A recent scientific study conducted by researchers at the Okinawa Postgraduate Institute of Science and Technology (OIST) revealed a pivotal role for acetylcholine, a neurotransmitter in the brain, in enabling organisms to break old habits and adapt to changes in the environment.
The study, published in Nature Communications, provides new insights into the neural mechanisms that control behavioral flexibility, which may open horizons for understanding and treating a number of neuropsychiatric disorders, such as addiction, obsessive-compulsive disorder, and Parkinson’s disease.
Advanced experiment on mice
The researchers relied on an experimental model using mice that were trained to navigate inside a virtual maze. The animals learned to choose the correct path that would lead to obtaining a reward. After the mice mastered the task, the scientists suddenly changed the correct path without warning.
This change caused the mice to lose the expected reward, allowing the researchers to monitor the brain’s response in the moment of “disappointment.” Using advanced imaging techniques known as two-photon microscopy, the team was able to monitor brain activity and the release of neurochemicals in real time.
Acetylcholine drives behavioral change
The results showed a significant increase in the secretion of acetylcholine in specific areas of the brain, coinciding with the change in the behavior of the mice, and a behavioral pattern known as “lose-shift behavior” emerged, where the mice began to change their choices after not obtaining the reward.
The study’s lead researcher, Dr. Gideon Sarpong, said, “The more acetylcholine is secreted, the more likely the mice are to change their future choices,” stressing that this substance plays a direct role in enabling the brain to break old habits.
Confirm the vital role of the chemical
To prove causality, the researchers reduced the ability of mice to produce acetylcholine, and as a result, a significant decrease in their ability to change their behavior after losing a reward was observed, which strengthened the hypothesis that this substance is necessary for the process of behavioral adaptation.
The scientists also noted that some groups of nerve cells did not show an increase in the secretion of acetylcholine, but rather recorded a slight decrease in some cases, which indicates a possible role for these cells in preserving previous memories associated with successful paths.
Dr. Sarpong explained that this mechanism may allow the brain to retain information about previously successful choices, so that it can be retrieved if appropriate conditions return in the future.
A deeper understanding of the human brain
Professor Jeffrey Wickens, head of the Neurobiology Research Unit at the institute and one of the study participants, pointed out that behavioral flexibility is a complex process that requires interaction between several regions of the brain, adding that the central role goes to the “striatum” region, where the cholinergic interneurons responsible for secreting acetylcholine are located.
“The neural mechanisms underlying behavior change have been obscure for years, due to their extreme complexity and reliance on the interaction of multiple networks in the brain,” Wickens said.
Promising medical prospects
These results open the door to the development of new treatments for a number of neurological and psychiatric disorders, as acetylcholine levels are affected in diseases such as Parkinson’s and schizophrenia.
The researchers confirmed that patients suffering from addiction or obsessive-compulsive disorder face difficulty in changing their behavior and breaking habits, which makes understanding these mechanisms an important step towards designing more effective treatments.
