Lead Acetate Exposure and Cerebral Amyloid Accumulation: Mechanistic Evaluations in APP/PS1 Mice.

Background: The role of environmental factors in Alzheimer's disease (AD) pathogenesis remains elusive. Mounting evidence suggests that acute and past exposure to the environmental toxicant lead (Pb) is associated with longitudinal decline in cognitive function, brain atrophy, and greater brain -amyloid () deposition. However, the nature of Pb-induced amyloid deposition and how it contributes to AD development remain unclear.

Demyelination and impaired oligodendrogenesis in the corpus callosum following lead exposure.

The corpus callosum is an oligodendrocyte-enriched brain region, replenished by newborn oligodendrocytes from oligodendrocyte progenitor cells (OPCs) in subventricular zone (SVZ). Lead (Pb) exposure has been associated with multiple sclerosis, a disease characterized by the loss of oligodendrocytes. This study aimed to investigate the effects of Pb exposure on oligodendrogenesis in SVZ and myelination in the corpus callosum.

Recurrent inhibition refines mental templates to optimize perceptual decisions.

Translating sensory inputs to perceptual decisions relies on building internal representations of features critical for solving complex tasks. Yet, we still lack a mechanistic account of how the brain forms these mental templates of task-relevant features to optimize decision-making. Here, we provide evidence for recurrent inhibition: an experience-dependent plasticity mechanism that refines mental templates by enhancing γ-aminobutyric acid (GABA)-mediated (GABAergic) inhibition and recurrent processing in superficial visual cortex layers.

An Accelerated PETALUTE MRI Sequence for In Vivo Quantification of Sodium Content in Human Articular Cartilage at 3T.

In this work, we demonstrate the sodium magnetic resonance imaging (MRI) capabilities of a three-dimensional (3D) dual-echo ultrashort echo time (UTE) sequence with a novel rosette petal trajectory (PETALUTE), in comparison to the 3D density-adapted (DA) radial spokes UTE sequence. We scanned five healthy subjects using a 3D dual-echo PETALUTE acquisition and two comparable implementations of 3D DA-radial spokes acquisitions, one matching the number of k-space projections (Radial-Matched Trajectories) and the other matching the total number of samples (Radial-Matched Samples) acquired in k-space. The PETALUTE acquisition enabled equivalent sodium quantification in articular cartilage volumes of interest (168.

Effects of ebselen addition on emotional processing and brain neurochemistry in depressed patients unresponsive to antidepressant medication.

Lithium is an effective augmenting agent for depressed patients with inadequate response to standard antidepressant therapy, but numerous adverse effects limit its use. We previously reported that a lithium-mimetic agent, ebselen, promoted a positive emotional bias-an indicator of potential antidepressant activity in healthy participants. We therefore aimed to investigate the effects of short-term ebselen treatment on emotional processing and brain neurochemistry in depressed patients with inadequate response to standard antidepressants.

Test-Retest Reproducibility of Reduced-Field-of-View Density-Weighted CRT MRSI at 3T.

Quantifying an imaging modality's ability to reproduce results is important for establishing its utility. In magnetic resonance spectroscopic imaging (MRSI), new acquisition protocols are regularly introduced which improve upon their precursors with respect to signal-to-noise ratio (SNR), total acquisition duration, and nominal voxel resolution. This study has quantified the within-subject and between-subject reproducibility of one such new protocol (reduced-field-of-view density-weighted concentric ring trajectory (rFOV-DW-CRT) MRSI) by calculating the coefficient of variance of data acquired from a test-retest experiment.

3D ultra-short echo time P-MRSI with rosette k-space pattern: Feasibility and comparison with conventional weighted CSI.

Phosphorus-31 magnetic resonance spectroscopic imaging (P-MRSI) provides valuable non-invasive information on tissue metabolism but is burdened by poor sensitivity and prolonged scan duration. Ultra-short echo time (UTE) acquisitions minimize signal loss when probing signals with relatively short spin-spin relaxation time (T), while also preventing first-order dephasing. Here, a three-dimensional (3D) UTE sequence with a rosette k-space trajectory is applied to P-MRSI at 3T.

Dissecting the chain of information processing and its interplay with neurochemicals and fluid intelligence across development.

Previous research has highlighted the role of glutamate and gamma-aminobutyric acid (GABA) in perceptual, cognitive, and motor tasks. However, the exact involvement of these neurochemical mechanisms in the chain of information processing, and across human development, is unclear. In a cross-sectional longitudinal design, we used a computational approach to dissociate cognitive, decision, and visuomotor processing in 293 individuals spanning early childhood to adulthood.

Ensemble Learning for Breast Cancer Lesion Classification: A Pilot Validation Using Correlated Spectroscopic Imaging and Diffusion-Weighted Imaging.

The main objective of this work was to evaluate the application of individual and ensemble machine learning models to classify malignant and benign breast masses using features from two-dimensional (2D) correlated spectroscopy spectra extracted from five-dimensional echo-planar correlated spectroscopic imaging (5D EP-COSI) and diffusion-weighted imaging (DWI). Twenty-four different metabolite and lipid ratios with respect to diagonal fat peaks (1.4 ppm, 5.

Event-related functional magnetic resonance spectroscopy.

Proton-Magnetic Resonance Spectroscopy (MRS) is a non-invasive brain imaging technique used to measure the concentration of different neurochemicals. "Single-voxel" MRS data is typically acquired across several minutes, before individual transients are averaged through time to give a measurement of neurochemical concentrations. However, this approach is not sensitive to more rapid temporal dynamics of neurochemicals, including those that reflect functional changes in neural computation relevant to perception, cognition, motor control and ultimately behaviour.

Repeated unilateral handgrip contractions alter functional connectivity and improve contralateral limb response times.

In humans, motor learning is underpinned by changes in sensorimotor network functional connectivity (FC). Unilateral contractions increase FC in the ipsilateral primary motor cortex (M1) and supplementary motor area (SMA); areas involved in motor planning and execution of the contralateral hand. Therefore, unilateral contractions are a promising approach to augment motor performance in the contralateral hand.

Microstructural and neurochemical plasticity mechanisms interact to enhance human perceptual decision-making.

Experience and training are known to boost our skills and mold the brain's organization and function. Yet, structural plasticity and functional neurotransmission are typically studied at different scales (large-scale networks, local circuits), limiting our understanding of the adaptive interactions that support learning of complex cognitive skills in the adult brain. Here, we employ multimodal brain imaging to investigate the link between microstructural (myelination) and neurochemical (GABAergic) plasticity for decision-making.

High-resolution 3D ultra-short echo time MRI with Rosette k-space pattern for brain iron content mapping.

Background: The iron concentration increases during normal brain development and is identified as a risk factor for many neurodegenerative diseases, it is vital to monitor iron content in the brain non-invasively.

Purpose: This study aimed to quantify in vivo brain iron concentration with a 3D rosette-based ultra-short echo time (UTE) magnetic resonance imaging (MRI) sequence.

Methods: A cylindrical phantom containing nine vials of different iron concentrations (iron (II) chloride) from 0.

Cerebellar GABA Change during Visuomotor Adaptation Relates to Adaptation Performance and Cerebellar Network Connectivity: A Magnetic Resonance Spectroscopic Imaging Study.

Motor adaptation is crucial for performing accurate movements in a changing environment and relies on the cerebellum. Although cerebellar involvement has been well characterized, the neurochemical changes in the cerebellum underpinning human motor adaptation remain unknown. We used a novel magnetic resonance spectroscopic imaging (MRSI) technique to measure changes in the inhibitory neurotransmitter GABA in the human cerebellum during visuomotor adaptation.

Characterizing Off-center MRI with ZTE.

Purpose: To maximize acquisition bandwidth in zero echo time (ZTE) sequences, readout gradients are already switched on during the RF pulse, creating unwanted slice selectivity. The resulting image distortions are amplified especially when the anatomy of interest is not located at the isocenter. We aim to characterize off-center ZTE MRI of extremities such as the shoulder, knee, and hip, adjusting the carrier frequency of the RF pulse excitation for each TR.

Ultra-short T components imaging of the whole brain using 3D dual-echo UTE MRI with rosette k-space pattern.

Purpose: This study aimed to develop a new 3D dual-echo rosette k-space trajectory, specifically designed for UTE MRI applications. The imaging of the ultra-short transverse relaxation time (uT ) of brain was acquired to test the performance of the proposed UTE sequence.

Theory And Methods: The rosette trajectory was developed based on rotations of a "petal-like" pattern in the k -k plane, with oscillated extensions in the k -direction for 3D coverage.

NIfTI-MRS: A standard data format for magnetic resonance spectroscopy.

Purpose: Multiple data formats in the MRS community currently hinder data sharing and integration. NIfTI-MRS is proposed as a standard spectroscopy data format, implemented as an extension to the Neuroimaging informatics technology initiative (NIfTI) format. This standardized format can facilitate data sharing and algorithm development as well as ease integration of MRS analysis alongside other imaging modalities.

Relapsing antibody-negative patients with features of neuromyelitis optica spectrum disorders: Differences in -acetylaspartate level in the cervical spinal cord indicate distinct underlying processes.

Background: Due to lack of biomarkers, antibody-negative patients with features of neuromyelitis optica spectrum disorders (NMOSD) are among the most challenging to diagnose and treat. Using unsupervised clustering, we recently identified 'MS-like', 'spinal MS-like', 'classic NMOSD-like' and 'NMOSD-like with brain involvement' subgroups in this cohort.

Objective: We used magnetic resonance spectroscopy (MRS) to examine differences in the level of key metabolites in the spinal cord between the four identified subgroups.

In Vivo Renal Lipid Quantification by Accelerated Magnetic Resonance Spectroscopic Imaging at 3T: Feasibility and Reliability Study.

A reliable and practical renal-lipid quantification and imaging method is needed. Here, the feasibility of an accelerated MRSI method to map renal fat fractions (FF) at 3T and its repeatability were investigated. A 2D density-weighted concentric-ring-trajectory MRSI was used for accelerating the acquisition of 48 × 48 voxels (each of 0.

Malleability of the cortical hand map following a finger nerve block.

Electrophysiological studies in monkeys show that finger amputation triggers local remapping within the deprived primary somatosensory cortex (S1). Human neuroimaging research, however, shows persistent S1 representation of the missing hand's fingers, even decades after amputation. Here, we explore whether this apparent contradiction stems from underestimating the distributed peripheral and central representation of fingers in the hand map.

Neurochemical and functional interactions for improved perceptual decisions through training.

Learning and experience are known to improve our ability to make perceptual decisions. Yet, our understanding of the brain mechanisms that support improved perceptual decisions through training remains limited. Here, we test the neurochemical and functional interactions that support learning for perceptual decisions in the context of an orientation identification task.