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Articles 31 - 60 of 85

Full-Text Articles in Vision Science

When The Brain Plays A Game: Neural Responses To Visual Dynamics During Naturalistic Visual Tasks, Jason Ki Jan 2021

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 …


Network-Level Mechanisms Underlying Effects Of Transcranial Direct Current Stimulation (Tdcs) On Visuomotor Learning, Pejman Sehatpour, Clément Dondé, Matthew J. Hoptman, Johanna Kreither, Devin Adair, Elisa Dias, Blair Vail, Stephanie Rohrig, Gail Silipo, Javier Lopez-Calderon, Antigona Martinez, Daniel C. Javitt Dec 2020

Network-Level Mechanisms Underlying Effects Of Transcranial Direct Current Stimulation (Tdcs) On Visuomotor Learning, Pejman Sehatpour, Clément Dondé, Matthew J. Hoptman, Johanna Kreither, Devin Adair, Elisa Dias, Blair Vail, Stephanie Rohrig, Gail Silipo, Javier Lopez-Calderon, Antigona Martinez, Daniel C. Javitt

Publications and Research

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation approach in which low level currents are administered over the scalp to influence underlying brain function. Prevailing theories of tDCS focus on modulation of excitation-inhibition balance at the local stimulation location. However, network level effects are reported as well, and appear to depend upon differential underlying mechanisms. Here, we evaluated potential network-level effects of tDCS during the Serial Reaction Time Task (SRTT) using convergent EEG- and fMRI-based connectivity approaches. Motor learning manifested as a significant (p <.0001) shift from slow to fast responses and corresponded to a significant increase in beta-coherence (p <.0001) and fMRI connectivity (p <.01) particularly within the visual-motor pathway. Differential patterns of tDCS effect were observed within different parametric task versions, consistent with network models. Overall, these findings demonstrate objective physiological effects of tDCS at the network level that result in effective behavioral modulation when tDCS parameters are matched to network-level requirements of the underlying task.


Visually Evoked Responses Are Enhanced When Engaging In A Video Game, Jason J. Ki, Lucas C. Parra, Jacek P. Dmochowski Jul 2020

Visually Evoked Responses Are Enhanced When Engaging In A Video Game, Jason J. Ki, Lucas C. Parra, Jacek P. Dmochowski

Publications and Research

While it is well known that vision guides movement, less appreciated is that the motor cortex also provides input to the visual system. Here, we asked whether neural processing of visual stimuli is acutely modulated during motor activity, hypothesizing that visual evoked responses are enhanced when engaged in a motor task that depends on the visual stimulus. To test this, we told participants that their brain activity was controlling a video game that was in fact the playback of a prerecorded game. The deception, which was effective in half of participants, aimed to engage the motor system while avoiding evoked …


Implementation Of A Computer-Vision System As A Supportive Diagnostic Tool For Parkinson’S Disease, Diego Machado Reyes May 2020

Implementation Of A Computer-Vision System As A Supportive Diagnostic Tool For Parkinson’S Disease, Diego Machado Reyes

Honors Theses

Parkinson’s disease is the second most common neurodegenerative disorder, affecting nearly 1 million people in the US and it is predicted that the number will keep increasing. Parkinson’s disease is difficult to diagnose due to its similarity with other diseases that share the parkinsonian symptoms and the subjectivity of its assessment, thus increasing the probabilities of misdiagnosis. Therefore, it is relevant to develop diagnostic tools that are quantitatively based and monitoring tools to improve the patient’s quality of life. Computer-based assessment systems have shown to be successful in this field through diverse approaches that can be classified into two main …


A Comparison Of Neural Activity For Peripersonal And Extrapersonal Viewing In Real And Virtual Environments, Olivia Eustice May 2020

A Comparison Of Neural Activity For Peripersonal And Extrapersonal Viewing In Real And Virtual Environments, Olivia Eustice

Honors Theses

This study involved a series of tests comparing the similarities and differences in neural activity at a subject’s peripheral and extrapersonal space in the real environment and virtual reality. We hypothesized that there would be similar brain activity at each of these environments depending on the focal distance of an object from the participant. Peripheral space is the visual space that is a reachable distance from a person. It has an overall neural pattern in the dorsal stream of the brain. Extrapersonal space is the visual space that does not directly surround a person and cannot be directly acted on. …


Otx2 Represses Sister Cell Fate Choices In The Developing Retina To Promote Photoreceptor Specification, Miruna Georgiana Ghinia Tegla, Diego F. Buenaventura, Diana Y. Kim, Cassandra Thakurdin, Kevin C. Gonzalez, Mark M. Emerson Apr 2020

Otx2 Represses Sister Cell Fate Choices In The Developing Retina To Promote Photoreceptor Specification, Miruna Georgiana Ghinia Tegla, Diego F. Buenaventura, Diana Y. Kim, Cassandra Thakurdin, Kevin C. Gonzalez, Mark M. Emerson

Publications and Research

During vertebrate retinal development, subsets of progenitor cells generate progeny in a non-stochastic manner, suggesting that these decisions are tightly regulated. However, the gene-regulatory network components that are functionally important in these progenitor cells are largely unknown. Here we identify a functional role for the OTX2 transcription factor in this process. CRISPR/Cas9 gene editing was used to produce somatic mutations of OTX2 in the chick retina and identified similar phenotypes to those observed in human patients. Single cell RNA sequencing was used to determine the functional consequences OTX2 gene editing on the population of cells derived from OTX2-expressing retinal progenitor …


Combining Eye Tracking And Verbal Response To Understand The Impact Of A Global Filter, Franceli L. Cibrian, Jazette Johnson, Viseth Sean, Hollis Pass, Louanne Boyd Apr 2020

Combining Eye Tracking And Verbal Response To Understand The Impact Of A Global Filter, Franceli L. Cibrian, Jazette Johnson, Viseth Sean, Hollis Pass, Louanne Boyd

Engineering Faculty Articles and Research

Visual attention guides the integration of two streams: the global, that rapidly processes the scene; and the local, that processes details. For people with autism, the integration of these two streams can be disrupted by the tendency to privilege details (local processing) instead of seeing the big picture (global processing). Consequently, people with autism may struggle with typical visual attention, evidenced by their verbal description of local features when asked to describe overall scenes. This paper aims to explore how one adult with autism see and understand the global filter of natural scenes.


Noncontact Multiscale Diffuse Optical Imaging Of Deep Tissue Hemodynamics In Animals And Humans, Siavash Mazdeyasna Jan 2020

Noncontact Multiscale Diffuse Optical Imaging Of Deep Tissue Hemodynamics In Animals And Humans, Siavash Mazdeyasna

Theses and Dissertations--Biomedical Engineering

Blood flow (BF) impacts the delivery of oxygen and nutrients to tissues and the removal of metabolic byproducts from tissues. Imaging of BF distributions helps characterize many diseases associated with tissue hypoxia/ischemia. The purpose of this study was to develop and validate a novel, noninvasive, noncontact, high-density camera-based speckle contrast diffuse correlation tomography (scDCT) device for use in both animal and human studies. The scDCT uses a galvo-mirror to remotely deliver the focused point near-infrared light to source positions and a sensitive 2D camera to quantify spatial diffuse speckle fluctuations, resulting from the movement of red blood cells in deep …


Color Transparency From Motions Of Backgrounds And Overlays, Zhehao Huang, Qasim Zaidi May 2019

Color Transparency From Motions Of Backgrounds And Overlays, Zhehao Huang, Qasim Zaidi

MODVIS Workshop

No abstract provided.


Computations Of Top-Down Attention By Modulating V1 Dynamics, David Berga, Xavier Otazu May 2019

Computations Of Top-Down Attention By Modulating V1 Dynamics, David Berga, Xavier Otazu

MODVIS Workshop

The human visual system processes information defining what is visually conspicuous (saliency) to our perception, guiding eye movements towards certain objects depending on scene context and its feature characteristics. However, attention has been known to be biased by top-down influences (relevance), which define voluntary eye movements driven by goal-directed behavior and memory. We propose a unified model of the visual cortex able to predict, among other effects, top-down visual attention and saccadic eye movements. First, we simulate activations of early mechanisms of the visual system (RGC/LGN), by processing distinct image chromatic opponencies with Gabor-like filters. Second, we use a cortical …


Quantified Measurement Of The Tilt Effect In A Family Of Café Wall Illusions, Nasim Nematzadeh Dr., David Martin Powers Prof. May 2019

Quantified Measurement Of The Tilt Effect In A Family Of Café Wall Illusions, Nasim Nematzadeh Dr., David Martin Powers Prof.

MODVIS Workshop

This abstract explores the tilt effect in a family of Café Wall illusions using a Classical Gaussian Receptive Field model (CRF). Our model constructs an intermediate representation called edge map at multiple scales (Fig. 1) that reveals tilt cues and clues involved in the illusory perception of the Café Wall pattern. We investigate a wide range of parameters of the stimulus including mortar width, luminance, tiles contrast, and phase of the tile displacement (the stimuli in Fig. 2). We show that this simple bioplausible model, simulating the contrast sensitivity of the retinal ganglion cells, can not only detect the tilts …


An Observer Model Version Of General Recognition Theory, Fabian Soto Phd May 2019

An Observer Model Version Of General Recognition Theory, Fabian Soto Phd

MODVIS Workshop

No abstract provided.


Vector Flow Imaging In Pediatric Cardiology - Extracting And Validating Data, Mason Belue May 2019

Vector Flow Imaging In Pediatric Cardiology - Extracting And Validating Data, Mason Belue

Biomedical Engineering Undergraduate Honors Theses

In the field of bedside cardiac diagnostic imaging, Doppler Ultrasound (DU) is the gold standard for diagnosing heart conditions. The largest benefit of DU is its ability to noninvasively image cardiac flow and allow the estimation of blood velocity and quantification of anatomical disease. However, to get correct velocity estimation, the position of the transducer in relation to the flow field needs to be known. This is the problem of angle/direction dependency and limits DUs accuracy when imaging in areas where perfect alignment or exact position of the transducer in relation to flow field is not possible or known, such …


Seeing Eye To Eye: A Machine Learning Approach To Automated Saccade Analysis, Maigh Attre May 2019

Seeing Eye To Eye: A Machine Learning Approach To Automated Saccade Analysis, Maigh Attre

Honors Scholar Theses

Abnormal ocular motility is a common manifestation of many underlying pathologies particularly those that are neurological. Dynamics of saccades, when the eye rapidly changes its point of fixation, have been characterized for many neurological disorders including concussions, traumatic brain injuries (TBI), and Parkinson’s disease. However, widespread saccade analysis for diagnostic and research purposes requires the recognition of certain eye movement parameters. Key information such as velocity and duration must be determined from data based on a wide set of patients’ characteristics that may range in eye shapes and iris, hair and skin pigmentation [36]. Previous work on saccade analysis has …


Development Of An Eye Movement Based Predictive Model For Discrimination Of Parkinson's Disease From Other Parkinsonisms And Controls, Mary Anisa Kannan Jan 2019

Development Of An Eye Movement Based Predictive Model For Discrimination Of Parkinson's Disease From Other Parkinsonisms And Controls, Mary Anisa Kannan

Theses and Dissertations

Purpose: Due to the neurological aspects of Parkinson’s Disease (PD) and the sensitivity of eye movements to neurological issues, eye tracking has the potential to be an objective biomarker with higher accuracy in diagnosis than current clinical standards. Currently when PD is diagnosed clinically, there is an accuracy of 74% when diagnosed by a general practitioner and 82% when diagnosed by a movement disorder specialist. This study was designed to: 1. Assess eye movements as a potential biomarker for Parkinson’s Disease. 2. Determine if eye movements can distinguish between Parkinson’s Disease and commonly confounded movement disorders with parkinsonian symptoms. 3. …


Collective Behavior Of Drosophila Melanogaster Neural Progenitor And Imaginal Disc Cells Within Controlled Microenvironments, Caroline D. Pena Jan 2019

Collective Behavior Of Drosophila Melanogaster Neural Progenitor And Imaginal Disc Cells Within Controlled Microenvironments, Caroline D. Pena

Dissertations and Theses

Regenerative therapies for the damaged visual system have introduced stem-derived cells to recapitulate developmental processes and initiate functional regeneration in different components of the eye. The developing visual system in Drosophila Melanogaster offers a model in which to analyze the associated processes in retinogenesis. The optic nerve is critical to vision and is developmentally preceded in Drosophila by a structure called the Optic Stalk (OS). Collective migration of neural and retinal progenitor cells (RPCs) from the developing brain lobes (DBL) to the Imaginal Disc (ID), through the OS, is a fundamental part of regenerative strategies in retina. Developmental signals governing …


A Microfluidic Tissue Array (Μfta) For Personalized Medicine Using Tumor Biopsies, A.H. R. Ahmed Jan 2019

A Microfluidic Tissue Array (Μfta) For Personalized Medicine Using Tumor Biopsies, A.H. R. Ahmed

Dissertations and Theses

Cancer is recognized as a complex disease with both genetic and epigenetic drivers that can vary from one individual to another. While very early research into cancer treated it as a clonal malfunction that could originate from as small as a single deregulated cell, the disease itself manifests itself with several more complexities beyond tumorigenic cells only. The tumor microenvironment itself – from the extracellular matrix to stromal cells - cooperate with tumor cells in a symbiotic manner towards metastatic progression. Clinical studies have provided more information regarding the degree of individualization possible, such that patients with similar genetic makeup …


Controlled Migration Of Retinal Progenitor Cells Within Electro-Chemotactic Fields, Shawn Mishra Jan 2019

Controlled Migration Of Retinal Progenitor Cells Within Electro-Chemotactic Fields, Shawn Mishra

Dissertations and Theses

Vision loss in retinal degenerative diseases is overwhelmingly attributed to damage and death of retinal photoreceptor cells. Studies in mouse retina have suggested that transplantation of isolated post-natal or stem cell-derived retinal progenitor cells (RPCs) to replace apoptotic or damaged photoreceptors may be a novel approach to restore vision. Thus far, outcomes project that the amount of restored visual response depends upon the migration of transplanted cells from insertion in the sub-retinal space to the outer nuclear layer (ONL). However, transplantation efficiency is exceedingly low – ~5% cells transplanted enter the retina – directly limiting the efficacy of the treatments. …


Novel Devices For Studying Acute And Chronic Mechanical Stress In Retinal Pigment Epithelial Cells, Farhad Farjood, Elizabeth Vargis Oct 2018

Novel Devices For Studying Acute And Chronic Mechanical Stress In Retinal Pigment Epithelial Cells, Farhad Farjood, Elizabeth Vargis

Biological Engineering Faculty Publications

Choroidal neovascularization (CNV) is a major cause of blindness in patients with age-related macular degeneration (AMD). Overexpression of vascular endothelial growth factor (VEGF), a potent angiogenic protein, by retinal pigment epithelial (RPE) cells is a key stimulator of CNV. Mechanical stress occurs during different stages of AMD and is a possible inducer of VEGF expression in RPE cells. However, robust and realistic approaches to studying acute and chronic mechanical stress under various AMD stages do not exist.The majority of previous work has studied cyclic stretching of RPE cells grown on flexible substrates, but an ideal model must be able to …


The Road Towards Image-Computable Models Of Human Visual Grasp Planning, Guido Maiello, Lina K. Klein, Vivian C. Paulun, Katherine R. Storrs, Roland W. Fleming May 2018

The Road Towards Image-Computable Models Of Human Visual Grasp Planning, Guido Maiello, Lina K. Klein, Vivian C. Paulun, Katherine R. Storrs, Roland W. Fleming

MODVIS Workshop

No abstract provided.


A Feature-Based Model Of Visually Perceiving Deformable Objects, Vivian C. Paulun, Filipp Schmidt, Roland W. Fleming May 2018

A Feature-Based Model Of Visually Perceiving Deformable Objects, Vivian C. Paulun, Filipp Schmidt, Roland W. Fleming

MODVIS Workshop

No abstract provided.


An Active Efficient Coding Model Of The Development Of Amblyopia, Samuel Eckmann, Lukas Klimmasch, Bertram Shi, Jochen Triesch May 2018

An Active Efficient Coding Model Of The Development Of Amblyopia, Samuel Eckmann, Lukas Klimmasch, Bertram Shi, Jochen Triesch

MODVIS Workshop

No abstract provided.


Collective Chemotaxis Of Retinal Neural Cells From Drosophila Melanogaster In Controlled Microenvironments, Stephanie Zhang Jan 2018

Collective Chemotaxis Of Retinal Neural Cells From Drosophila Melanogaster In Controlled Microenvironments, Stephanie Zhang

Dissertations and Theses

More than 172 million people are influenced by a retinal disorder that stems from either age-related or developmental causes. Of those, 1.5 million people endure a developmental retinal disorder. In the developing retina, neural cells undergo a series of highly complicated differentiation and migration process. A main cause of these diseases is abnormal collective migration of neural progenitors hindering the retinogenesis process. However, our grasp of collective migration and signaling molecules, critical to the developing retina, is incompletely understood. Understanding the molecular mechanisms, such as the fibroblast growth factor pathway, that regulate glial and neuronal migration provides decisive insights in …


Open Source Artificial Intelligence In A Biological/Ecological Context, Trevor Grant Oct 2017

Open Source Artificial Intelligence In A Biological/Ecological Context, Trevor Grant

Annual Symposium on Biomathematics and Ecology Education and Research

No abstract provided.


Development Of Portable Hyperspectral Imaging Device, Chenxi Li, Youngkee Jung, Iyll-Joon Doh, Euiwon Bae Aug 2017

Development Of Portable Hyperspectral Imaging Device, Chenxi Li, Youngkee Jung, Iyll-Joon Doh, Euiwon Bae

The Summer Undergraduate Research Fellowship (SURF) Symposium

Most of the conventional hyperspectral imaging devices require sophisticated optical components, occupy a large footprint, and requires an initial capital investment for laboratories which mostly suits for laboratories benchtop system. The requirement of shipping the sample and waiting an extended period of time to get the results are the main downsides of this traditional approach. Capitalize in many specific field applications and diagnosis, portable devices provide both convenience and on-site results which are desirable for government agencies and food safety inspectors. This project was aimed to develop a low-cost, portable hyperspectral device for food safety applications. A smartphone was used …


Modeling Accommodation Control Of The Human Eye: Chromatic Aberration And Color Opponency, Agostino Gibaldi, Steven A. Cholewiak, Marty S. Banks May 2017

Modeling Accommodation Control Of The Human Eye: Chromatic Aberration And Color Opponency, Agostino Gibaldi, Steven A. Cholewiak, Marty S. Banks

MODVIS Workshop

Accommodation is the process by which the eye lens changes optical power to maintain a clear retinal image as the distance to the fixated object varies. Although luminance blur has long been considered the driving feature for accommodation, it is by definition unsigned (i.e., there is no difference between the defocus of an object closer or farther than the focus distance). Nonetheless, the visual system initially accommodates in the correct direction, implying that it exploits a cue with sign information. Here, we present a model of accommodation control based on such a cue: Longitudinal Chromatic Aberration (LCA). The model relies …


Heuristics From Statistics—Modeling The Behavior And Perception Of Non-Rigid Materials, Vivian C. Paulun, Roland W. Fleming May 2017

Heuristics From Statistics—Modeling The Behavior And Perception Of Non-Rigid Materials, Vivian C. Paulun, Roland W. Fleming

MODVIS Workshop

No abstract provided.


Modelling Grip Point Selection In Human Precision Grip, Guido Maiello, Lina Klein, Vivian C. Paulun, Roland W. Fleming May 2017

Modelling Grip Point Selection In Human Precision Grip, Guido Maiello, Lina Klein, Vivian C. Paulun, Roland W. Fleming

MODVIS Workshop

No abstract provided.


Ocular Lens Engineering: A Regenerative Approach To Correcting Visual Impairments, Dallin Busby, Joshua Hansen, Cameron Crook, Diane Donaldson, Alonzo Cook Feb 2017

Ocular Lens Engineering: A Regenerative Approach To Correcting Visual Impairments, Dallin Busby, Joshua Hansen, Cameron Crook, Diane Donaldson, Alonzo Cook

Biomedical Engineering Western Regional Conference

No abstract provided.


Eye Movement Control: An Index For Athleticism, Brittany L. Oshea Jan 2017

Eye Movement Control: An Index For Athleticism, Brittany L. Oshea

Theses and Dissertations

Athletic potential is one of the most complex human traits. An elite athlete is produced from a complex interaction of an innumerable number of traits exhibited by the athlete. However, it’s not clear whether these traits are innate, allowing the athlete to excel, or, alternatively, are a consequence of practice. To be successful, athletes rely heavily on sensory information from the visual and vestibular systems. This study investigated the relationship eye movement control has with innate athleticism by comparing the saccadic and Vestibulo-Ocular Reflex (VOR) responses of former, no longer practicing, elite athletes against their age and gender matched counterparts …