About this Research Topic
Gamma aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the brain, and glutamate (Glu) the principal excitatory transmitter. For several aspects of mental health it is important that there is a balance between both of these molecules, and it is already known that in several psychiatric conditions (i.e. schizophrenia, depression, bipolar disorder, autism), one or both of these metabolites are altered. Currently, proton magnetic resonance spectroscopy (1H-MRS) is the only non-invasive neuroimaging technique that allows in vivo investigation of glutamatergic and GABAergic abnormalities within brain regions of interest. In the last years MRS underwent important advances, with a more widespread use of ultra-high field (≥7T) MRS and editing techniques, which enable separate detection of GABA and Glu.
The goal of this Research Topic is to present a variety of studies that illustrate the vast potential that 1H-MRS offers to investigate Glu and/or GABA metabolism related to different psychiatric conditions. Studies must be based on in vivo clinical examinations, with specific quantification of Glu and/or GABA, and must include a critical analysis of the limitations common to these types of studies, like inter individual variability, presence of various confounding factors, methodological issues regarding the technique used, and the inherent inability to distinguish metabolites released by synaptic activity from other metabolic pools. By including a variety of different study designs, i.e. longitudinal studies after a given therapeutic intervention, functional MRS studies, or dynamic MRS studies during ketamine injection, we aim to expand our understanding on GABA and Glu metabolism, that can be measured by MRS. We also strongly encourage studies with larger sample sizes as they allow for a better stratification of confounding factors.
Some of the issues we would like to cover in this Research Topic are:
• GABA and/or Glutamate profile of specific psychiatric diseases or mood states
• Effect of interventions like meditation, transcranial magnetic stimulation (TMS), diet or exercise on GABA and/or
• Effects of medication therapy on GABA and/or Glutamate
• MRS dynamic studies addressing Glutamate or GABA metabolism
Studies of interest to this Research Topic are not strictly limited to studies in patients. We also encourage the submission of papers addressing methodological aspects or presenting innovative methods for correct quantification and interpretation of the values measured for GABA and Glu. Finally, we welcome manuscripts with a conceptual or methodological focus, papers reporting original data, as well as meta-analyses and review papers.
Keywords: GABA, Glutamate, Magnetic Resonance Spectroscopy (MRS), Mental Disorders, Depression
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