What is it about?
We examined the role of two prefrontal brain regions in three inhibitory learning experiments. This study used laboratory rats to test the effects of small drug injections directly into the brain. Trained rats investigate the location in which food is delivered, and learning about different signals is therefore reflected in their exploration in the part of the experimental chambers where the food is dropped. Different drugs were used to (1) generally inactivate the brain; (2) selectively stimulate dopamine; and (3) block dopamine from acting in these regions. An experimental signal was usually followed by food, but sometimes, when presented together with another (inhibitory) signal, the food delivery was cancelled. Rats in all three experiments showed discrimination, responding more on occasions when the positive signal was presented alone and less when the inhibitory signal was also presented. This discrimination was reduced but preserved following inactivation of either brain region. Similarly, the rats showed inhibitory discrimination following infusions of drugs to stimulate or block dopamine activity. Like the effects of inactivation, the selective blocker reduced responding. Thus, the drug infusions were effective, but there was no evidence to suggest that inactivation of the prefrontal areas examined impaired the inhibitory discrimination, and no evidence for dopamine modulation of such learning in the prefrontal part of the brain either.
Featured Image
Photo by Mathurin NAPOLY / matnapo on Unsplash
Why is it important?
Everyday thinking requires both the formation of connections between related events and the ability to hesitate through inhibition, to show discrimination on occasions when these connections are broken. Conversely, impaired inhibitory discrimination is implicated in brain disorders involving impulse control. The prefrontal area of the brain and its chemical modulation by dopamine are thought to provide important mechanisms for inhibition and impulsivity.
Perspectives
A role for dopamine within the prefrontal part of the brain in this specific kind of inhibitory discrimination has not been previously reported and was not found here. These negative findings apparently contradict earlier evidence showing a role for prefrontal dopamine in other kinds of inhibition, and suggest that different sites of dopamine action, or other chemical signalling mechanisms, may be involved in this important aspect of learning.
Helen Cassaday
University of Nottingham
Read the Original
This page is a summary of: Effects of manipulating prefrontal activity and dopamine D1 receptor signaling in an appetitive feature-negative discrimination learning task., Behavioral Neuroscience, September 2024, American Psychological Association (APA),
DOI: 10.1037/bne0000603.
You can read the full text:
Contributors
The following have contributed to this page
