Central nervous system (display 87)

The expansion of the cerebral cortex is an evolutionary characteristic specific to mammals. Its relative size varies according to the species. Despite being limited by the cranium, the cortex has developed considerably. The multitude of folds that we observe are the result of the mechanical compression of the expanding cortex within a skull with a constant volume.

This folding phenomenon, characterised by sulci (depressions) and gyri (convolutions), has allowed a significant increase in the surface of the cortex while maintaining short connections. A folded brain is termed gyrencephalic, while an almost smooth brain is said to be lissencephalic. The size of the convolutions is not always linked to brain complexity or the number of neurons present, but rather to the size of individuals and their endocranial volume. Elephants, dolphins and humans have a very convoluted cortex. Small mammals, such as rats, whose brain represents 0.53% of their body weight, often have an almost smooth cortex.

Paul Gervais (1816-1879) integrated the Professorship of Comparative anatomy of the Muséum national d’Histoire naturelle in 1834 and became preparer of specimens in 1841. Having submitted his doctoral thesis in 1844, he moved to Montpellier where he taught at the Science Faculty and quickly became Professor of Zoology and Comparative anatomy. In 1865 he returned to Paris where he secured a job at the Sorbonne. Three years later he replaced Étienne Serres (1786-1868) as holder of the Professorship of Comparative anatomy. He was admitted to the Académie des Sciences in 1874. 

A devoted scientist, his anatomical research focused on osteology but also on neuroanatomy, as evidenced by the mammal cerebral casts exhibited here. A bust erected in his honour stands at the entrance of the gallery.