The human brain is made up of billions of neurons that are interconnected to form the circuits enabling life. However, the brain is not static and neuronal connections can change, a phenomenon termed neuronal plasticity. Often this occurs by making new neurons, but this process is highly controlled as it poses risks for altering existing critical connections. As such, how those brain regions maintain plasticity has been a focus in research efforts.
One of these brain regions of the brain thought to be relatively stable is the cerebral cortex, which is largely responsible for human cognitive capacity. However, a recent study published in eLife and led by scientists from the University of Turin demonstrate the cerebral cortices of 12 mammal species with a range of brain sizes — including the large-brained chimpanzees — achieve neuronal plasticity by maintaining a reserve population of immature neurons.
The researchers noted that larger cortices contained more immature neurons. However, one striking feature of these neurons is their characteristics are very similar across all 12 species. This suggests that these cells are very important in mammalian brains, as they have remained largely unchanged through years of evolution.
It seems the cerebral cortex is more adaptable than once thought and that flexibility has been maintained through evolution. This work also highlights the need to continue studying these populations of immature neurons. The researchers call for similar investigations into immature neuron populations' potential role in maintaining proper connections in the brain. As we learn about these immature neurons, it may be possible to use this information to better predict cortex neurodegeneration, which often leads to conditions like Alzheimer’s Disease.