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Full-Text Articles in Life Sciences

Distributed Activity Patterns For Objects And Their Features: Decoding Perceptual And Conceptual Object Processing In Information Networks Of The Human Brain, Marc N. Coutanche Jan 2013

Distributed Activity Patterns For Objects And Their Features: Decoding Perceptual And Conceptual Object Processing In Information Networks Of The Human Brain, Marc N. Coutanche

Publicly Accessible Penn Dissertations

How are object features and knowledge-fragments represented and bound together in the human brain? Distributed patterns of activity within brain regions can encode distinctions between perceptual and cognitive phenomena with impressive specificity. The research reported here investigated how the information within regions' multi-voxel patterns is combined in object-concept networks. Chapter 2 investigated how memory-driven activity patterns for an object's specific shape, color, and identity become active at different stages of the visual hierarchy. Brain activity patterns were recorded with functional magnetic resonance imaging (fMRI) as participants searched for specific fruits or vegetables within visual noise. During time-points in which ...


Stress, Monoamines, And Cognitive Flexibility, Kevin Snyder Jan 2013

Stress, Monoamines, And Cognitive Flexibility, Kevin Snyder

Publicly Accessible Penn Dissertations

Stress has been implicated in psychiatric disorders that are characterized by impaired executive function, which is mediated by the prefrontal cortex (PFC). The stress-related neuropeptide, corticotropin-releasing factor (CRF) regulates monoamine systems that project to the PFC, including the locus coeruleus norepinephrine (LC-NE) system and the dorsal raphe-serotonin (DRN-5-HT) system. CRF actions on these systems may underlie cognitive symptoms of stress-related disorders. The age at which stress occurs can determine its impact, and adolescent stress has been linked to adult psychopathology. This dissertation explores the role of CRF in stress-induced modulation of the LC-NE and DRN-5-HT systems and the developmental time ...


The Neural Representation Of Value And Individual Differences In Human Intertemporal Choice, Nicole Cooper Jan 2013

The Neural Representation Of Value And Individual Differences In Human Intertemporal Choice, Nicole Cooper

Publicly Accessible Penn Dissertations

Intertemporal choices, or decisions that involve tradeoffs between rewards and time, are ubiquitous in our daily lives. The tendency to devalue, or discount, future rewards has been linked to maladaptive long-term health and financial outcomes. Despite their broad clinical relevance, individual differences in discounting preferences are poorly understood. In this thesis, we make progress on the understanding of the neural basis of these decisions and factors that affect individual differences. The first two chapters focus on neurobiology. Chapter 2 investigates the decision-related variables that best explain the observed patterns of BOLD activity in ventromedial prefrontal cortex (VMPFC) and ventral striatum ...


Change And Impact Of Microrna Modification With Age In Drosophila Melanogaster, Masashi Abe Jan 2013

Change And Impact Of Microrna Modification With Age In Drosophila Melanogaster, Masashi Abe

Publicly Accessible Penn Dissertations

microRNAs (miRNAs) are 20~24nt small RNAs that are critical for many biological aspects, from development to age-associated processes. Starting from the identification of the first miRNA, lin-4, hundreds of miRNAs have been discovered across species. To reveal the role of miRNAs in aging, studies have profiled changes in miRNA levels with age. However, increasing evidence suggests that miRNAs show heterogeneity in length and sequence in different biological contexts. Despite the observation of such heterogeneity, it is largely unknown how such heterogeneity is generated, and whether it is biologically regulated or important. Here we report the characterization of a novel ...


The Impact Of Motivation On Object-Based Visual Attention Indexed By Continuous Flash Suppression., Vanessa Troiani Jan 2013

The Impact Of Motivation On Object-Based Visual Attention Indexed By Continuous Flash Suppression., Vanessa Troiani

Publicly Accessible Penn Dissertations

Motivationally-relevant stimuli summon our attention and benefit from enhanced processing, but the neural mechanisms underlying this prioritization are not well understood. Using an interocular suppression technique and functional neuroimaging, this work has the ultimate aim of understanding how motivation impacts visual perception. In Chapter 2a, we demonstrate that novel objects with a more rich reward history are prioritized in awareness more quickly than objects with a lean reward history. In Chapter 2b, we show that faces are prioritized in awareness following social rejection, and that the amount faces are prioritized correlates with individual differences in social motivation. Chapters 3 & 4 ...


Fringe Benefits, Catherine Brinkley Jan 2013

Fringe Benefits, Catherine Brinkley

Publicly Accessible Penn Dissertations

This study tests the hypothesis that increased rugosity (the ratio between urban perimeter and farmland area) of the rural-urban fringe allows farms to create greater value for their regions through greater access to urban markets. Findings show that increased rugosity is not associated with farmland loss despite correlating with greater population growth. Rugosity is, instead, associated with higher agricultural sales per acre and more farm-to-city networks. Using the urban interface as a variable to understand farm production and stabilization, this paper includes a spatial statistical analysis of county-level metro-area farm products, farmland loss, and demographics in relation to the concentricity ...


Ovarian Hormone-Induced Neural Plasticity In The Hypothalamic Ventromedial Nucleus, Sarah L. Ferri Jan 2013

Ovarian Hormone-Induced Neural Plasticity In The Hypothalamic Ventromedial Nucleus, Sarah L. Ferri

Publicly Accessible Penn Dissertations

Ovarian hormones act throughout the brain and body to influence a range of functions and behaviors. Estrogens and progesterone are neuroprotective and have important health implications. However, our understanding of the mechanisms underlying many of their actions is incomplete. The goal of this thesis is to elucidate details of ovarian hormone-induced neural plasticity, specifically as it relates to female reproductive behavior and dendritic morphology in the hypothalamic ventromedial nucleus (VMH). First, I tested the hypothesis that the mechanisms of female receptivity are conserved across two species with very different mating strategies: prairie voles, which exhibit monogamy, induced estrous, and induced ...


Effects Of Uncertainty On Perceived And Physiological Stress And Psychological Outcomes In Stroke-Survivor Caregivers, Eeeseung Byun Jan 2013

Effects Of Uncertainty On Perceived And Physiological Stress And Psychological Outcomes In Stroke-Survivor Caregivers, Eeeseung Byun

Publicly Accessible Penn Dissertations

Caregiver status is a known risk factor for morbidity and mortality. In the time period immediately after a stroke, high levels of uncertainty about the family member's recovery and the sudden assumption of a new caregiver role may be acutely stressful. Little is known, however, about caregivers' experiences in the very early period of caregiving or how caregiver stress may contribute subsequently to health. The purpose of this study was to examine the effect of uncertainty on caregiver perceived and physiological stress and psychological outcomes (burden, health-related quality of life [HRQOL] and depressive symptoms) within 2 weeks poststroke (baseline ...


The Impact Of Mild Traumatic Brain Injury On Neuronal Networks And Neurobehavior, Tapan P. Patel Jan 2013

The Impact Of Mild Traumatic Brain Injury On Neuronal Networks And Neurobehavior, Tapan P. Patel

Publicly Accessible Penn Dissertations

Despite its enormous incidence, mild traumatic brain injury is not well understood. One aspect that needs more definition is how the mechanical energy during injury affects neural circuit function. Recent developments in cellular imaging probes provide an opportunity to assess the dynamic state of neural networks with single-cell resolution. In this dissertation, we developed imaging methods to assess the state of dissociated cortical networks exposed to mild injury. We probed the microarchitecture of an injured cortical circuit subject to two different injury levels, mild stretch (10% peak) and mild/moderate (35%). We found that mild injury produced a transient increase ...