Figure 1.

Study design and timeline. (A) Training schedule for animals training on the sustained attention task or Morris water maze. All animals were maintained on a 12:12-h LD schedule with animals training at one of three training times (ZT4: 4 h after lights-on; ZT10: 10 h after lights-on; and ZT16: 4 h after lights-off). (B) Design for four experimental groups used in this study: Group I animals consisted of three different time-of-day SAT training groups. White bars represent training at ZT4, gray bars represent training at ZT10, black bars represent training at ZT16. Group II and Group IV animals consisted of animals training at ZT4 and ZT16 only. Group III animals trained on the SAT at ZT4 only. Group II animals had their training times reversed after reaching asymptotic performance. dSAT represents a challenge session where the middle 54 trials of a training session are performed in the presence of a flashing house-light as a distracter (see Materials and Methods and Fig. 3D, below, for illustration). Group III animals were trained to criterion on the SAT on the full version of the task (162 trials, ∼40 min). After reaching criterion, animals continued training for 30 additional days on an 8-min version of the task. Group IV animals were trained on the Morris water maze for a period of 28 d. Following training, animals were housed in constant darkness until the remote memory test 14 d later. Sustained attention task (SAT), distracter sustained attention task (dSAT).