Superposition of test-retest difference spectra for JDE of GSH acquired using a semi-LASER sequence (voxel size 3×3×3 cm3, TR 3 s, TE 72 ms, 64 averages per JDE condition, acquisition time 7 min) during the two study sessions (#1 and #2, left) and their difference (right). Extra: Superposition of test-retest difference spectra for JDE of GABA acquired using a semi-LASER sequence (voxel size 3×3×3 cm3, TR 3 s, TE 72 ms, 128 averages per JDE condition, acquisition time 13 min) during the two study sessions (#1 and #2, left) and their difference (right) of a subject on medication known to impact GABA concentrations.