/pdf/dynamic-functional-connectivity-analysis-reveals-transient-3lbnpyeab3.pdf

Dynamic functional connectivity analysis reveals transient states of dysconnectivity in schizophrenia

Background/Aims: Anxious responses are evolutionarily adaptive, but excessive fear can become disabling and lead to anxiety disorders. Translational models of anxiety might be useful sources for understanding the neurobiology of fear and anxiety and can contribute to future proposals of therapeutic intervention for the disorders studied. Brain-derived neurotrophic factor (BDNF), which is known for its importance on neuroplasticity and contextual memory, has emerged as a relevant element for emotional memory. Recent studies show that the Val 66 Met BDNF polymorphism

/pdf/translational-findings-on-brain-derived-neurotrophic-factor-3mrvoaflnv.pdf

Translational Findings on Brain-Derived Neurotrophic Factor and Anxiety: Contributions from Basic Research to Clinical Practice

Purpose: The purpose of this study is to describe the Gannet toolkit for the quantitative batch analysis of gamma-aminobutyric acid (GABA) -edited MRS data.


Materials and Methods: Using MEGA-PRESS editing and standard acquisition parameters, four MEGA-PRESS spectra were acquired in three brain regions in 10 healthy volunteers. These 120 datasets were processed without user intervention with Gannet, a Matlab-based tool that takes raw time-domain data input, processes it to generate the frequency-domain edited spectrum, and applies a simple modeling procedure to estimate GABA concentration relative to the creatine or, if provided, the unsuppressed water signal. A comparison of four modeling approaches is also presented.


Results: All data were successfully processed by Gannet. Coefficients of variation across subjects ranged from 11% for the occipital region to 17% for the dorsolateral prefrontal region. There was no clear difference in fitting performance between the simple Gaussian model used by Gannet and the other more complex models presented.


Conclusion: Gannet, the GABA Analysis Toolkit, can be used to process and quantify GABA-edited MRS spectra without user intervention.

/pdf/gannet-a-batch-processing-tool-for-the-quantitative-analysis-3klt85rbda.pdf

Gannet: a batch-processing tool for the quantitative analysis of gamma-aminobutyric acid-edited MR spectroscopy spectra

Neuregulin-ERBB Signaling in the Nervous System and Neuropsychiatric Diseases

ObjectiveThe thalamus and cerebral cortex are connected via topographically organized, reciprocal connections. Previous studies have revealed thalamic abnormalities in schizophrenia; however, it is not known whether thalamocortical networks are differentially affected in the disorder. To explore this possibility, the authors examined functional connectivity in intrinsic low-frequency blood-oxygen-level-dependent (BOLD) signal fluctuations between major divisions of the cortex and thalamus using resting-state functional MRI (fMRI).MethodSeventy-seven healthy subjects and 62 patients with schizophrenia underwent resting-state fMRI. To identify functional subdivisions of the thalamus, the authors parceled the cortex into six regions of interest: the prefrontal cortex, motor cortex/supplementary motor area, somatosensory cortex, temporal lobe, posterior parietal cortex, and occipital lobe. Mean BOLD time series were extracted for each region of interest and entered into a seed-based functional connectivity an...

/pdf/thalamocortical-dysconnectivity-in-schizophrenia-2fypzxfskf.pdf

Thalamocortical dysconnectivity in schizophrenia.

Investigation of Anatomical Thalamo-Cortical Connectivity and fMRI Activation in Schizophrenia

γ-Aminobutyric acid (GABA) is the chief inhibitory neurotransmitter of the human brain, and GABA-ergic dysfunction has been implicated in a variety of neuropsychiatric disorders. Recent MRS techniques have allowed the quantification of GABA concentrations in vivo, and could therefore provide biologically relevant information. Few reports have formally characterized the reproducibility of these techniques, and differences in field strength, acquisition and processing parameters may result in large differences in measured GABA values. Here, we used a J-edited, single-voxel spectroscopy method of measurement of GABA + macromolecules (GABA + ) in the anterior cingulate cortex (ACC) and right frontal white matter (rFWM) at 3 T. We measured the coefficient of variation within subjects (CVw) and intra-class correlation coefficients on two repeated scans obtained from 10 healthy volunteers with processing procedures developed in-house for the quantification of GABA + and other major metabolites. In addition, by segmenting the spectroscopic voxel into cerebrospinal fluid, gray matter and white matter, and employing a linear regression technique to extrapolate metabolite values to pure gray and white matter, we determined metabolite differences between gray and white matter in ACC and rFWM. CVw values for GABA + /creatine, GABA + /H2O, GABA + , creatine, partially co-edited glutamate + glutamine (Glx)/creatine, partially co-edited Glx and N-acetylaspartic acid (NAA)/creatine were all below 12% in both ACC and rFWM. After extrapolation to pure gray and pure white matter, CVw values for all metabolites were below 16%. We found metabolite ratios between gray and white matter for GABA + /creatine, GABA + , creatine, partially co-edited Glx and NAA/creatine to be 0.88 ± 0.21 (standard deviation), 1.52 ± 0.32, 1.77 ± 0.4, 2.69 ± 0.74 and 0.70 ± 0.05, respectively. This study validates a reproducible method for the quantification of brain metabolites, and provides information on gray/white matter differences that may be important in the interpretation of results in clinical populations. Published in 2011 by John Wiley & Sons, Ltd.

http://mason.gmu.edu/%7Easavosty/PDFs/Geramita%20et%20al%20(2011)%20NMR.pdf

Reproducibility of prefrontal γ-aminobutyric acid measurements with J-edited spectroscopy

Genetic modulation of GABA levels in the anterior cingulate cortex by GAD1 and COMT

Impact of the Brain-Derived Neurotrophic Factor Val66Met Polymorphism on Levels of Hippocampal N-Acetyl-Aspartate Assessed by Magnetic Resonance Spectroscopic Imaging at 3 Tesla

Antonina A. Savostyanova

Papers

Investigation of Anatomical Thalamo-Cortical Connectivity and fMRI Activation in Schizophrenia

Reproducibility of prefrontal γ-aminobutyric acid measurements with J-edited spectroscopy

Genetic modulation of GABA levels in the anterior cingulate cortex by GAD1 and COMT

Impact of the Brain-Derived Neurotrophic Factor Val66Met Polymorphism on Levels of Hippocampal N-Acetyl-Aspartate Assessed by Magnetic Resonance Spectroscopic Imaging at 3 Tesla