Scientists have identified a group of brain cells in mice that facilitates their ability to turn left or right. This discovery could potentially be used in future treatments for Parkinson’s disease. Have you ever wondered what happens in the brain when we move left or right? Most people don’t do this; they just perform these movements automatically. However, this seemingly simple action is governed by a complex process.

In a new study, scientists have identified a missing part of the complex neural network required for left-right turns. The discovery was made by a research team consisting of Associate Professor Jared Cragg, Professor Ole Keen and colleagues from the Department of Neurology at the University of Copenhagen.

In 2020, Ole Keen, Jared Cragg, and colleagues described “brain steering,” a network of neurons in the lower brainstem that controls left and right movements during walking. However, it was not clear at the time how this left-right circuit was controlled by other parts of the brain, such as the basal ganglia.

Connection with basal ganglia

“We have now discovered a new group of neurons in the brainstem that receives information directly from the basal ganglia and controls the right-left circuit,” explains Ole Keen.

Eventually, this discovery could help people with Parkinson’s disease. The study was published in a reputable scientific journal Nature Neuroscience. The basal ganglia are located deep in the brain. It has been known for many years that they play a key role in the control of voluntary movements.

Years ago, scientists learned that it was possible to affect right and left hand movements in mice by stimulating the basal ganglia. They didn’t know how to do it.

“When you walk, you shorten the stride length of the right leg before turning right and the left leg before turning left. The newly discovered network of neurons is located in a part of the brainstem known as PnO. These are cells that receive signals from the basal ganglia and regulate the length of the step when we turn, thus turning right or left.” those who determine whether we act or not,” explains Jared Cragg.

The study therefore provides a key to understanding how these absolutely necessary movements are produced by the brain. In the new study, scientists examined the brains of mice because their brainstems are very similar to the human brainstem. Therefore, researchers expect to find a similar left-right circuit in the human brain.

Parkinson’s patients have difficulty turning left and right

Parkinson’s disease is caused by a lack of dopamine in the brain. This affects the basal ganglia, and the researchers behind the new study believe it results in the failure to activate the right-left circuit in the brainstem. And it makes sense when you look at the symptoms that Parkinson’s patients experience in the later stages of the disease; They often have difficulty turning while walking.

In a new study, scientists examined this in mice with symptoms similar to those of people with Parkinson’s disease. They created the so-called Parkinson’s model by removing dopamine from the brains of mice, thus giving them motor symptoms similar to those experienced by people with Parkinson’s disease.

“These mice had difficulty turning, but by stimulating PnO neurons we were able to alleviate the turning difficulty,” says Jared Cragg.

Using deep brain stimulation, scientists may eventually develop similar stimulation for humans. However, they currently cannot stimulate human brain cells as accurately as in mouse models using advanced optogenetic methods.

“Neurons in the brainstem are in disarray, and electrical stimulation of the type used in human deep brain stimulation cannot distinguish cells from each other. But our knowledge of the brain is constantly increasing, and we will eventually be able to begin to study targeted deep brain stimulation in humans,” concludes Ole Keen.