Life Sciences Commons^™

Characterizing Complex Affective Processing Across Age And In Relation To Social Anxiety Symptoms, M. Catalina Camacho

Arts & Sciences Electronic Theses and Dissertations

Humans require a shared understanding of others’ emotions for adaptive social functioning. For instance, if someone tells a joke and another person laughs, we assume the laughing person was happy because we have a shared concept for such positive interactions. Children develop and refine these concepts as they grow up, but the underlying neural processing that supports this development is unknown. Identifying the neurodevelopment underlying emotion processing could provide important insight to emotional disorders. For example, social anxiety is associated differences in the detection and interpretation of negative or neutral emotional cues, but the underlying neurodevelopment of this behavior is …

Altered Network Organization And Screen Time Use In Childhood Attention-Deficit / Hyperactivity Disorder (Adhd), Elizabeth Jane Hawkey

Arts & Sciences Electronic Theses and Dissertations

Introduction: Symptoms of attention-deficit/hyperactivity disorder (ADHD) have been associated with alterations in functional connectivity involving networks in the developing brain that support optimal cognitive control. However, a clear profile of altered connectivity has yet to emerge, and it remains unclear whether changes in behavioral patterns such as screen time (ST) contribute to ADHD symptomatology and altered connectivity in networks that support cognitive control. The current study examined connectivity between large-scale networks associated with cognitive control (CC), measures of executive function (EF) which index CC, and ST in children with ADHD. Methods: Our sample included 11,874 children (ages 9-11, 52% male) …

Testing Candidate Cerebellar Presymptomatic Biomarkers For Autism Spectrum Disorder, Zoe Wilson Hawks

Arts & Sciences Electronic Theses and Dissertations

Background: Autism spectrum disorder (ASD) is a neurodevelopmental disorder diagnosed on the basis of social impairment, restricted interests, and repetitive behaviors. Contemporary theories posit that cerebellar-mediated error signaling impairments contribute to the causation of ASD. However, the relationship between infant cerebellar functional connectivity (fcMRI) and later ASD behaviors and outcomes has not been investigated. Such work is critical to establish early (presymptomatic) cerebellar correlates of ASD. Methods: Data from the Infant Brain Imaging Study (n=94, 68 male) were used to evaluate cerebellar fcMRI as a presymptomatic biomarker for ASD. Specifically, brain-behavior associations were analyzed for 6-month cerebellar connections in relation …

The Feeling Mind, Maria Doulatova

Arts & Sciences Electronic Theses and Dissertations

According to standard conceptions of agency, our reasons and intentions guide our actions. That is, goal-directed intentions play a key role in practical deliberation, planning, and execution of action. Furthermore, purposeful, goal-directed behavior warrants attributions of responsibility or “reactive attitudes” like resentment, anger, gratitude and forgiveness. However, recent developments of the dual-process theory of mind cast doubt on the empirical adequacy of this picture. While people take themselves to be responding to relevant reasons, they are often bypassed by irrelevant affective or automatic reactions. In this work I go beyond the dual-process theory of mind to offer a mechanistic account …

The Role Of Enampt-Mediated Systemic Nad+ Biosynthesis In Aging And Lifespan, Mitsukuni Yoshida

Arts & Sciences Electronic Theses and Dissertations

Aging is a systemic decline in tissue functions that occurs during the course of our life leading to the development of age-associated health deteriorations and ultimately to the expiration of life. Over the past few decades, population aging has become increasingly evident in many parts of the world, leading to increased prevalence of age-related disabilities and diseases. Because age is a major risk factor for many chronic diseases, extensive research effort has been spent to identify common age-associated molecular changes contributing to the pathogenesis and progression of these health issues. One such molecule identified to play a central role in …

Evaluating Everyday Behaviors With Delayed And/Or Probabilistic Consequences Through A Discounting Framework, Yu-Hua Yeh

Arts & Sciences Electronic Theses and Dissertations

Delay and probability discounting refer to the decrease in subjective value of an outcome as the time until its occurrence increases and the likelihood of its occurrence decreases, respectively. Significant differences between the discounting of gains and losses, either delayed or probabilistic, have been documented in the literature. A recent study that investigated similarities and differences between the discounting of delayed gains, delayed losses, and probabilistic losses, found qualitative individual differences (i.e., subgroups) present only in the discounting of losses (Yeh et al., 2020). The current study expanded the previous investigation of subgroups to the discounting of probabilistic gains (Experiment …

Relating Spontaneous Activity And Cognitive States Via Neurodynamic Modeling, Matthew Singh

Arts & Sciences Electronic Theses and Dissertations

Stimulus-free brain dynamics form the basis of current knowledge concerning functional integration and segregation within the human brain. These relationships are typically described in terms of resting-state brain networks—regions which spontaneously coactivate. However, despite the interest in the anatomical mechanisms and biobehavioral correlates of stimulus-free brain dynamics, little is known regarding the relation between spontaneous brain dynamics and task-evoked activity. In particular, no computational framework has been previously proposed to unite spontaneous and task dynamics under a single, data-driven model. Model development in this domain will provide new insight regarding the mechanisms by which exogeneous stimuli and intrinsic neural circuitry …

Dismantling Of Obesity-Related Policies, Alexandra Borosova Morshed

Arts & Sciences Electronic Theses and Dissertations

This dissertation fills an important research gap in the study of obesity policymaking by characterizing to what extent the phenomenon of dismantling is happening at the state level for obesity-related policies targeting the context of consumption, identifying determinants, and characterizing actors and processes involved. The five-year rate of dismantling of these policies is close to one-third for any attempts and one-tenth for enacted dismantling. Food and beverage tax policies face a particularly high rate of dismantling. Case studies and news coverage of state- level dismantling identified actors, motivations, and strategies used in the process of dismantling. Review of health-related empirical …

Pillars Of The Nutrition Transition: The Global Impacts Of Ultra-Processed Foods And Beverages On Overweight And Obesity And National Nutrient Supplies, Jacob Eaton

Arts & Sciences Electronic Theses and Dissertations

Malnutrition in some form impacts nearly one-third of the global population. Across the world, countries are undergoing the Үutrition transitionӠfrom traditional and largely unprocessed diets to Western-style, energy-dense diets. At the same time, rates of overweight and obesity and diet-related chronic diseases continue to climb. Ultra-processed foods (UPF), sugar-sweetened beverages (SSB), and vegetable oils are three of the foods driving the nutrition transition. This dissertation calculates changes in the global food supply between 1961 and 2013 and quantifies the influence of UPF and SSB (as measured through sales) on national nutrient supplies between 2005 and 2013 and trends in adult …

Neural Mechanisms Of Cognitive Individual Difference: An Investigation Of The Human Connectome Project, Shelly Renee Cooper

Arts & Sciences Electronic Theses and Dissertations

Considering individual differences in task activation functional magnetic resonance imaging (t-fMRI) can be challenging because they may arise from variability in activity in brain regions, in the tasks themselves, or some combination thereof. Delineating sources of between-subjects variance is particularly important for cognitive control where task goals are at the forefront. Here we applied structural equation modeling (SEM) to the Human Connectome Project to examine if activity could be partitioned into separable brain and task individual difference dimensions. A series of SEMs were defined with varying numbers of latent factors, where the inputs were parcels of two cognitive control-related brain …

Genomic Contributors To Individual Differences In Reward-Related Neural Activity, Lindsay Jane Michalski

Arts & Sciences Electronic Theses and Dissertations

Aberrant reward-related behavior, including impulsive and risk-taking behaviors, is a common feature of externalizing psychopathology (e.g., attention deficit hyperactivity disorder, antisocial personality disorder, and substance-use disorders). Through imaging studies, these behaviors have been linked to dysregulated reactivity within a diffuse reward-related corticostriatal neural network, including the striatum, frontal regions (namely orbital, ventromedial, and dorsolateral cortices), the insula, and the hippocampus. Because variability in risk-taking behavior and related psychopathology is moderately-to-largely heritable (i.e., with estimates ranging from 40 – 80%), a genetically-informed approach is well-positioned to provide valuable insight into the etiology of reward-related neural and behavioral phenotypes that characterize externalizing …

Aging Of The Reproductive System And Of Germline Stem Cells In Caenorhabditis, Zuzana Kocsisova

Arts & Sciences Electronic Theses and Dissertations

C. elegans hermaphrodites display dramatic age-related decline of reproduction early in life while somatic functions are still robust. To understand why the germline fails so early, we analyzed the assembly line of oocyte production that generates fertilized eggs in mated hermaphrodites with sufficient sperm. Aging germlines displayed both sporadic and population-wide changes. A small fraction of aging animals displayed endomitotic oocytes in the germline and other defects. By contrast, all animals displayed age-related decreases in germline size and function. As early as day 3 of adulthood, animals displayed fewer stem cells and a slower cell cycle, which combine to substantially …

Isolating Item And Subject Contributions To The Subsequent Memory Effect, Jihyun Cha

Arts & Sciences Electronic Theses and Dissertations

The subsequent memory effect (SME) refers to the greater brain activation during encoding of subsequently recognized items compared to subsequently forgotten items. Previous literature regarding SME has been primarily focused on identifying the role of specific regions during encoding or factors that potentially modulate the phenomenon. The current dissertation examines the degree to which this phenomenon can be explained by item selection effects; that is, the tendency of some items to be inherently more memorable than others. To estimate the potential contribution of items to SME, I provided participants a fixed set of items during encoding, which allowed me to …

Mechanics Of Phenotypic Aging Trajectories In C. Elegans And Humans, William Zhang

Arts & Sciences Electronic Theses and Dissertations

Overall, my dissertation integrates longitudinal measurements of physiology to investigate the aging process. In the first half, I examine the surprising and largely unexplained degree of variation in lifespan within even homogeneous populations. I sought to understand how physiological aging differs between long- and short-lived individuals within a population of genetically identical C. elegans reared in a homogeneous environment. Using a novel culture apparatus, I longitudinally monitored aspects of aging physiology across a large population of isolated individuals. Aggregating several measures into an overall estimate of senescence, I find that long- and short-lived individuals start adulthood on an equal physiological …

A Formative Assessment Of The Vulnerability Context Of Three Indigenous Communities In Rural Ecuador For Improved Intervention Design, Ivy Blackmore

Arts & Sciences Electronic Theses and Dissertations

Nearly 20 % of the current world population are small-scale producers living in rural areas who rely on agriculture and related activities to support their families (IFAD, 2016; World Bank, 2008). Despite the almost 76 billion USD of official development assistance committed to agriculture improvement projects and associated activities over the past decade, many of the intended beneficiaries remain poor and struggle to meet their basic needs. The lack of success in addressing rural poverty highlights the need for quality research focused on understanding what type of intervention/s could help rural communities sustainably improve their livelihood security.

The goal of …

Evaluation Of Neurobiological Risk Factors For Alcohol Consumption; Convergent Evidence For Predispositional Effects Of Brain Volume, David Baranger

Arts & Sciences Electronic Theses and Dissertations

Alcohol is one of the most widely used psychoactive substances and accounts for 5% of global disease burden. The goal of the present work is to help advance efforts to both identify prognostic markers of risk, and to understand the mechanisms by which alcohol consumption impacts health. Early life stress is one of the strongest predictors of mental illness, including alcohol dependence, and has been hypothesized to impact risk via modulation of striatal reward functions and reward learning. Studies examined the effect of stress on reward learning and processing, and tested for moderation by genetic and environmental risk. Results were …

The Impact Of Delay On Retrieval Success In The Parietal Memory Network, Nathan Anderson

Arts & Sciences Electronic Theses and Dissertations

Recent work has identified a Parietal Memory Network (PMN), which exhibits regular patterns of activation during memory encoding and retrieval. Among these characteristic patterns, this network displays a strong “retrieval success” effect, showing greater activation for correctlyremembered studied items (hits) compared to correctly-rejected novel items (CRs). To date, most relevant studies have used short retention intervals. Here, we ask if the retrieval success effect seen in the PMN would remain consistent over a delay. Twenty participants underwent fMRI while encoding and recognizing scenes. Greater activity for hits than for correctly-rejected lures within PMN regions was observed after a short delay …

Neurogenetics Of The Externalizing Spectrum, Caitlin E. Carey

Arts & Sciences Electronic Theses and Dissertations

Externalizing spectrum disorders, which include attention-deficit/hyperactivity disorder, oppositional defiant disorder, conduct disorder, alcohol and substance use disorders, and antisocial personality disorder, are characterized by behavioral disinhibition and are thought to be manifestations of a common heritable liability factor throughout the lifespan. However, relatively little is known about their underlying etiology. Here, I probe genetic and neural risk mechanisms for externalizing psychopathology in three complementary studies. First, I report an indirect association between genetic risk for childhood attention-deficit/hyperactivity disorder (ADHD) and problem drinking in young adulthood, mediated by heightened reward-related neural activity within the ventral striatum, among 404 college students. I …

Population Genomics Of A Baboon Hybrid Zone In Zambia, Kenneth Lyu Chiou

Arts & Sciences Electronic Theses and Dissertations

Hybridization is increasingly recognized as a common, important process shaping the evolution of organisms including humans. Across hybrid zones, the genomes of incipient species are mixed and recombined through hybridization and backcrossing, creating conditions ideal for evaluating the actions of natural selection on gene variants in novel genomic contexts. This dissertation aims to increase our understanding of hybridization using a Zambian baboon study system in which two species, Kinda baboons (Papio kindae) and grayfoot baboons (Papio griseipes), hybridize despite exhibiting pronounced differences in body size and behavior. Using genome-wide genotypic data prepared using double-digest RADseq, I scan for genomic regions …

Coexistence Of Confamilial, Folivorous Indriids, Propithecus Diadema And Indri Indri, At Betampona Strict Nature Reserve, Madagascar, Lana Kerker Oliver

Arts & Sciences Electronic Theses and Dissertations

In this dissertation, I examine how two confamilial and ecologically similar indriids, indri (Indri indri), and diademed sifakas (Propithecus diadema) maintain coexistence in Betampona Nature Reserve (BNR), an eastern lowland rainforest in Madagascar. These two species occur sympatrically throughout much of their species ranges and are similarly-sized folivorous primates. As anatomic folivores, they present an opportunity to investigate how niche differentiation and resource partitioning allow two sympatric primate species with similar feeding patterns to coexist. I examined coexistence strategies and the general behavioral ecology of each species by examining their activity patterns, dietary profiles, home range use, and daily path …

Perceiving Oldness In Parietal Cortex: Fmri Characterization Of A Parietal Memory Network, Adrian Gilmore

Arts & Sciences Electronic Theses and Dissertations

The manner in which the human brain recognizes certain stimuli as novel or familiar is a matter of ongoing investigation. The overarching goal of this dissertation is to improve our understanding of how this may be accomplished. More specifically, work contained herein focuses on a recently described "parietal memory network" (PMN; Gilmore et al., 2015) that shows opposite patterns of activity when perceiving novel or familiar stimuli: deactivating in response to novelty, and activating in response to familiarity. Critically, our understanding of this network is based on explicit memory tasks, in which subjects are deliberately instructed to learn or remember …

A Quantitative Genetic Analysis Of Craniofacial Variation In Baboons, Jessica Lynn Joganic

Arts & Sciences Electronic Theses and Dissertations

This dissertation is an explication of baboon craniofacial variation and its genetic basis. Intraspecific variation is the result of input from and complex interactions among genetic information, functional demands, and developmental processes. The relative effect of each of these on craniofacial variation, as well as the degree of inter-trait covariance, determines whether traits can respond to selection and what that response might look like. Using a sample of pedigreed baboons, I quantify craniofacial variation to address specific questions regarding the distribution and magnitude of phenotypic, genetic, and environmental variation patterns. In addition, I identify regions of the genome containing genetic …

Relationships Between Age And White Matter Integrity In Children With Phenylketonuria, Erika M. Wesonga

Arts & Sciences Electronic Theses and Dissertations

Objective: Phenylketonuria (PKU) is a hereditary metabolic disorder associated with cognitive compromise. Diffusion tensor imaging (DTI) has allowed detection of poorer microstructural white matter integrity in children with PKU, with decreased mean diffusivity (MD) in comparison with healthy children. However, very little research has been conducted to examine the trajectory of white matter development in this population. The present study investigated potential differences in the developmental trajectory of MD between children with early- and continuously-treated PKU and healthy children across a range of brain regions.

Methods: Children with PKU (n = 31, mean age = 12.2 years) were …

Are There Multiple Kinds Of Episodic Memory? An Fmri Investigation Comparing Autobiographical And Recognition Memory Tasks, Hung-Yu Chen

Arts & Sciences Electronic Theses and Dissertations

What brain regions underlie retrieval from episodic memory? The bulk of research addressing this question has relied upon laboratory-based recognition memory. Another, less dominant tradition has employed autobiographical methods, whereby people recall events from their lifetime, often after being cued with words or pictures. Previous research comparing regions underlying successful memory retrieval between these two methodological approaches has shown mixed results. To examine the neural processes underlying recognition memory for materials encountered in the laboratory and autobiographical memory, we conducted a within-subject study using fMRI. We showed participants indoor and outdoor scenes under two types of instructions: In the lab-based …