Figure 1.
Schematic timeline of the experimental design.
ASL: arterial spin labelling, WM: working memory.
Figure 2.
Areas of significant perfusion change during the WM task (p<0.001, uncorrected, k = 150).
The location of the left DLPFC voxel (white rectangle) is shown for comparison. Results are presented on an axial slice (MNI z-coordinate = 24) of a T1-weighted image from a single subject.
Figure 3.
Representative MEGA-PRESS spectra.
(A) Averaged MEGA-PRESS spectra (averaged across the subject group) acquired at rest (left) and during the WM task. The GABA peak at 3.0 ppm appears to increase between the resting spectrum and the first WM spectrum, and then decrease during performance of the WM task (panels 2-5). The dashed line marks the resting state peak. Glx: glutamate + glutamine concentration, GABA: gamma-aminobutyric acid, NAA: N-acetylaspartate, IU: institutional units. (B) LCModel output for a single subject: the fit is shown in red, superimposed on the edited spectrum (in black). The top panel shows the residuals between the MRS data and the spectral fit.
Figure 4.
Fractional change in GABA during the WM task, relative to the baseline resting level at time = 0.
The fractional change in GABA during the consecutive resting spectra is shown for comparison.
Figure 5.
Changes in the Glx (glutamine plus glutamate) neurotransmitter concentration (with standard deviations) during session-specific rest (session 1: open bar, session 2: solid black bar) and working memory (session 1 only: solid grey bar) measurements.
Figure 6.
Correlation between resting GABA and resting perfusion in the DLPFC voxel.