The effects of MK-801 injections and dorsal cortex lesions on maze learning in turtles (Chrysemys picta)

Abstract

The present studies examined the effects of dorsal cortex lesions and injections of MK-801, an NMDA receptor blocker, on learning of a position habit in a maze. In Experiment 1, turtles were trained in a T-maze for food reward. After they had mastered this task, the turtles were randomly assigned to three groups: dorsal cortex lesion, MK-801 injection, or sham-lesion/saline-injection control. The animals were run in an X-maze for 40 days or until they reached criterion. In comparison with controls, the lesion and MK-801 groups were significantly impaired in X-maze learning. Experiment 2 examined the effects of MK-801 injections on measures of general activity. These measures were not affected by injections of MK-801. The results provide evidence for the involvement of the turtle dorsal cortex and the NMDA receptor in the acquisition of a position habit.