GABA - an Inhibitory Neurotransmitter
Understanding neurotransmitter levels and activity is fundamental to elucidating normal and diseased brain function, with glutamtate (Glu) and gamma-aminobutyric acid (GABA) being the human brain's primary excitatory and inhibitor neurotransmitters respectively. 1H MRS in a well-established tool to provide in vivo measurement of steady-state GABA, Glu, and glutamine (Gln, a companion molecule to Glu) concentrations for a variety of conditions including neurodevelopment, aging, psychiatric disorders, and neurodegenerative diseases. Glu+Gln levels (usually denoted as a Glx peak) are routinely measured using single- (or multl-) voxel short echo-time spectroscopy; although robust separation of the Glu and Gln signals remains an active area of research. In contrast, naturally low brain GABA levels (typical 0.5-1 mM) require spectral editing to measure with 1H MRS. The most commonly used GABA-editing sequence is MEGA-PRESS, which filters out the GABA signal based on the molecule’s J-coupling. While effective, this approach suffers from co-edited macromolecules, artifacts, and low SNR. Under this project, we seek to develop an improved GABA-editing pulse sequence to address these limitations.