Scientists have created a brain map to study Parkinson's disease and schizophrenia

Deep in the brain is a system of structures that helps a person move, make decisions, form habits, and regulate emotions. Her work disorders are associated with neurological and mental illnesses, but scientists still have not fully understood which cells are involved in these processes. An international team of researchers has compiled the most detailed map of this area of the brain to date and has already used it to find a more targeted approach to the treatment of Parkinson's disease. More information about what other discoveries have been made can be found in the Izvestia article.

Map of 25.5 million basal ganglia cells

The international project brought together hundreds of scientists from more than 50 scientific institutions in nine countries. The researchers studied 25.5 million cells: about 21 million human cells, 3 million macaque cells, and 1.5 million needle cells. Previously collected data on the brains of mice was also used for comparison.

The scientists determined cell types, gene activity, their location, and molecular characteristics. As a result, they were able to create a detailed system for describing the basal ganglia, a group of interconnected structures located deep in the brain. They are involved in movement control, learning, habit formation, motivation, and emotional reactions.

The results are presented in a series of 27 scientific papers published in the journals Cell, Cell Reports Medicine, Cell Systems, Cell Genomics and Neuron. The authors expect that the atlas will become a common base for researchers who study the work of the brain and the mechanisms of disease development.

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A new type of neuron associated with schizophrenia

One of the results of the project was the discovery of a previously undescribed group of STR D2 SMYD2-HTR7 neurons. These cells belong to a type of striatum neurons, the largest structure of the basal ganglia. A comparison of cellular data with the results of genetic studies has shown that this group is associated with DNA variants that increase the risk of schizophrenia and bipolar disorder.

The researchers also found cellular features associated with depression and post-traumatic stress disorder. In addition, separate work within the framework of the project revealed changes in certain groups of striatum cells in people with autism. Previously, research on this condition has mainly focused on the cerebral cortex, so the findings indicate a possible role for deeper structures.

At the same time, the discovered connections do not mean that specific neurons directly cause mental disorders. Scientists have yet to figure out how genetic features affect the functioning of these cells and whether such changes can become a target for future therapies.

The search for a more accurate therapy for Parkinson's disease

The researchers demonstrated the practical significance of the atlas using the example of Parkinson's disease. In this disease, the functioning of neural systems associated with dopamine is disrupted, which leads, among other things, to motor symptoms. The scientists used information about the cellular composition of the striatum to determine more precisely where the therapeutic effect should be directed.

In experiments on mice with a model of Parkinson's disease, the researchers used a genetic switch — an enhancer that allows them to affect a specific group of cells. With his help, the scientists increased the level of the dopamine precursor directly in the cells of the striatum. This approach has helped to alleviate the symptoms and reduce the severity of common side effects.

According to the publication, targeted gene therapy in experiments proved to be no less effective than exposure to a wider group of cells, but it was safer. So far, the results have been obtained only in animal models. Additional studies are needed before using this approach in patients.

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How the map will help to study other brain diseases

Basal ganglia is not only associated with Parkinson's disease and schizophrenia. Their work disorders are also studied in the context of Huntington's disease, Tourette's syndrome, obsessive-compulsive disorder and addictions. A detailed map will allow researchers to determine which cell types are involved in pathological processes and compare their molecular characteristics with data on a healthy brain.

Another advantage of the project is the ability to compare cell structures in different species. This is especially important for neuroscience: many experiments cannot be performed on a living human brain, so scientists use animal models. Comparing data on humans, macaques, igrunka, and mice helps to understand which cell features are preserved in different species and to what extent the experimental results are applicable to humans.

All the data and tools of the project are planned to be made available to the scientific community. In the future, the researchers expect to use the created system as the basis for a larger-scale map of the entire human brain. According to the project participants, the atlas can become a starting point for the development of methods that will affect specific cell groups rather than entire brain regions.