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Detection of metabolite changes in response to a varying visual stimulation paradigm using short-TE 1 H MRS at 7 T.
- Source :
-
NMR in biomedicine [NMR Biomed] 2017 Feb; Vol. 30 (2). Date of Electronic Publication: 2016 Dec 23. - Publication Year :
- 2017
-
Abstract
- The two-fold benefit of <superscript>1</superscript> H magnetic resonance spectroscopy (MRS) at high B <subscript>0</subscript> fields - enhanced sensitivity and increased spectral dispersion - has been used previously to study dynamic changes in metabolite concentrations in the human brain in response to visual stimulation. In these studies, a strong visual on/off stimulus was combined with MRS data acquisition in a voxel location in the occipital cortex determined by an initial functional magnetic resonance imaging experiment. However, 1) to exclude the possibility of systemic effects (heartbeat, blood flow, etc.), which tend to be different for on/off conditions, a modified stimulation condition not affecting the target voxel needs to be employed, and 2) to assess important neurotransmitters of low concentration, in particular γ-aminobutyric acid (GABA), it may be advantageous to analyze steady-state, rather than dynamic, conditions. Thus, the aim of this study was to use short-TE <superscript>1</superscript> H MRS methodology at 7 T to detect differences in steady-state metabolite levels in response to a varying stimulation paradigm in the human visual cortex. The two different stimulation conditions were termed voxel and control activation. Localized MR spectra were acquired using the SPECIAL (spin-echo full-intensity acquired localized) sequence. Data were analyzed using LCModel. Fifteen individual metabolites were reliably quantified. On comparison of steady-state concentrations for voxel versus control activation, a decrease in GABA of 0.05 mmol/L (5%) and an increase in lactate of 0.04 mmol/L (7%) were found to be the only significant effects. The observed reduction in GABA can be interpreted as reduced neuronal inhibition during voxel activation, whereas the increase in lactate hints at an intensification of anaerobic glycolysis. Differences from previous studies, notably the absence of any changes in glutamate, are attributed to the modified experimental conditions. This study demonstrates that the use of advanced <superscript>1</superscript> H MRS methodology at 7 T allows the detection of subtle changes in metabolite concentrations involved in neuronal activation and inhibition.<br /> (Copyright © 2016 John Wiley & Sons, Ltd.)
- Subjects :
- Adult
Algorithms
Brain anatomy & histology
Female
Humans
Male
Middle Aged
Molecular Imaging methods
Reproducibility of Results
Sensitivity and Specificity
Signal Processing, Computer-Assisted
Tissue Distribution
Brain metabolism
Lactic Acid metabolism
Photic Stimulation methods
Proton Magnetic Resonance Spectroscopy methods
Visual Cortex metabolism
Visual Perception physiology
gamma-Aminobutyric Acid metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1099-1492
- Volume :
- 30
- Issue :
- 2
- Database :
- MEDLINE
- Journal :
- NMR in biomedicine
- Publication Type :
- Academic Journal
- Accession number :
- 28008663
- Full Text :
- https://doi.org/10.1002/nbm.3672