During each 120s trial, forty single-shot echo-planar images (TR=3s, effective TE=40ms, flip angle 90° were collected in each of 19 to 21 coronal slices spanning the entire head volume and oriented perpendicular to the midsagittal line between the anterior and posterior commissures. Images were 7mm thick and spaced 1mm apart, with a 20cm square field of view in a 64x64 matrix for an in-plane resolution of 3.125mm, and were acquired on a General Electric Signa 1.5T system with a standard birdcage head coil. Scanning was synchronised to the onset of stimulation by using a trigger pulse from the scanner to cue stimulus delivery. Following the functional scan, T1-weighted (TR=500ms, TE=8ms) and high-resolution echo-planar (spin-echo, TR=3s, TE=80ms) images were acquired in 256x256 matrices, in the same planes and with the same field of view as the functional images.