David Ress

Baylor College of Medicine, Neuroscience, Faculty Member

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Steven Pinker

Harvard University

Timothy Jordan

Canadian University of Dubai

Don Ross

University College Cork

Daniel Weiskopf

Georgia State University

Vittorio Gallese

Università degli Studi di Parma (Italy)

Fabio Cuzzolin

Oxford Brookes University

Susanna Schellenberg

Rutgers, The State University of New Jersey

Isad Saric

University of Sarajevo

Dalson Figueiredo

Universidade Federal de Pernambuco

Carlo Semenza

Università degli Studi di Padova

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Papers by David Ress

Comparison of the BOLD hemodynamic response function at 3T and 9.4T

Kinesthetic Feedback During 2DOF Wrist Movements via a Novel MR-Compatible Robot

IEEE Transactions on Neural Systems and Rehabilitation Engineering, Sep 1, 2017

We demonstrate the interaction control capabilities of the MR-SoftWrist, a novel MR-compatible ro... more We demonstrate the interaction control capabilities of the MR-SoftWrist, a novel MR-compatible robot capable of applying accurate kinesthetic feedback to wrist pointing movements executed during fMRI. The MR-SoftWrist, based on a novel design that combines parallel piezoelectric actuation with compliant force feedback, is capable of delivering 1.5 N•m of torque to the wrist of an interacting subject about the flexion/extension and radial/ulnar deviation axes. The robot workspace, defined by admissible wrist rotation angles, fully includes a circle with a 20 deg radius. Via dynamic characterization, we demonstrate capability for transparent operation with low (10% of maximum torque output) backdrivability torques at nominal speeds. Moreover, we demonstrate a 5.5 Hz stiffness control bandwidth for a 14 dB range of virtual stiffness values, corresponding to 25-125% of the device's physical reflected stiffness in the nominal configuration. We finally validate the possibility of operation during fMRI via a case study involving one healthy subject. Our validation experiment demonstrates the capability of the device to apply kinesthetic feedback to elicit distinguishable kinetic and neural responses without significant degradation of image quality or task-induced head movements. With this study, we demonstrate the feasibility of MR-compatible devices like the MR-SoftWrist to be used in support of motor control experiments investigating wrist pointing under robot-applied force fields. Such future studies may elucidate fundamental neural mechanisms enabling robot-assisted motor skill learning, which is crucial for robot-aided neurorehabilitation.

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Review of: "Coupling between Human Brain Cortical Thickness and Glucose Metabolism from Regional to Connective level: a PET/MRI study

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Development, control, and MRI-compatibility of the MR-SoftWrist

ABSTRACT This paper presents the MR-SoftWrist: a parallel 3DOF MR-compatible wrist robot with com... more ABSTRACT This paper presents the MR-SoftWrist: a parallel 3DOF MR-compatible wrist robot with compliant actuation. Through a design that aligns the wrist joint axes to the device DOFs and uses custom MR-compatible force-feedback actuation, the MR-SoftWrist can measure and support wrist movements during fMRI. The device has a circular workspace for wrist flexion/extension and radial/ulnar deviation with 18 deg radius, and is capable of generating 1.75 Nm joint torque. Control experiments validate the device&#39;s workspace, along with position and zero torque control capabilities. In zero torque mode the maximum force felt by the user is 0.15 Nm, less than 10% of the device&#39;s torque output. The device is shown to have no significant affect on imaging quality during fMRI.

Simple Signed-Distance Function Depth Calculation Applied to Measurement of the fMRI BOLD Hemodynamic Response Function in Human Visual Cortex

Computational Modeling of Objects Presented in Images. Fundamentals, Methods, and Applications, 2017

Functional magnetic resonance imaging (fMRI) often relies on a hemodynamic response function (HRF... more Functional magnetic resonance imaging (fMRI) often relies on a hemodynamic response function (HRF) elicited by a brief stimulus. At conventional spatial resolutions (! 3 mm), signals in a voxel include contributions from various tissue types and pia vasculature. To better understand these contributions, full characterization of the depth dependence of the HRF is required in gray matter as well as and its apposed white-matter and pial vasculature. We introduce new methods to calculate 3D depth that combines a signed-distance function with an algebraic morphing definition of distance. The new scheme is much simpler than methods that rely upon deformable surface propagation. The method is demonstrated by combining the distance map with high-resolution fMRI (0.9-mm voxels) measurements of the depth-dependent HRF. The depth dependence of the HRF is reliable throughout a broad depth range in gray matter as well as in white-matter and extra-pial compartments apposed to active gray matter. The proposed scheme with high-resolution fMRI can be useful to separate HRFs in the gray matter from undesirable and confounding signals.

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X-ray diagnostic for measurement of hot-electron power loss

Review of Scientific Instruments, Oct 1, 1990

A significant fraction of the power lost from a confined plasma can be carried by energetic elect... more A significant fraction of the power lost from a confined plasma can be carried by energetic electrons. When such electrons are incident on a probe or limiting surface, they produce thick-target x rays. It is shown that a properly filtered measurement of this x-ray flux is proportional to the electron-power loss, with little dependence on the electron loss mechanism and velocity-space distribution. The diagnostic was successfully implemented to study the radial loss of hot electrons in the Tandem Mirror Experiment-Upgrade. The method provides a very fast measurement of electron loss processes, and could therefore be useful in other areas of plasma research such as magnetic confinement in tokamaks, and inertial-confinement fusion.

<title>Imaging with x-ray lasers</title>

Proceedings of SPIE, Feb 1, 1994

Collisionally pumped soft x-ray lasers now operate over a wavelength range extending from 35 - 30... more Collisionally pumped soft x-ray lasers now operate over a wavelength range extending from 35 - 300 angstroms. These sources have high peak brightness and are now being utilized for x-ray imaging and plasma interferometry. In this paper we will describe our efforts to probe long scalelength plasmas using Moire deflectometry and soft x-ray imaging. The progress in the development of short pulse x-ray lasers using a double pulse irradiation technique which incorporates a travelling wave pump will also be presented.

Under-sampled functional MRI using low-rank plus sparse matrix decomposition

High spatial resolution in functional magnetic resonance imaging improves its sensitivity to brai... more High spatial resolution in functional magnetic resonance imaging improves its sensitivity to brain activation signals by reducing partial volume effects. However, the long acquisition times required for high spatial resolution limit the temporal resolution in fMRI studies. Consequently, the low temporal sampling bandwidth leads to increase in physiological noise and poor modeling of the functional activation dynamics. Thus, fast techniques capable of recovering fMRI time-series from under-sampled data are desirable to improve the sensitivity and specificity of fMRI for functional brain mapping. This paper presents an under-sampled fMRI recovery using low-rank plus sparse matrix decomposition signal model. This model is suited for blocked or slow event-related fMRI studies, where the low-rank matrix captures the temporally static T*2-weighted image patterns and, the sparse matrix captures the pseudo-periodic brain activation signal. The preliminary results of under-sampled recovery on in-vivo fMRI data show recovery of BOLD activation in human superior colliculus with contrast-to-noise ratio ≥ 4.4 (85% of reference) up to acceleration factors of 3.

Efficient, High-Spatial Resolution Neutron Detector for Coded Aperture Imaging of ICF Targets

APS, Nov 1, 1996

ABSTRACT Imaging the burning core of an ICF target using fusion neutrons requires an efficient de... more ABSTRACT Imaging the burning core of an ICF target using fusion neutrons requires an efficient detector. Current systems use plastic scintillator arrays 10-cm thick. These limit detector spatial resolution to &gt; 2 mm. We propose using a neutron-sensitive liquid-filled bubble chamber for recording coded aperture images. Each detected neutron forms only one bubble and the threshold energy for bubble formation can be selected. The bubble chamber can be made thick for efficiency, is insensitive to gamma-ray background, and has a resolution &lt; 100 mum. An efficient, high-resolution detector could revolutionize coded-aperture imaging system design. For example, a magnification of 10 instead of 200 would be required to achieve 10 mum source resolution. Target-to-aperture distance and aperture diameter could be greatly increased. Larger diameter apertures would increase signal level, and be easier to fabricate, characterize, and align. The cost of a bubble chamber detector should be significantly less than the equivalent plastic scintillator array with its associated readout system.

Somatosensory responses in the deep layers of superior colliculus

Comparison of the BOLD hemodynamic response function at 3T and 9.4T

AA Neuronal Correlates of Visual Attention and Perception

... to our own, but measured in an area of visual cortex that is believed to subserve object reco... more

A time-resolved x-ray ring coded-aperture microscope for inertial confinement fusion applications

Review of Scientific Instruments, Jun 1, 1993

For energetic x rays (hv≥3 keV), ring coded-aperture imaging gives better signal-to-noise ratio t... more For energetic x rays (hv≥3 keV), ring coded-aperture imaging gives better signal-to-noise ratio than equivalent-resolution pinhole cameras for inertial confinement fusion (ICF) targets. We have created a time-resolved ring coded-aperture microscope by combining a 4×3 array of annular apertures with a gated microchannel-plate x-ray imager. The new instrument can produce 500-ps duration sequences of images with a temporal resolution of 80 ps and a spatial resolution of 5 to 6 μm. In demonstration experiments, coded images of imploded targets directly driven by the Omega laser at the Laboratory for Laser Energetics showed the formation and dissolution of the target cores with improved detail. Contour plots of the images indicate that the laser illumination pattern is imprinted in the imploded core region. The gated ring-aperture microscope will be useful in detailed studies of ICF target hydrodynamics.

Recent Results from the Nova Neutron Microscope

APS Division of Plasma Physics Meeting Abstracts, Nov 1, 1996

ABSTRACT An improved design of the neutron penumbral-aperture microscope (NPAM) is presently bein... more ABSTRACT An improved design of the neutron penumbral-aperture microscope (NPAM) is presently being installed on the Nova laser facility. The alignment system has been substantially redesigned to avoid earlier problems with thermal drift and vibration. The new scheme uses a single-mode optical fiber to inject the alignment beam that serves as the straight-line reference. New penumbral coding apertures have been fabricated using a simple grinding procedures to form the mandrels that are subsequently electroplated with gold and acid etched to form the apertures. Recent characterization experiments with sychrotron radiation verify the utility of the new apertures. With the new alignment system and apertures, we expect to achieve 15-mum spatial resolution. The NPAM will be described, particularly the improvements, and available experimental images will be presented.

fMRI measurements of orientation-selective adaptation

Journal of Vision, Mar 14, 2010

Right temporal pole volume reduction in PTSD

Progress in Neuro-psychopharmacology & Biological Psychiatry, Jun 1, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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FMRI cortical activity predicts pattern-detection performance

NeuroImage, May 1, 2000

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Design of thick apertures for high-resolution neutron penumbral imaging

IEEE Transactions on Nuclear Science, Apr 1, 1990

A general technique is presented for designing the thick apertures required to image penetrating ... more A general technique is presented for designing the thick apertures required to image penetrating radiation with high resolution. The new apertures are tapered in such a way that the radius of curvature varies inversely with distance from the source plane. The technique is used to design a high-resolution neutron penumbral-aperture microscope planned for the Nova laser. The design provides a resolution (determined by the sharpness of the aperture point-spread function) of 110 p over a field of view of 150 p. Thc point-spread function of these apertures is sufficiently isoplanatic and distortion-free to allow linear reconstruction of complex source distributions. The design is generally appropriate for similar imaging techniques, such as high-resolution neutron or gamma-ray pinhole imaging.

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Demonstration of an x-ray ring-aperture microscope for inertial-confinement fusion experiments

Applied Physics Letters, Jan 27, 1992

We are investigating the use of annular (ring) apertures to image high-energy x-ray emission (≳4 ... more We are investigating the use of annular (ring) apertures to image high-energy x-ray emission (≳4 keV) from inertial-confinement fusion targets. In our scheme, a coded image is formed on a detector (such as x-ray film) by x rays that pass through a narrow annulus cut in a sheet of high-Z material such as gold. Signal-to-noise ratio calculations show a factor of 10 advantage of ring-aperture imaging over conventional pinhole imaging. Simultaneous pinhole and ring-aperture images of small (≊20 μm diam), laser-driven, x-ray sources were obtained in recent experiments. We used a 10-μm-wide, 1-mm-diam annulus in a 6-μm thickness of gold; a 10-μm-diam pinhole was in the center of the annulus. Unfolds of the coded images have signal-to-noise ratios a factor of 20 larger than the pinhole images. The ring-aperture microscope is a promising new technique to image inertial-confinement fusion targets and other compact sources of high-energy x rays.

Reliability of the depth-dependent high-resolution BOLD hemodynamic response in human visual cortex and vicinity

Magnetic Resonance Imaging, Jun 1, 2017

Functional magnetic resonance imaging (fMRI) often relies on a hemodynamic response function (HRF... more Functional magnetic resonance imaging (fMRI) often relies on a hemodynamic response function (HRF), the stereotypical blood oxygen level dependent (BOLD) response elicited by a brief (<4 seconds) stimulus. Early measurements of the HRF used coarse spatial resolutions (≥3 mm voxels) that would generally include contributions from white matter, gray matter, and the extra-pial compartment (the space between the pial surface and skull including pial blood vessels) within each voxel. To resolve these contributions, high-resolution fMRI (0.9-mm voxels) was performed at 3T in early visual cortex and its apposed white-matter and extra-pial compartments. The results characterized the depth dependence of the HRF and its reliability during nine fMRI sessions. Significant HRFs were observed in white-matter and extra-pial compartments as well as in gray matter. White-matter HRFs were faster and weaker than in the gray matter, while extra-pial HRFs were comparatively slower and stronger. Depth trends of the HRF peak amplitude were stable throughout a broad depth range that included all three compartments for each session. Across sessions, however, the depth trend of HRF peak amplitudes was stable only in the white matter and deep-intermediate gray matter, while there were strong session-to-session variations in the superficial gray matter and the extra-pial compartment. Thus, high-resolution fMRI can resolve significant and dynamically distinct HRFs in gray matter, white matter, and extra-pial compartments.

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Comparison of the BOLD hemodynamic response function at 3T and 9.4T

Kinesthetic Feedback During 2DOF Wrist Movements via a Novel MR-Compatible Robot

IEEE Transactions on Neural Systems and Rehabilitation Engineering, Sep 1, 2017

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Review of: "Coupling between Human Brain Cortical Thickness and Glucose Metabolism from Regional to Connective level: a PET/MRI study

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Development, control, and MRI-compatibility of the MR-SoftWrist

Simple Signed-Distance Function Depth Calculation Applied to Measurement of the fMRI BOLD Hemodynamic Response Function in Human Visual Cortex

Computational Modeling of Objects Presented in Images. Fundamentals, Methods, and Applications, 2017

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X-ray diagnostic for measurement of hot-electron power loss

Review of Scientific Instruments, Oct 1, 1990

<title>Imaging with x-ray lasers</title>

Proceedings of SPIE, Feb 1, 1994

Under-sampled functional MRI using low-rank plus sparse matrix decomposition

Efficient, High-Spatial Resolution Neutron Detector for Coded Aperture Imaging of ICF Targets

APS, Nov 1, 1996

Somatosensory responses in the deep layers of superior colliculus

Comparison of the BOLD hemodynamic response function at 3T and 9.4T

AA Neuronal Correlates of Visual Attention and Perception

... to our own, but measured in an area of visual cortex that is believed to subserve object reco... more

A time-resolved x-ray ring coded-aperture microscope for inertial confinement fusion applications

Review of Scientific Instruments, Jun 1, 1993

Recent Results from the Nova Neutron Microscope

APS Division of Plasma Physics Meeting Abstracts, Nov 1, 1996

fMRI measurements of orientation-selective adaptation

Journal of Vision, Mar 14, 2010

Right temporal pole volume reduction in PTSD

Progress in Neuro-psychopharmacology & Biological Psychiatry, Jun 1, 2020

Download

FMRI cortical activity predicts pattern-detection performance

NeuroImage, May 1, 2000

Download

Design of thick apertures for high-resolution neutron penumbral imaging

IEEE Transactions on Nuclear Science, Apr 1, 1990

Download

Demonstration of an x-ray ring-aperture microscope for inertial-confinement fusion experiments

Applied Physics Letters, Jan 27, 1992

Reliability of the depth-dependent high-resolution BOLD hemodynamic response in human visual cortex and vicinity

Magnetic Resonance Imaging, Jun 1, 2017

Functional magnetic resonance imaging (fMRI) often relies on a hemodynamic response function (HRF... more Functional magnetic resonance imaging (fMRI) often relies on a hemodynamic response function (HRF), the stereotypical blood oxygen level dependent (BOLD) response elicited by a brief (<4 seconds) stimulus. Early measurements of the HRF used coarse spatial resolutions (≥3 mm voxels) that would generally include contributions from white matter, gray matter, and the extra-pial compartment (the space between the pial surface and skull including pial blood vessels) within each voxel. To resolve these contributions, high-resolution fMRI (0.9-mm voxels) was performed at 3T in early visual cortex and its apposed white-matter and extra-pial compartments. The results characterized the depth dependence of the HRF and its reliability during nine fMRI sessions. Significant HRFs were observed in white-matter and extra-pial compartments as well as in gray matter. White-matter HRFs were faster and weaker than in the gray matter, while extra-pial HRFs were comparatively slower and stronger. Depth trends of the HRF peak amplitude were stable throughout a broad depth range that included all three compartments for each session. Across sessions, however, the depth trend of HRF peak amplitudes was stable only in the white matter and deep-intermediate gray matter, while there were strong session-to-session variations in the superficial gray matter and the extra-pial compartment. Thus, high-resolution fMRI can resolve significant and dynamically distinct HRFs in gray matter, white matter, and extra-pial compartments.

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