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Parameters of the dorsal bundle extinction effect: previous extinction experience.
Pharmacology, Biochemistry, and Behavior
|June 1, 1978
Summary
Lesioning the dorsal noradrenergic bundle prolongs extinction responding in rats. However, prior extinction experience or partial reinforcement during acquisition prevents this effect, suggesting learning history modulates noradrenergic influences on behavior.
Area of Science:
- Neuroscience
- Behavioral Neuroscience
- Neurobiology
Background:
- The dorsal noradrenergic bundle plays a crucial role in regulating behavioral responses, including those during extinction learning.
- Previous research has indicated that lesions to this bundle can lead to prolonged responding during extinction of operant behaviors.
Purpose of the Study:
- To investigate the parameters influencing the dorsal bundle extinction effect, with a specific focus on the role of previous extinction experience.
- To determine if prior exposure to extinction or specific training paradigms can prevent the development of prolonged extinction responding.
Main Methods:
- Utilizing the neurotoxin 6-hydroxydopamine to selectively lesion the dorsal noradrenergic bundle, significantly depleting telencephalic noradrenaline.
- Employing operant lever pressing tasks with continuous reinforcement (CRF) and extinction phases.
- Investigating the impact of repeated extinction trials and acquisition training involving successive visual discrimination on extinction behavior.
Main Results:
- Lesions to the dorsal noradrenergic bundle replicated the prolonged responding in extinction effect.
- This effect was attenuated or absent when animals had prior experience with extinction or underwent partial reinforcement during acquisition.
- Experience with extinction during the acquisition phase, such as through successive visual discrimination training, also prevented exaggerated extinction responding.
Conclusions:
- The dorsal noradrenergic bundle's role in extinction is not absolute and can be modulated by the animal's learning history.
- Previous exposure to extinction or specific training paradigms can override or prevent the development of the dorsal bundle extinction effect.
- These findings contribute to understanding the neurobiological mechanisms underlying behavioral flexibility and the impact of learning on noradrenergic system function.