NYU researchers identify the brain mechanism that drives learning

I remember when I first learned about the history of science by reading about the countless scientists, physicians, medical experts and polymaths that existed hundreds of years ago. All the way from the Babylonians to Einstein and how modern science has developed today.

Learning about all of these fascinating people that existed generations before myself, and heavily influenced the medical practices that are still used today, was hugely enjoyable, to say the least.

This way of learning was simply encouraged by wanting to extensively learn about a new subject, not because I knew I would receive a specific reward by the time I finished the last page.

In other words, the only incentive I had to learn was simply just to broaden my mind.

Now, for a long time, researchers have believed that rewards such as food and money heavily encourage learning, which causes the release of dopamine, known as a "feel-good" hormone.

However, contrary to popular belief, a new study carried out by researchers at NYU Grossman School of Medicine in New York City suggests that learning can still occur, despite the absence of an incentive for pleasure.

The primary purpose of the study was to study the relationship between dopamine and the brain chemical known as acetylcholine, which plays a crucial role in learning and memory.

Previous neuroscience research has shown that these two hormones tend to compete with each other, meaning that a boost in one hormone thus causes a decline in the other.

The authors of the study focused on when, and under what circumstances, the dopamine levels are high at the same time when acetylcholine levels are low. They discovered that the situation occurs rather frequently, even in the absence of rewards.

In fact, it was shown that these hormones constantly ebb and flow in the brain like a river, with dopamine levels regularly raised whilst the acetylcholine levels stayed low.

"Our findings challenge the current understanding of when and how dopamine and acetylcholine work together in the brain.

"Rather than creating unique conditions for learning, rewards take advantage of a mechanism that is already in place and is constantly at work."

Anne Krok, lead author and medical student at NYU.

To conduct their research, the team gave dozens of mice access to a wheel on which they could choose to run or willingly rest.

Occasionally, the researchers offered the mice some water. They then proceeded to record rodent brain activity, allowing them to measure the amount of dopamine and acetylcholine released.

Using water as a treatment, as expected, created the typical patterns of both hormones that are prompted by rewards.

However, the team also observed that before receiving the water as a treatment, both hormones had already followed the "ebb and flow" cycles approximately twice every second, during which the levels of one hormone dipped, whilst the other surged considerably.

Krok also noted that this pattern continued regardless of whether the rodents were running or standing still.

Senior author and neuroscientist, Nicolas Tritsch, PhD, commented: "These results may help explain how the brain learns and rehearses on its own, without the need for external incentives."

He added: "Perhaps this pulsing circuit triggers the brain to reflect on past events and to learn from them."

Despite admitting that this study was not designed to determine whether or not mouse brains process information the same as humans, Professor Tritsch believes that the results may offer insights into neuropsychiatric conditions tied to dopamine, such as ADHD and schizophrenia.

This study was published in detail on the 9th of August in the peer-reviewed medical journal Nature.