Skip to main content
. Author manuscript; available in PMC: 2012 Oct 28.
Published in final edited form as: Cell. 2011 Oct 28;147(3):509–524. doi: 10.1016/j.cell.2011.10.009

FIGURE 1. Auditory Fear Conditioning in Rats.

FIGURE 1

In a typical auditory fear conditioning procedure, rats are habituated to the conditioning chamber but given no stimuli. During the conditioning session the electric shock unconditioned stimulus (US) is paired with the auditory conditioned stimulus (CS) several times (usually 1–5). The effects of conditioning are then assessed in a test session during which the conditioned stimulus is presented alone. Most studies measure “freezing” behavior, which is an innate defensive response elicited by the conditioned stimulus after conditioning. An unpaired control group in which the conditioned stimulus and unconditioned stimulus are presented in a non-overlapping manner is often used. The conditioned stimulus elicits little or no freezing prior to conditioning in either the paired or unpaired group (not shown). Both the paired and unpaired group freeze during the training session due to the shock presentation. In the test session, the paired group exhibits considerably more conditioned stimulus-elicited freezing than the unpaired. Differences between the paired and unpaired group reflect the association that is learned as a result of conditioned-unconditioned stimuli pairing.