Fig. 1.

Paradigm. (A) Structure-from-motion (SFM). An ambiguous sphere, which could be perceived as rotating in one of two directions (as indicated), was presented on each 60 sec trial. Participants reported the perceived direction of rotation continuously and the percept duration was examined. (B–D) Example of voxel placement for one participant for the large (yellow) and small (red) voxels used for GABA magnetic resonance spectroscopy (MRS) presented in coronal (B), sagittal (C), and axial (D) planes.