The apparatus and training procedure were identical to that previously described (Lichtman, et al 1995). Each of the eight arms was baited with a 45-mg Noyes pellet placed 5 cm from the end and guillotine doors were used to increase the likelihood that the rats would use a spatial search strategy. At the start of each session, the subject was placed in the center platform with all doors down. Five s later, all of the doors were raised and the subject was allowed to enter a maze arm. The subject was considered to have entered an arm once all four of its paws crossed the threshold into a maze arm. The other seven guillotine doors were then gently lowered. After the subject returned to the center platform the remaining door was lowered and a 5-s ITI was imposed. All eight doors were then raised for the next trial. The session ended when all eight arms had been visited or 10 min had elapsed, whichever came first. An observer scored the number of correct responses, as well as re-entry errors and
