Fear Conditioning

Fear Conditioning

Introduction

The theory of fear Conditioning was introduced by conducted by Pavlov in which he chose dogs as a sample to conduct the experiment upon. The theory of fear conditioning can serve as the tools for the trainers in two guidelines: when the autonomic responses are trained (the process to drool, production of adrenaline or reduction in adrenaline secretion) without the usage of the stimulus that is responsible for the creation of this type of retort and the creation of a connection between stimuli and its affect on the animal (the cause and effect relationship). This is categorized into primary and secondary stimuli. The stimulus in which the untrained subject shows its reaction is known as the unconditioned stimulus or the primary stimulus. Nevertheless, the second category of the Stimuli is known as the secondary stimulus. In this category the subject shows its reaction but there is one condition for it; the subject should be trained to react or behave in certain way first. This process is known as the conditioned stimulus or the secondary stimuli. (LeDoux 1996)

Discussion

Rats weighing 260-360 g were habituated to the fear conditioning chamber (context A) for 30 minutes one day prior to conditioning. Context A consisted of a Plexiglas rodent conditioning chamber with a metal grid floor (Coulbourn Instruments, Lehigh Valley, PA), illuminated by a single house light, and enclosed within a sound-attenuating chamber. The conditioning chamber was interfaced to a stimulus controller (Coulbourn Instruments, Lehigh Valley, PA). (Goosens 2001) The chamber was cleaned with a 70% EtOH solution between subjects. On conditioning day, rats were placed in context A and left to explore the chamber for three minutes prior to presentation of stimuli. Rats in the paired (P5) group were exposed to five tones (CS; 5 kHz, 75 dB, 20 s) that co-terminated with a foot shock (US; 1.0 mA, 500 ms). In the control conditions, an unpaired (UP5) group was presented with non-overlapping presentations of the CS and US. The presentation of the stimuli for UP5 was ordered so that there was one occurrence in which a CS followed a CS and US followed a US. In this way the tone was less predictive of the occurrence of a shock. The time between stimulus onset (intertrial interval; ITI) for all groups was 30-90 s (60 s mean). Animals were removed from the chamber 60 s following the final stimulus presentation. A naïve (N) group was exposed to the fear conditioning chamber alone for ten minutes. Rats in the behavior group were placed back into the fear conditioning chamber (context A) 24 hours later for analysis of freezing to the original training context (contextual fear memory). (Goosens 2001)

Three days following testing for contextual memory, rats were tested for retention of auditory fear conditioning in a novel context (Context B) to mask environmental cues of the conditioning chamber. Context B consisted of plastic flooring covered with fresh bedding, altered geometry and spatial cues (red and black tape) relative to context A, four additional cue lights ...