Papers by Wolfgang Weber-fahr
Journal of Cerebral Blood Flow & Metabolism, 2015
The combination of optogenetics with functional magnetic resonance imaging is a promising tool to... more The combination of optogenetics with functional magnetic resonance imaging is a promising tool to study the causal relationship between specific neuronal populations and global brain activity. We employed this technique to study the brain response to recruitment of glutamatergic neurons in the mouse hippocampus. The light-sensitive protein channelrhodopsin-2 was expressed in α-CamKII-positive glutamatergic neurons in the left hippocampus (N = 10). Functional magnetic resonance imaging was performed during local laser stimulation, with stimulus duration of 1 second. The hemodynamic response to these stimuli was analyzed on a whole-brain level. In a secondary analysis, we examined the impact of the stimulation locus on the dorso-ventral axis within the hippocampal formation. The hemodynamic response in the mouse hippocampus had an earlier peak and a shorter duration compared to those observed in humans. Photostimulation was associated with significantly increased blood oxygen level-de...
Advantages and challenges of small animal magnetic resonance imaging as a translational tool
Neuropsychobiology, 2014
The utilization of magnetic resonance imaging (MRI) methods in rodent models of psychiatric disor... more The utilization of magnetic resonance imaging (MRI) methods in rodent models of psychiatric disorders provides considerable benefits for the identification of disease-associated brain circuits and metabolic changes. In this review, we discuss advantages and challenges of animal MRI and provide an overview of the major structural (voxel-based morphometry and diffusion tensor imaging) and functional approaches [resting-state functional MRI (rs-fMRI), MR spectroscopy (MRS), regional cerebral blood volume measurement and arterial spin labelling] that are applied in animal MRI research. The review mainly focuses on rs-fMRI and MRS. Finally, we take a look at some recent developments and refinements in the field.
31 P RINEPT MRSI and VBM reveal alterations in brain aging associated with major depression
Magnetic Resonance in Medicine, 2014
Phosphomono- and diesters, the major components of the choline peak in (1) H magnetic resonance s... more Phosphomono- and diesters, the major components of the choline peak in (1) H magnetic resonance spectroscopy, are associated with membrane anabolic and catabolic mechanisms. With the refocused insensitive nuclei-enhanced polarization transfer technique, these phospholipids are edited and enhanced in the (31) P MR spectrum. In depressed patients, alterations of the choline peak and cerebral volume have been found, indicating a possible relation. Thus, combining MR phosphorous spectroscopy and volumetry in depressed patients seems to be a promising approach to detect underlying pathomechanisms. Depressed in-patients were either treated with antidepressive medication or with electroconvulsive therapy and compared to matched healthy controls. (31) P magnetic resonance spectroscopy imaging was conducted before and after the treatment phases. A 3D MRI dataset for volumetry was acquired in a dedicated (1) H head coil. Phosphocholine and phosphoethanolamine were increased in depressed patients. Though patients responded to the treatments, phospholipids were not significantly altered. An increased age-related gray matter loss in fronto-limbic regions along with an altered relation of phosphomonoesters/phosphodiesters with age were found in depressed patients. The findings of increased phosphomonoesthers and an age*group interaction for gray matter volumes need further research to define the role of phospholipids in major depression and possible associations to gray matter loss. Magn Reson Med 73:1390-1400, 2015. © 2014 Wiley Periodicals, Inc.
Altered phospholipid metabolism in schizophrenia: a phosphorus 31 nuclear magnetic resonance spectroscopy study
Psychiatry research, Jan 30, 2013
Phospholipid (PL) metabolism is investigated by in vivo 31P magnetic resonance spectroscopy (MRS)... more Phospholipid (PL) metabolism is investigated by in vivo 31P magnetic resonance spectroscopy (MRS). Inconsistent alterations of phosphocholine (PC), phosphoethanolamine (PE), glycerophosphocholine (GPC) and glycerophosphoethanolamine (GPE) have been described in schizophrenia, which might be overcome by specific editing techniques. The selective refocused insensitive nuclei-enhanced polarization transfer (RINEPT) technique was applied in a cross-sectional study involving 11 schizophrenia spectrum disorder patients (SZP) on stable antipsychotic monotherapy and 15 matched control subjects. Metabolite signals were found to be modulated by cerebrospinal fluid (CSF) content and gray matter/brain matter ratio. Corrected metabolite concentrations of PC, GPC and PE differed between patients and controls in both subcortical and cortical regions, whereas antipsychotic medication exerted only small effects. Significant correlations were found between the severity of clinical symptoms and the as...
European neuropsychopharmacology : the journal of the European College of Neuropsychopharmacology, 2014
Treatment-resistant depression (TRD) remains a pressing clinical problem. Optimizing treatment re... more Treatment-resistant depression (TRD) remains a pressing clinical problem. Optimizing treatment requires better definition of the function and specificity of the brain circuits involved. To investigate disease-related alterations of brain function we used a genetic animal model of TRD, congenital learned helplessness (cLH), and functional magnetic resonance imaging as a translational tool. High-resolution regional cerebral blood volume (rCBV) and resting-state functional connectivity measurements were acquired at 9.4T to determine regional dysfunction and interactions that could serve as vulnerability markers for TRD. Effects of cLH on rCBV were determined by statistical parametric mapping using 35 atlas-based regions of interest. Effects of cLH on functional connectivity were assessed by seed region analyses. Significant bilateral rCBV reductions were observed in the lateral habenula, dentate gyrus and subiculum of cLH rats. In contrast, focal bilateral increase in rCBV was observed...
Tissue segmentation changes statistical significance for 1H MRSI of the thalamus in schizophrenic patients
Effects of Tissue Segmentation on MRSI Results in the Hippocampal Region
Whole brain 31P RINEPT in a depressed patient undergoing ECT
Improved MR-Morphometry analysis techniques: What do they detect in the Schizophrenic Brain?
In which cases of TLE is H-MRSI not predictive for good surgical outcome after selective amygdalo-hippocampectomy?
Fig.1: Position of the single voxel in T2 and T1 images for left amygdala Fig.2: Example spectra ... more Fig.1: Position of the single voxel in T2 and T1 images for left amygdala Fig.2: Example spectra with LCModel fit with SNR=5 (left) and with SNR=3 (right) of the single voxel for left amygdala Fig. 3: Boxplots of NAA (left) and tCr (right) concentrations in mmol/l in the left amygdala of healthy controls and patients with BPD HC BPD healthy controls vs BPD patients 8.00
Automated Image Segmentation for MRSI Quantitation using SPM96
MRS studies typically require a high signal-to-noise ratio (SNR), especially for 13 C-spectroscop... more MRS studies typically require a high signal-to-noise ratio (SNR), especially for 13 C-spectroscopy where the low natural abundance of 13 C (1.1%) is a problem. Since the SNR depends on the third power of the Larmor frequency, the relative small frequency of 13 C increases this limitation for 13 C in comparison with 1 H-MRS. There are methods to enhance the signal like polarization transfer. Another way is to lower the noise. Cryo-coils use the fact that there are two noise sources, which can directly be diminished. Noise arising from the coil itself and the preamplifier can greatly be lessened by lowering its operating temperature. Thus mainly the noise from the sample itself is left. We present in vitro and in vivo data from one of the first 13 C-cryo-coils for mouse brain.
SPM96 for automated image segmentation in MRSI
Frontal dysfunction and antipsychotics: A combined fMRI and MRSI study
Differential effects of atypicals and typical neuroleptics on function and neuronal viability of the anterior cingulate gyrus in schizophrenia
Visual information processing in neuroleptic-naive schizophrenic patients: A fMRI study
Functional magnetic resonance imaging and schizophrenia: Medication effects, methodological limitations and perspectives
block design experiments, the subjects were played pre-recorded sentences: (i) a pure prosody exp... more block design experiments, the subjects were played pre-recorded sentences: (i) a pure prosody experiment (sentences filtered to remove semantic information); (ii) assessment of activation by appropriate emotional prosody; and (iii) attend to the emotion as depicted by prosody vs. the emotion denoted by the semantics of the sentence. Behavioural data does not indicate significant differences in performance between appropriate and inappropriate prosody, nor does it indicate a performance deficit in schizophrenics for processing semantic or prosodic styimuli. Individual fMRI data indicates that in controls, attending to prosody activated areas including the expected ones: right middle temporal gyrus (prosodic processing) and superior frontal gyrus. We predict schizophrenic patients will show functional abnormalities in this network. These results have implications for understanding the neural basis of language processing in schizophrenia. computed using three methods: percentage method, proportional-change method and net-gradient method. The relative sensitivity of the methods was assessed on the basis of the magnitude of motor cortex activation associated with the finger press. Results indicated that the fast-infusion protocol, which enabled higher scanning frequency, was more sensitive to transient rCBF changes than the slow-infusion method for all correlation analysis techniques. Of the three correlational analysis techniques the net-gradient method was most sensitive to variations in the radiotracer uptake for both infusion protocols.
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Papers by Wolfgang Weber-fahr