(a) Spatial working memory (WM) task, 4-target version. (b) Regions of interests (ROIs) used for time-course analysis, SFG (blue), MFG (magenta), and IFG (green). Ketamine reduced task-related activation during the encoding and early maintenance (EEM) phase, [F(1,686)=9.48, p=0.0022. EEM (yellow), later maintence (LM) (green), and response (purple) analysis periods indicated by vertical bars. BOLD, blood oxygen level dependent; IFG, inferior frontal gyrus; MFG, middle frontal gyrus; SFG, superior frontal gyrus.