A Behavioral Analysis of the Spatial Learning Deficit Induced by the NMDA Receptor Antagonist MK-801 (Dizocilpine) in the Rat

This study analyzes whether the disruptive effects of the noncompetitive NMDA receptor antagonist MK-801 (0.01– 0.1 mg/kg SC) on spatial learning can be dissociated from sensorimotor disturbances in the rat. Two different modifications of the Morris swim maze task with a hidden underwater platform were used: with or without local cue. Retention was tested either 24 h or 7 days after training as a probe trial (without platform). The present data indicate that MK-801 produces an impairment of spatial learning that cannot be dissociated from motor or sensory mechanisms. These findings support the view that NMDA receptors probably contribute to, but are not essential for, spatial learning in the water maze.