A group of researchers took on the case of a patient, anonymously referred to as RFS, and studied the manifestations of his rare brain disease called corticobasal syndrome. In their paper, the researchers describe how the patient could comprehend numbers, symbols, letters, and the numbers two to nine.
However, what they found peculiar was that he could not recognize numbers zero and one. According to a senior author and cognitive scientist from John Hopkins University, when RFS looks at a digit, his brain has to "see" the figure before he could unsee it.
In the study, the researchers investigated the process that went on inside his "awareness". The disease under study is known to cause significant trauma in two locations of the brain, namely the cortex and basal ganglia.
Aside from not recognizing zero and one, RFS also lost his competence to perceive, describe, or even copy old Arabic numerals. The full findings of the study were published in the journal PNAS on June 22, 2020.
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What is Corticobasal Syndrome?
According to the Weill Institute for Neurosciences Memory and Aging Center, Corticobasal syndrome (CBS) is a condition that causes alterations in movement, language skills, or both. People with CBS may have a hard time controlling their arm or leg.
Furthermore, CBS may begin with movement problems, such as stiff muscles on one side of the body involving the upper and lower extremities. The cause of CBS is currently unknown.
Scientists know that a large build-up of a protein called tau is apparent in some people with CBS. Tau usually occurs in the brain, but it is not yet clear what causes its build-up.
Moreover, CBS is a disease that changes with time. A person with CBS can live for many years with the disease. Previous studies suggest that a person with CBS may live an average of six to eight years with the disease, although this can differ on a case to case basis.
Mental Processes in the Perception of Figures
In a video of one of their trials, RFS tries to copy an orange '8' displayed on a laptop screen in front of him. But instead, he draws what he calls "spaghetti", with an orange background.
In another test, the team tried to put pictures or words near or inside large block numbers. The patient could easily see the images in equivalent letters. However, he couldn't see the pictures that were placed inside the numbers.
Although it seemed peculiar, the researchers believe that RFS was genuinely experiencing a strange perceptual anomaly. At first, they were considering the possibility of RFS experiencing a psychiatric, psychogenic or functional impairment.
However, at the time, he was also seeing a psychiatrist who vouches that there was no suspicion detected regarding his cognitive, perceptual, or physical symptoms, as reflected by his functional disorder.
For nearly eight years, the authors of the study worked with RFS, and it was only until they studied his brain using an EEG, that they understood what actually happened.
According to Teresa Schubert, a cognitive scientist from Harvard, the patient was unaware of the presence of a word, for example. However, his brain was capable of detecting it and could identify what particular word it was.
David Rothlein, from VA Boston Healthcare, said that his brain detected the faces in the digits without him being aware of its presence. He concludes that the findings reveal that RFS's brain is undergoing complex processing, even without his awareness.
