Petr Bednarik

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Several laboratories have consistently reported small concentration changes in lactate, glutamate, aspartate, and glucose in the human cortex during prolonged stimuli. However, whether such changes correlate with blood oxygenation level-dependent functional magnetic resonance imaging (BOLD-fMRI) signals have not been determined. The present study aimed at(More)
PURPOSE To determine the test-retest reproducibility of neurochemical concentrations obtained with a highly optimized, short-echo, single-voxel proton MR spectroscopy (MRS) pulse sequence at 3T and 7T using state-of-the-art hardware. METHODS A semi-LASER sequence (echo time = 26-28 ms) was used to acquire spectra from the posterior cingulate and(More)
Hippocampal dysfunction is known to be associated with several neurological and neuropsychiatric disorders such as Alzheimer's disease, epilepsy, schizophrenia and depression; therefore, there has been significant clinical interest in studying hippocampal neurochemistry. However, the hippocampus is a challenging region to study using (1) H MRS, hence the(More)
In this study, we retrospectively analyzed the anatomical MRI data acquired from 52 subjects with type 1 diabetes (26M/26F, 36 ± 11 years old, A1C = 7.2 ± 0.9%) and 50 age, sex and BMI frequency-matched non-diabetic controls (25M/25F, 36 ± 14 years old). The T1D group was further sub-divided based on whether subjects had normal, impaired, or indeterminate(More)
1 Department of Radiology, Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, MN, United States, 2 Department of Pediatrics, University of Minnesota, Minneapolis, MN, United States, 3 Central European Institute of Technology (CEITEC), Masaryk University, Brno, Czechia, 4 MARBILab, Centro Fermi Museo Storico Della Fisica e(More)
The aim of the current study is visualization of task-related variability in EEG-fMRI data, performed as a blind-search analysis without stimulus timings, using a methodology that is based on Kilner's et al. heuristic approach [2]. We show that filters of the relative EEG spectra with different frequency responses visualize different task-related brain(More)
BACKGROUND The effect of brain-vessel pathology on mortality in 57 consecutive PD patients was studied. METHODS Baseline clinical, neuropsychological, ultrasonographic (US), and MR data obtained from patients who died (n = 18) during a 4-year follow-up period were compared with the data of patients who survived. RESULTS US/MRI data displayed a(More)
Electroencephalography (EEG) oscillations reflect the superposition of different cortical sources with potentially different frequencies. Various blind source separation (BSS) approaches have been developed and implemented in order to decompose these oscillations, and a subset of approaches have been developed for decomposition of multi-subject data. Group(More)
In the present study, we aimed at determining the metabolic responses of the human visual cortex during the presentation of chromatic and achromatic stimuli, known to preferentially activate two separate clusters of neuronal populations (called "blobs" and "interblobs") with distinct sensitivity to color or luminance features. Since blobs and interblobs(More)
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