Importance of preoperative training and maze difficulty in task performance following hippocampal damage in the gerbil.

A series of experiments was conducted to evaluate the effects of preoperative training on three variations of a spatial working memory task following ischemic damage to the hippocampus. A discrete trial, pair-run procedure in a standard T-maze apparatus was used. Ischemic and sham gerbils were tested on a Win/Shift, Win/Shift Delay (10 s), or Win/Stay task with or without preoperative training. Gerbils tested on the Win/Shift or Win/Shift Delay tasks did not exhibit improved performance as a result of pretraining. Ischemic gerbils in Win/Shift tasks exhibited working memory impairment with or without preoperative training. In contrast, pretraining was found to significantly improve the performance of gerbils tested in the Win/Stay task. Choice accuracy of pretrained ischemic gerbils was not significantly different from controls. These data suggest that preoperative training can influence performance, however the difficulty of the task and/or the amount of pretraining are important variables. The tendency for rodents to alternate makes the Win/Shift task ideal when extensive training or testing is not possible.