Locus coeruleus contrast and diffusivity metrics differentially relate to age and memory performance.

Neurocognitive aging researchers are increasingly focused on the locus coeruleus, a neuromodulatory brainstem structure that degrades with age. With this rapid growth, the field will benefit from consensus regarding which magnetic resonance imaging (MRI) metrics of locus coeruleus structure are most sensitive to age and cognition. To address this need, the current study acquired magnetization transfer- and diffusion-weighted MRI images in younger and older adults who also completed a free recall memory task.

Examining iron-related off-target binding effects of F-AV1451 PET in the cortex of Aβ+ individuals.

The presence of neurofibrillary tangles containing hyper-phosphorylated tau is a characteristic of Alzheimer's disease (AD) pathology. The positron emission tomography (PET) radioligand sensitive to tau neurofibrillary tangles (F-AV1451) also binds with iron. This off-target binding effect may be enhanced in older adults on the AD spectrum, particularly those with amyloid-positive biomarkers.

Nigral volume loss in prodromal, early, and moderate Parkinson's disease.

The loss of melanized neurons in the substantia nigra pars compacta (SNc) is a hallmark pathology in Parkinson's disease (PD). Melanized neurons in SNc can be visualized using magnetization transfer (MT) effects. Nigral volume was extracted in data acquired with a MT-prepared gradient echo sequence in 33 controls, 83 non-manifest carriers (42 LRRK2 and 41 GBA nonmanifest carriers), 65 prodromal hyposmic participants, 105 PD patients and 26 48-month PD patients from the Parkinson's Progressive Markers Initiative.

Locus coeruleus integrity predicts ease of attaining and maintaining neural states of high attentiveness.

The locus coeruleus (LC), a small subcortical structure in the brainstem, is the brain's principal source of norepinephrine. It plays a primary role in regulating stress, the sleep-wake cycle, and attention, and its degradation is associated with aging and neurodegenerative diseases associated with cognitive deficits (e.g.

In vivo detection of substantia nigra and locus coeruleus volume loss in Parkinson's disease using neuromelanin-sensitive MRI: Replication in two cohorts.

Patients with Parkinson's disease undergo a loss of melanized neurons in substantia nigra pars compacta and locus coeruleus. Very few studies have assessed substantia nigra pars compacta and locus coeruleus pathology in Parkinson's disease simultaneously with magnetic resonance imaging (MRI). Neuromelanin-sensitive MRI measures of substantia nigra pars compacta and locus coeruleus volume based on explicit magnetization transfer contrast have been shown to have high scan-rescan reproducibility in controls, but no study has replicated detection of Parkinson's disease-associated volume loss in substantia nigra pars compacta and locus coeruleus in multiple cohorts with the same methodology.

Nigral volumetric and microstructural measures in individuals with scans without evidence of dopaminergic deficit.

Introduction: Striatal dopamine transporter (DAT) imaging using I-ioflupane single photon positron emitted computed tomography (SPECT) (DaTScan, GE) identifies 5-20% of newly diagnosed Parkinson's disease (PD) subjects enrolling in clinical studies to have scans without evidence of dopaminergic deficit (SWEDD). These individuals meet diagnostic criteria for PD, but do not clinically progress as expected, and they are not believed to have neurodegenerative Parkinsonism. Inclusion of SWEDD participants in PD biomarker studies or therapeutic trials may therefore cause them to fail.

A Novel Hidden Markov Approach to Studying Dynamic Functional Connectivity States in Human Neuroimaging.

Hidden Markov models (HMMs) are a popular choice to extract and examine recurring patterns of activity or functional connectivity in neuroimaging data, both in terms of spatial patterns and their temporal progression. Although many diverse HMMs have been applied to neuroimaging data, most have defined states based on activity levels (intensity-based [IB] states) rather than patterns of functional connectivity between brain areas (connectivity-based states), which is problematic if we want to understand connectivity dynamics: IB states are unlikely to provide comprehensive information about dynamic connectivity patterns. We addressed this problem by introducing a new HMM that defines states based on full functional connectivity (FFC) profiles among brain regions.

Improving Between-Group Effect Size for Multi-Site Functional Connectivity Data via Site-Wise De-Meaning.

Multi-site functional MRI (fMRI) databases are becoming increasingly prevalent in the study of neurodevelopmental and psychiatric disorders. However, multi-site databases are known to introduce site effects that may confound neurobiological and measures such as functional connectivity (FC). Although studies have been conducted to mitigate site effects, these methods often result in reduced effect size in FC comparisons between controls and patients.

Impact of Locus Coeruleus and Its Projections on Memory and Aging.

Locus coeruleus (LC) is the primary source of norepinephrine to the brain and its efferent projections innervate many brain regions, including the thalamus. The LC degrades with normal aging, but not much is known regarding whether its structural connectivity evolves with age or predicts aspects of cognition. Here, we use high-resolution diffusion tensor imaging-based tractography to examine structural connectivity between LC and the thalamus in younger and older adults.

Subtyping Autism Spectrum Disorder Via Joint Modeling of Clinical and Connectomic Profiles.

Autism spectrum disorder (ASD) is a highly heterogeneous developmental disorder with diverse clinical manifestations. Neuroimaging studies have explored functional connectivity (FC) of ASD through resting-state functional magnetic resonance imaging studies; however, the findings have remained inconsistent, thus reflecting the possibility of multiple subtypes. Identification of the relationship between clinical symptoms and FC measures may help clarify the inconsistencies in earlier findings and advance our understanding of ASD subtypes.

Graph convolutional network for fMRI analysis based on connectivity neighborhood.

There have been successful applications of deep learning to functional magnetic resonance imaging (fMRI), where fMRI data were mostly considered to be structured grids, and spatial features from Euclidean neighbors were usually extracted by the convolutional neural networks (CNNs) in the computer vision field. Recently, CNN has been extended to graph data and demonstrated superior performance. Here, we define graphs based on functional connectivity and present a connectivity-based graph convolutional network (cGCN) architecture for fMRI analysis.

Context-dependent dynamic functional connectivity alteration of lateral occipital cortex in schizophrenia.

Schizophrenia has long been associated with dysfunction in visual perception. One important region underlying this is lateral occipital cortex (LOC), a mid-level visual region critical for object recognition. Although LOC of patients has exhibited structural and functional abnormalities in MR brain imaging studies, how it interacts with other networks over time under rest and with task demands remains to be clarified.

Application of Convolutional Recurrent Neural Network for Individual Recognition Based on Resting State fMRI Data.

In most task and resting state fMRI studies, a group consensus is often sought, where individual variability is considered a nuisance. None the less, biological variability is an important factor that cannot be ignored and is gaining more attention in the field. One recent development is the individual identification based on static functional connectome.

Increased inflammation and brain glutamate define a subtype of depression with decreased regional homogeneity, impaired network integrity, and anhedonia.

Combined increases in peripheral inflammation and brain glutamate may identify a subtype of depression with distinct neuroimaging signatures. Two contrasting subgroups of depressed subjects-with and without combined elevations in plasma C-reactive protein (CRP) and basal ganglia glutamate (high and low CRP-Glu, respectively) were identified by hierarchical clustering using plasma CRP (indexing peripheral inflammation) and magnetic resonance spectroscopy (MRS)-based measurement of left basal ganglia glutamate. High CRP-Glu group status was associated with greater severity of anhedonia and cognitive and motor slowing.

Neuromelanin detection by magnetic resonance imaging (MRI) and its promise as a biomarker for Parkinson's disease.

The diagnosis of Parkinson's disease (PD) occurs after pathogenesis is advanced and many substantia nigra (SN) dopamine neurons have already died. Now that therapies to block this neuronal loss are under development, it is imperative that the disease be diagnosed at earlier stages and that the response to therapies is monitored. Recent studies suggest this can be accomplished by magnetic resonance imaging (MRI) detection of neuromelanin (NM), the characteristic pigment of SN dopaminergic, and locus coeruleus (LC) noradrenergic neurons.

Investigating Brain Connectomic Alterations in Autism Using the Reproducibility of Independent Components Derived from Resting State Functional MRI Data.

Autism is a developmental disorder that is currently diagnosed using behavioral tests which can be subjective. Consequently, objective non-invasive imaging biomarkers of Autism are being actively researched. The common theme emerging from previous functional magnetic resonance imaging (fMRI) studies is that Autism is characterized by alterations of fMRI-derived functional connections in certain brain networks which may provide a biomarker for objective diagnosis.

Improved Neuroimaging Atlas of the Dentate Nucleus.

The dentate nucleus (DN) of the cerebellum is the major output nucleus of the cerebellum and is rich in iron. Quantitative susceptibility mapping (QSM) provides better iron-sensitive MRI contrast to delineate the boundary of the DN than either T-weighted images or susceptibility-weighted images. Prior DN atlases used T-weighted or susceptibility-weighted images to create DN atlases.

A New Generation of Brain-Computer Interfaces Driven by Discovery of Latent EEG-fMRI Linkages Using Tensor Decomposition.

A Brain-Computer Interface (BCI) is a setup permitting the control of external devices by decoding brain activity. Electroencephalography (EEG) has been extensively used for decoding brain activity since it is non-invasive, cheap, portable, and has high temporal resolution to allow real-time operation. Due to its poor spatial specificity, BCIs based on EEG can require extensive training and multiple trials to decode brain activity (consequently slowing down the operation of the BCI).

In vivo detection of lateral-ventral tier nigral degeneration in Parkinson's disease.

The objective of this study was to measure neuromelanin-sensitive MRI contrast changes in the lateral-ventral tier of substantia nigra pars compacta in Parkinson's disease (PD). Histopathological studies of PD have demonstrated both massive loss of melanized dopamine neurons and iron accumulation in the substantia nigra pars compacta. Neurodegeneration is most profound in the lateral-ventral tier of this structure.

Parkinson's disease-related increase of T2*-weighted hypointensity in substantia nigra pars compacta.

Background: In PD, at the time of diagnosis, approximately 50% of melanized dopaminergic neurons in SNpc have died, yet ongoing neuronal death and neuromelanin release with associated neuroinflammation and microglial activation continue, as does local iron accumulation. Previous studies investigating nigral iron accumulation used T / T2*-weighted contrasts to define the regions of interest in the SN. Given that T / T2*-weighted contrasts lack sensitivity to neuromelanin and thereby SNpc, neuromelanin-sensitive MRI provides better delineation of SNpc and allows the examination of increased iron deposition in SNpc more specifically and accurately.

A Functional Magnetic Resonance Imaging Study of Head Movements in Cervical Dystonia.

Cervical dystonia (CD) is a neurological disorder characterized by abnormal movements and postures of the head. The brain regions responsible for these abnormal movements are not well understood, because most imaging techniques for assessing regional brain activity cannot be used when the head is moving. Recently, we mapped brain activation in healthy individuals using functional magnetic resonance imaging during isometric head rotation, when muscle contractions occur without actual head movements.

Protein MRI contrast agent with unprecedented metal selectivity and sensitivity for liver cancer imaging.

With available MRI techniques, primary and metastatic liver cancers that are associated with high mortality rates and poor treatment responses are only diagnosed at late stages, due to the lack of highly sensitive contrast agents without Gd(3+) toxicity. We have developed a protein contrast agent (ProCA32) that exhibits high stability for Gd(3+) and a 10(11)-fold greater selectivity for Gd(3+) over Zn(2+) compared with existing contrast agents. ProCA32, modified from parvalbumin, possesses high relaxivities (r1/r2: 66.

Age-related increases in basal ganglia glutamate are associated with TNF, reduced motivation and decreased psychomotor speed during IFN-alpha treatment: Preliminary findings.

Inflammation-induced alterations in central nervous system (CNS) metabolism have focused on glutamate. At excessive concentrations, glutamate is toxic to glia and neurons, and inflammatory cytokines have been shown to influence glutamate turnover by blocking glutamate reuptake and increasing glutamate release. Increased glutamate has also been found in depression, a disorder associated with increased inflammation.

A bacterial gene, mms6, as a new reporter gene for magnetic resonance imaging of mammalian cells.

Magnetic resonance imaging (MRI) allows for noninvasive, deep tissue imaging with high spatial resolution, making it an attractive modality for in vivo cellular imaging. Since reporter genes can generate magnetic resonance (MR) contrast based on molecular activity, they offer a potentially powerful tool for cellular imaging. The mms6 gene was originally identified in magnetotactic bacteria (MTB), which is known to play a key role in magnetic crystal formation.

Connectomic profiles for individualized resting state networks and regions of interest.

Functional connectivity analysis of human brain resting state functional magnetic resonance imaging (rsfMRI) data and resultant functional networks, or RSNs, have drawn increasing interest in both research and clinical applications. A fundamental yet challenging problem is to identify distinct functional regions or regions of interest (ROIs) that have accurate functional correspondence across subjects. This article presents an algorithmic framework to identify ROIs of common RSNs at the individual level.