Figure 1.

Schematic representation of the IA task used in our studies. During the training session, the rat is placed in the lit (safe) compartment of a two-chamber apparatus. After 10 s, the door separating the compartments is automatically opened, allowing the rat access to the dark (shock) compartment. Because of their exploratory drive and nocturnal nature, the rats quickly enter the dark compartment. The time the rat takes to enter the dark compartment is taken as acquisition latency. Upon entering, the door is closed, and a mild electric footshock is delivered from the grid floor. A few seconds later, the rat is returned to the home cage. During testing, the rat is placed back into the lit compartment, and the time the animal takes (latency) to enter the dark compartment is measured (test). Under normal conditions, the animals develop a significant avoidance of the compartment that was previously associated with the footshock. The latency score is used as a behavioral readout of the memory of the context that was previously associated with experiencing a footshock.