Calibration of BOLD fMRI using breath holding reduces group variance during a cognitive task.

The proportionality of blood oxygen level-dependent (BOLD) response during a cognitive task and that from a hypercapnic challenge was investigated in cortical structures involved in working memory (WM). Breath holding (BH) following inspiration was used to induce a BOLD response characteristic of regional vasomotor reactivity but devoid of metabolic changes. BOLD effects measured during BH were used to normalize individual subject activations during WM, which effectively reduced the confounding influence of individual- and region-specific differences in hemodynamic responsivity common to both tasks.

Report on a multicenter fMRI quality assurance protocol.

Temporal stability during an fMRI acquisition is very important because the blood oxygen level-dependent (BOLD) effects of interest are only a few percent in magnitude. Also, studies involving the collection of groups of subjects over time require stable scanner performance over days, weeks, months, and even years. We describe a protocol designed by one of the authors that has been tested for several years within the context of a large, multicenter collaborative fMRI research project (FIRST-BIRN).

Rapid MRI method for mapping the longitudinal relaxation time.

A novel method for mapping the longitudinal relaxation time in a clinically acceptable time is developed based on a recent proposal [J.-J. Hsu, I.

Modelling of wastewater treatment plants--how far shall we go with sophisticated modelling tools?

Several levels of complexity are available for modelling of wastewater treatment plants. Modelling local effects rely on computational fluid dynamics (CFD) approaches whereas activated sludge models (ASM) represent the global methodology. By applying both modelling approaches to pilot plant and full scale systems, this paper evaluates the value of each method and especially their potential combination.

Partial-k-space acquisition method for improved SNR efficiency and temporal resolution in 3D fMRI.

Previous studies have shown the relative importance of physiological noise and thermal noise in 2D MR images. Since physiological noise is proportional to the signal, it can be the dominant component at the center of k-space. In this study we demonstrate that the signal-to-noise ratio (SNR) efficiency and temporal resolution for 3D functional MRI (fMRI) are increased by the use of a partial-k-space acquisition method.

Neural correlates of rapid spectrotemporal processing in musicians and nonmusicians.

Our results suggest that musical training alters the functional anatomy of rapid spectrotemporal processing, resulting in improved behavioral performance along with a more efficient functional network primarily involving traditional language regions. This finding may have important implications for improving language/reading skills, especially in children struggling with dyslexia.

Dual-echo spiral in/in acquisition method for reducing magnetic susceptibility artifacts in blood-oxygen-level-dependent functional magnetic resonance imaging.

MRI signal dropout in gradient recalled echo acquisitions limits the capability of blood-oxygen-level-dependent functional magnetic resonance imaging (fMRI) to study activation tasks that involve the orbitofrontal, temporal, and basal areas of the brain where significant macroscopic magnetic susceptibility differences exist. Among the various approaches aimed to address this issue, the acquisition method based on spiral in/out trajectories is one of the most time-efficient and effective techniques. In this study, we extended further the spiral in/out approach into 3D acquisition and compared the effectiveness of the different spiral in/out trajectory combinations in reducing signal dropout.

Neural correlates of individual differences in pain-related fear and anxiety.

Although individual differences in fear and anxiety modulate the pain response and may even cause more suffering than the initiating physical stimulus, little is known about the neural systems mediating this relationship. The present study provided the first examination of the neural correlates of individual differences in the tendency to (1) feel anxious about the potentially negative implications of physical sensations, as measured by the anxiety sensitivity index (ASI), and (2) fear various types of physical pain, as indexed by the fear of pain questionnaire (FPQ). In separate sessions, participants completed these questionnaires and experienced alternating blocks of noxious thermal stimulation (45-50 degrees C) and neutral thermal stimulation (38 degrees C) during the collection of whole-brain fMRI data.

Control over brain activation and pain learned by using real-time functional MRI.

If an individual can learn to directly control activation of localized regions within the brain, this approach might provide control over the neurophysiological mechanisms that mediate behavior and cognition and could potentially provide a different route for treating disease. Control over the endogenous pain modulatory system is a particularly important target because it could enable a unique mechanism for clinical control over pain. Here, we found that by using real-time functional MRI (rtfMRI) to guide training, subjects were able to learn to control activation in the rostral anterior cingulate cortex (rACC), a region putatively involved in pain perception and regulation.

Relaxation times of breast tissue at 1.5T and 3T measured using IDEAL.

Purpose: To accurately measure T1 and T2 of breast fibroglandular tissue and fat at 1.5T and 3T, and note the partial volume effects of the admixture of fibroglandular tissue and fat on the relaxation rates using an approach termed iterative decomposition of water and fat with echo asymmetry and least squares estimation (IDEAL) imaging.

Materials And Methods: T1 and T2 values were measured on the right breasts of five healthy women at 1.

The contribution of novel brain imaging techniques to understanding the neurobiology of mental retardation and developmental disabilities.

Studying the biological mechanisms underlying mental retardation and developmental disabilities (MR/DD) is a very complex task. This is due to the wide heterogeneity of etiologies and pathways that lead to MR/DD. Breakthroughs in genetics and molecular biology and the development of sophisticated brain imaging techniques during the last decades have facilitated the emergence of a field called Behavioral Neurogenetics.

The role of ventral frontostriatal circuitry in reward-based learning in humans.

This study examined changes in behavior and neural activity with reward learning. Using an event-related functional magnetic resonance imaging paradigm, we show that the nucleus accumbens, thalamus, and orbital frontal cortex are each sensitive to reward magnitude, with the accumbens showing the greatest discrimination between reward values. Mean reaction times were significantly faster to cues predicting the greatest reward and slower to cues predicting the smallest reward.

Contributions of the hippocampus and the striatum to simple association and frequency-based learning.

Using fMRI and a learning paradigm, this study examined the independent contributions of the hippocampus and striatum to simple association and frequency-based learning. We scanned 10 right-handed young adult subjects using a spiral in/out sequence on a GE 3.0 T scanner during performance of the learning paradigm.

Effects of spatial and temporal resolution for MR image-guided thermal ablation of prostate with transurethral ultrasound.

Purpose: To describe approaches for determining optimal spatial and temporal resolutions for the proton resonance frequency shift method of quantitative magnetic resonance temperature imaging (MRTI) guidance of transurethral ultrasonic prostate ablation.

Materials And Methods: Temperature distributions of two transurethral ultrasound applicators (90 degrees sectored tubular and planar arrays) for canine prostate ablation were measured via MRTI during in vivo sonication, and agree well with two-dimensional finite difference model simulations at various spatial resolutions. Measured temperature distributions establish the relevant signal-to-noise ratio (SNR) range for thermometry in an interventional MR scanner, and are reconstructed at different resolutions to compare resultant temperature measurements.

Motifs that mediate dendritic targeting in hippocampal neurons: a comparison with basolateral targeting signals.

One model for dendritic protein sorting in neurons is based on parallels with basolateral targeting in Madin-Darby Canine Kidney (MDCK) epithelial cells. The goal of this study was to further evaluate this model by analyzing the neuronal targeting of several proteins that contain well-defined basolateral sorting motifs. When we expressed FcRgammaII-B2 and CD44, two basolateral markers whose sorting depends on dihydrophobic motifs, they were unpolarized in hippocampal neurons.

Foundations of advanced magnetic resonance imaging.

During the past decade, major breakthroughs in magnetic resonance imaging (MRI) quality were made by means of quantum leaps in scanner hardware and pulse sequences. Some advanced MRI techniques have truly revolutionized the detection of disease states and MRI can now-within a few minutes-acquire important quantitative information noninvasively from an individual in any plane or volume at comparatively high resolution. This article provides an overview of the most common advanced MRI methods including diffusion MRI, perfusion MRI, functional MRI, and the strengths and weaknesses of MRI at high magnetic field strengths.

The neural bases of amusement and sadness: a comparison of block contrast and subject-specific emotion intensity regression approaches.

Neuroimaging studies have made substantial progress in elucidating the neural bases of emotion. However, few studies to date have directly addressed the subject-specific, time-varying nature of emotional responding. In the present study, we employed functional magnetic resonance imaging to examine the neural bases of two common emotions--amusement and sadness--using both (a) a stimulus-based block contrast approach and (b) a subject-specific regression analysis using continuous ratings of emotional intensity.

Distributed neural representation of expected value.

Anticipated reward magnitude and probability comprise dual components of expected value (EV), a cornerstone of economic and psychological theory. However, the neural mechanisms that compute EV have not been characterized. Using event-related functional magnetic resonance imaging, we examined neural activation as subjects anticipated monetary gains and losses that varied in magnitude and probability.

Breath holding reveals differences in fMRI BOLD signal in children and adults.

Application of fMRI to studies of cognitive development is of growing interest because of its sensitivity and non-invasive nature. However, interpretation of fMRI results in children is presently based on vascular dynamics that have been studied primarily in healthy adults. Comparison of the neurological basis of cognitive development is valid to the extent that the neurovascular responsiveness between children and adults is equal.

Contributions of amygdala and striatal activity in emotion regulation.

Background: Emotional information can facilitate or interfere with cognitive processes. In this study, we examined the influence of emotional information in biasing performance and the biological basis underlying this influence.

Methods: Ten human subjects (five female) were scanned with functional magnetic resonance imaging while performing an emotional go/nogo task.

Reflecting upon feelings: an fMRI study of neural systems supporting the attribution of emotion to self and other.

Understanding one's own and other individual's emotional states is essential for maintaining emotional equilibrium and strong social bonds. Although the neural substrates supporting ref lection upon one's own feelings have been investigated, no studies have directly examined attributions about the internal emotional states of others to determine whether common or distinct neural systems support these abilities. The present study sought to directly compare brain regions involved in judging one's own, as compared to another individual's, emotional state.

Mitigation of susceptibility-induced signal loss in neuroimaging using localized shim coils.

Correction of magnetic field distortions is essential for obtaining accurate brain blood-oxygen-level-dependent functional magnetic resonance imaging (fMRI) activation maps. The present work introduces an active shimming method that utilizes the magnetic field generated by resistive shim coils placed in the mouth to locally homogenize the magnetic field in the inferior portion of the frontal lobe, where the field is most seriously distorted. The shimming field can be optimized in situ patient by patient for the region of interest of the scanner operator's choice.

A needs index for mental health care in England based on updatable data.

Background: Mathematical models relating rates of mental health care use to population characteristics such as social deprivation are widely used in both planning and researching mental health services. The models currently in wide use in England are based on data mostly derived from the 10-yearly population censuses. These are perceived to be out of date many years before new census data are available for their replacement.

ICA-based procedures for removing ballistocardiogram artifacts from EEG data acquired in the MRI scanner.

Electroencephalogram (EEG) data acquired in the MRI scanner contains significant artifacts, one of the most prominent of which is ballistocardiogram (BCG) artifact. BCG artifacts are generated by movement of EEG electrodes inside the magnetic field due to pulsatile changes in blood flow tied to the cardiac cycle. Independent Component Analysis (ICA) is a statistical algorithm that is useful for removing artifacts that are linearly and independently mixed with signals of interest.