Neuroscience and Neurobiology Commons^™

Investigating Task-Free Functional Connectivity Patterns In Newborns Using Functional Near-Infrared Spectroscopy, Homa Vahidi

Electronic Thesis and Dissertation Repository

Robust functional connectivity in sensorimotor resting-state network (RSN) has been linked to positive neurodevelopmental outcomes in neonates. In the current study, we aimed to map the developmental trajectory of sensorimotor RSN in awake neonates using functional near-infrared spectroscopy (fNIRS). We acquired fNIRS resting-state data from 41 healthy newborns (17 females, gestational age range=36+0 to 42+1 weeks) within the first 48 hours after birth. At the group level, we observed robust positive connectivity in numerous channel-pairs across the sensorimotor network, especially in the left hemisphere. Next, we examined the relationship between functional connectivity, gestational age and postnatal age, while controlling for …

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 …

Resistance Training Improves White Matter Structural Connectivity In Older Adults At-Risk For Cognitive Decline, Ryu Lien

Undergraduate Student Research Internships Conference

Diabetes is a global health concern that impacts 415 million people worldwide. Individuals who are at-risk for diabetes (characterized by high blood glucose and/or being overweight) have white matter atrophy, decreased cognitive function, and an increased risk of Alzheimer’s disease (AD). Recently, resistance training (RT) has been shown to lower white matter atrophy and white matter lesion volume. However, investigating changes in white matter tracts is complex, hence previous findings remain inconclusive. Diffusion tensor imaging (DTI) serves as a highly sensitive tool that enables visualization and characterization of white matter tracts and has the potential to combat this complexity. The …

Rapid Microscopic Fractional Anisotropy Imaging Via An Optimized Linear Regression Formulation., N J J Arezza, D H Y Tse, C A Baron

Medical Biophysics Publications

Water diffusion anisotropy in the human brain is affected by disease, trauma, and development. Microscopic fractional anisotropy (μFA) is a diffusion MRI (dMRI) metric that can quantify water diffusion anisotropy independent of neuron fiber orientation dispersion. However, there are several different techniques to estimate μFA and few have demonstrated full brain imaging capabilities within clinically viable scan times and resolutions. Here, we present an optimized spherical tensor encoding (STE) technique to acquire μFA directly from the 2nd order cumulant expansion of the powder averaged dMRI signal obtained from direct linear regression (i.e. diffusion kurtosis) which requires fewer powder-averaged signals than …

Evaluating Anesthetic Protocols For Non-Human Primate Functional Neuroimaging, Megha Verma

Electronic Thesis and Dissertation Repository

Functional magnetic resonance imaging (fMRI) is a non-invasive technique that can be used to measure a proxy of neural activity in vivo with high spatial specificity. One subject can be followed for a long period of time to assess changes in functional brain organization. However, fMRI is extremely sensitive to motion. The challenges of training non-human primates to reduce motion in an MRI scanner motivate the study of anesthesia which is commonly used to substitute for this training. In this thesis, I compare three different commonly used anesthetic protocols: isoflurane, propofol-fentanyl in combination, and fentanyl alone, to test which of …

Advances In Image Acquisition And Filtering For Mri Neuroimaging At 7 Tesla, Andrew T. Curtis

Electronic Thesis and Dissertation Repository

Performing magnetic resonance imaging at high magnetic field strength promises many improvements over low fields that are of direct benefit in functional neuroimaging. This includes the possibility of improved signal-to-noise levels, and increased BOLD functional contrast and spatial specificity. However, human MRI at 7T and above suffers from unique engineering challenges that limit the achievable gains. In this thesis, three technological developments are introduced, all of which address separate issues associated with functional magnetic resonance neuroimaging at very high magnetic field strengths.

First, the image homogeneity problem is addressed by investigating methods of RF shimming — modifying the excitation portion …

Neural Circuits Involved In Mental Arithmetic: Evidence From Customized Arithmetic Training, Christian Battista

Electronic Thesis and Dissertation Repository

An arithmetic training study was conducted using a novel paradigm known as Customized Arithmetic Training (CAT). Using the CAT system, self-reports obtained from the participants were used to generate individually tailored problem sets. These problem sets balanced strategy use such that each participant started with an equal amount of problems solved by fact retrieval (e.g., 2 + 2 = 4) and an equal amount of problems solved by procedural calculation (e.g., 34 + 37). Following the training period, participants solved trained and untrained problems from their customized arithmetic sets while undergoing an fMRI scan, after which they again provided self-reported …