that causes problems with memory, thinking, and behavior and is thought to

Alzheimer's disease affects a large number of Americans every year, and research on the causes and possible prevention continues to increase. Alzheimer's disease is a form of dementia that causes problems with memory, thinking, and behavior and is thought to be caused by beta-amyloid plaques that form in the brain. In recent years, dogs have been used more and more as an animal model looking at Alzheimer's disease and cognitive dysfunction. Dogs serve as a reliable animal model because effected dogs naturally form the same beta-amyloid plaques that affected humans do as they age. Previous research has shown that older dogs perform worse on various memory tasks than do younger dogs, however researchers have struggled to find a test for dog cognitive dysfunction that is brief and can be performed in the home. The current study aimed to find a brief memory task that requires few materials, but is still reliable. The results of this study do not support the hypothesis that older dogs would perform worse than younger dogs if tested to find a treat with varying time delays of 15, 30, and 45 seconds. The results of this experiment showed a main effect of age (F = 8.40, d.f. 1, 19, p < 0.01) and delay (F = 15.14, d.f. 2, 30, p < 0.01), but age-delay interaction was not significant (F = 2.53, d.f. 2, 30, p = 0.09). Future studies should be performed using a larger sample size and this same protocol to attempt to raise the participation level of the dogs.

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2016-12