Discriminative Avoidance Behavior Research Articles

Magnesium pemoline: Effect on acquisition and retention of discriminated avoidance behavior

Recently, Plotnikoff suggested that magnesium pemoline, a mild CNS-stimulant, enhanced learning and memory in rats whereas other CNS-stimulants did not. We compared magnesium pemoline with another CNS-stimulant, d-amphetamine, and a placebo, in a bar-press avoidance situation. Both drug groups showed faster acquisition than the placebo; the magnesium pemoline group, in addition, showed less intertrial responding than the d-amphetamine group. Magnesium pemoline appears to enhance avoidance performance by increasing the rats’ responsivity to the warning signal. There was no enhanced retention due to the drug.

Drug-induced modifications of discriminated avoidance behavior in rats.

Rats were trained to avoid electric shocks in a three-compartment box, with a procedure requiring either correct active avoidance responses (crossing into the lighted exit compartment) or passive avoidance (no-crossing when both exit compartments were darkened). The effects of various CNS drugs on the learned avoidance behavior were investigated.

METHOD FOR DISCRIMINATIVE AVOIDANCE TRAINING.

Experiments were performed in which the typical procedure for obtaining discriminated avoidance behavior with rats in a lever-pressing apparatus was compared with a new procedure which allowed only avoidance but not escape from the shock. When either escape or avoidance is possible, the rats make a majority of escape responses, but where escape is impossible avoidance behavior is rapidly established.

Determining thresholds of aversive brain stimulation

This study describes a method for determining thresholds of aversive brain stimulation. Chronically indwelling electrodes were implanted in selected brain areas of monkeys, who were then trained to press a lever in order to reduce the electric current stimulating these areas. In the absence of a response, the current rose in small steps until responding, which decreased the current in steps, was again initiated. Following the demonstration of rather precise, immediate control of lever pressing by the brain stimulation, variables affecting magnitude and variability of the threshold were explored. It was found that an increase in size of the current steps increased peak current levels and width of the oscillations. Using a variation of the technique where responding terminated brain stimulation (rather than reducing it in steps), it was shown that increasing the number of responses required for termination elevated threshold and lowered variability. An analgesic drug, anileridine, caused a threshold rise with larger doses having greater effects. In an experiment where maximum current was selectively limited, it was found that current levels the animal would tolerate continuously were levels that normally evoked responding. These data were interpreted as indicating that behavioral control by brain stimulation is complicated by discriminated avoidance behavior with lower current levels functioning as warning stimuli.