Fig. 1. Training and testing timeline. Five days of cued (flagged) training on a fixed, submerged platform (days 1-5) was followed by 2 days of rest (days 6-7). Noncued training (days 8-12) occurred on the same fixed platform location, with visual cues as to platform location now available from the surrounding room only. Two days of rest followed (days 13 and 14). Hemodilution or sham hemodilution (day 15) was followed by 1 day of rest (day 16). Reference memory testing (day 17) examined the ability to remember the position of the platform trained upon during the prehemodilution phase. Subsequently (days 18-26), working memory was tested using a criteria-driven, moving platform paradigm.