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Abstract #3343

Diurnal Stability of MEGA-PRESS Measurements of GABA Concentration

Richard AE Edden1,2, C John J. Evans3,4, David J. McGonigle3,5

1Russell H Morgan Department of Radiology and Radiological Sciences, The Johns Hopkins University, Baltimore, MD, United States; 2FM Kirby Research Center for Functional MRI, Kennedy Krieger Institute, Baltimore, MD, United States; 3CUBRIC, School of Psychology, Cardiff University, United Kingdom; 4GE HealthCare, Slough, United Kingdom; 5School of Biosciences, Cardiff University, United Kingdom

Edited MRS measurements of GABA are being widely applied in clinical and basic neuroscience studies. GABA concentration is known to vary with the menstrual cycle, and GABA is key to the suprachiasmatic nucleis circadian clock, but no study has addressed diurnal GABA variation in cortical regions. In spite of this, it is rare to control for time-of-day in designing studies. This study measures GABA in visual and sensorimotor cortex in 8 individuals at 5 timepoints in a day, and concludes that methods are insensitive to any diurnal variation in GABA concentration, but that regional and inter-individual differences can be seen.