Active Avoidance/Shuttle BoxTask

General Overview
Active avoidance is a fear-motivated associative avoidance task. In this task the mouse has to learn to predict the occurrence of an aversive event (shock) based on the presentation of a specific stimulus (tone), in order to avoid the aversive event by moving to a different compartment. The measures recorded include number of avoidances (the mouse crossing to the other compartment during the warning signal), number of non-responses (the mouse failing to cross to the other compartment during the trial), response latency (latency to avoid or escape), number of intertrial responses (i.e., crossing the barrier within the intertrial interval), and serve as an index of learning and allows memory to be assessed.

Apparatus
Training chamber consist of a rectangular chamber divided into 2 compartments. Both compartments are lighted by overhead stimulus lights. The two compartments are separated by an automatic guillotine door and each has a grid floor through which a footshock can be delivered.

Procedure

Habituation
On habituation day a mouse is placed in one of the two compartments and allowed to ambulate freely between the two compartments of the shuttle box for 10 minutes in order to become familiarized with the learning environment.

Training
On training day a mouse is placed in one of the two compartments and allowed to ambulate freely between the two compartments of the shuttle box for 1 minute (lights are on in both compartments). After 1 minute the light, used as the conditioned stimulus (CS), is switched off in the compartment in which the mouse is in, and 5 seconds later, a footshock is delivered (unconditioned stimulus (US), 0.3mA, 5 second duration). The shock and light co-terminate such that the light is on for 10 seconds. If the mouse fails to make a response, both CS and US are terminated after 5 seconds of foot shock. During intertrial intervals, mice are permitted to move freely and to cross back and forth between compartments. The next trial always starts in the compartment where the mouse was located at the end of the ITI.

If the mouse jumps to the other compartment during CS presentation, this is recorded as an Active Avoidance. If the mouse jumps to the other side when both CS and US are present, this is recorded as an Escape Response. If the animal fails to change compartments during the trial, this is recorded as a Failure to Respond. The intertrial intervals are random between 20 – 60 seconds. Each mouse receives 100-trials per day in 50 trial sessions separated by at least 1 hour for a total of 8 days and 800 trials.