We investigated the effects of aging on brain activation in the auditory cortex and the frontal-parietal (FPN) and cingulo-opercular (CON) executive control networks during bimodal selective attention using functional magnetic resonance imaging (fMRI). ...

Read advocacy news from the week of October 7, 2016

Neurological disease drives symptoms through pathological changes to circuit functions. Therefore, understanding circuit mechanisms that drive behavioral dysfunction is of critical importance for quantitative diagnosis and systematic treatment of neurological disease. Here, we describe key technologies that enable measurement and manipulation of neural activity and neural circuits. Applying these approaches led to the discovery of circuit mechanisms underlying pathological motor behavior, arousal regulation, and protein accumulation. Finally, we discuss how optogenetic functional magnetic resonance imaging reveals global scale circuit mechanisms, and how circuit manipulations could lead to new treatments of neurological diseases.

Functional MRI (fMRI) based on blood oxygenation level dependent (BOLD) contrast relies on changes in brain hemodynamics. Recently, a new method for fMRI, named Activity-Induced Manganese Dependent (AIM) MRI, was reported as being independent of hemodynamics. We investigated whether AIM MRI would detect neurotransmitter-induced brain activity in the rat. The aim of this study is to produce new neurotransmitter-sensitive MR contrast. Dopamine (n = 5) and norepinephrine (n = 5) groups were used. The paradigm consisted of 6 steps as follows; 1) T1 weighted (T1W) MRI acquisition without manganese chloride (MnCl2), 2) 25% mannitol injection for BBB disruption, 3) MRI acquisition after MnCl2 and saline injection, 4) same acquisition as #3, 5) MRI acquisition after MnCl2 and neurotransmitter injection, and 6) MRI acquisition after MnCl2 and glutamate injection. There were 3 major results: 1) Neurotransmitter-induced brain activity mapping was successfully performed with phAIM MRI. 2) Dopamine-induced enhancement ...

The ability to detect individual Alzheimer's amyloid plaques in vivo by magnetic resonance microimaging (MRI) should improve diagnosis and also accelerate discovery of effective therapeutic agents for Alzheimer's disease (AD). Here, we perform in vivo and ex vivo MRI on double transgenic AD mice as well as wild-type mice at varying ages and correlate these with thioflavin-S and iron staining histology. Quantitative counts of individual plaques on MRI increase with age and correlate with histologically determined plaque burden. Plaques 20 μm in diameter can be detected in AD mice as young as 3 months of age with ex vivo MRI. Plaques 35 μm in diameter can be detected by 9 months of age with in vivo MRI. In vivo MRI of individual Alzheimer's amyloid plaques provides a noninvasive estimate of plaque burden in transgenic AD mice that might be useful in assessing the efficacy of amyloid reduction therapies.

Neuroimaging studies are accumulating fast. A significant number of these studies use functional magnetic resonance imaging (fMRI) and report stereotactic brain coordinates. In the last 15 years meta-analytic software tools have been developed to identi...

Aims: The aim of this study is to map the course and the components of the crus cerebri and the longitudinal fibres of the pons using ultra-high resolution magnetic resonance imaging. Methods: A postmortem human brain was obtained from a 65-year-old mal...

Three Dimensional Digital Mouse Atlas Using μMRI S.W. Ruffins, M. Dhenain, & R.E. Jacobs Biological Imaging Center, Beckman Institute, Caltech, Pasadena, CA 91125 Gene expression patterns, receptor domains, arrays of innervation, cell lineage patterns, and a host of other types of information in the embryo and adult take place in 3 spatial and 1 temporal dimensions. They occur within the context of the specific specimen being examined. Digital atlases provide a means to place specific data within the context of normal anatomy, analyze the information in multiple dimensions, and examine relationships between different types of information. In this work we present a prototypical digital atlas of the mouse embryo based on microscopic Magnetic Resonance Imaging (μMRI). μMRI is a qualitatively different, although complementary, imaging method to those used in constructing atlases with classical histological techniques. It is able to non-invasively and in 3 dimensions distinguish soft tissues within optically op...

Although blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) has been widely used to explore human brain function, questions remain regarding the ultimate spatial resolution of positive BOLD fMRI, and indeed the extent to which functional maps revealed by positive BOLD correlate spatially with maps obtained with other high-spatial-resolution mapping techniques commonly used in animals, such as optical imaging of intrinsic signal (OIS) and single-unit electrophysiology. Here, we demonstrate that the positive BOLD signal at 9.4T can reveal the fine topography of individual fingerpads in single-condition activation maps in nonhuman primates. These digit maps are similar to maps obtained from the same animal using intrinsic optical imaging. Furthermore, BOLD fMRI reliably resolved submillimeter spatial shifts in activation in area 3b previously identified with OIS ([Chen et al., 2003][1]) as neural correlates of the “funneling illusion.” These data demonstrate that at high fie...

Brain imaging techniques can now be used to interrogate the anatomical connections of the living human brain. Diffusion imaging, a type of magnetic resonance imaging, provides information that can be used to estimate the routes of fibre pathways. This a...