Life Sciences Commons^™

A Causal Inference Approach For Spike Train Interactions, Zach Saccomano

Dissertations, Theses, and Capstone Projects

Since the 1960s, neuroscientists have worked on the problem of estimating synaptic properties, such as connectivity and strength, from simultaneously recorded spike trains. Recent years have seen renewed interest in the problem coinciding with rapid advances in experimental technologies, including an approximate exponential increase in the number of neurons that can be recorded in parallel and perturbation techniques such as optogenetics that can be used to calibrate and validate causal hypotheses about functional connectivity. This thesis presents a mathematical examination of synaptic inference from two perspectives: (1) using in vivo data and biophysical models, we ask in what cases the …

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 …

Ultrastructural Correlates Of Axons And Synapses Belonging To Different Circuits In Ferret Primary Visual Cortex, Anjelique Sawh

Dissertations and Theses

The goal of this study was to determine differences in distinctive layers of mammalian primary visual cortex through analysis of their ultrastructural characteristics. Characterizing brain circuitry using 3-dimensional reconstruction of electron microscopy images, and subsequent ultrastructural analysis of axonal populations provides us with a better understanding of the connectivity of the neural circuits. By quantifying ultrastructural differences in axonal processes such as synaptic densities, types of synapses and their post-synaptic densities (PSDs), mitochondrial volumes, synaptic vesicle aggregates, dendritic targets, and bouton volumes, we aimed to understand whether differences in anatomical specializations among different cortical layers could underlie differences in function …

Novel Strategies For Glutamate Clearance In The Glia-Deprived Synaptic Hub Of C. Elegans, Joyce Chan

Dissertations, Theses, and Capstone Projects

As the major excitatory neurotransmitter in the mammalian brain, Glutamate (Glu) is critical for normal neuronal physiology. Disruption in Glu clearance results in hyper-stimulation of glutamatergic circuits, potentially leading to excitotoxic neurodegeneration. The canonical model of brain connectivity describes glutamatergic synapses as well insulated and enveloped by glia. These glia express Glu Transporters (GluTs) which work to clear Glu following synaptic activity. However, critical areas of the brain such as the mammalian hippocampus display poor synaptic isolation, which may result in Glu spillover between adjacent synapses and subsequent loss of circuit specificity. How accurate signal transmission is achieved in these …

Neural Processing Of Semantic Content In Movies, Maximilian Nentwich

Dissertations and Theses

Naturalistic stimuli, such as movies, contain interacting, multimodal and semantic features and allow for free exploration through eye movements. The full extent of neural responses to features such as motion, film cuts and eye movement behavior has not been established. The main hypothesis of this thesis is that complex multimodal and semantic stimuli in naturalistic movies engage a widespread ensemble of locations across the entire brain. To address this question I analyzed simultaneous intracranial and eyetracking data from over 6,000 electrodes across 23 patients with intractable epilepsy. Responses to fast eye movements – saccades – and film cuts are widespread …

When The Brain Plays A Game: Neural Responses To Visual Dynamics During Naturalistic Visual Tasks, Jason Ki

Dissertations and Theses

Many day-to-day tasks involve processing of complex visual information in a continuous stream. While much of our knowledge on visual processing has been established from reductionist approaches in lab-controlled settings, very little is known about the processing of complex dynamic stimuli experienced in everyday scenarios. Traditional investigations employ event-related paradigms that involve presentation of simple stimuli at select locations in visual space and discrete moments in time. In contrast, visual stimuli in real-life are highly dynamic, spatially-heterogeneous, and semantically rich. Moreover, traditional experiments impose unnatural task constraints (e.g., inhibited saccades), thus, it is unclear whether theories developed under the reductionist …

Analysis Of Newspaper Coverage Of Psilocybin From January 1, 1989 To December 31, 2019, Dax Oliver

Dissertations, Theses, and Capstone Projects

Psilocybin is a chemical compound that has received a lot of attention from medical researchers in recent years. However, this research is not merely a medical issue but a social and political one as well. In the 1960s, psilocybin and other psychedelic compounds were widely ingested outside of clinical settings. This alarmed some of the American public, resulting in severe legal restrictions on psilocybin use and research.

Today, many psilocybin advocates hope that it will avoid the negative public sentiment of the 1960s. To help gauge public sentiment about other psychoactive compounds, some studies have examined newspaper coverage, but there …

Mechanisms Of Value-Biased Prioritization In Fast Sensorimotor Decision Making, Kivilcim Afacan-Seref

Dissertations and Theses

In dynamic environments, split-second sensorimotor decisions must be prioritized according to potential payoffs to maximize overall rewards. The impact of relative value on deliberative perceptual judgments has been examined extensively, but relatively little is known about value-biasing mechanisms in the common situation where physical evidence is strong but the time to act is severely limited. This research examines the behavioral and electrophysiological indices of how value biases split-second perceptual decisions and the possible mechanisms underlying the process. In prominent decision models, a noisy but statistically stationary representation of sensory evidence is integrated over time to an action-triggering bound, and value-biases …

Sensory Perception, Adrian Rodriguez-Contreras

Open Educational Resources

Different types of sensory systems with their functional modalities will be presented. The biological bases for how these functions are generated and modified will then be described. As vision is the principal means of perception, we will focus in this course most on visual processing. Scientific data will be integrated into the lectures, such that students develop critical skills in analyzing data and proposing hypotheses.

The 5-Ht1a-R Knockout Mouse As A Model Of Later Life Anxiety Disorders: Implications For Sex Differences, Tatyana Budylin

Dissertations, Theses, and Capstone Projects

Anxiety affects nearly twice as many women as it affects men across all cultures and economic groups. Importantly, girls have a higher chance of inheriting anxiety disorders than boys, and many anxiety disorders appear at a very young age. However, little is known about sex differences in brain and behavioral development and how they relate to anxiety in adulthood. Serotonin 1A receptor (5-HT_1A-R) mediated signaling has been implicated in depression and anxiety, however most studies that focus on the involvement of the 5-HT_1A-R have been conducted in adults. Little is known about how the 5-HT_{1A …}

Mechanisms Of Microglia Mediated Apolipoprotien E Neurotoxicity, Pardeep Singh

Dissertations and Theses

No abstract provided.

What Role Is Neuroscience Playing In New State Raise-The-Age Laws?, Dane N. Stallone

Capstones

Several states have cited neuroscientific evidence to help justify new raise-the-age laws that raise the age at which offenders can be tried as adults. Neuroscience shows that adolescent brains continue to mature well into their 20s. How much influence neuroscience should have in determining legal policy, however, remains contested among experts.

https://theartofscienceme.wordpress.com/2019/01/05/what-role-is-neuroscience-playing-in-new-state-raise-the-age-laws/

Non-Canonical Activation Of Creb/Crh-1 Mediates Neuroprotection In A Caenorhabditis Elegans Model Of Excitotoxic Necrosis, K. Genevieve Feldmann

Dissertations, Theses, and Capstone Projects

Excitotoxicity, which is a major cause of neurodegeneration in brain ischemia, can also activate neuroprotective pathways. A frequently suggested neuroprotective cascade involves the activation of the transcription factor CREB by its phosphorylation, but on its own this mode of CREB activation is promiscuous. We aim to elucidate the specific mechanism of CREB activation in excitotoxicity-induced neuroprotection, focusing on three suggested models: CREB phosphorylation by calcium-activated kinases in the cytoplasm or nucleus, and the activation of CREB by CRTC (an important cofactor). Using a C. elegans model of excitotoxicity, we demonstrate that CREB’s neuroprotective effect is mainly seen in neurons exposed …

Rules And Mechanisms For Efficient Two-Stage Learning In Neural Circuits, Tiberiu Teşileanu, Bence Ölveczky, Vijay Balasubramanian

Publications and Research

Trial-and-error learning requires evaluating variable actions and reinforcing successful variants. In songbirds, vocal exploration is induced by LMAN, the output of a basal ganglia-related circuit that also contributes a corrective bias to the vocal output. This bias is gradually consolidated in RA, a motor cortex analogue downstream of LMAN. We develop a new model of such two-stage learning. Using stochastic gradient descent, we derive how the activity in ‘tutor’ circuits (e.g., LMAN) should match plasticity mechanisms in ‘student’ circuits (e.g., RA) to achieve efficient learning. We further describe a reinforcement learning framework through which the tutor can build its teaching …

Variance Predicts Salience In Central Sensory Processing, Ann M. Hermundstad, John J. Briguglio, Mary M. Conte, Jonathan D. Victor, Vijay Balasubramanian, Gašper Tkačik

Publications and Research

Information processing in the sensory periphery is shaped by natural stimulus statistics. In the periphery, a transmission bottleneck constrains performance; thus efficient coding implies that natural signal components with a predictably wider range should be compressed. In a different regime—when sampling limitations constrain performance—efficient coding implies that more resources should be allocated to informative features that are more variable. We propose that this regime is relevant for sensory cortex when it extracts complex features from limited numbers of sensory samples. To test this prediction, we use central visual processing as a model: we show that visual sensitivity for local multi-point …