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Man unable to 'see' numbers after suffering rare brain disease
He can't identify the numbers 2 through 9. But strangely, he can still see ones and zeros.
- When a man who was diagnosed with the neurodegenerative disease corticobasal syndrome looks at the numbers 2 through 9, he sees unintelligible squiggly lines.
- The disability appears to be a peculiar type of metamorphopsia, a visual defect that causes linear objects, like the lines on a grid, to look curvy or rounded.
- The study has some interesting implications on theories of consciousness.
Someone writes the number 8 on a piece of paper. You look at it, see a shape, but you can't identify what number it is, or whether it's a number at all. The markings just look like "spaghetti."
It sounds strange, but that's exactly what happened to a man who suffers from a rare neurodegenerative disease called corticobasal syndrome, and now can't recognize the digits 2 through 9. This disease, caused by damage to the cortex and basal ganglia, often leads to memory problems and difficulty moving, but the inability to identify numbers seems to be a very rare symptom.
In a new study published in Proceedings of the National Academy of Sciences (PNAS), a team of researchers describe how the unique disability sheds light on how the brain processes visual awareness.
The inability to identify numbers posed an immediate puzzle for researchers. If the man (named "RFS" in the paper) can read letters and words, but not numbers, that means his brain must be identifying the numbers — and then selectively discriminating against them.
Johns Hopkins University - Schuberta et al.
The disability appears to be a peculiar type of metamorphopsia, a visual defect that causes linear objects, like the lines on a grid, to look curvy or rounded.
"When he looks at a digit, his brain has to 'see' that it is a digit before he can not see it -- it's a real paradox," said senior author and cognitive scientist, Michael McCloskey, in a news release. "In this paper what we did was to try to investigate what processing went on outside his awareness."
RFS was also unable to see words or drawings placed inside or near the numbers 2 through 9. For example, he wasn't able to see an image of a violin drawn inside the number 3. But when the violin was placed far enough away from the number, he was able to see it.
In an electroencephalography (EEG) experiment, the team found that even though RFS said he didn't see images placed near numbers, his brain was registering that words were there.
"He was completely unaware that a word was there, yet his brain was not only detecting the presence of a word, but identifying which particular word it was, such as 'tuba'," Harvard University cognitive scientist Teresa Schubert said in a press release.
Is it possible that RFS' disability can be explained by a psychological issue?
"Given the rare form of RFS' metamorphopsia, how can we be sure that his deficit is genuine? With any unusual deficit, there is the possibility that the underlying dysfunction is psychiatric, psychogenic, or 'functional', rather than an impairment of basic perceptual/cognitive processes," the team wrote in the paper.
"We believe this unlikely in the present case for multiple reasons … At the time of our study RFS was seeing a psychiatrist for help in adjusting to his condition, and the psychiatrist had no suspicion that any of his perceptual, cognitive, or physical symptoms reflected a functional disorder. In addition, RFS' performance in two-choice discrimination was not below chance, as is often found in cases of malingered deficits."
The research has some interesting implications for theories of consciousness. As the paper states, some theories propose that humans are able to perform "certain types of complex cognitive processes" because our consciousness interacts with deeper-level processes in the brain. But the results suggest consciousness may play less of a role, because RFS seems to be "computing complex, task-sensitive representations in the absence of awareness."
- Study finds link between brain damage and religious fundamentalism ›
- Many vegetative patients are actually 'covertly conscious' - Big Think ›
- 7 new things we've learned about the brain - Big Think ›
Some mysteries take generations to unfold.
- In 1959, a group of nine Russian hikers was killed in an overnight incident in the Ural Mountains.
- Conspiracies about their deaths have flourished ever since, including alien invasion, an irate Yeti, and angry tribesmen.
- Researchers have finally confirmed that their deaths were due to a slab avalanche caused by intense winds.
a: Last picture of the Dyatlov group taken before sunset, while making a cut in the slope to install the tent. b: Broken tent covered with snow as it was found during the search 26 days after the event.
Photographs courtesy of the Dyatlov Memorial Foundation.<p>Finally, a <a href="https://www.nature.com/articles/s43247-020-00081-8" target="_blank">new study</a>, published in the Nature journal Communications Earth & Environment, has put the case to rest: it was a slab avalanche.</p><p>This theory isn't exactly new either. Researchers have long been skeptical about the avalanche notion, however, due to the grade of the hill. Slab avalanches don't need a steep slope to get started. Crown or flank fractures can quickly release as little as a few centimeters of earth (or snow) sliding down a hill (or mountain). </p><p>As researchers Johan Gaume (Switzerland's WSL Institute for Snow and Avalanche Research SLF) and Alexander Puzrin (Switzerland's Institute for Geotechnical Engineering) write, it was "a combination of irregular topography, a cut made in the slope to install the tent and the subsequent deposition of snow induced by strong katabatic winds contributed after a suitable time to the slab release, which caused severe non-fatal injuries, in agreement with the autopsy results."</p><p>Conspiracy theories abound when evidence is lacking. Twenty-six days after the incident, a team showed up to investigate. They didn't find any obvious sounds of an avalanche; the slope angle was below 30 degrees, ruling out (to them) the possibility of a landslide. Plus, the head injuries suffered were not typical of avalanche victims. Inject doubt and crazy theories will flourish.</p>
Configuration of the Dyatlov tent installed on a flat surface after making a cut in the slope below a small shoulder. Snow deposition above the tent is due to wind transport of snow (with deposition flux Q).
Photo courtesy of Communications Earth & Environment.<p>Add to this Russian leadership's longstanding battle with (or against) the truth. In 2015 the Investigative Committee of the Russian Federation decided to reopen this case. Four years later the agency concluded it was indeed a snow avalanche—an assertion immediately challenged within the Russian Federation. The oppositional agency eventually agreed as well. The problem was neither really provided conclusive scientific evidence.</p><p>Gaume and Puzrin went to work. They provided four critical factors that confirmed the avalanche: </p><ul><li>The location of the tent under a shoulder in a locally steeper slope to protect them from the wind </li><li>A buried weak snow layer parallel to the locally steeper terrain, which resulted in an upward-thinning snow slab</li><li>The cut in the snow slab made by the group to install the tent </li><li>Strong katabatic winds that led to progressive snow accumulation due to the local topography (shoulder above the tent) causing a delayed failure</li></ul><p>Case closed? It appears so, though don't expect conspiracy theories to abate. Good research takes time—sometimes generations. We're constantly learning about our environment and then applying those lessons to the past. While we can't expect every skeptic to accept the findings, from the looks of this study, a 62-year-old case is now closed.</p><p> --</p><p><em>Stay in touch with Derek on <a href="http://www.twitter.com/derekberes" target="_blank">Twitter</a> and <a href="https://www.facebook.com/DerekBeresdotcom" target="_blank" rel="noopener noreferrer">Facebook</a>. His most recent book is</em> "<em><a href="https://www.amazon.com/gp/product/B08KRVMP2M?pf_rd_r=MDJW43337675SZ0X00FH&pf_rd_p=edaba0ee-c2fe-4124-9f5d-b31d6b1bfbee" target="_blank" rel="noopener noreferrer">Hero's Dose: The Case For Psychedelics in Ritual and Therapy</a>."</em></p>
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Research reveals a new evolutionary feature that separates humans from other primates.
- Researchers find a new feature of human evolution.
- Humans have evolved to use less water per day than other primates.
- The nose is one of the factors that allows humans to be water efficient.
A model of water turnover for humans and chimpanzees who have similar fat free mass and body water pools.
Credit: Current Biology
Being skeptical isn't just about being contrarian. It's about asking the right questions of ourselves and others to gain understanding.