Fig. 1. Effects of anesthesia with (top ) and recovery from (bottom ) S , R (±)-ketamine, S (+)-ketamine, and R (−)-ketamine on regional cerebral metabolic rate for glucose. Regional cerebral metabolic rate for glucose was measured while rats were anesthetized with equimolar doses or were recovering from equi-anesthetic doses. Bars indicate the percentage of regions in which regional cerebral metabolic rate for glucose was significantly (P < 0.01) increased (solid ) and decreased (hatched ).