Performance Of Avoidance Behavior Research Articles

Analysis of striopallidal interactions in the control of avoidance behavior.

The effects of chronic administration of phenamine (15 microg) into the neostriatum and bicucculline (5 microg) in the globus pallidus of rats on the performance of avoidance behavior in a shuttle box were studied. Agents were injected daily for three weeks, and control animals received physiological saline. Activation of the dopaminergic system of the neostriatum compensated for decreases in avoidance behavior due to surgical trauma, increased the intensity of spontaneous activity in the "open field," and induced motor stereotypy. Administration of bicucculline into the globus pallidus produced sharp worsening of conditioned reflex avoidance behavior throughout the treatment period (spontaneous movement activity showed no significant change), with recovery only occurring two weeks after the last microinjection. Simultaneous treatment with phenamine into the neostriatum and bicucculline into the globus pallidus resulted in compensation for the inhibitory effects of bicucculline. Several phases were observed in behavioral changes, apparently reflecting the dynamics of interactions between the neo- and paleostriatum. The significance of the coordination of intrastriatal functions for the regulatory activity of the basal ganglia is discussed.

Effects of dopamine depletions in the medial prefrontal cortex on active avoidance and escape in the rat

Dopamine systems have been implicated in the performance of avoidance behavior, and the dopaminergic innervation of medial prefrontal cortex is known to be responsive to stressful stimuli. In the present investigation, injections of 6-hydroxydopamine were used to produce moderate depletions of dopamine in the medial prefrontal cortex of rats trained to perform an active avoidance/escape task. In this task, 0.5 mA shock was presented for 5 s every 30 s, and the rat could escape shock presentation, or avoid the shock for 30 s, by pressing a lever. Depletion of dopamine in the medial prefrontal cortex did not affect total number of responses, and did not impair avoidance responding (i.e. responding when the shock was off), and in fact dopamine-depleted animals tended to make slightly more avoidance responses than control animals. Prefrontal dopamine depletions did result in a significant decrease in the number of escape responses (i.e. responding to terminate shock when the shock was on). Moreover, dopamine depletions significantly decreased response efficiency, which is an index of the reduction of shock time produced per level pressing response. Previous work has indicated that dopamine antagonists and accumbens dopamine depletions have dramatic effects on avoidance behavior; thus present results indicate that prefrontal cortex dopamine depletions do not mimic the effects of interference with subcortical dopamine systems. The selective effects of dopamine depletions on escape behavior in the present study suggest that rats with medial prefrontal dopamine depletions have an impairment in the ability to respond appropriately to the direct presentation of footshock. These findings may have implications for the functional significance of stress-induced increases in prefrontal cortex dopamine activity.

Rhythmic theta-like unit activity of the hippocampal formation during acquisition and performance of avoidance behavior in rabbits

Neuronal activity was recorded from the hippocampal formation during instrumental conditioning of avoidance behavior in rabbits. The conditional stimuli (CSs) were pure tones, the unconditional stimulus (UCS) was a constant-current footshock, and the response was locomotion in a rotating wheel apparatus. Prior to conditioning the rabbits received pretraining, involving noncontingent presentations of the CSs and the UCS. The specific focus of this report is on neuronal records which displayed rhythmic bursts of action potentials similar to the theta rhythm of the EEG. Early in training, rhythmic theta-like neuronal bursts occurred throughout the CS-UCS interval on trials manifesting the initialmost behavioral conditioned responses (CRs). Late in training during asymptotic CR performance there was a build-up in the frequency and rhythmicity of neuronal bursts prior to the CR. The maximum frequency of bursting (9–10 Hz) always occurred just prior to the CR. Relatively little theta-like activity occurred in the early portions of the CS-UCS interval, in the late stage of training. During pretraining ample preresponse theta-like activity occurred in some subjects but not in others. However, no subject manifested a systematic build-up in bursting prior to behavioral responses in pretraining.