A role for acetylcholine in spatial memory in turtles.

The present research was undertaken to determine whether acetylcholine plays a role in memory for a maze in turtles. Cholinergic cells have been observed in the basal forebrain of turtles, and the basal forebrain of turtles projects to the dorsal cortex, a region that has been implicated in associative function. In Experiment 1, turtles were trained on an X-maze for water reward and then given lesions of the dorsal cortex or basal forebrain or sham lesions and retested postoperatively on the maze. Both dorsal cortex and basal forebrain lesions impaired performance on the maze. In Experiment 2, turtles were trained on the maze and then given saline, scopolamine, or methylscopolamine on a 1-day retention test. Scopolamine in the higher doses impaired maze performance on the test day, but methylscopolamine did not. The highest dose of scopolamine had no effect on measures of general activity, showing that the effects of the drug were specific to the learned task.