When rats perform a continuous alternation task on a T-maze, many hippocampal neurons fire differentially on left and right turn trials, even when they traverse the stem of the maze that is common to both types of episodes (Wood et al. Neuron 27:623, 2000). Wood & Ainge (SFN 2003 #91.1) found that continuous alternation can be performed without an intact hippocampus, but the hippocampus is critical when a delay is enforced between alternations. To examine whether firing patterns differ in hippocampal-independent and hippocampal-dependent tasks, we recorded the activity of CA1 neurons while rats performed the task continuously or were restrained on each trial for 30 sec. in the start area. Preliminary observations indicated that some cells have different patterns of activity in the two conditions related to differences in behavior. For example, in the delay condition, some cells fired robustly when the animal was held in, or as it left the start area. However, other cells showed differential firing during t...