Activation induced changes in GABA: Functional MRS at 7 T with MEGA-sLASER

• Published in: NeuroImage (Orlando, Fla.) Vol. 156; pp. 207 - 213
• Main Authors: Chen, Chen, Sigurdsson, Hilmar P., Pépés, Sophia E., Auer, Dorothee P., Morris, Peter G., Morgan, Paul S., Gowland, Penny A., Jackson, Stephen R.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Limited 01.08.2017
• Subjects: Activation; Adiabatic; Adiabatic flow; Autism; Brain; Brain research; Contamination; Cortex (motor); Creatine; Editing; Glutamine; Macromolecules; Magnetic resonance spectroscopy; Metabolism; Metabolites; Motor task performance; Neurotransmitters; NMR; Nuclear magnetic resonance; Physiology; Schizophrenia; Spectroscopic analysis; Spectroscopy; Spectrum analysis; Tourette syndrome; γ-Aminobutyric acid
• ISSN: 1053-8119; 1095-9572
• DOI: 10.1016/j.neuroimage.2017.05.044

Functional magnetic resonance spectroscopy (fMRS) has been used to assess the dynamic metabolic responses of the brain to a physiological stimulus non-invasively. However, only limited information on the dynamic functional response of γ-aminobutyric acid (GABA), the primary inhibitory neurotransmitter in the brain, is available. We aimed to measure the activation-induced changes in GABA unambiguously using a spectral editing method, instead of the conventional direct detection techniques used in previous fMRS studies. The Mescher-Garwood-semi-localised by adiabatic selective refocusing (MEGA-sLASER) sequence was developed at 7T to obtain the time course of GABA concentration without macromolecular contamination. A significant decrease (−12±5%) in the GABA to total creatine ratio (GABA/tCr) was observed in the motor cortex during a period of 10min of hand-clenching, compared to an initial baseline level (GABA/tCr =0.11±0.02) at rest. An increase in the Glx (glutamate and glutamine) to tCr ratio was also found, which is in agreement with previous findings. In contrast, no significant changes in NAA/tCr and tCr were detected. With consistent and highly efficient editing performance for GABA detection and the advantage of visually identifying GABA resonances in the spectra, MEGA-sLASER is demonstrated to be an effective method for studying of dynamic changes in GABA at 7T.