Characterizing Cell Populations in the Substantia Nigra

The substantia nigra, an important relay station of the brain, is responsible for controlling the execution of diverse movements. In a study published today in Cell Reports, University of Basel researchers more precisely characterized two of the substantia nigra’s cell populations.

All of our movements are centrally controlled by the brain. Different brain regions and neuronal networks play an essential role in this process, including the substantia nigra, which receives and distributes signals in order to appropriately orchestrate the execution of a desired movement. Using a mouse model, the research team identified two cell populations in the substantia nigra that are responsible for different aspects of locomotion.

The researchers investigated the substantia nigra anatomically, genetically, and functionally. It became apparent that this region consists of several different types of nerve cells, of which they successfully identified two populations to describe in more detail. One of these populations is responsible for initiating motor tasks, and the other ensures continuity of movements.

“The heterogeneity of neuronal populations in the brain, also in the substantia nigra, is a well acknowledged concept. In our study, not only do we decipher the function of two nerve cell groups but we also show that they work together to produce correct locomotion,” says first author Giorgio Rizzi.

The findings of the study are also important in regard to Parkinson’s disease. Parkinson’s patients suffer from motor control abnormalities due to the degeneration of certain nerve cells.

“Interestingly, these cells are interaction partners of the population we identify as essential for movement initiation,” says senior author Kelly Tan. “This means that the signals of the cell population are no longer received and transmitted, and this dysfunction may underlie the movement initiation impairment symptom observed in Parkinson’s disease patients.”

In the future, the research team aims to continue identifying other cell populations of the substantia nigra and to elucidate their motor functions.

“With regard to Parkinson’s disease, we will assess how each network is altered as a result of the disease and how this affects movement,” Tan says. “If we understand the circuit modifications, we may find a way to tackle this neurodegenerative disorder and relieve the symptoms of Parkinson’s disease patients.”

Image: These are two cell populations in the substantia nigra that are responsible for different aspects of locomotion. Image courtesy of University of Basel, Biozentrum.