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Associations Between Early Childhood Sleep, Memory Function, And Brain Development Across The Nap Transition, Sanna Lokhandwala

Doctoral Dissertations

Preschool-age children often distribute their sleep across a midday nap and overnight sleep. Skipping the nap is suggested to increase the duration and depth of deep sleep (i.e., slow wave activity; SWA). Moreover, missing the midday nap has been shown to impair learning processes. This may be because children’s brains at this point in development are immature, necessitating the intervening nap period to strengthen memories before they are forgotten. Nonetheless, at some point during the preschool years, many children begin transitioning naturally out of napping. It is unclear whether the memory benefits of overnight SWA after a skipped nap depend …

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 …

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 …

Motivated Attention To Social And Nonsocial Reward Images: Examining Relations With Externalizing Risk In Children, Adaeze C. Egwuatu

Doctoral Dissertations

Children that exhibit issues with externalizing behaviors often experience maladaptive outcomes in later life. Externalizing problems during middle childhood (e.g., 6-10 years old) are linked to issues with emotion regulation, which are, in turn, caused by disrupted attention and emotion reactivity to reward. Externalizing problems during this period have also been linked diminished processing of social reward stimuli, suggesting externalizing risk in children may be reflected in contrasting patterns in processing of non-social and social rewards. However, research comparing how differences in affective processing of specific reward content (i.e. social versus non-social) patterns relate to externalizing behavior within normative development …

Role Of The Prefrontal Cortex In Reward Seeking Behaviors, Jessica Caballero-Feliciano

Doctoral Dissertations

Disorders associated with compulsive seeking of rewards, like binge-eating, are associated with abnormalities of the prefrontal cortex in humans, which is analogous to the prelimbic (PL) and infralimbic (IL) subregions of the medial prefrontal cortex (mPFC) in rodents. Although studies have examined the role of the mPFC in drug seeking behaviors, studies examining natural reward seeking behaviors (i.e. food and sucrose) are often unclear and contradictory. This dissertation aims to characterize the role of the PL and IL mPFC in operant sucrose seeking behaviors. We used pharmacological and chemogenetic tools to selectively inactivate the PL, IL and PL-nucleus accumbens (NAc) …

Mental Fatigue: Examining Cognitive Performance And Driving Behavior In Young Adults, Abigail F. Helm

Doctoral Dissertations

Mental fatigue causes an increase in task-based EEG theta and alpha power and a decrease in performance (for a review, see Tran et al., 2020). However, little is known about the emergence of mental fatigue in resting state EEG recordings and whether the progression of mental fatigue over time is influenced by individual differences. The current dissertation examined the utility of resting state EEG as a measure of mental fatigue by testing whether EEG power changed in young adults over the course of a cognitively demanding battery of tasks. The current dissertation also tested how this measure of mental fatigue …

Shared Neural Substrates Of Perception And Memory: Testing The Assumptions And Predictions Of The Representational-Hierarchical Account, D. Merika W. Sanders

Doctoral Dissertations

Proponents of the representational-hierarchical (R-H) account claim that memory and perception rely on shared neural representations. In the ventral visual stream, posterior brain areas are assumed to represent simple information (e.g. low-level image properties), but the complexity of representations increases toward more anterior areas, such as inferior temporal cortex (e.g., object-parts, objects), extending into the medial temporal lobe (MTL; e.g. scenes). This view predicts that brain structures along this continuum serve both memory and perception; a structure’s engagement is determined by the representational demands of a task, rather than the cognitive process putatively involved. In a neuroimaging study, I searched …

How Perception Of Decision Environment And Future Information Affects Changes In Delay Discounting Rates: Differences Across U.S. And China, Differences Before And After The U.S. 2018 Midterm Elections, Fran Walsh

Masters Theses

In this thesis, I will explore the idea that choices between present, smaller value options and future, larger value options depend on how much individuals trust the future to deliver the reward. Due to this aspect of trust, the individual must build their estimate of trust based on information for their present environment and their future expectations. This estimate of future trust can change across different time points in the same environment (i.e., before and after a national election) and between environments in the same time point (i.e., between two countries experiencing different economic rates of change). In this set …

Electrophysiological Correlates Of Natural Language Processing In Children And Adults, Margaret Ugolini

Doctoral Dissertations

To understand the causes of differences in language ability we must measure the specific and separable processes that contribute to natural language comprehension. Specifically, we need measures of the three language subsystems – semantics, syntax, and phonology – as they are used during the comprehension of real speech. Event-Related Potentials (ERPs) are a promising approach to reaching this level of specificity. Previous research has identified distinct ERP effects for each of the subsystems – the N400 to semantic anomalies, the Anterior Negativity and P600 to syntactic anomalies, and the Phonological Mapping Negativity to unexpected speech sounds. However, these studies typically …

Changes In Color Guidance Over The Course Of A Complex Visual Search, Ryan Papargiris

Masters Theses

When searching for an object, we store a mental representation of the target, which guides our search through the use of attention. The effectiveness of this search guidance varies depending on the task and the relationship between target and distractors. With a better understanding of how search guidance changes over time within a trial, we can better compare the differences between experimental conditions. Eye tracking data from a variety of search tasks were analyzed to determine how color guidance varied over the course of the trial. Color guidance for a given fixation was evaluated based on the distance in color …

One Year Change In Cognitive Function In Male And Female Common Marmosets (Callithrix Jacchus), Brianna Healey

Masters Theses

Long term cognitive studies in humans and nonhuman primates such as macaques are difficult because of their long lifespan. The common marmoset (Callithrix jacchus) is a non-human primate who shares with humans many features characteristic of primates, including a complex brain and cognitive function. They also have a short lifespan (~10 years) that makes them a great model in studies of cognitive aging. This study focuses on the rate of decline in cognitive function in male and female marmosets based on performance on reversal learning tasks over 2 years of testing.

We found that marmosets improved their overall …

Sex, Motivation, And Reversal Learning In The Common Marmoset (Callithrix Jacchus), Alyssa Carlotto

Masters Theses

This study examined the relationships between motivation and cognitive performance in male and female common marmosets (Callithrix jacchus). This question was driven by prior data from the Lacreuse lab showing a robust female impairment in reversal learning, as assessed by the number of trials needed to acquire a reversal following a simple discrimination between two stimuli. This thesis tested the hypothesis that the female impairment in reversal learning was mediated by deficits in motivation. Two sets of measures were used to test this hypothesis. I evaluated physical effort via testing on the progressive ratio (PR), a test that …

Integration Of Robotic Perception, Action, And Memory, Li Yang Ku

Doctoral Dissertations

In the book "On Intelligence", Hawkins states that intelligence should be measured by the capacity to memorize and predict patterns. I further suggest that the ability to predict action consequences based on perception and memory is essential for robots to demonstrate intelligent behaviors in unstructured environments. However, traditional approaches generally represent action and perception separately---as computer vision modules that recognize objects and as planners that execute actions based on labels and poses. I propose here a more integrated approach where action and perception are combined in a memory model, in which a sequence of actions can be planned based on …

Hearing And Seeing A Speaker: How Perceptual And Cognitive Factors Modulate The Dynamics Of Audiovisual Speech Perception, Elina Kaplan

Doctoral Dissertations

In face-to-face conversations, listeners process and combine speech information obtained from hearing and seeing the speaker talk. Audiovisual speech typically leads to more robust recognition of speech, as it provides more information for recognition but also as it helps listeners adjust to speaker idiosyncrasies. The goal of the current thesis was to examine how certain perceptual and cognitive factors modulate how listeners use visual speech to facilitate momentary speech perception and to adjust to a speaker’s idiosyncrasies. Results showed that (older) listeners’ sensitivity to cross-modal synchrony is related to the size of the audiovisual interactions during early perceptual processing. Furthermore, …

Effort-Related Motivational Dysfunctions: Behavioral And Neurochemical Studies Of The Wistar-Kyoto Rat Model Of Depression, Brendan Abbott

Masters Theses

Depression and related disorders are characterized by motivational dysfunctions, including deficits in behavioral activation and exertion of effort. Animal models of relevance to depression represent a critical starting point in elucidating the neurobiological mechanisms underlying motivational dysfunctions. The present study explored the use of the Wistar-Kyoto (WKY) animal model of depression to examine effort-related functions as measured by voluntary wheel running and performance on a mixed fixed ratio 5/progressive ratio (FR5/PR) operant task. Given the known link between activational aspects of motivation and the mesocorticolimbic dopamine (DA) system, the behavioral effects of d-amphetamine (0.5 and 1.0 mg/kg, IP), a psychostimulant …

Sleep, And Its Relation To Non-Motor Deficits In Patients With Cerebellar Ataxia, Akshata Sonni

Doctoral Dissertations

The cerebellum is a highly connected structure, and its involvement in sleep – which is a dynamic process that is modulated by a complex set of neural systems – can come about through a number of neural pathways. We conducted two studies aimed at furthering our understanding of cerebellar involvement in sleep behavior and physiology, as well as measuring the impact of poor sleep on mood and cognition in patients with cerebellar degeneration. First, by means of an online battery including measures of sleep and neuropsychiatric function, we collected data from 176 patients with cerebellar ataxia. We found strong evidence …

Assessing The Long-Term Sequelae Of Mild Traumatic Brain Injury, Janna Mantua

Doctoral Dissertations

A mild traumatic brain injury (mTBI), also known as a concussion, is defined as an injury that results in an alteration of consciousness or mental status. Previous studies have shown mTBI populations experience a number of chronic (> 1 year) symptoms, such as sleep disturbances (e.g., sleep stage alterations), mood alterations (e.g., depressive symptoms), and cognitive alterations (e.g., poor concentration). The three chapters of this dissertation sought to explore these long-term sequelae and the possible interrelations between them. In the first experiment, sleep-dependent memory consolidation of neutral stimuli was probed in a chronic mTBI sample and a control, uninjured sample. …

The Role Of Sleep On Inhibitory Control In Young Children With Attention-Deficit/Hyperactivity Disorder (Adhd), Amanda Cremone

Doctoral Dissertations

Alongside the hallmark symptoms of hyperactivity and inattention, children with attention-deficit/hyperactivity disorder (ADHD) often report having sleep problems. Although sleep deficits are consistently found when evaluated subjectively, impairments in sleep physiology are inconsistent. Compared to typically developing (TD) children, children with ADHD have greater spectral power in the delta (0.5 to 4 Hz) and theta frequency bands (4 to 7 Hz). Moreover, activity in these bands is differentially related to cognitive outcomes in ADHD and TD populations. As such, this dissertation sought to examine relations between sleep physiology and inhibitory control, a primary deficit of ADHD, in young children with …

Explicit Learning Of Phonotactic Patterns Disrupts Language Learning, Evan Hare

Masters Theses

Learning environment has been proposed to be a cause of age of acquisition effects in second language acquisition. Explicit learning in adults is linked to fast initial gains but poorer ultimate attainment whereas implicit learning in children requires more input but leads to greater proficiency in the long run. The current study used ERP measures to determine if explicit learning of a phonotactic pattern interferes with implicit learning of that same pattern in adults. Listeners were told to figure out the pattern of consonants that can go together in a word by listening to 16 CVCV nonsense words in which …

A Representational-Hierarchical Account: A New Theory Of False Memories, D. Merika Wilson

Masters Theses

Past research has supported a representational-hierarchical theory of memory and perception that extends the ventral visual stream into the medial temporal lobe. In this account, representations are organized in a hierarchical manner, such that structures located further anterior in the brain contain complex representations of whole objects and areas further posterior in the visual cortex contain representations of simple features. When conjunctive representations are compromised, an individual must rely on simple-feature representations to complete mnemonic and perceptual tasks. However, these simple-feature representations are susceptible to feature-level interference, which can cause false recognition of novel objects. The goal of the present …

The Neural Correlates Of Emotion Reactivity And Regulation In Young Children With Adhd, Claudia I. Lugo-Candelas

Doctoral Dissertations

Attention-deficit hyperactivity disorder (ADHD) is the most frequently occurring pediatric neurobehavioral disorder. Although emotion reactivity and regulation are frequently impaired in ADHD, few studies have examined these factors in preschool aged children with ADHD, and none have explored the neural correlates of emotion reactivity and regulation in this group though event-related potentials (ERPs). Children aged 4 to 7 with (n = 24) and without (n = 30) ADHD symptoms completed an attention task composed of four blocks: baseline, frustration, suppression, and recovery. In the frustration and suppression blocks, negative affect was induced by false negative feedback. During the …

Behavioral And Neural Mechanisms Of Impulsive Choice, Jesse Mcclure

Doctoral Dissertations

Impulsive choice is defined as the preference for a small immediate reward over a larger delayed reward. Individual variablity in impulsive choice correlates with many socially relevant behaviors. Although forms of impulsive choice have been studied in both behavioral ecology and psychology, the exchange of knowledge between these fields is just beginning. Drawing from both of these fields will improve our research methods allowing for a more detailed understanding of this complex behavior. Existing tasks to measure impulsive choice conflate the delay and quantity of the reward. To address this, I have drawn from foraging research to establish a method …

Estrogen-Sensitive Learning Is Not Affected By Combination Ethinyl Estradiol And Levonorgestrel Oral Contraceptive Use, Darlene F. Ficco

Doctoral Dissertations

Two studies were conducted to explore the cognitive effects of combination ethinyl estradiol and levonorgestrel contraceptive use during late adolescence and young adulthood. Three groups of females, naturally cycling, active pill phase, and hormone-free interval phase, were tested on a battery of estrogen-sensitive, i.e., place learning and word generation, and estrogen-insensitive, i.e., map drawing, mental rotation, digit span, story recall, and object recall, tasks. Study 2 was conducted as a means to replicate the findings observed in Study 1 and to manipulate task difficulty and sensitivity. Two measures of mood were administered, and salivary estradiol levels at time of testing …

Associations Between Anxiety And Attention In Laboratory-Housed Rhesus Macaques (Macaca Mulatta), Lauren E. Hobbs

Masters Theses

Previous studies completed with humans have revealed insight into the effects of anxiety on attention tasks such the dot-probe task, but there is little information about such effects on non-human primates. This study aimed to assess whether anxiety or anxious behaviors would impact rhesus macaque performance on a three stimuli paradigm similar to the dot-probe task. Utilizing images of conspecifics (strong threat, mild threat, and neutral), eight monkeys were video recorded completing a task that required them to slide two doors, which held these images, to the side to obtain a treat. We hypothesized that behavioral phenotype (high or low …

Attention Modulates Erp Indices Of The Precedence Effect, Benjamin H. Zobel

Masters Theses

When presented with two identical sounds from different locations separated by a short onset asynchrony, listeners report hearing a single source at the location of the lead sound, a phenomenon called the precedence effect (Wallach et al., 1949; Haas, 1951). When the onset asynchrony is above echo threshold, listeners report hearing the lead and lag sounds as separate sources with distinct locations. Event-related potential (ERP) studies have shown that perception of separate sound sources is accompanied by an object-related negativity (ORN) 100-250 ms after onset and a late posterior positivity (LP) 300-500 ms after onset (Sanders et al., 2008; Sanders …

Age-Related Changes In Sleep-Dependent Consolidation Of Visuo-Spatial Memory, Akshata Sonni

Masters Theses

Healthy aging is associated with a reduction in slow-wave sleep (SWS), crucial for declarative memory consolidation in young adults; consequently, previously observed benefits of sleep on declarative learning in older adults could reflect a passive role of sleep in protecting memories from waking interference, rather than an active, stabilizing effect. To dissociate the passive and active roles of sleep, a visuo-spatial task was administered; memory was probed after a 12 hr interval consisting of either daytime wake or overnight sleep and post-wake/post-sleep stability of the memories was tested following task-related interference. Ninety five older adults (mean=65.43 yrs; SD=7.6 yrs) and …