• What is the problem/issue being addressed?
The cerebellum is a key structure involved in voluntary movement, motor learning and cognition. Understanding day-to-day fine motor coordination, but also how cerebellar dysfunctions can cause such a large spectrum of diseases (ataxia, dystonia, tremor, and some forms of autism and schizophrenia), requires us to decipher how information is processed within this structure. The cerebellum is made of a large cortical section, the well-studied cerebellar cortex, that performs extraordinarily complex sensorimotor processing, and a set of tiny neuronal nuclei, whose function is less well understood: the Cerebellar Nuclei (CN). Once computed in the cerebellar cortex, the cortical output is channelled through these small CN, which are the actual output of the cerebellum. How information is transformed after this computational funnel is unclear.
Recent advances have shown that the CN are composed of multiple subpopulations of neurons, that may be specialized in the control of distinct behaviours, although it is not clear which ones. Anatomical and experimental evidence also suggest that some of the inputs originating from outside the cerebellum (mossy fibres and climbing fibres) can directly influence the CN, indicating that the CN are more than just a relay. Understanding the properties of these inputs, and if and how they affect specific subpopulations in the CN is key to understand what processing happens during this last step of the cerebellar computations. This ultimately determines how the cerebellum controls other brain regions.
• Why is it important for society?
Fundamental research impacts society by deepening our understanding of how the brain works. Brain structures like the cerebellum are highly conserved across species, and many of the observation can be used to increase our understanding of the human brain. Besides increasing our understanding of the world, describing the functioning and network organization of a major brain structure like the cerebellum has potential medical and technological applications. It can lead to novel therapies for pathologies that are due to cerebellar disfunctions (ataxia, tremors), but also to other brain pathologies or disorders that have been shown to involve the cerebellum as part of bigger brain circuits, such as schizophrenia or autism. It can also have technological applications since some AI or robotic technologies are inspired by the cerebellar system.
• What are the overall objectives?
The main objective of this project was to improve our understanding of the processing rules in the cerebellar nuclei, by looking at how individual cells respond to different type of extracerebellar inputs, how they integrate different sources of information at the dendritic level, and how they process information at the level of the neuronal network.
