Bassem Hassan, Scientific Director and Deputy General Director at the Paris Brain Institute, explains the development of the human brain.

About Bassem Hassan

"I’m the Scientific Director of the Paris Brain Institute, and my research concerns how the brain develops.
I am a neurobiologist and the Research Director at Inserm, a public scientific and technological institute dedicated to biomedical research. My passion is to understand the fundamental mechanisms of the development and differentiation of the nervous system. My lab studies the genetic mechanisms that regulate the development of the nervous system."

How our brains form

Brain development refers to the process of how our brain forms during its embryonic stages – to the entire process and the time that passes between the moment that we have a set of cells in the developing embryo that are fated to become the brain until the moment where that brain is ready to act and function.

We all start life as a fertilised egg that divides and grows and grows. At some point, some part of that growth becomes what we would call differentiated – has a specific potential, in this case, to become the brain, but not something else. So, the cells that are going to make your brain in embryonic development stop being able to make anything else and can only make your brain. At that point, it’s a sheath of cells which turns on itself and becomes something we call the neural tube. Now, the more frontal, or anterior, parts of this neural tube are what are going to become the brain. The back parts are going to become the spinal cord. So, the brain is this frontal part. From that moment on, this sheath of cells is now competent to form brain cells.

Key Points

• The relationship between brain plasticity and brain stability (homeostasis) is key to healthy brain development.
• Humans are aging beyond what the brain has evolved to age, so we are starting to see degeneration in later years.
• The blueprint for the brain – from its robustness to its core vulnerabilities, which will determine its susceptibility to brain diseases in later life – is actually built in during development.