Rachel A Yotter

University of Pennsylvania | UP · Section of Biomedical Image Analysis - SBIA

Recent studies using surface-based morphometry of structural magnetic resonance imaging data have suggested that some changes in bipolar disorder (BP) might be neurodevelopmental in origin. We applied a novel analysis of cortical complexity based on fractal dimensions in high-resolution structural MRI scans of 18 bipolar disorder patients and 26 he...

Background Alterations of cortical thickness have been shown in imaging studies of schizophrenia but it is unclear to what extent they are related to disease phenotype (including symptom profile) or other aspects such as genetic liability, disease onset and disease progression. Aims To test the hypothesis that cortical thinning would vary across di...

Schizophrenia is assumed to be a neurodevelopmental disorder, which might involve disturbed development of the cerebral cortex, especially in frontal and medial temporal areas. Based on a novel spherical harmonics approach to measuring complexity of cortical folding, we applied a measure based on fractal dimension (FD) to investigate the heterogene...

The development of amyloid imaging compounds has allowed in vivo imaging of amyloid deposition. In this study, we examined the spatial patterns of amyloid deposition throughout the brain using Pittsburgh Compound Blue ((11)C-PiB) positron emission tomography data from the Baltimore Longitudinal Study of Aging. We used a new methodology that allowed...

The aim of this large-sample cross-sectional voxel-based morphometry (VBM) study of anatomical brain data was to investigate linear and nonlinear age-related trajectories of grey matter volume in the human brain during the adult lifespan. To date, there are only a few structural brain studies investigating local nonlinear aspects at the voxel level...

Surface reconstruction methods allow advanced analysis of structural and functional brain data beyond what can be achieved using volumetric images alone. Automated generation of cortical surface meshes from 3D brain MRI often leads to topological defects and geometrical artifacts that must be corrected to permit subsequent analysis. Here, we propos...

Skull-stripping and parceling of the brain by region-growing techniques.

A spherical map of a cortical surface is often used for improved brain registration, for advanced morphometric analysis (eg, of brain shape), and for surface-based analysis of functional signals recorded from the cortex. Furthermore, for intersubject analysis, it is usually necessary to reparameterize the surface mesh into a common coordinate syste...

Altered cortical surface complexity and gyrification differences may be a potentially sensitive marker for several neurodevelopmental disorders. We propose to use spherical harmonic (SPH) constructions to measure cortical surface folding complexity. First, we demonstrate that the complexity measure is accurate, by applying our SPH approach and the...

Intracellular phospholipases A₂ (inPLA₂) are activated during monoaminergic neurotranismision and act as key enzymes in cell membrane repair and remodelling, neuroplasticity, neurodevelopment, apoptosis, synaptic pruning, neurodegenerative processes and neuroinflammation. Several independent studies found increased inPLA₂ activity in drug-naïve fir...

Cortical surface complexity is a potential structural marker for certain diseases such as schizophrenia. In this study, we developed a measure of fractal dimension (FD) calculated from lowpass-filtered spherical harmonic brain surface reconstructions. A local FD measure was also computed at each vertex in a cortical surface mesh, visualizing local...

Surface reconstruction based on the projection-based thickness (PBT) method and creation of a brain phantom with equal thickness for evaluation and comparison to the Laplacian approach.

Projection-based thickness (PBT) approach to estimate the thickness of brain tissues.

A brain surface reconstruction allows advanced analysis of structural and functional brain data that is not possible using volumetric data alone. However, the generation of a brain surface mesh from MRI data often introduces topological defects and artifacts that must be corrected. We show that it is possible to accurately correct these errors usin...

Voxel-based estimation of the cortical thickness and reconstruction of the central surface comparing voxel-based Tnear and TLaplacian approach.

For Abstract see ChemInform Abstract in Full Text.

A comparison of performance in three pH-sensitive CHEMFET devices in a standard 1.6 micron CMOS process using aluminum oxide, silicon nitride, and silicon oxide is described. Experimental results compare sensitivity, resolution, and signal-to-noise ratio for the three devices across their usable lifetime. The best signal to noise ratio (19.3 dB) oc...

Recent developments in lab-on-a-chip applications have increased the need for low-power, small-footprint photodetectors to detect luminescent reporters used to monitor biological events. Presented is a CMOS photodiode structure that is optimized to detect green light, the peak emission wavelength of commonly used fluorophores and other luminescent...

A review of optical, chemical, and biological sensors to detect metabolic activity at the single-cell level is presented in the context of the development of lab-on-a-chip research instrumentation. The sensors reviewed include optical sensors, at both research and commercial levels, that can optically detect intracellular metabolites including aden...

A review of solid-state chemical and electrochemical sensors to detect metabolic activity at the extracellular, single-cell level is presented in the context of the development of lab-on-a-chip research instrumentation. Metabolic processes in cells are briefly reviewed with the goal of quantifying the role of metabolites within the cell. Sensors re...

A low noise, high sensitivity resonant photodetector was realized using an interdigitated silicon photodiode and integrated oscillator circuitry. By placing the photodiode in a resonant loop and using an innovative transduction mechanism, an improvement in the noise performance of the device is observed. Specifically, an increase of 10% in signal t...

We have demonstrated the fabrication of a micromachined fluidic inclinometer for the first time. The micromachined fluidic inclinometer uses capacitance to detect the angle of inclination, and it is capable of measuring inclination with greater than 1° resolution. Several fluidic systems and geometries are tested to optimize speed of response and l...

A review of photodetectors for optical detection in biological applications is presented. The intent is to provide an overview of the performance metrics and trade-offs among popular photodetectors in order to facilitate an easier match among the photodetector, biological stimulus, and optical pathway. The characteristics and nonidealities of fluor...

Thesis (Ph. D.)--University of Washington, 2007. The hippocampus is one of the few brain areas that has a highly linear feed-forward network architecture. Despite massive efforts to unravel hippocampal mnemonic function through pharmacological, genetic, electrophysiological, lesion, and modeling studies, the role of the hippocampal network is still...