Figure 3.

Representative ¹H MR spectra acquired in one fMRS session during four periods, CHROM and subsequent REST (a), ACHROM and subsequent REST (b) (see Figure 1). These ¹H MR spectra illustrate the spectral quality routinely achieved in this study (semi-LASER, TE = 26 ms, TR = 5 s, number of scans = 32, VOI = 2 × 2 × 2 cm³). Top traces show the difference spectra (STIM – REST). The residual peaks at 2 and 3 ppm originate from the linewidth difference between STIM and REST spectra. Small concentration changes of lactate (1.3 ppm) and glutamate (∼2.4 ppm) are also discernible in the difference spectra. Gaussian apodization was used for display purposes (σ = 0.17 s) Insets: MPRAGE images with overlaid fMRI maps show the position of the VOI selected for fMRS.