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Item Adaptive forgetting with uncontrolled and controlled removal processes(2020-08-17) Kim, Hyojeong; Lewis-Peacock, Jarrod A.; Preston, Alison R.; Joseph, Joseph E.; Banich, Marie T.Memory is essential to guide our behavior by which goal-relevant information is accessed in an accurate and timely manner. One of the fundamental cognitive abilities to accomplish such function is to remove unnecessary information from long-term memory and outdated thoughts from working memory. Removing information facilitates information processing in service of the goal-directed behavior by reducing the potential interruption from the irrelevant information and thus increasing cognitive capacity. The research in this dissertation focuses on the removal of information as adaptive memory operations in both unintentional (“bottom-up” implicit learning) and controlled processes (“top-down” cognitive control). To identify the neural mechanisms of removal and link these to specific behavioral outcomes, my approach relies on using functional MRI (fMRI) with multivariate pattern analyses (MVPA). Experiment 1 demonstrated how the automatic learning that generates memory-based predictability alters long-term retention of the memory. While unreliable predictions, which violated real outcome, were more likely forgotten, more generic predictions that matched the outcome in an abstract level were retained. Experiment 2 tested neural consequences in different removal methods that recruit top-down cognitive control in working memory. The different removal operations employed distinct neural systems and removed the representation of item being removed from working memory with different speeds as well as with different impacts on memory capacity. Building upon Experiment 2, Experiment 3 examined representational changes during these removal operations in the ventral visual cortex and hippocampus. While sensory representations reflected different attentional states depending on removal operations, hippocampal representations reflected top-down inhibitory regulation states. The findings also suggest that these removal operations lead to qualitative alterations of representation, which implies different long-term memory forgetting. As a whole, the research in this dissertation is seeking to improve our understanding of memory removal in two key ways: (1) define the role of implicit processes in prediction-based forgetting from LTM, and (2) precisely characterize the control and consequences for multiple operations of removing information from working memory.Item Alcohol-induced fragmentary blackouts : associated memory processes and neural correlates(2010-08) Wetherill, Reagan Rochelle, 1979-; Fromme, Kim; Schnyer, David M.; Tucker, David M.; Beevers, Christopher; Springer, David W.Alcohol-induced blackouts, or periods of anterograde amnesia without loss of consciousness, were a diagnostic indicator in Jellinek’s (1952) theory of alcoholism and have been correlated with alcohol use problems (Campbell & Hodgins, 1993; Goodwin, Crane, & Guze, 1969; Ryback, 1970; Tarter & Schneider, 1976). Other findings suggest that blackouts are a warning sign of problem drinking, but not a predictor of alcohol use disorders (Anthenelli, Klein, Tsuang, Smith, & Schuckit, 1994). Most published research on blackouts focuses on cognitive deficits among older alcohol-dependent adults, yet recent research indicates prevalence rates for blackouts as high as 50% among college students (White, Jamieson-Drake, & Swartzwelder, 2002). In addition, young adults who reported experiencing a blackout were later told that they had vandalized property, driven a car, or engaged in other risky behaviors without remembering (Buelow & Koeppel, 1995). Despite their high prevalence and associated negative consequences, relatively little is known about alcohol-induced blackouts or their neural, social, and behavioral correlates among non-dependent populations. The current research explored individual variation in memory functioning under sober and intoxicated conditions and alcohol’s effects on neural activation during memory processes.Item An improvement solution for C-PAC dashboard(2021-05-07) Su, Yiran, 1997-; Julien, Christine, D. Sc.The Configurable Pipeline for the Analysis of Connectomes (C-PAC) is an automated processing pipeline for resting state functional MRI (R-fMRI) data. The C-PAC dashboard is a React.js-based web application, a visualization solution to provide runtime instructions for the C-PAC clusters, and to present C-PAC clusters' processing results. The dashboard provides services including C-PAC pipeline configuration, submitting C-PAC jobs, etc. The article introduced an improvement for the original C-PAC dashboard, in order to provide more configurable options and a better user experience. This includes flexible C-PAC cluster management, new options for fMRI scans data specifying, and better run-time status presentation for C-PAC clusters. The implementation is based on React JavaScript, which is a library of JavaScript. Two React libraries, React-Redux and Redux-Saga are also applied. The dashboard system validation is accomplished by observing global status changes in the browser's debugging mode, as well as enumerate combinations of possible user operations.Item Biological mechanisms underlying the unity and diversity of executive functions in childhood(2018-09-14) Engelhardt, Laura Ellen; Tucker-Drob, Elliot Max; Church-Lang, Jessica; Harden, Kathryn P; Preston, Alison R; Petrill, StephenExecutive functions (EFs) are supervisory cognitive processes that coordinate the execution of other cognitive operations necessary for learning and everyday functioning. In spite of a growing literature associating EFs with health-relevant outcomes across the lifespan, relatively little is known about the sources of individual differences in these processes during childhood and adolescence. Our research team and others have begun to investigate EF within a multidimensional structure, whereby individual differences in EFs are attributable to variance specific to individual tasks, variance common to tasks via domain-specific factors, and variance shared across domains via a general EF factor. This dissertation presents three papers that explore the biological sources of the EF structure in a population-based sample of 7- to 15-year-olds from the Texas Twin Project. Given the role of EF in models of complex reasoning and intelligence, Paper 1 uses a twin approach to estimate the extent to which genetic contributions to EF overlap with genetic influences on intelligence. I find that a general EF factor representing variance common to inhibition, switching, working memory, and updating domains accounts for substantial proportions of variance in intelligence, primarily via genetic pathways. In Paper 2, I turn to cortisol, an established biomarker of stress reactivity, as a second biological mechanism that explains individual differences in EF in childhood. We investigate associations between EF performance and neuroendocrine output via cortisol measured over three distinct time scales. We find that general EF most strongly correlates with cortisol trajectories surrounding an acute stressor and that the association is due to entirely shared genetic influences. Paper 3 assesses the extent to which children’s and adolescents’ neural activity converges across EF domains and whether these patterns are consistent with adult EF-related activity. Using functional magnetic resonance imaging to examine brain activity shared across EF tasks in a large pediatric sample, we find that brain regions that are consistently engaged across switching, updating, and inhibition tasks closely correspond to the cingulo-opercular and fronto-parietal networks identified in adult studies. The integration of behavioral genetic, neuroimaging, and endocrine methodologies enable us to test specific neurobiological mechanisms by which genetic and environmental processes affect EFs.Item Bridging the gap between psychological and neural models of judgment : applying a dual-process framework to neural systems of social and emotional judgment(2012-05) Bhanji, Jamil Palacios; Beer, Jennifer S., 1974-; Maddox, W T.; Henderson, Marlone D.; Gershoff, Andrew D.; Schnyer, David M.Psychological models of judgment and decision-making that focus on dual processes distinguish between two modes of judgment. One mode of judgment uses incomplete, probabilistic associations that lead to good-enough judgments for most situations. A second mode of judgment uses more complete information and applies deterministic decision rules to reason through a decision. The two modes operate in parallel but they can also interact and may be viewed as ends of a continuum. Although some psychology researchers have hypothesized that the two modes of information processing are carried out by distinct neural systems, neural research has not fully tested the distinctions that psychological research has drawn between the two modes. Three studies aim to address the gap between psychological and neural models of judgment and decision-making. Study 1 addresses the lack of neural research comparing judgments based on probabilistic information (characteristic of the first mode of judgment in dual-process models) with judgments based on deterministic rules (characteristic of the second mode of judgment in dual-process models). Specifically, Study 1 compares basic probabilistic judgments and deterministic rule-based judgments to identify neural regions that are preferentially associated with one mode of judgment. Study 2 moves toward a more ecologically valid investigation of neural systems associated with judgments based on probabilistic associations. That is, Study 2 examines a probabilistic cue that is used in real-world judgments: affect. Study 3 examines neural regions associated with the interaction of the two modes of judgment in the underexplored domain of social evaluation. Modes of judgment may interact when the second mode of judgment uses new information to adjust a judgment previously driven by the first mode of judgment, as when a hiring manager uses information about a job candidate to adjust a first impression initially based on appearance. Study 3 examines the neural systems involved when people use newly available information to adjust a previously made affectively-driven judgment. Findings in the three studies contribute to scientific understanding of how neural regions support judgment, but do not definitively identify separable neural systems for dual-process modes of judgment.Item Cerebrovascular reactivity and the fMRI-BOLD response in cardiorespiratory fitness(2015-08) Gonzales, Mitzi Michelle; Haley, Andreana P.; Tanaka, Hirofumi; Mumford, Jeanette A; Schnyer, David M; Maddox, W. ToddAccumulating evidence indicates that poorer vascular health accelerates cognitive decline and increases the likelihood of dementia in old age. Aerobic fitness, as a protective factor against vascular dysfunction, may thus serve to attenuate age-related cognitive pathology. The overarching aim of the current investigations was to determine the impact of cardiorespiratory fitness on cognition and its underlying neural substrates. Sedentary and endurance-trained middle-aged adults underwent general health assessment, neuropsychological testing, and functional magnetic resonance imaging (fMRI) during a working memory task and a hypercapnic (breath-hold) challenge. As compared with sedentary age-matched controls, the endurance-trained adults displayed a trend towards better executive function performance and faster reaction time on the working memory task, indicating enhanced speed of information processing. The neural substrates underlying fitness-related cognitive enhancement were explored by examining the blood oxygen level dependent (BOLD) response to a 2-Back working memory task. Additionally, breath-hold calibration of the working memory task was performed in order reduce vascular variance and provide a closer approximation of the neural contributions to the BOLD signal. After breath-hold calibration, the endurance-trained adults displayed greater working memory-related activation in the right middle frontal gyrus, indicating that fitness likely benefits the neural processes underlying cognition over and above global fitness-related changes in cerebrovascular reactivity. Finally, endothelial function was examined as a potential mechanism underlying fitness-related differences in cerebrovascular reactivity. Peripheral endothelial function failed to predict the BOLD signal to hypercapnia, suggesting that the response may be governed by nonendothelial-dependent vasoregulators. In summary, higher cardiorespiratory fitness at midlife may increase executive function abilities by enabling greater recruitment of neural resources during challenging cognitive tasks. Longitudinal studies will be instrumental in determining if these fitness-related changes are capable of modulating the trajectory of cognitive decline across the lifespan.Item Characterizing the age-related decline of memory monitoring : neuroimaging and genetic approaches(2011-05) Pacheco, Jennifer Lynn; Schnyer, David M.; Maddox, W T.; Beevers, Christopher G.; Haley, Andreana; Holahan, CaroleMemory monitoring, or the ability to accurately assess one’s memory retrieval success, is known to be declined for older adults. The behavioral decline has been well explored, and is specific to tasks of source monitoring; tasks involving item memory monitoring do not show age-related deficits. This study attempts to further characterize the decline by exploring neuroanatomical contributions to the decline, and genetic influences that may explain performance variability in older adults. Older adults were genotyped for the serotonin transporter (5-HTTLPR) gene, and those that are carriers of the low-expressing allele demonstrate the expected age-related decline of source monitoring performance when compared to younger adults. Interestingly, older adults who lack this allele did not display any decline in performance when compared to younger adults. Neuroanatomical correlates of task performance indicate that prefrontal regions in the inferior and lateral cortices support accurate source memory monitoring, likely through their role in the proper selection of memory cues and inhibition of irrelevant information. This relationship suggests that age-related atrophy occurring in these structures could be responsible for the performance deficits on source memory monitoring tasks. There was no direct relationship seen between genotype for the 5-HTTLPR gene and cortical volumes, however diffusion tensor imaging shows that older adults who carry this allele have altered connections between the medial temporal lobe, responsible for memory retrieval, and prefrontal cortex, which monitors the retrieval process. Through stronger connections of critical networks, older adults who lack the 5-HTTLPR short allele may be able to compensate for the age-related atrophy seen in the prefrontal cortex. Functional results further indicate that the older adult non-carriers recruit inferior and lateral frontal regions to a greater extent than the older adult carriers during accurate memory monitoring. These results begin to suggest a neuroprotective mechanism for the 5-HTTLPR genotype, wherein some older adults may be able to postpone the expected decline of memory monitoring by retaining the ability to recruit essential inferior frontal structures through more organized white matter pathways.Item Content representation in the human medial temporal lobe(2015-05) Liang, Jackson Chit; Preston, Alison R.; Colgin, Laura L; Drew, Michael R; Poldrack, Russell A; Schnyer, David MThe transformation of sensory inputs into complex memory representations is fundamental to human experience; yet, little is known about how this crucial process is achieved. When you meet your friend at the new cafe in town, what part of the brain encodes this novel scene into long term memory? What part encoded your friend’s favorite t-shirt, so that the sight of it gives you a feeling of familiarity rather than surprise? It is well-established that the medial temporal lobe (MTL) is crucial to both processes, but the MTL is not a single homogeneous region. In fact, it is composed of several anatomically distinct subregions including hippocampus, perirhinal cortex (PRC) and parahippocampal cortex (PHC). However, the computations performed by each subregion to encode individual events is still unclear. The present research tests the central hypothesis that different forms of event content are transformed into memory by distinct subregions within the MTL. A critical barrier in the study of content representation thus far has been its focus on comparing univariate peak activations in a region to different stimulus materials. To go beyond this limited approach, we employed multivariate statistical analyses that takes into account how event content is represented by distributed activity in MTL subregions. First, we examine the content-specific contributions of MTL subregions to episodic encoding and retrieval. Then, we demonstrate how these distributed representations support memory-based prediction to resolve ambiguities in our environment.Item Decoding mental representations for neurofeedback in motor and imagery tasks(2023-08) Kilmarx, Justin; Lewis-Peacock, Jarrod A.; Sulzer, James S.; Djurdjanovic, Dragan; Alambeigi, Farshid; Millán, JoséThe inability to execute coordinated movements can have a profound impact on an individual’s ability to complete the activities of daily living. Often times, these impairments arise as a result of neurological injury such as a stroke. Conventional physical therapy of the affected limb is often ineffective, possibly because it treats the symptom rather than the cause of the problem: impaired motor control circuitry in the brain. A potential method to address this issue is to employ neuroimaging technology to guide neuroplastic changes in the brain to restore motor function. The first aim of this dissertation was to develop and validate the use of a neurofeedback training target derived from functionally aligned data of healthy individuals. Our results showed a significant improvement in classification accuracy of individual finger presses when group data was aligned based on function rather than anatomy. This indicates that our functionally aligned template could provide an effective target for neural reinforcement of finger individuation beyond traditional anatomically aligned templates. For more severely impaired individuals, neuroimaging can also be used to develop assistive technologies by creating a connection between the brain and an external device, a technology known as a Brain-Computer Interface (BCI). In this work, we sought to address some of the current gaps in BCI usability by investigating the implementation of a visual imagery control paradigm. The second aim in this dissertation attempted to characterize the flexibility of visual imagery by mapping out the neural representational space of imagery for multiple image categories. While we were able to significantly identify when an individual was engaged in visual imagery compared to resting, our classifier was unable to accurately discern between the category-level neural activity. Our third aim expounded on this topic by investigating some of the key experimental components that contribute to successful performance. The results showed that visual imagery following a perception cue provided a stronger, more easily classifiable signal than visual imagery following an auditory cue. These results indicate that visual imagery is a challenging, yet possible BCI paradigm that could be useful in situations where other methods are ill suited.Item Extending PrAGMATiC : modeling covariances between responses across the human cortex(2021-05-07) Noble Hernandez, Daniel Alejandro; Huth, Alexander G.The human brain can be understood and organised as a topographic map of cortical areas. Dividing the brain into these distinct subsections has long been an ongoing effort, with a number of often disagreeing attempts to create this map – representative across individuals – being made over time. Both surgical and computational techniques have been broadly utilized in this pursuit, focusing on characterizing these chosen cortical areas based on their structural and functional similarities across individuals. Because the general anatomy is fairly well-understood now, computational methods are favoured; a popular approach taken involves measuring the responses of areas of the cortex according to functional magnetic resonance imaging (fMRI) data. We take a related – but modified – approach in this paper, delineating a model that uses the covariances oof the responses across the cortex rather than the cortical responses themselves. An extension of the existing hierarchical, Bayesian, probabilistic and generative model PrAGMATiC, our mathematical formulation of the model assumes and samples from an underlying Wishart, rather than Gaussian, distribution. This will allow the model to learn parameters to describe the functional covariances of responses at vertices across the cortex. Since direct comparisons of functional values, rather than their covariances, are not readily achieved in resting state fMRI, this formulation will be able to identify cortical parcellations using resting state fMRI data by providing a framework under which comparisons are possible.Item Hemodynamic measurements and modeling for functional magnetic resonance imaging(2014-05) Khan, Reswanul Kabir; Hoffmann, Gerald W.In imaging, short wavelength (high-frequency) particles scattered from targets typically yield greater spatial resolutions than longer wavelengths. X-Rays, for example are typically within 2 orders of magnitude of a nanometer wavelength to achieve desired resolutions for medical imaging. Although better for imaging, this poses a health risk for subjects as ionizing radiation and this limits its use. Functional Magnetic Resonance Imaging (fMRI) avoids this issue by using radiation of much larger wavelengths, 4.8 m (62.5 MHz), that are relatively harmless. Instead of scattering, these photons are used to excite protons between spin-states in an external magnetic field. Magnetization relaxation rates and dephasing as a function of space and time are then measured to reconstruct images. This dissertation develops experimental methods to understand and interpret the biophysical underpinnings of fMRI in terms of blood flow and oxygen concentration changes. In neuroscience, fMRI may be used to deduce brain activity. Brain activity is a general term related to neuronal firing rate, which metabolizes oxygen. Deoxygenated blood increases proton spin dephasing. This is the physical mechanism that ultimately yields contrast in the fMRI signal. This is known as Blood-Oxygen Level Dependent (BOLD) contrast. A critical piece of information in this process, hemodynamics, is the dynamics of cerebral (brain) oxygen concentrations in relation to blood flow. The hemodynamics of BOLD contrast fMRI and its relation to brain activity is vital. In this dissertation, I have classified hemodynamic data as a function of space and time in cerebral cortex as well as testing a rudimentary hemodynamic model. I have taken fMRI measurements in three human subjects to identify spatial and temporal hemodynamic trends in brain. Furthermore, I've analyzed laser-speckle imaging in three subjects to identify spatiotemporal trends in blood speed. The final portion of this dissertation relates developments of a hemodynamic model of BOLD.Item High resolution fMRI reveals distinct forms of associative novelty in the medial temporal lobe(2012) Manthuruthil, Christine; Preston, AlisonBoth Alzheimer’s Disease and Parkinson’s Disease involve alterations to the structure of the medial temporal lobe (MTL). Varying patterns of neuronal connectivity, however, suggest that not only does the MTL support learning and memory, but that its subregions play distinct roles in these processes as well. The exact nature of these contributions remains an area of active investigation. Examinations of associative novelty may offer an important tool for characterizing the processes carried out by different subregions. Associative novelty can be further broken down into associative novelty per se, which are simply novel stimulus configurations, and associative mismatch novelty, which are novel stimulus configurations that violate existing expectations. In this study, we used high resolution fMRI to characterize different associative novelty signals across the MTL; specifically, we were interested in whether there was a dissociation of associative novelty signal types between MTL subregions, or instead, a functional specialization for associative novelty signal types distributed across these subregions. Establishing subregional function could help elucidate the spectrum of cognitive deficits manifest in both Parkinson’s and Alzheimer’s patients.Item Measuring visual stimulation and attention signals in human superior colliculus using high-resolution fMRI(2013-05) Katyal, Sucharit; Ress, David BruceThe superior colliculus (SC) is a laminated oculomotor structure in the midbrain. In non-human primates SC has long been known to contain a retinotopically-organized map of visual stimulation in its superficial layers, which is aligned to a map of saccadic eye movements in the deeper layers. Microstimulation and electrophysiology experiments have shown that SC also plays a key role in covert visuospatial attention and suggest that attentional modulation also occurs in a retinotopic manner. Retinotopic organization of the visual field can be non-invasively mapped in humans using functional MRI with a technique called phase-encoded retinotopy. In this technique, rotating wedges and expanding rings of visual stimuli are used to map the polar angle and eccentricity dimensions of a polar coordinates system, respectively. A similar technique can also be used to map spatial attention by keeping the visual stimulus constant and cueing subjects to attend to apertures of rotating wedges and expanding rings within the stimulus. A previous study using fMRI has shown the polar angle representation of visual stimulation in human SC but was unable to find a representation of eccentricity. This work uses high-resolution fMRI along with special surface analysis techniques developed in our lab to demonstrate maps of both polar angle and eccentricity for visual stimulation. Moreover, visual attention is also shown to be topographically organized within SC and in registration with visual stimulation. Finally, in human visual cortex, fMRI is known to show activity for sustained spatial attention even in the absence of a significant visual stimulus, an attentional "base response". In this work, SC is shown to exhibit a similar sustained attention base response using a threshold-contrast detection paradigm. This base response was compared with a response for attention with visual stimulation. The peak amplitude of the base response occurred more deeply within SC tissue than the peak for attention with stimulation. It is proposed that this reflects the specific attentional enhancement of the deeper visuomotor neurons, which are hypothesized to be a direct neuronal correlate of the oculomotor theory of attention.Item Quantifying individual differences in patterns of functional brain network organization in youths(2021-07-16) Demeter, Damion Vanton; Church-Lang, Jessica; Lewis-Peacock, Jarrod A.; Preston, Alison R.; Gordon, Evan M.During childhood, the brain undergoes rapid periods of development that are vital for the cognitive processes supporting goal directed behavior. Some of these processes are termed ‘executive functions’, and the development of these skills not only impacts academic achievement, but also lifelong success. Successful navigation of executive function relies on the specialized integration of brain regions, thus requiring a network- level view of brain organization to better understand associations with behavioral outcomes. This dissertation examines multiple methods of quantifying patterns of brain activity at rest and tests the association of these measures with individual differences in youth executive function task performance. Study 1 identified patterns of brain activity unique to an individual (termed resting state neural fingerprints) in both youths and adults, using support vector machine classifiers. We found that the classifiers successfully identified an individual’s scan from their own previous scan and one twin’s scan from their co-twin’s scan. Our results suggest that resting state functional fingerprints are stable over time and vary by genetic relatedness. Study 2 quantified patterns of resting state functional network organization in youths, using graph metrics chosen from previous work in the literature. We then tested methodological factors that impact the ability of these graph metrics to predict measures of executive function task performance. Sample size had the largest impact on our models and even successful models accounted for very little sample variance. These results suggest that graph metrics do capture functional network organization associated with executive functions, but that graph metrics alone are too reductionist to capture complex patterns of brain activation associated with executive function behaviors. Study 3 identified and categorized cortical hubs in youths – regions supporting communication between brain networks – and tested their ability to predict executive function task outcomes. We found that cortical hub parcels in youths qualitatively resemble those found in adults, but form unique, youth-specific categories. Additionally, hubs integrating sensorimotor information and executive function networks related to behavioral outcomes. These studies demonstrate how measures of brain network organization and integration can improve our understanding of the developing brain, and their role in supporting goal directed behavior and individual differences.Item Resting state functional connectivity of the limbic cerebellum in ASD : vermis lobules IV, VII, and IX(2019-07-24) Boothe, Anne Cadence; Keith, Timothy Z., 1952-; Allen, Greg, doctor of clinical psychology; Bunner, Melissa R.; Stark, Kevin D.Cerebellar abnormalities have been identified in patient populations with disruptions in emotional functioning, often associated with the limbic system. Functional imaging research has provided evidence for a limbic cerebellum. Areas of the cerebellum, including the cerebellar vermis, have been shown to participate in emotional processing functions traditionally related to that of limbic system structures. However, the functional connectivity of specific areas of cerebellar vermis has not been extensively researched using resting-state functional connectivity magnetic resonance imaging (rs-fcMRI). Additionally, emotional processing deficits, often related to limbic system functioning, are associated with multiple patient populations including autism spectrum disorder (ASD). ASD is a pervasive neurodevelopmental disorder associated with deficits in language, social, and cognitive functioning. The cerebellum is one of the most consistent sites of brain abnormality in ASD; however, the connections between the cerebellar vermis and the limbic system have yet to be explored in this population using rs-fcMRI. The purpose of the present study was to investigate the functional connectivity of the limbic cerebellum using a resting-state fcMRI procedure in both typically developing individuals and those with ASD. This study aimed to increase current understanding of the organization of the brain, potential functions of the cerebellum, and provide insight into a disorder with established cerebellar abnormalities through the investigation of the connections of the cerebellar vermis in both typically developing individuals and those with ASD. Results indicated significant functional connectivity between three distinct areas of cerebellar vermis (vermis lobules IV, VII, and IX) and structures of the limbic system, including the cingulate gyrus, for the control group. Functional correlations between these regions suggest potential for cerebellar involvement in emotional processes, warranting further study. There were no differences in functional connectivity found for the superior posterior and inferior posterior vermis in ASD when compared to controls. An increase in anterior vermis functional connectivity in the ASD group extended to a small area in the left cingulate gyrus, a limbic system region. Results suggest limited differences in cerebellar vermis functional connectivity between groups.Item Resting state functional connectivity of the limbic cerebellum: vermis lobules IV, VII, and IX(2015-12) Kostic, Anne Cadence; Allen, Greg, doctor of clinical psychology; Stark, KevinThe cerebellum is classically known for its role in motor functioning; however, research has shown cerebellar involvement in other domains, including memory, attention, and emotional functioning. Animal studies, lesion studies, and imagining studies have contributed to our understanding of the wide array of cerebellar functions. Research specifically examining connections between the cerebellum and other systems of the brain has greatly expanded our understanding of the complexities of the cerebellum’s dynamic involvement with functional brain systems in addition to the motor system. Additionally, research has found the cerebellum to be involved in multiple disorders and is one of the most consistent sites of abnormality in autism. Connections between the cerebellum and the limbic system are thought to support cerebellar involvement in emotional functioning, affect, social cognition, and possibly in disorders indicative of impaired limbic-related functions, including autism. However, the functional connectivity of the limbic system and the cerebellum has not been comprehensively studied using functional connectivity magnetic resonance imaging (fcMRI) procedures. Therefore, the purpose of this present study is to determine the functional connectivity of specific cerebellar vermis with structures of the limbic system to contribute to the understanding of the organization of the limbic cerebellum. This study uses fcMRI and functional connectivity analysis to determine to functional coherence of three vermis ROIs with limbic structures. It is hypothesized that posterior vermis lobule ROIs will show significant functional coherence with limbic brain regions, suggesting posterior vermis involvement in the circuitry of the limbic cerebellum.Item Reward modulation of medial temporal lobe function during associative encoding and cued recall(2010-05) Wolosin, Sasha Monica; Preston, Alison R.; Beer, Jennifer S.Emerging evidence suggests that hippocampal memory processing is modulated by midbrain regions under conditions of reward, resulting in enhanced encoding of episodic information—long-term memory for events. Current theories further suggest that hippocampal subregions may have distinct roles in episodic memory formation, and may be differentially influenced by dopaminergic midbrain inputs. Using high-resolution functional magnetic resonance imaging (fMRI), the present study investigated hippocampal subregional function as well as activation in surrounding medial temporal lobe (MTL) cortex, midbrain, and nucleus accumbens during associative encoding and cued recall under varying conditions of reward. A high-value or low-value monetary cue preceded a pair of objects indicating potential reward for successful retrieval of the association. At test, participants performed cued recall followed by match (correct association) or mismatch (incorrect association) probe decisions and received feedback on their performance. Behaviorally, cued recall performance was superior for pairs preceded by high reward cues at encoding relative to pairs preceded by low reward cues. FMRI analysis revealed regions within hippocampus, parahippocampal cortex, nucleus accumbens, and midbrain showing subsequent memory effects (greater encoding activation for remembered, compared to forgotten associations) and reward effects (greater activation for high-value, compared to low-value associations) during stimulus encoding. Within several of these regions, individual differences in reward-related encoding activation were correlated with the degree of the behavioral reward effect (better memory for high-value compared to low-value object pairs). At retrieval, regions in midbrain and subiculum predicted successful associative recall, and regions within hippocampus, parahippocampal cortex, nucleus accumbens, and midbrain showed reward effects in the absence of explicit reward cues. Within several MTL regions, activation was greater for match than mismatch probes. These findings are consistent with theories suggesting that reward-based motivation influences memory formation through interactions between dopaminergic midbrain and hippocampus.Item The consistency of control engagement in developmental populations(2020-08-07) Roe, Mary Abbe; Church-Lang, Jessica; Preston, Alison R; Lewis-Peacock, Jarrod A; Neta, MaitalControl regions of the brain flexibly respond to changing task demands and support cognitive abilities that are important for learning and academic success. Deficits in task control brain function have been implicated in developmental learning disorders of reading and attention, which often present with overlapping behavioral characteristics. This dissertation presents three studies that use a multi-task approach to explore associations between academic or behavioral skills and control brain function in children with and without learning difficulties. Study 1 investigated task control activation across lexical and non-lexical tasks in a sample of 3rd-5th grade struggling readers. We found altered control engagement in struggling readers during a reading task, but not during a non-lexical task, suggesting that altered engagement of control in struggling readers is specific to the reading process rather than a reflection of a global control deficit. Study 2 investigated consistencies across different tasks in control brain activation when children made mistakes relative to when they responded correctly. We found that the majority of adult-derived brain regions important during errors also showed consistent engagement in children across three tasks, except in bilateral frontal areas, which may be regions that distinguish mature from immature error processing. Study 3 assessed brain activation during and after errors on two tasks in children with and without attention-deficit/hyperactivity disorder (ADHD). We found that children engaged primarily cingulo-opercular and parietal task control regions during error trials, but both cingulo-opercular and fronto-parietal control regions during the trials after an error. During error processing, we found activation differences between children with and without ADHD in default, sensorimotor, and visual systems, and regions within these systems showed task-specific differences. Examining the consistency of control activation across tasks provides insight into domain-general or task-specific neural mechanisms that have the potential to be markers of difficulty, or targets for intervention, in children with learning or attention disorders.Item The crossroads of working memory, attention, and perception : how distraction impacts short-term memories(2021-04-02) Mallett, Remington Ray; Lewis-Peacock, Jarrod A.; Church, Jessica A; Schnyer, David M; Sprague, Thomas CEveryday experience consists of a constant tradeoff between perceiving external information while retaining internal information in memory. These two sources of information – internal and external – are used simultaneously to guide complex and goal-directed behavior. How do these two contrasting sources interact? This dissertation specifically addresses how the internal maintenance of information (i.e., memory) is able to function efficiently despite the processing of incoming information (i.e., perception). The following studies focus on (1) how working memory prioritization impacts the influence of memory on distracting perceptual processes, (2) how working memory prioritization impacts the influence of distraction on neural memory representations, (3) how incoming perception alters internal memory representations, and (4) how overloading perceptual processing impacts memory retention. Collectively, these works speak to the various consequences of distraction on working memory. By focusing on both the behavioral and neural consequences of distraction, this dissertation aims to contribute to a more comprehensive understanding of how the brain handles complex internal cognitive tasks amidst a dynamic external environment.Item The development of bias in perceptual and financial decision-making(2014-08) Chen, Mei-Yen, Ph. D.; Poldrack, Russell A.; Maddox, W. Todd; Huk, Alexander C.; Pillow, Jonathan; Dhillon, Inderjit S.Decisions are prone to bias. This can be seen in daily choices. For instance, when the markets are plunging, investors tend to sell stocks instead of purchasing them with lower prices because people in general are more sensitive to the potential losses than the potential gains, or loss averse, in making financial choices. This also can be seen in laboratory tests. When participants receive higher payoffs for successfully discriminating a visual stimulus as one choice against the other, they begin choosing this higher-rewarded option more often even though the objective evidence indicates the alternative. In my dissertation, I used mathematical models and functional magnetic resonance imaging (fMRI) to track the development of bias in perceptual and financial decision-making and presented evidence characterizing the experience-sensitive and domain-general decision-making process in the human brains. The first chapter showed that bias could be developed through associating decision contexts and reward feedback from trial to trial in perceptual decision-making. Although the surface task differed, this learning process involved the same prediction error driven mechanisms implemented in the dopaminergic system as in financial decision-making. Furthermore, the frontal cortex increased its strength of connection between visual and value systems that accounted for the growth of perceptual bias. The second chapter extended this feedback-driven acquisition process to examine the influences of experience on loss aversion in financial decision-making. The results showed that people learned to make riskier or more conservative decisions according to the feedback that they had received in different decision contexts. This alternation in loss aversion was achieved through modulation of the value system’s sensitivity toward the potential gains in evaluation. The frontal cortex mediated this change. The third chapter used a mathematical model to identify the changes in financial decision-making that occurred faster than the temporal resolution of fMRI. The results suggested that people might simplify financial information into some rules of thumb for making a choice. These findings not only integrated the knowledge in different domains of decision neuroscience but also shed lights onto how one may refine the decision-making process against experiences.