The Effect of Electric Shock and Fear Conditioning on KAMIN Effect in Rats

Abstract

The question of what causes KAMIN effect is still remained. Recently, it is popularly thought that KAMIN effect is “shock-induced” phenomenon. There are, however, some researchers who do not agree to this explanation. One of my purposes is to investigate whether KAMIN effect is induced only by electric shocks. Another is to try to get an alternative explanation of KAMIN effect by comparing avoidance respones as an index of external behavior with heart rate changes as an index of internal behavior. Subjects were 54 male albino rats. They were given one of two preceding procedures of fear conditionning and electric shock trial, and then were ramdomly divided into one of four retention interval groups (0, 1, 3, 24 hrs.). After their retention intervals, they were tasked one-way avoidance training. The number of avoidance responses of the rats given the preceding procedure of fear conditioning showed a typical V-shaped curve as function of retention intervals, but that of the rats given only shocks did not showed a typical curve, but a modified-V-shaped curve with a rising end. This means that the avoidance responses have not been facilitated immediately after administration of electric shocks. Since the results of HR changes to the CS and the shuttle box situation did not revealed specific changes in the one-hour groups, as compared with 3 and 24 hour groups, the present results could not be explaned by either memory or drive theory. It might be thought that the first part of V-shaped curve in KAMIN effect is made by facilitating effect of avoidance response immediately after learning of CS-UCS relationship, and that the middle and last parts are produced only by effect of electric shocks.