Cognitive Neuroscience Commons^™

Target Selection And Enhancement During Attentional Tracking, Marvin R. Maechler

Dartmouth College Ph.D Dissertations

At any waking moment, we are bombarded with more sensory information than we can fully process. Attention is necessary to deal with the dynamic world we live in. One fundamental function of vision and attention is to keep track of moving objects, but what are the targets of attention during tracking?

One of the first theories of attentional tracking predicted that targets would be selected at early processing stages. By employing the double-drift illusion, which dissociates physical and perceived positions of moving objects, we investigated which of these positions is selected for tracking. Contrary to earlier theories and in line …

Cerebrospinal Fluid Biomarkers Not Associated With Neurologic Compromise Among Mild Cognitively Impaired Reverters With Parkinson's Disease, Cameron Ryczek

Electronic Theses, Projects, and Dissertations

Parkinson's Disease (PD) is a neurodegenerative disease characterized by motor (e.g. tremors) and non-motor symptoms (e.g. cognitive impairment). PD patients' change in cognitive functioning can be observed using the following classifications: cognitively intact, mild cognitive impairment (MCI), or dementia (PDD). MCI has many subtypes, one of which is MCI reversion which is defined as those with MCI at one time point reverting to cognitively intact later. While there is limited research into the utility of MCI reversion and its relationship with cerebrospinal fluid (CSF) biomarkers in PD, this study will begin to elucidate this relationship. To this end, data from …

Head Stabilization And Cortical Activation In Contact Sport Athletes During Walking Under Different Visual Task Constraints, Sam Zeff

Doctoral Dissertations

Contact sport participation exposes athletes to repetitive sub-concussive head impacts, which have been shown to elicit cortical neurophysiologic, cognitive, and motor performance alterations that have the potential to disrupt visual perception. Despite the growing concern regarding sub-concussive impacts, our understanding of their implications on motor performance and risk for further injury is limited. A stable head provides a consistent perceptual platform for the visual and vestibular sensory systems, but the effects of contact sport participation on head stability and visual perception remain poorly understood. The goal of this dissertation was to understand whether contact sport participation modifies athletes’ ability to …

Sex Differences In Stress Reactivity, Brain Morphology, And Oxytocin In The Hypothalamus Of The Gray Short-Tailed Opossum (Monodelphis Domestica), Esperanza I. Zacarias, Daniela Rodriguez, Alexandra Chalons, Sasawan Heingraj, Nicole Altamirano, Joseph Rafac, John L. Vandeberg, Mario Gil

Research Colloquium

Understanding the effects of stress on behavior and cognition is important due to its impact on mental health and wellbeing (Schneiderman et al. 2005). Translational animal research can contribute to the development of new treatments that can improve therapeutic outcomes and our understanding of the neurobiology of stress. In the present study, we complement behavioral stress reactivity with immunohistochemical localization of oxytocin in the hypothalamus, a neuropeptide that regulates stress (Neumann & Slattery, 2016). Oxytocin has potential therapeutic use for mental health disorders (Neumann & Slattery, 2016), and the effects of oxytocin seem to be sexually dimorphic (Love, 2018). Using …

Understanding The Resources, Barriers, Facilitators And Interests About Aging And Dementia Research Of Community Members From The Rio Grande Valley, Karla Daniela Lopez Lorenzo, Rosa V. Pirela Mavarez, Gabriela Osuna, Kendra Stine, Nahalie Chacon De Alvarez, Noe Garza, Gladys E. Maestre

Research Symposium

Background: One of ten people aged 65 develops Alzheimer’s Disease and it is one of the sixth-leading cause of death in the United States. The Rio Grande Valley (RGV) is mostly constituted by Hispanic/Latinos (93%), a population that has a 1.5X increased risk of AD onset. Nevertheless, there are not enough resources to support people living with dementia and their care partners. This study will leverage research efforts deployed by the RGV Alzheimer’s Disease Resource Center for Minority Aging Research to understand the social representations about the resources, barriers, facilitators, and interests of the RGV community about dementia and Alzheimer’s …

The Neural Sequalae Of Subjectively Experiencing Autobiographical Memories From The Remote Past And Recent Present Using Fmri, Ava G. Peruski, Nim Singh, Brendan E. Depue

The Cardinal Edge

Autobiographical memory is central to one's sense of self and continuity from past to present. Despite this, there is little research on the neural correlates underlying individual subjective experience of autobiographical memory and how that is related to brain phenomena (i.e., activity, communication). The purpose of this study was to help minimize this gap. We recruited twenty healthy adult participants, who were asked to generate memory cues (1-3 word descriptions) for locations and objects from their early and recent life. After 24 hours, participants were shown these cues then asked to recall the appropriate memory while in an fMRI scanner. …

Selective Recruitment Of Cerebellum In Cognition, Ladan Shahshahani

Electronic Thesis and Dissertation Repository

Previous studies of cerebellar function in humans have shown that it is activated by a myriad of tasks ranging from motor learning and language to working memory and more. These studies have prompted a deviation from the traditional view of the cerebellum as a purely motor structure. However, the precise contribution of the cerebellum to these tasks remains ambiguous.

A prevalent assumption in fMRI studies is interpreting BOLD activation as evidence of the cerebellum's involvement in specific tasks. However, this interpretation is potentially misleading, especially considering that the BOLD signal predominantly represents cerebellar input, with output activity largely absent. Consequently, …

Examining Metacognitive Access To Low-Level Ensemble Representations, Vladimir Mudragel

Dissertations, Theses, and Capstone Projects

Ensemble perception is a process that allows our sensory systems to rapidly extract summary information about the stimuli in the environment. For example, we are able to get a sense of the average number of items in a group of similar items (Burr & Ross, 2008; Halberda, Sires, & Feigenson, 2006) or the average size of a group of similar shapes of different sizes (Ariely, 2001). It is theorized that the qualitative result of ensemble perception is that it provides a gist impression of the current environment, which then enables attentional processes in the brain to determine which parts of …

Automatic Analysis Of The Frequency, Vigor, And Complexity Of Spontaneous Locomotion Bouts Of Mice With Loss And Gain Of Function Of The G Protein-Coupled Receptor Smoothened In Cholinergic Neurons, Aleksandra Feshchenko

Dissertations, Theses, and Capstone Projects

Locomotion, a fundamental behavior, is classically assessed using simple metrics of velocity and total distance moved in an open field. This behavior however offers rich data about the organization and breadth of actions an animal can take while only facing limitations due to the bio-mechanical constraints of the organism. Importantly, these actions are not biased towards a particular task-solution space imposed by many behavioral paradigms. Here, to analyze motor complexity in freely ambulating mice, we developed a method for the automatic and unbiased identification of locomotor bouts which we call Bout Finder (BF). This analysis utilizes Open Feld data to …

Brainwaves, Memory, And Reward, Rebecca Mccune

Dissertations, Theses, and Capstone Projects

The development of effective educational curricula for enhancing learning involves the crucial consideration of effort and rewards. In the realm of education, teachers commonly employ rewards as motivational tools. Traditionally, these rewards are given to students as a recognition of their successful performance. However, a thought-provoking idea emerges: What if we were to extend rewards to students not solely based on accurate answers, but also on the effort they invest, even in cases where their actual response might be incorrect? Our study explores the potential impact of this approach on the way information is absorbed and subsequently retained, specifically focusing …

White Matter Connectome Associations With Reading Functions In Children, Chenglin Lou

Electronic Thesis and Dissertation Repository

This thesis investigated associations between the white matter connectome and reading in children with a wide range of reading abilities. It is well established that the connectome supports the interplay among brain regions and connections within an integrated system. In this dissertation, I examine the hypothesis that it could therefore represent multiple mapping processes among reading components and further explain variations in reading performance. Such associations between the organization of the connectome and reading skills have not been well explored. This thesis aimed to address this issue by considering both the relationship between connectome measures and standardized reading performance out …

Fraction Magnitude Understanding Across Learning Formats: An Fmri Study, Chloe A. Henry

Electronic Thesis and Dissertation Repository

Knowledge of fraction magnitudes are an important, but notoriously difficult mathematical concept to master. Behavioural work has begun to explore and compare the instructional tools used for fraction learning. However, how fraction instructional tools are processed in the brain remains an underexplored question. Therefore, in the present thesis, we used functional brain MRI methodology to examine the neural activity of adult participants while completing a fraction verification task using the number line and area model, two common methods of fraction learning. We found that both models commonly recruited fronto-parietal activity, the neural regions typically implicated in number processing. However, we …

The Directional Effect Of Target Position On Spatial Selective Auditory Attention, Heesung Park

Dissertations, 2020-current

Spatial selective auditory attention plays a crucial role in listening in a mixture of competing speech sounds. Previous neuroimaging studies have reported alpha band neural activity modulated by auditory attention, along with the alpha lateralization corresponding to attentional focus. A greater cortical representation of the attended speech envelope compared to the ignored speech envelope was also found, a phenomenon known as 'neural speech tracking’. However, little is known about the neural activities when attentional focus is directed on speech sounds from behind the listener, even though understanding speech from behind is a common and essential aspect of daily life. The …

Investigating The Roles Of The Dorsal And Ventral Striatum In Humor Comprehension And Appreciation Throughout Health, Aging, And Parkinson’S Disease, Maggie Prenger

Electronic Thesis and Dissertation Repository

Humor processing is thought to involve two distinct components. The first, humor comprehension, involves detecting and resolving incongruities that are present within a humorous stimulus. This is related to cognitive processes such as ambiguity resolution, response inhibition, working memory, and cognitive flexibility, functions that are mediated in part by the dorsal portion of the striatum (DS). Humor appreciation, on the other hand, refers to the subjective amusement and mirth that one experiences in response to a joke. This is related to reward processing, which implicates the ventral portion of the striatum (VS). Across three separate studies, we investigated the involvement …

The Consolidation Of Memory Associations, Kyle A. Kainec

Doctoral Dissertations

Creating memories is a fundamental challenge for the human brain. To create memories, defining features of experiences must be stored distinguishably without forgetting other memories. Memory associations represent co-occurring features and defining features across experiences. Memory associations are represented as networks of information that are stored in the brain. New memory associations are encoded during experiences and can be used to update existing memory associations during offline intervals. However, the mechanisms that underlie how encoded memory associations are stored within existing networks during offline intervals remains unclear. The experiments in this dissertation address a significant theoretical gap in understanding the …

The Modulation Of Lfp Characteristics In The Freely Moving Common Marmoset, William Jm Assis

Electronic Thesis and Dissertation Repository

The hippocampus is a neural structure critical for navigation. Neurons in this region, along with others, create a functional network which generates large-amplitude modulations known as local field potential (LFP) activity. Prior LFP research has predominantly used rodent animal models, however recent studies have shown that frequencies associated with navigation in other mammals do not correlate to those of the rodent. We hypothesized that LFP characteristics in the common marmoset are modulated by the speed and axis of travel of the animal. Two marmosets were placed in a free moving 3-dimensional environment where movement and neurological activity were recorded. Results …

Disentangling The Role Of Parvalbumin-Expressing Interneurons In Stimulus-Response Learning And Cognitive Flexibility, Harleen Rai

Electronic Thesis and Dissertation Repository

Habits enable animals to efficiently navigate their surroundings while tending to more cognitively demanding environmental factors. One mechanism underlying habit is known as stimulus-response (S-R) learning, which takes place in the dorsolateral striatum (DLS). However, there is limited knowledge regarding the complex striatal microcircuits involved in S-R learning and cognitive flexibility. Recently, attention has turned toward the GABAergic Parvalbumin-expressing (PV) interneurons that can modulate striatal outputs. Here, we utilized chemogenetic techniques and touchscreen cognitive assessments to analyze the influence of PV neurons on S-R learning in mice. When PV neurons were inhibited, during the acquisition of a S-R and cognitive …

Category Learning Dlpfc Single-Dissociation By Fnirs, Tim Qiu

Electronic Thesis and Dissertation Repository

It remains an open question whether modern neuroimaging clearly dissociates the Explicit system that learns by encoding rules, and the Implicit system that learns by encoding information-integration boundaries. Further, there are nearly no applications of fNIRS as a modality in studying category learning. We conduct two behavioural experiments to validate a carefully controlled categorization task intended to dissociate Explicit and Implicit systems. Then we apply fNIRS neuroimaging within-subjects to localize a neuroanatomical dissociation. We localized two effects to R DLPFC (1) a simple single-dissociation of higher activity in RB categorization, and (2) a negative relationship between overall task performance and …

Shedding Light On Hearing In Coma: Investigating The Applicability Of Functional Near-Infrared Spectroscopy For Assessing Auditory Function And Aiding Prognosis In Patients With Acute Disorders Of Consciousness, Reza Moulavi Ardakani

Electronic Thesis and Dissertation Repository

There is a critical need for a bedside neuroimaging tool to aid in the prediction of functional recovery outcomes for patients with acute disorders of consciousness (DoC) in the early days following severe brain injury. Current neurobehavioral examinations and prognosis tools have limitations in predicting good outcomes, leading to potential mistreatment or premature withdrawal of life support. Functional near-infrared spectroscopy (fNIRS) is a viable candidate for such purposes due to its portability and cost-effectiveness. Auditory processing, viewed as a multi-level and multifaceted brain function, could provide a sensitive and specific marker of residual cognitive function in unresponsive patients. This study …

Postexercise Executive Function And Cortical Hemodynamics During The Different Phases Of The Menstrual Cycle, Priyanka Persaud

Electronic Thesis and Dissertation Repository

Resting cerebral blood flow (CBF) is increased during the luteal (LUT) phase of the menstrual cycle; however, it is unclear whether this change impacts a postexercise executive function (EF) benefit. Female participants (N=16) performed three experimental sessions: a V̇O_2peak task and 20-min single bouts of moderate intensity aerobic exercise (i.e., 80% of lactate threshold) during their follicular (FOL) and luteal (LUT) menstrual cycle phases. A separate group of male participants (N=21) additionally completed a V̇O_2peak test and a 20-min exercise intervention. Middle cerebral artery velocity (MCAv) was measured during exercise via transcranial Doppler ultrasound to estimate CBF and …