Cognitive Neuroscience Commons^™

Neuroimaging Correlates Of Differences In Learning From Repeated Probabilistic Outcomes, Allison E. Rudolph

CMC Senior Theses

Learning from experience requires integrating feedback over time, yet individuals vary widely in how effectively they extract structure from probabilistic environments. This study examined how such variability relates to neural responses in the ventral striatum (vStr), caudate nucleus, hippocampus, and medial prefrontal cortex (mPFC). Seventy-four participants across childhood, adolescence, and adulthood completed a modified Iowa Gambling Task during fMRI scanning, choosing whether to play or pass on four machines differing in expected value and variance. Behavioral learning slopes, calculated across six runs for each machine, were used to classify participants as learners or non-learners. Learners showed clearer improvement over time …

Investigation Of Rna-Binding Protein Expression Changes In The Hippocampus Following Doxorubicin And Cyclophosphamide Treatment, Lijie Chen

Dissertations and Theses

This study investigated the molecular mechanisms underlying chemotherapy-induced cognitive impairment (CICI) following doxorubicin and cyclophosphamide treatment in a rat model, revealing three significant alterations in hippocampal tissue: selective downregulation of heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1) (21% decrease, p=0.0298), compromised astrocytic network integrity evidenced by reduced GFAP-positive area in cornu ammonis 3 (CA3) (24%, pB=0.026) and dentate gyrus (DG) (19%, pB=0.027) regions, and elevated cellular senescence marker p19Arf specifically in DG (69%, pB=0.033) and CA3 (27%, pB=0.024). The inverse relationship between hnRNPA1 reduction and p19Arf elevation suggests a potential mechanistic link between RNA dysregulation and senescence induction, with pronounced vulnerability in …

Neural Correlates Of Socially Rewarding Memories In Posttraumatic Stress Disorder, Kyle P. Blidy

MUSC Theses and Dissertations

Significance. Memory disturbances for emotional content are central to PTSD, yet most research focuses on trauma memories. Recent evidence suggests that enhancing access to positive memories could improve mood, affect regulation, self-esteem, and integration of trauma memories. However, the neurocognitive mechanisms underlying positive memory encoding in PTSD are poorly understood. No study has examined memory for positive social items in PTSD, which is important because PTSD entails social withdrawal and reduced accessibility to positive memory. Additionally, positive memories embedded in a social context have enhanced subjective value and strengthening their accessibility may confer greater benefits to wellbeing compared to non-social …

Robust And Generalizable Representations In The Hippocampus, Hung-Tu Chen

Dartmouth College Ph.D Dissertations

An intelligent system must balance generalizing across similar experiences with maintaining the distinctiveness of each experience. This thesis explores how the hippocampus manages this balance through its neural representations to support adaptive behavior. In Chapter 1, I provide an overview of key hippocampal phenomena that contribute to this process, including remapping, splitter signal, and replay. In Chapter 2, I challenge the concept of random remapping by showing that it is possible to predict, better than chance, how a given experience will be encoded in the hippocampus across different subjects. This suggests that encoding of related experiences, which was previously thought …

An Erp Measure Of Non-Conscious Memory Reveals Dissociable Implicit Processes In Human Recognition Using An Open-Source Automated Analytic Pipeline, Richard J. Addante, Javier Lopez-Calderon, Nathan Allen, Carter Luck, Alana Muller, Lindsey Sirianni, Cory S. Inman, Daniel L. Drake

Psychology Student Publications

Non-conscious processing of human memory has traditionally been difficult to objectively measure and thus understand. A prior study on a group of hippocampal amnesia (N = 3) patients and healthy controls (N = 6) used a novel procedure for capturing neural correlates of implicit memory using event-related potentials (ERPs): old and new items were equated for varying levels of memory awareness, with ERP differences observed from 400 to 800 ms in bilateral parietal regions that were hippocampal-dependent. The current investigation sought to address the limitations of that study by increasing the sample of healthy subjects (N = …

Withdrawal From Voluntary Oral Methamphetamine Reveals Female Specific Susceptibilities To Behavioral Deficits And Neurochemical Perpetuators Of Neurotoxicity And Drug Seeking Behavior, Nicoletta K. Memos

Dissertations, Theses, and Capstone Projects

MA is a potent, highly addictive psychomotor stimulant known to produce neurotoxic effects on the brain leading to neurological impairments^1-6 characterized by neurodegeneration of dopaminergic fibers, cell bodies and pathways, as well as brain regions such as the hippocampus, frontal cortex, and midbrain^1,5.

In MA addiction, women are more vulnerable to the behavioral and cognitive effects of MA compared to men. Adult human literature reveals gender differences in usage patterns and women demonstrate increased vulnerability to the neurotoxic effects and health effects of MA use. Women begin drug use at an earlier age, escalate drug use quicker, …

The Effects Of Astrocytic Derived Insulin-Like Growth Factor (Igf-1) On Cognition And Astrocytes, Destiny Wilson

Honors Theses

Insulin-like growth factor 1 (IGF-1) is a neuroendocrine signaling hormone that plays a vital role in growth and development, as well as learning and memory. Inhibition of this hormone results in cognitive impairments like those seen with age-related decline. While a majority of research has focused on the role of IGF-1 on neurons, the role of astrocytes still needs to be explored. Our research investigates how astrocytes and cognition are affected as a result of direct regulation of localized IGF-1 production in early development and after puberty. Preliminary studies in our laboratory established a connection between IGF-1 and glial fibrillary …

Cognitively Normal Women With Alzheimer’S Disease Proteinopathy Show Relative Preservation Of Memory But Not Of Hippocampal Volume, Jessica Z.K. Caldwell, Jeffrey L. Cummings, Sarah J. Banks, Sebastian Palmqvist, Oskar Hansson

School of Medicine Faculty Research

Background: We examined interactive effects of sex, diagnosis, and cerebrospinal fluid (CSF) amyloid beta/phosphorylated tau ratio (Aβ/P-tau) on verbal memory and hippocampal volumes. Methods: We assessed 682 participants (350 women) from BioFINDER (250 cognitively normal [CN]; and 432 symptomatic: 186 subjective cognitive decline [SCD], 246 mild cognitive impairment [MCI]). General linear models evaluated effects of Alzheimer’s disease (AD) proteinopathy (CSF Aß/p-tau ratio), diagnosis, and sex on verbal memory (ADAS-cog 10-word recall), semantic fluency (animal naming fluency), visuospatial skills (cube copy), processing speed/attention functions (Symbol Digit Modalities Test and Trail Making Part A), and hippocampal volumes. Results: Amyloid-positive (Aβ/P-tau+) CN women …

Voluntary Oral Methamphetamine Reveals Susceptibilities To Spatial Memory Deficits, Decreased Dopamine Marker Expression And Increased Neuroinflammation In The Hippocampus Of Male And Female Mice, Jorge A. Avila

Dissertations, Theses, and Capstone Projects

Methamphetamine is an addictive illicit psychostimulant that produces lasting neurochemical and behavioral changes. The mechanisms underlying these deficits have been characterized in animal models using extremely high doses. Currently, better translational models are needed to understand the onset and progression of these deficits that more accurately reflect the gradual and voluntary dosing parameters as chosen by an abuser. To that end, a new model of methamphetamine administration, labeled Voluntary Oral Methamphetamine Administration (VOMA), offers a means to examine the progression of neurotoxicity, behavioral deficits, and the addiction process through a voluntary consumption framework.

Female populations show consistent vulnerabilities to methamphetamine, …

Acc Theta Improves Hippocampal Contextual Processing During Remote Recall, Ryan A. Wirt, James M. Hyman

Psychology Faculty Research

Consolidation studies show that, over time, memory recall becomes independent of the medial temporal lobes. Multiple lines of research show that the medial frontal cortex, including the anterior cingulate cortex (ACC), is involved with contextual information processing and remote recall. We hypothesize that interactions between the ACC and hippocampal area CA1 will change as memories became more remote. Animals are re-exposed to multiple environments at different retention intervals. During remote recall, ACC-CA1 theta coherence increases, with the ACC leading area CA1. ACC theta regulates unit spike timing, gamma oscillations, and ensemble and single-neuron information coding in CA1. Over the course …

Interhemispheric Communication And Lateralization In The Mouse Hippocampus, Jake Jordan

Dissertations, Theses, and Capstone Projects

The hippocampus is essential for memory and spatial navigation. Many theories have been proposed to explain how the hippocampus contributes to cognition; however, none has fully explained relevant neurophysiological and behavioral data. Hemispheric lateralization of hippocampal function has been reported in humans and in rodents, and lateralization of hippocampal neural circuitry has been reported in rodents. Most theories of hippocampal function fail to consider the hippocampus as a bilateral structure with hemispheric differences. Further, proposed theories of hippocampal lateralization have their own limitations in explaining empirical data concerning left/right function. Little is known about communication between the hippocampi across hemispheres. …

Exploring The Role Of Insulin Receptor Signaling In Hippocampal Learning And Memory, Neuronal Calcium Dysregulation, And Glucose Metabolism, Hilaree N. Frazier

Theses and Dissertations--Pharmacology and Nutritional Sciences

In the late 90’s, emerging evidence revealed that the brain is insulin-sensitive, highlighted by broad expression of brain-specific insulin receptors and reports of circulating brain insulin. Contemporary literature robustly supports the role of insulin signaling in normal brain function and suggests that insulin-related processes diminish with aging, evidenced by decreased signaling markers, reduced insulin receptor density, and lower levels of insulin transport across the blood-brain barrier. In the context of pathological cognitive decline, clinical trials using intranasal insulin delivery have reported positive outcomes on memory and learning in patients with mild cognitive decline or early-stage Alzheimer’s disease. However, while the …

Baseline White Matter Hyperintensities And Hippocampal Volume Are Associated With Conversion From Normal Cognition To Mild Cognitive Impairment In The Framingham Offspring Study., Katherine J Bangen, Sarah R Preis, Lisa Delano-Wood, Philip A Wolf, David J Libon, Mark W Bondi, Rhoda Au, Charles Decarli, Adam M Brickman

Rowan-Virtua School of Osteopathic Medicine Departmental Research

INTRODUCTION: We examined associations between magnetic resonance imaging (MRI) markers of cerebrovascular disease and neurodegeneration with mild cognitive impairment (MCI) diagnosis at baseline and conversion from normal cognition to MCI at follow-up.

METHODS: Framingham Offspring participants underwent brain MRI and neuropsychological assessment at baseline (n=1049) and follow-up (n=561). Participants were classified at baseline and at follow-up as cognitively normal or MCI using sensitive neuropsychological criteria. White matter hyperintensity (WMH) volume, covert brain infarcts, hippocampal volume, and total cerebral brain volume were quantified.

RESULTS: Baseline measures of WMH and hippocampal volume were associated with MCI status cross-sectionally and also with conversion …

Axonal Activity In Vivo: Technical Considerations And Implications For The Exploration Of Neural Circuits In Freely Moving Animals, Jeremy M. Barry

Dartmouth Scholarship

While extracellular somatic action potentials from freely moving rats have been well characterized, axonal activity has not. We have recently reported extracellular tetrode recordings of short duration waveforms (SDWs) with an average peak-trough duration less than 172μs. These waveforms have significantly shorter duration than somatic action potentials and tend to be triphasic. The present review discusses further data that suggests SDWs are representative of axonal activity, how this characterization allows for more accurate classification of somatic activity and could serve as a means of exploring signal integration in neural circuits. The review also discusses how axons may function as more …

Spike Field Coherence (Sfc) For Ripples In Rat Hippocampus, Pranav Singla

Honors Scholar Theses

The aim of this project was to determine coherence between two types of neural recordings which can be obtained from the rat hippocampus: spikes and local field potentials. Extracellular recording makes it possible to determine spiking activity from individual neurons in the vicinity of the recording electrode. Local field potential recording gives a combined activity of many neurons (thousands) at once to determine an overall picture of the coordination of the cells in real time. Here we examine the relationship between these two signals, focusing on place cells which spike at their maximal rate only at certain positions in physical …

Focal Cortical Thickness Correlates Of Exceptional Memory Training In Vedic Priests, Giridhar P. Kalamangalam, Timothy M. Ellmore

Publications and Research

The capacity for semantic memory—the ability to acquire and store knowledge of the world—is highly developed in the human brain. In particular, semantic memory assimilated through an auditory route may be a uniquely human capacity. One method of obtaining neurobiological insight into memory mechanisms is through the study of experts. In this work, we study a group of Hindu Vedic priests, whose religious training requires the memorization of vast tracts of scriptural texts through an oral tradition, recalled spontaneously during a lifetime of subsequent spiritual practice. We demonstrate focal increases of cortical thickness in regions of the left prefrontal lobe …

Short-Term Activity-Dependent Changes In Schaffer Collateral Axon Function, Benjamin Michael Owen

Theses, Dissertations and Capstones

Schaffer collaterals are the unmyelinated axons of pyramidal neurons in the CA3 area of the hippocampus, a brain structure essential for memory formation. Schaffer collateral axons conduct electrical signals in the form of action potentials from CA3 pyramidal cells to synaptic terminals in area CA1. The fidelity with which these axons conduct action potentials determines the nature of the information which can be transmitted between areas CA3 and CA1. Conduction fidelity may be affected by both normal and abnormal patterns of firing, fluctuations in ion concentration, and some drugs and toxins. In this dissertation, I examined the function of Schaffer …

Vestibular And Attractor Network Basis Of The Head Direction Cell Signal In Subcortical Circuits, Benjamin J. Clark, Jeffrey S. Taube

Dartmouth Scholarship

Accurate navigation depends on a network of neural systems that encode the moment-to-moment changes in an animal's directional orientation and location in space. Within this navigation system are head direction (HD) cells, which fire persistently when an animal's head is pointed in a particular direction (Sharp et al., 2001a; Taube, 2007). HD cells are widely thought to underlie an animal's sense of spatial orientation, and research over the last 25+ years has revealed that this robust spatial signal is widely distributed across subcortical and cortical limbic areas. The purpose of the present review is to summarize some of …

Mechanism Of Triazolo-Benzodiazepine And Benzodiazepine Action In Anxiety And Depression: Behavioral Studies With Concomitant In Vivo Ca1 Hippocampal Norepinephrine And Serotonin Release Detection In The Behaving Animal, Patricia A. Broderick, Omotola Hope, Pierrot Jeannot

Publications and Research

1. Real time, in vivo microvoltammetric studies were performed, using miniature carbon-based sensors, to concurrently detect norepinephrine (NE) release and serotonin (5-HT) release, in 2 separate electrochemical signals, within CA₁ region of hippocampus in the freely moving and behaving, male, Sprague Dawley laboratory rat.

2. Concurrently, four parameters of open-field Behavior I.E. Ambulations, Rearing, Fine Movements and Central Ambulatory behavior (a measure of anxiety reduction behavior), were assayed by infrared photobeam detection.

3. Time course studies showed that the mechanism of action of the triazolobenzodiazepine (TBZD), adinazolam, (Deracyn®) is dramatically different from that of the classical benzodiazepine (BZD), diazepam …