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Distributions of current produced by transcranial direct current stimulation (tDCS) in humans were predicted by a finite-element model representing several individual and collective refinements over prior efforts. A model of the entire human head and brain was made using a finely meshed (1.1x1.1x1.4mm(3) voxel) tissue dataset derived from the MRI data set(More)
OBJECTIVE We sought an electrical modeling approach to evaluate the potential application of finite element method (FEM) modeling to predict current pathways and intensities in the brain after transcranial electrical stimulation. METHODS A single coronal MRI section through the head, including motor cortex, was modeled using FEM. White matter compartments(More)
A prototype electrical impedance tomography system was evaluated prior to its use for the detection of intraperitoneal bleeding, with the assistance of patients undergoing continuous ambulatory peritoneal dialysis (CAPD). The system was sensitive enough to detect small amounts of dialysis fluid appearing in subtractive images over short time periods.(More)
Transcranial direct current stimulation (tDCS) is an emerging neuromodulation therapy that has been experimentally determined to affect a wide range of behaviors and diseases ranging from motor, cognitive, and memory processes to depression and pain syndromes. The effects of tDCS may be inhibitory or excitatory, depending on the relative polarities of(More)
Magnetic resonance electrical impedance tomography (MREIT) has the potential to provide conductivity and current density images with high spatial resolution and accuracy. Recent experimental studies at a field strength of 3 T showed that the spatial resolution of conductivity and current density images may be similar to that of conventional MR images as(More)
We sought to determine the feasibility of directly studying neural tissue activity by analysis of differential phase shifts in MRI signals that occurred when trickle currents were applied to a bath containing active or resting neural tissue. We developed a finite element bidomain model of an aplysia abdominal ganglion in order to estimate the sensitivity of(More)
Electrode properties are key to the quality of measured biopotential signals. Ubiquitous health care systems require long-term monitoring of biopotential signals from normal volunteers and patients in home or hospital environments. In these settings it is appropriate to use dry textile electrode networks for monitoring purposes, rather than the gel or(More)
In magnetic resonance electrical impedance tomography (MREIT), we measure the induced magnetic flux density inside an object subject to an externally injected current. This magnetic flux density is contaminated with noise, which ultimately limits the quality of reconstructed conductivity and current density images. By analysing and experimentally verifying(More)
The Howland current pump is a popular bioelectrical circuit, useful for delivering precise electrical currents. In applications requiring high precision delivery of alternating current to biological loads, the output impedance of the Howland is a critical figure of merit that limits the precision of the delivered current when the load changes. We explain(More)