Figure 1.

Behavior and electrophysiological recording. A, Rat engaged in a DNMS trial, during the sample lever press. Depth EEG was recorded via a cable, which is visible in the picture. B, Example EEG traces from each of the recorded areas in a control rat are shown around the moment of a sample lever press (dotted line). C–E, Representative thionin-stained coronal sections illustrating electrode placements in the CA3 (C), CA1 (D), and PFC (E). Arrows indicate the locations of the deepest electrode. F, Outline of the DNMS task. The rat was required to press a sample lever (“sample”; left lever in this case), followed by an imposed delay period during which the rat had to break an infrared beam on the opposite wall. After the imposed delay the rat was required to press the opposite lever (“nonmatch”; right lever in this case, indicated by a dashed arrow) to gain a food reward.