New study on the size, structure, and functions of the cerebellum

In a new research done at San Diego State University, scientists have reconstructed, unfolded, and flattened the entire cerebellar surface, down to the level of individual folia. This was done to quantitatively measure its total surface area, better characterize its regional structure, and provide a full-resolution human cerebellar base map. Unlike the human neocortex, the surface of the human cerebellum has never been computationally reconstructed to the level of all individual small folds (folia).

By using an ultra-high-field 9.4 Tesla MRI machine to scan the brain and custom software to process the resulting images, an SDSU neuroimaging expert discovered the tightly packed folds actually contain a surface area equal to 78% of the cerebral cortex’s surface area, even though the cerebellum is roughly one-eighth the volume of the neocortex. The unfolded and flattened surface comprises a narrow strip 10 cm wide, and almost 1 m long.

Reconstruction of the pial surface of the human cerebellum.

These findings suggest a prominent role for the cerebellum in the evolution of distinctively human behaviors and cognition. During active movements involving multiple body parts and skin contact points, parallel fibers that extend across multiple patches can integrate information from many distant body parts to speed, refine, and coordinate complex actions. Furthermore, the large cerebellum may have been as important as a large neocortex for the origin of some distinctively human abilities (e.g., language, extensive toolmaking, complex sociality).

“When you think of the cognition required to write a scientific paper or explain a concept, you have to pull in information from many different sources. And that’s just how the cerebellum is set up.”, said Martin Sereno, psychology professor, cognitive neuroscientist and director of the SDSU MRI Imaging Center.

Source (San Diego State University. “‘Little brain’ or cerebellum not so little after all.” ScienceDaily. ScienceDaily, 31 July 2020.)

Paper: Sereno, M.I., Diedrichsen, J., Tachrount, M., Testa-Silva, G., d’Arceuil, H. and De Zeeuw, C., 2020. The human cerebellum has almost 80% of the surface area of the neocortex. Proceedings of the National Academy of Sciences.