by Researchers at the University of Copenhagen have made an important discovery regarding the neural circuitry responsible for controlling right and left turns in the brain. Led by Assistant Professor Jared Cregg and Professor Ole Kiehn from the Department of Neuroscience, the team has identified a previously unknown group of neurons that receive signals from the basal ganglia and regulate the right-left circuit.
In a study conducted in 2020, Kiehn, Cregg, and their colleagues identified a network of neurons in the brainstem that acts as the “steering wheel” for right and left movements during walking. However, the researchers were unsure about how this circuit was controlled by other parts of the brain at the time, such as the basal ganglia.
The basal ganglia are deep brain structures that have long been known to be involved in voluntary movements. Previous studies had shown that by stimulating the basal ganglia, researchers could influence right and left-hand movements in mice. However, the mechanism behind this control was not understood.
The newly discovered group of neurons is located in a region of the brainstem called PnO and receives direct signals from the basal ganglia. These neurons adjust step lengths while making turns, thereby determining whether an individual moves to the right or left.
The findings of this study may have implications for individuals with Parkinson’s disease. Parkinson’s disease is characterized by a lack of dopamine in the brain, which affects the basal ganglia. The researchers believe that this dopamine deficiency leads to the failure to activate the brainstem’s right-left circuit. This is consistent with the difficulties experienced by people with Parkinson’s disease when turning while walking.
To investigate this further, the researchers studied mice whose brainstem closely resembles that of humans. By removing dopamine from the brains of these mice, they created a Parkinson’s disease model. The mice exhibited motor symptoms similar to those experienced by individuals with the disease, including difficulties in making turns.
However, by stimulating the PnO neurons, the researchers were able to alleviate these turning difficulties in the mice. This suggests that deep brain stimulation, a technique used in humans, could potentially be used to alleviate Parkinson’s symptoms related to turning difficulties.
Nevertheless, translating these findings to humans presents challenges. The researchers used advanced optogenetic techniques in mice, where they genetically modified cells to be light-sensitive and then stimulated them with light. Current deep brain stimulation in humans relies on electrical stimulation, which cannot distinguish between specific neuron populations in the brainstem.
However, as our understanding of the brain continues to improve, more focused deep brain stimulation techniques for humans may become feasible in the future.
By shedding light on the neural circuitry responsible for right and left turns in the brain, this study provides valuable insights into the fundamental mechanisms underlying voluntary movements. Further research in this area could lead to new therapeutic approaches for conditions that affect motor control, such as Parkinson’s disease.
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1. Source: Coherent Market Insights, Public sources, Desk research
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