RFS, an engineering geologist in his late 60s, began to experience headaches, amnesia, tremors, and difficulty walking in October 2010. Doctors couldn’t determine the cause—they suspected a stroke, then discovered that he had a disease called corticobasal syndrome, which kills off brain cells. In the following days numbers became increasingly unfamiliar to RFS. He could no longer recognize most of the numbers, but could still perform mental and other mathematical operations. He mastered a new system of them, where l stands for 2 and ⌈ stands for 8.
The tests performed by a group of neuroscientists revealed that RFS’s deficit is not a simple visual malfunction.Rather, the deficit depended on his interpretation: As soon as his unconscious brain circuits registered a number, everything went haywire. His amazingly specific deficit could help neuroscientists understand how conscious awareness arises in the brain.
- The mysterious case of man who can read letters—but not numbers—exposes roots of consciousness. Sam Kean. 2020/07/29. sciencemag.org
- Lack of awareness despite complex visual processing: Evidence from event-related potentials in a case of selective metamorphopsia