Choroidal blood flow decreases with age: an MRI study.

Purpose: To verify that a visual fixation protocol with cued eye blinks achieves sufficient stability for magnetic resonance imaging (MRI) blood-flow measurements and to determine if choroidal blood flow (ChBF) changes with age in humans.

Methods: The visual fixation stability achievable during an MRI scan was measured in five normal subjects using an eye-tracking camera outside the MRI scanner. Subjects were instructed to blink immediately after recorded MRI sound cues but to otherwise maintain stable visual fixation on a small target.

Effective connectivity associated with auditory error detection in musicians with absolute pitch.

It is advantageous to study a wide range of vocal abilities in order to fully understand how vocal control measures vary across the full spectrum. Individuals with absolute pitch (AP) are able to assign a verbal label to musical notes and have enhanced abilities in pitch identification without reliance on an external referent. In this study we used dynamic causal modeling (DCM) to model effective connectivity of ERP responses to pitch perturbation in voice auditory feedback in musicians with relative pitch (RP), AP, and non-musician controls.

Brain high-energy phosphates and creatine kinase synthesis rate under graded isoflurane anesthesia: An in vivo (31) P magnetization transfer study at 11.7 tesla.

Purpose: The creatine kinase rate of metabolic adenosine triphosphate (ATP) synthesis is an important metabolic parameter but is challenging to measure in vivo due to limited signal-to-noise ratio and long measurement time.

Theory And Methods: This study reports the implementation of an accelerated (31) P Four Angle Saturation Transfer (FAST) method to measure the forward creatine kinase (CK) rate of ATP synthesis. Along with a high-field scanner (11.

Quantitative cerebral blood flow measurements using MRI.

Magnetic resonance imaging can be utilized as a quantitative and noninvasive method to image cerebral blood flow. The two most common techniques used to detect cerebral blood flow are dynamic susceptibility contrast (DSC) perfusion MRI and arterial spin labeling perfusion MRI. Herein we describe the use of these two techniques to measure cerebral blood flow in rodents, including methods, analysis, and important considerations when utilizing these techniques.

Methylene blue is neuroprotective against mild traumatic brain injury.

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. Methylene blue (MB) has known energy-enhancing and antioxidant properties. This study tested the hypothesis that MB treatment reduces lesion volume and behavioral deficits in a rat model of mild TBI.

Morphosyntax can modulate the N400 component: event related potentials to gender-marked post-nominal adjectives.

Event-related potential studies of grammatical gender agreement often report a left anterior negativity (LAN) when agreement violations occur. Some studies have shown that during sentence comprehension gender violations can also interact with semantic processing to modulate a negativity associated with processing meaning - the N400. Given that the LAN and N400 overlap in time, they are identified by their scalp distributions and purported functional roles.

Left-hemisphere activation is associated with enhanced vocal pitch error detection in musicians with absolute pitch.

The ability to process auditory feedback for vocal pitch control is crucial during speaking and singing. Previous studies have suggested that musicians with absolute pitch (AP) develop specialized left-hemisphere mechanisms for pitch processing. The present study adopted an auditory feedback pitch perturbation paradigm combined with ERP recordings to test the hypothesis whether the neural mechanisms of the left-hemisphere enhance vocal pitch error detection and control in AP musicians compared with relative pitch (RP) musicians and non-musicians (NM).

ICA model order selection of task co-activation networks.

Independent component analysis (ICA) has become a widely used method for extracting functional networks in the brain during rest and task. Historically, preferred ICA dimensionality has widely varied within the neuroimaging community, but typically varies between 20 and 100 components. This can be problematic when comparing results across multiple studies because of the impact ICA dimensionality has on the topology of its resultant components.

FMRI of deep brain stimulation at the rat ventral posteromedial thalamus.

Background: Functional magnetic resonance imaging (fMRI) of deep brain stimulation (DBS) has potentials to reveal neuroanatomical connectivity of a specific brain region in vivo.

Objective: This study aimed to demonstrate frequency and amplitude tunings of the thalamocortical tract using DBS fMRI at the rat ventral posteromedial thalamus.

Methods: Blood oxygenation level dependent (BOLD) fMRI data were acquired in a total of twelve rats at a high-field 11.

Neuroprotective efficacy of methylene blue in ischemic stroke: an MRI study.

Methylene blue (MB) has unique energy-enhancing and antioxidant properties and is FDA-approved drug to treat methemoglobinemia and cyanide poisoning. This study evaluated the efficacy of MB to treat ischemic stroke in rats using longitudinal MRI and behavioral measures. Rats were subjected to 60-minute middle-cerebral-artery occlusion.

MRI under hyperbaric air and oxygen: effects on local magnetic field and relaxation times.

Purpose: Hyperbaric oxygen therapy has shown efficacies in the treatment of a number of diseases. The goal of this study was to develop a rodent hyperbaric chamber for MRI studies and to investigate the effects of hyperbaric air and hyperbaric oxygen on local magnetic field (B0 ) and MRI relaxation parameters in the rat brain.

Methods: A hyperbaric chamber, constructed to fit inside an animal MRI scanner, was pressurized with air to four atmospheres, while oxygen was delivered locally via nose cone.

Comparison of retinal and cerebral blood flow between continuous arterial spin labeling MRI and fluorescent microsphere techniques.

Purpose: To compare basal retinal and cerebral blood flow (BF) values using continuous arterial spin labeling (CASL) MRI and fluorescent microspheres.

Materials And Methods: A total of 41 animals were used. BF was measured using an established microsphere technique (a mixture of 2.

Neural network of cognitive emotion regulation--an ALE meta-analysis and MACM analysis.

Cognitive regulation of emotions is a fundamental prerequisite for intact social functioning which impacts on both well being and psychopathology. The neural underpinnings of this process have been studied intensively in recent years, without, however, a general consensus. We here quantitatively summarize the published literature on cognitive emotion regulation using activation likelihood estimation in fMRI and PET (23 studies/479 subjects).

Bimodal Imaging Using Neodymium Doped Gadolinium Fluoride Nanocrystals with Near-Infrared to Near-Infrared Downconversion Luminescence and Magnetic Resonance Properties.

Here we report the synthesis, characterization and application of a multifunctional surface functionalized GdF:Nd nanophosphor that exhibits efficient near infrared (NIR) fluorescence as well as magnetic properties, which can be utilized for bimodal imaging in medical applications. The nanoparticles are small with an average size of 5 nm and form stable colloids that last for several weeks without settling, enabling the use for several biomedical and photonic applications. Their excellent NIR properties, such as nearly 11 % quantum yield of the 1064 nm emission, make them ideal contrast agents and biomarkers for and NIR optical bioimaging.

Neural bases of food perception: coordinate-based meta-analyses of neuroimaging studies in multiple modalities.

Objective: The purpose of this study was to compare the results of the three food-cue paradigms most commonly used for functional neuroimaging studies to determine: i) commonalities and differences in the neural response patterns by paradigm and ii) the relative robustness and reliability of responses to each paradigm.

Methods: Functional magnetic resonance imaging studies using standardized stereotactic coordinates to report brain responses to food cues were identified using online databases. Studies were grouped by food-cue modality as: i) tastes (8 studies); ii) odors (8 studies); and, iii) images (11 studies).

Effects of cerebral ischemic and reperfusion on T2*-weighted MRI responses to brief oxygen challenge.

This study characterized the effects of cerebral ischemia and reperfusion on T2*-weighted magnetic resonance image (MRI) responses to brief oxygen challenge (OC) in transient (60 minutes) cerebral ischemia in rats. During occlusion, the ischemic core tissue showed no significant OC response, whereas the perfusion-diffusion mismatch tissue showed markedly higher percent changes relative to normal tissue. After reperfusion, much of the pixels with initial exaggerated OC responses showed normal OC responses, and the majority of these tissues were salvaged as defined by endpoint T2 MRI.

Sulcal depth-position profile is a genetically mediated neuroscientific trait: description and characterization in the central sulcus.

Genetic and environmental influences on brain morphology were assessed in an extended-pedigree design by extracting depth-position profiles (DPP) of the central sulcus (CS). T1-weighted magnetic resonance images were used to measure CS length and depth in 467 human subjects from 35 extended families. Three primary forms of DPPs were observed.

Laser speckle contrast imaging of blood flow in rat retinas using an endoscope.

Laser speckle contrast imaging (LSCI) offers a cost-effective means to image blood flow in vivo. However, it is not commonly used to image rodent retinas because of the challenges associated with imaging through the curved cornea and delivering light through the highly scattering lens. A solution to overcome these problems by using LSCI in conjunction with an endoscope to obtain high spatiotemporal blood flow images is described.

Multi-region hemispheric specialization differentiates human from nonhuman primate brain function.

The human behavioral repertoire greatly exceeds that of nonhuman primates. Anatomical specializations of the human brain include an enlarged neocortex and prefrontal cortex (Semendeferi et al. in Am J Phys Anthropol 114:224-241, 2001), but regional enlargements alone cannot account for these vast functional differences.

Concurrent TMS to the primary motor cortex augments slow motor learning.

Transcranial magnetic stimulation (TMS) has shown promise as a treatment tool, with one FDA approved use. While TMS alone is able to up- (or down-) regulate a targeted neural system, we argue that TMS applied as an adjuvant is more effective for repetitive physical, behavioral and cognitive therapies, that is, therapies which are designed to alter the network properties of neural systems through Hebbian learning. We tested this hypothesis in the context of a slow motor learning paradigm.

Decreased in vitro mitochondrial function is associated with enhanced brain metabolism, blood flow, and memory in Surf1-deficient mice.

Recent studies have challenged the prevailing view that reduced mitochondrial function and increased oxidative stress are correlated with reduced longevity. Mice carrying a homozygous knockout (KO) of the Surf1 gene showed a significant decrease in mitochondrial electron transport chain Complex IV activity, yet displayed increased lifespan and reduced brain damage after excitotoxic insults. In the present study, we examined brain metabolism, brain hemodynamics, and memory of Surf1 KO mice using in vitro measures of mitochondrial function, in vivo neuroimaging, and behavioral testing.

Postocclusive reactive hyperemia occurs in the rat retinal circulation but not in the choroid.

Purpose: We tested the hypothesis that retinal blood flow has a postocclusive reactive hyperemia response modulated by occlusion duration and metabolic activity, and that choroidal blood flow does not.

Methods: Anesthetized and paralyzed rats (n = 34) were studied. Retinal and choroidal blood flow was measured by laser speckle imaging and laser Doppler flowmetry, respectively.

Chronic rapamycin restores brain vascular integrity and function through NO synthase activation and improves memory in symptomatic mice modeling Alzheimer's disease.

Vascular pathology is a major feature of Alzheimer's disease (AD) and other dementias. We recently showed that chronic administration of the target-of-rapamycin (TOR) inhibitor rapamycin, which extends lifespan and delays aging, halts the progression of AD-like disease in transgenic human (h)APP mice modeling AD when administered before disease onset. Here we demonstrate that chronic reduction of TOR activity by rapamycin treatment started after disease onset restored cerebral blood flow (CBF) and brain vascular density, reduced cerebral amyloid angiopathy and microhemorrhages, decreased amyloid burden, and improved cognitive function in symptomatic hAPP (AD) mice.

Intrinsic connectivity network mapping in young children during natural sleep.

Structural and functional neuroimaging have substantively informed the pathophysiology of numerous adult neurological and psychiatric disorders. While structural neuroimaging is readily acquired in sedated young children, pediatric application of functional neuroimaging has been limited by the behavioral demands of in-scanner task performance. Here, we investigated whether functional magnetic resonance imaging (fMRI) acquired during natural sleep and without experimental stimulation offers a viable strategy for studying young children.

Magnetic resonance imaging of the retina: from mice to men.

This mini-review provides an overview of magnetic resonance imaging (MRI) applications to study rodent, cat, non-human primate, and human retinas. These techniques include T(1) - and T(2) -weighted anatomical, diffusion, blood flow, blood volume, blood-oxygenation level dependent, manganese-enhanced, physiological, and functional MRI. Applications to study the retinas in diabetic retinopathy, glaucoma, and retinal degeneration are also reviewed.