Figure 1.

Experiment design. A, Each column lists the type of behavior, odor sets, and design used for each experiment. The symbols next to each experiment are those used in the following figures. The odor sets and odors used are identified in Table 1. E1 and E2 were between-subjects designs (rats learned 1 task). E3 and E4 were within-subjects designs (rats learned both tasks). B, Schematic of the behavioral panels used. For both tasks, there is a center odor port. When rats stick their noses into the port, odor is delivered for as long as they remain in the port. For GNG, there is a single response port (A) in which a rat makes a response to odor A. No response is made to odor B. For TAC, there are two response ports. The left port is for responses to odor A and the right port for responses to odor B. See Materials and Methods for complete details. C, Schematic of the operant box used in E4 in which rats performed GNG and TAC tasks in the same session. On one side of the box was a GNG panel and on the other side of the box was a TAC panel. A light was illuminated on the panel to indicate which task to do for any given trial. See Materials and Methods for complete details.