18 years ago, a young woman was born without a part of her brain (the entire left hemisphere) but still has above-average reading skills. Note that the left hemisphere is generally the part of the brain used in language. She also has a slightly above average IQ.





Brain scans (which assess cerebral perfusion using complex molecules labeled with technetium-99m, capable of crossing the blood-brain barrier) revealed that the young woman had more brain tissue involved in reading than what is usually found in the majority of individuals. Tests of his brain activity indicate that the right side of her brain has taken over some of the functions that the left hemisphere usually does, showing that the organ has adapted to compensate for the missing tissue.





The parents of the young woman, known here as C1, noticed that something was out of the ordinary when she was 7 months old already. Most babies stop clenching their thumbs with their fists around this age, but C1 continued to do so with her right hand. It was when C1 was 10 months old that a scintigraphy revealed that there was a pocket of liquid where the left hemisphere of her brain should have been.





C1 has been diagnosed with hemi-hydranencephaly, an extremely rare disease in which a large part of the cerebral cortex is missing. To date, only 9 cases have been reported worldwide.





At the age of 14 months, C1 was enrolled in a research project: a team of scientists, based at the University of Chicago, followed her progress until her 16 years, as well as those of 64 other children with a brain said to be normal (full) and 40 children who had had a stroke in the weeks before or after birth.





Brain compensation that gets worse over time