A French man who lives a relatively normal, healthy life – despite missing 90 percent of his brain – is causing scientists to rethink what it is from a biological perspective that makes us conscious. Despite decades of research, our understanding of consciousness – being aware of one’s existence – is still pretty thin. We know that it’s somehow based in the brain, but then how can someone lose the majority of their neurons and still be aware of themselves and their surroundings?
First described in The Lancet in 2007, the case of the man with the missing brain has been puzzling scientists for almost 10 years. The French man was 44 years old at the time the journal article came out, and although his identity was kept confidential, the researchers explained how he’d lived most of his life without realising anything was wrong with him. He only went to the doctor complaining of mild weakness in his left leg, when brain scans revealed that his skull was mostly filled with fluid, leaving just a thin outer layer of actual brain tissue, with the internal part of his brain almost totally eroded away.You can see his scans above:
Doctors think the majority of the man’s brain was slowly destroyed over the course of 30 years by the build-up of fluid in the brain, a condition known as hydrocephalus. He’d been diagnosed with it as an infant and treated with a stent, but it was removed when he was 14 years old, and since then, the majority of his brain seems to have been eroded. But despite his minimal remaining brain tissue, the man wasn’t mentally disabled – he had a low IQ of 75, but was working as a civil servant. He was also married with two children, and was relatively healthy.
Not only did his case study cause scientists to question what it takes to survive, it also challenges our understanding of consciousness. In the past, researchers have suggested that consciousness might be linked to various specific brain regions – such as the claustrum, a thin sheet of neurons running between major brain regions, or the visual cortex. But if those hypotheses were correct, then the French man shouldn’t be conscious, with the majority of his brain missing.