Figure 2.

(A) Schematic of the T-maze alternation task: solid lines indicate the forced sample phase while dashed lines indicate the correct response in the choice phase. Arm access could be blocked by placing a barrier at the entrance of the arm (effectively turning the cross-maze into a T-maze configuration). Initial training on the task (Stage 1) permitted the use of multiple strategies supporting alternation, i.e., allocentric, intramaze, idiothetic, direction alternation (with reference to a known bearing). The task was then systematically modified in order to prevent the use of intramaze cues (Stage 2) or the use of intramaze and visual allocentric cues (Stage 3). These manipulations included using two mazes instead of one (Stage 2 and 3) or running in the dark, as illustrated with the dark gray hatched background (Stage 3); (B) percentage of correct choices for all three stages; (C) schematic of the geometric cue task. Rats were tested in a rectangular insert within a circular maze. A curtain was drawn around the maze throughout to encourage the use of intramaze cues for learning. The solid circles depict the submerged platform and the dotted circles indicate the geometrically identical platform location (on each trial there was only one platform). The visible landmark (black bar) was attached to the platform for Sessions 2–5 of the experiment; (D) the mean escape latencies for the two groups during training when they were required to find a platform beneath a landmark in a circular pool (Session 1), beneath a landmark in a rectangular pool (Session 2–5), and without a landmark in a rectangular pool (Session 5–18). The vertical lines depict the standard error of the mean. Abbreviations: LMNx, lateral mammillary nuclei lesion group; Sham, surgical control; *p < 0.05. Data are taken from Vann (2011).