While the astonishing case of a French man living a normal life despite having lost 90% of his brain was first reported in 2007 in the journal The Lancet, the story is resurfacing as part of the international conference of the Association for the Scientific Study of Consciousness. The portrait of this unusual subject was presented during the event, provoking new questions amongst the scientific community. How can a human lead a normal life with only 10% of his brain? The specialist Axel Cleeremans from the Université Libre de Bruxelles sheds light on the question.

Listening to Cleeremans paint the portrait of the patient during the conference held in June in Buenos Aires, one can only conclude that there's still a lot we don't know about the brain. For decades, scientists have told us that the brain is the body's control center and that any significant injury can cause serious, and often irreversible damage. But the exceptional clinical case of this 44 year-old French man whose skull contains mostly cerebrospinal fluid is raising lots of questions among the scientific community.

Complaining of weakness in his left leg, the subject finally decided to go to the hospital. The doctors ordered an MRI and were astonished to discover that 90% of his brain had disappeared! All that remained was a thin layer of cerebral tissue. Yet, and that’s the most amazing part, the man is in good health and leads a perfectly normal life. Married with two children and employed as a civil servant, the doctors reported that all of his mental capacities were fully intact, with an overall IQ of 75 (a score which is below average, but above scores associated with mental retardation). His daily life is in no way affected despite the areas controlling sensitivity, speech and hearing being considerably restricted.

After looking over his records, the doctors discovered that hydrocephalus had been detected in the patient at the age of 6 months. The disease is characterized by an abnormal accumulation of cerebrospinal fluid in the skull. At the time, a surgical intervention was performed in order to drain the excess liquid to other parts of the body through a small tube. Due to the development of other problems, the treatment was removed at the age of 14. It was most likely from this age that the fluid began building up, leaving less and less space for the brain, until only 10% of the space remained.

In the magazine Science Post, Cleeremans, a professor of cognitive science, emphasizes that this case report questions fundamental theories about consciousness. According to him, if the brain isn’t injured suddenly but gradually over time, it can perhaps adapt. This hypothesis about neuroplasticity or brain plasticity has already been put forward, but was until today applied only to learning.

Could the brain be more adaptive than we think?