Life Sciences Commons^™

Exploring And Training Spatial Reasoning Via Eye Movements: Implications On Performance, Victoria A. Roach

Electronic Thesis and Dissertation Repository

This dissertation sought to determine if eye movements could serve as an indicator of success in spatial reasoning, and if eye movements associated with successful completion could be applied to strategically improve spatial reasoning.

Using the line images of Shepard and Metzler, an electronic test of mental rotations ability (EMRT) was designed. Two versions of the test were created, allowing for both a timed (6 seconds per question) and untimed testing environment. Four experiments were designed and completed to relate mental rotation ability (MRA) scores from the EMRT, to patterns in chrononumeric and visual salience data. In each experiment, participants …

Seasonality Of The Stress Response In House Sparrows (Passer Domesticus)., Michael R. Hasstedt

Electronic Thesis and Dissertation Repository

Seasonal changes in plasma corticosterone (CORT) levels indicate that birds modify their stress response through the year. Although this has been well documented, the method by which birds achieve this seasonality is not well understood. In this study I used house sparrows to determine if changes in glucocorticoid receptor (GR) immunoreactivity in several stress-related brain nuclei showed seasonal variation. The house sparrowsshowed seasonal variation in their stress response with baseline CORT levels being highest during the breeding season and lowest during winter. There was also significant change in plasma CORT post-dexamethasone during breeding, but not during other times of the …

Laminar Fmri In Auditory Cortex At 7t, Jacob Jl Matthews

Electronic Thesis and Dissertation Repository

Auditory cortex is involved in the perception, attention, memory and imagery of sounds. Neuroimaging has been a rich source of information on which cortical areas are recruited for different tasks. However, a more detailed understanding has been confined to animal studies using invasive imaging modalities, and high-resolution functional descriptions of auditory cortex, including columnar/laminar specific activity, topographical organization within layers, and the way these representations transfer between processing structures remain poorly understood in humans. We present 7T fMRI as a non-invasive tool for high-resolution functional imaging of human auditory cortex on the laminar scale. We describe MATLAB tools for optimizing …

Determining Attention Deficits In Mouse Models Of Alzheimer’S Disease Using Touchscreen Systems, Talal Masood

Electronic Thesis and Dissertation Repository

Behavioural testing in mouse models of Alzheimer’s disease (AD) suffers from lack of standardization and reproducibility issues between laboratories. In order to solve this, a touchscreen system has been developed for mice based on the CANTAB. There are several cognitive dysfunctions that occur due to AD, including deficits in attention that can be tested using the touchscreens. In this study, we tested two mouse models of familial AD (5xFAD and 3xTG) with mutations that lead to an accelerated rate of amyloidosis. Both male and female mice were tested at two separate locations in order to test for the reproducibility of …

Contribution Of The Dorsolateral Prefrontal Cortex To Attentional And Mnemonic Processes In Visual Search, Brandon Belbeck

Electronic Thesis and Dissertation Repository

A key characteristic of selective visual attention is that it may be deployed on the basis of our knowledge or goals of the task at hand. Here, we used cryogenic deactivation to investigate the contribution of the dorsolateral PFC to cognitive flexibility and working memory, as well as their relation to the deployment of attention. Macaque monkeys performed visual search tasks requiring them to foveate a target in an array of stimuli. These included a feature search, a constant-target conjunction search, a variable-target search and variable-target with delay search task, with each being more cognitively demanding than the last. Bilateral …

A Kinematic Analysis Of Visual And Haptic Contributions To Precision Grasping In A Patient With Visual Form Agnosia And In Normally-Sighted Populations, Robert Whitwell

Electronic Thesis and Dissertation Repository

Skilled arm and hand movments designed to obtain and manipulate objects (prehension) is one of the defining features of primates. According to the two visual system hypothesis (TVSH) vision can be parsed into two systems: (1) the ventral ‘stream’ of the occipital and inferotemporal cortex which services visual perception and other cognitive functions and (2) the ‘dorsal stream’ of the occipital and posterior parietal cortex which services skilled, goal-directed actions such as prehension. A cornerstone of the TVSH is the ‘perception-action’ dissociation observed in patient DF who suffers from visual form agnosia following bilateral damage to her ventral stream. DF …

Category-Specific Item Recognition And The Medial Temporal Lobe, Christopher B. Martin

Electronic Thesis and Dissertation Repository

Much neuropsychological and neuroimaging research has been focused on the contributions of different medial temporal lobe (MTL) structures to recognition memory. The majority of these studies have linked perirhinal cortex (PrC) to item recognition, whereas the hippocampus and parahippocampal cortex (PhC) have primarily been associated with the recollection of contextual detail pertaining to a specific prior stimulus encounter. Here, I report results from three fMRI studies that examined the neural correlates of item recognition with a specific focus on the relationship between such signals and category-specific effects in the MTL. In Chapter 2, I reveal that category-specific representations in both …

The Relationship Between Dairy Product Consumption And Cognitive Performance In A Group Of Community-Dwelling Healthy Older Adults, Mariam R. Ismail

Electronic Thesis and Dissertation Repository

Dietary intake is one of the modifiable factors that may affect older adults’ cognitive function in their later years. Very little research has considered the potential role of dairy products on cognitive function. The aim of the present study was twofold: first, to investigate whether there is a difference in cognitive performance between older adults who consumed the recommended amount of dairy products (3 servings per day) and individuals who consumed less than the recommended amount (1 or 2 servings per day); second, to examine whether there is an association between the nutrients contained in the dairy products and cognitive …

Neural Correlates Of Spontaneous Bold Fluctuations: A Simultaneous Lfp-Fmri Investigation In The Non-Human Primate, Masoomeh Hashemi

Electronic Thesis and Dissertation Repository

Resting-state functional magnetic resonance imaging (rs-fMRI) is widely used to explore functional connectivity (FC) between brain regions across neurological and psychiatric diseases. However, the neural basis of spontaneous low frequency blood-oxygen level dependent (BOLD) fluctuations is poorly understood.

Here, we acquired rs-fMRI data in macaque monkeys together with simultaneous recordings of local field potentials (LFPs) in prefrontal cortex area 9/46d. We first evaluated the correlation between LFPs (1-100 Hz) and BOLD signals and found unique frequency power correlates of positive and negative FC. Anti-correlation of high and low power envelopes indicated that ongoing cross-frequency interactions are a neural correlate of …