Deficient activity in the neural systems that mediate self-regulatory control in bulimia nervosa.

Context: Disturbances in neural systems that mediate voluntary self-regulatory processes may contribute to bulimia nervosa (BN) by releasing feeding behaviors from regulatory control.

Objective: To study the functional activity in neural circuits that subserve self-regulatory control in women with BN.

Design: We compared functional magnetic resonance imaging blood oxygenation level-dependent responses in patients with BN with healthy controls during performance of the Simon Spatial Incompatibility task.

Computational and experimental optimization of a double-tuned (1)H/(31)P four-ring birdcage head coil for MRS at 3T.

Purpose: To optimize the homogeneity and efficiency of the B(1) magnetic field of a four-ring birdcage head coil that is double-tuned at the Larmor frequencies of both (31)P and (1)H and optimized to acquire magnetic resonance spectroscopy (MRS) data at 3T for the study of infants.

Materials And Methods: We developed a finite difference time domain (FDTD) tool in-house to iteratively compute and seek the range of geometric and electromagnetic parameters of a dual-tuned, four-ring birdcage coil that would produce the desired resonance patterns, optimize homogeneity of the B(1)-field, and maximize efficiency of the coil. To demonstrate the validity of our computational results, we constructed three RF coils: one dual-tuned coil that was based on the calculated optimized parameters and two single-tuned coils that had dimensions similar to those of the dual-tuned coil, but tuned at the Larmor frequencies of both (31)P and (1)H, respectively.

A Tc-99m SPECT study of regional cerebral blood flow in patients with transient global amnesia.

Objectives: This study aimed to determine whether regional cerebral blood flow (rCBF) is abnormal in patients who have Transient Global Amnesia (TGA).

Methods: We obtained noninvasive rCBF measurements using Tc-99m-ethyl cysteinate diamer Single Photon Emission Computed Tomography (SPECT) in 7 patients diagnosed with TGA within 4 days of onset of the amnestic episode while the patients were still symptomatic and in 17 age-matched healthy control subjects. We assessed memory functioning using the Hopkins's Verbal Learning Test (HVLT) and Statistical Parametric Mapping to compare rCBF across diagnostic groups.

EEG functional connectivity in term age extremely low birth weight infants.

Objective: The hypothesis is tested that electrocortical functional connectivity (quantified by coherence) of extremely low birth weight (ELBW) infants, measured at term post-menstrual age, has regional differences from that of full term infants.

Methods: 128 lead EEG data were collected during sleep from 8 ELBW infants with normal head ultrasound exams and 8 typically developing full term infants. Regional spectral power and coherence were calculated.

Cranial computed tomographic findings in a large group of children with drowning: diagnostic, prognostic, and forensic implications.

Objectives: The primary aim of this study is to better define both the type and incidence of cranial computed tomography (CT) abnormalities in children following submersion injury.

Design: This is a retrospective chart review; patients were selected from a drowning registry that extends from January 1989 to April 2006.

Setting: Children's Hospital, San Diego.

The neural bases of obsessive-compulsive disorder in children and adults.

Functional imaging studies have reported with remarkable consistency hyperactivity in the orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), and caudate nucleus of patients with obsessive-compulsive disorder (OCD). These findings have often been interpreted as evidence that abnormalities in cortico-basal ganglia-thalamo-cortical loops involving the OFC and ACC are causally related to OCD. This interpretation remains controversial, however, because such hyperactivity may represent either a cause or a consequence of the symptoms.

The ellipsoidal area ratio: an alternative anisotropy index for diffusion tensor imaging.

In the processing and analysis of diffusion tensor imaging (DTI) data, certain predefined morphological features of diffusion tensors are often represented as simplified scalar indices, termed diffusion anisotropy indices (DAIs). When comparing tensor morphologies across differing voxels of an image, or across corresponding voxels in different images, DAIs are mathematically and statistically more tractable than are the full tensors, which are probabilistic ellipsoids consisting of three orthogonal vectors that each has a direction and an associated scalar magnitude. We have developed a new DAI, the "ellipsoidal area ratio" (EAR), to represent the degree of anisotropy in the morphological features of a diffusion tensor.

Neuroimaging studies of normal brain development and their relevance for understanding childhood neuropsychiatric disorders.

Objective: To review the maturational events that occur during prenatal and postnatal brain development and to present neuroimaging findings from studies of healthy individuals that identify the trajectories of normal brain development.

Method: Histological and postmortem findings of early brain development are presented, followed by a discussion of anatomical, diffusion tensor, proton spectroscopy, and functional imaging findings from studies of healthy individuals, with special emphasis on longitudinal data.

Results: Early brain development occurs through a sequence of major events, beginning with the formation of the neural tube and ending with myelination.

Statistical Modelling of Brain Morphological Measures Within Family Pedigrees.

Large, family-based imaging studies can provide a better understanding of the interactions of environmental and genetic influences on brain structure and function. The interpretation of imaging data from large family studies, however, has been hindered by the paucity of well-developed statistical tools for that permit the analysis of complex imaging data together with behavioral and clinical data. In this paper, we propose to use two methods for these analyses.

A note on the validity of statistical bootstrapping for estimating the uncertainty of tensor parameters in diffusion tensor images.

Diffusion tensors are estimated from magnetic resonance images (MRIs) that are diffusion-weighted, and those images inherently contain noise. Therefore, noise in the diffusion-weighted images produces uncertainty in estimation of the tensors and their derived parameters, which include eigenvalues, eigenvectors, and the trajectories of fiber pathways that are reconstructed from those eigenvalues and eigenvectors. Although repetition and wild bootstrap methods have been widely used to quantify the uncertainty of diffusion tensors and their derived parameters, we currently lack theoretical derivations that would validate the use of these two bootstrap methods for the estimation of statistical parameters of tensors in the presence of noise.

Exploited species impacts on trophic linkages along reef-seagrass interfaces in the Florida Keys.

The removal of fish biomass by extensive commercial and recreational fishing has been hypothesized to drastically alter the strength of trophic linkages among adjacent habitats. We evaluated the effects of removing predatory fishes on trophic transfers between coral reefs and adjacent seagrass meadows by comparing fish community structure, grazing intensity, and invertebrate predation potential in predator-rich no-take sites and nearby predator-poor fished sites in the Florida Keys (USA). Exploited fishes were more abundant at the no-take sites than at the fished sites.

Neuropsychological near normality and brain structure abnormality in schizophrenia.

Objective: Cognitive deficits are prominent in schizophrenia. Patients have an average score one standard deviation below normal on a broad spectrum of cognitive tests. It has been repeatedly noted, however, that 20%-25% of patients differ from this general pattern and score close to normal on neuropsychological testing.

The risks and benefits of searching for incidental findings in MRI research scans.

We weigh the presumed benefits of routinely searching all research scans for incidental findings (IFs) against its substantial risks, including false-positive and false-negative findings, and the possibility of triggering unnecessary, costly evaluations and perhaps harmful treatments. We argue that routinely searching for IFs may not maximize benefits and minimize risks to participants.

Thinning of sensorimotor cortices in children with Tourette syndrome.

The basal ganglia portions of cortico-striato-thalamo-cortical (CSTC) circuits have consistently been implicated in the pathogenesis of Tourette syndrome, whereas motor and sensorimotor cortices in these circuits have been relatively overlooked. Using magnetic resonance imaging, we detected cortical thinning in frontal and parietal lobes in groups of Tourette syndrome children relative to controls. This thinning was most prominent in ventral portions of the sensory and motor homunculi that control the facial, orolingual and laryngeal musculature that is commonly involved in tic symptoms.

An affective circumplex model of neural systems subserving valence, arousal, and cognitive overlay during the appraisal of emotional faces.

Increasing evidence supports the existence of distinct neural systems that subserve two dimensions of affect--arousal and valence. Ten adult participants underwent functional magnetic resonance imaging during which they were presented a range of standardized faces and then asked, during the scan, to rate the emotional expressions of the faces along the dimensions of arousal and valence. Lower ratings of arousal accompanied greater activity in the amygdala complex, cerebellum, dorsal pons, and right medial prefrontal cortex (mPFC).

The neurophysiological bases of emotion: An fMRI study of the affective circumplex using emotion-denoting words.

Objective: We aimed to study the neural processing of emotion-denoting words based on a circumplex model of affect, which posits that all emotions can be described as a linear combination of two neurophysiological dimensions, valence and arousal. Based on the circumplex model, we predicted a linear relationship between neural activity and incremental changes in these two affective dimensions.

Methods: Using functional magnetic resonance imaging, we assessed in 10 subjects the correlations of BOLD (blood oxygen level dependent) signal with ratings of valence and arousal during the presentation of emotion-denoting words.

Seamless warping of diffusion tensor fields.

To warp diffusion tensor fields accurately, tensors must be reoriented in the space to which the tensors are warped based on both the local deformation field and the orientation of the underlying fibers in the original image. Existing algorithms for warping tensors typically use forward mapping deformations in an attempt to ensure that the local deformations in the warped image remains true to the orientation of the underlying fibers; forward mapping, however, can also create "seams" or gaps and consequently artifacts in the warped image by failing to define accurately the voxels in the template space where the magnitude of the deformation is large (e.g.

Study of the development of fetal baboon brain using magnetic resonance imaging at 3 Tesla.

Direct observational data on the development of the brains of human and nonhuman primates is on remarkably scant, and most of our understanding of primate brain development is extrapolated from findings in rodent models. Magnetic resonance imaging (MRI) is a promising tool for the noninvasive, longitudinal study of the developing primate brain. We devised a protocol to scan pregnant baboons serially at 3 T for up to 3 h per session.

Inhibitory deficits in Tourette's syndrome.

A developmental approach to the study of psychopathology can broaden understanding of a wide variety of complex psychological disorders. This article reviews research on Tourette's syndrome (TS), a developmental disorder characterized by unwanted motor and vocal tics. Over the past decade, knowledge of the neurobiology and pathophysiology of TS has progressed rapidly.

Partner-matching for the automated identification of reproducible ICA components from fMRI datasets: algorithm and validation.

The analysis of functional magnetic resonance imaging (fMRI) data is complicated by the presence of a mixture of many sources of signal and noise. Independent component analysis (ICA) can separate these mixtures into independent components, each of which contains maximal information from a single, independent source of signal, whether from noise or from a discrete physiological or neural system. ICA typically generates a large number of components for each subject imaged, however, and therefore it generates a vast number of components across all of the subjects imaged in an fMRI dataset.

Selective biasing of a specific bistable-figure percept involves fMRI signal changes in frontostriatal circuits: a step toward unlocking the neural correlates of top-down control and self-regulation.

Attention, suggestion, context and expectation can all exert top-down influence on bottom-up processes (e.g., stimulus-driven mechanisms).

Voxel-wise comparisons of the morphology of diffusion tensors across groups of experimental subjects.

Water molecules in the brain diffuse preferentially along the fiber tracts within white matter that form the anatomical connections across spatially distant brain regions. A diffusion tensor (DT) is a probabilistic ellipsoid composed of three orthogonal vectors, each having a direction and an associated scalar magnitude, that represent the probability of water molecules diffusing in each of those directions. The 3D morphologies of DTs can be compared across groups of subjects to reveal disruptions in structural organization and neuroanatomical connectivity of the brains of persons with various neuropsychiatric illnesses.