SAN DIEGO—Books fly from the shelf as Superman fans the pages in a blur devouring the information at blinding speed. Superhuman mental powers, including his extraordinary sense of hearing and blazing speed-reading, are as vital to Superman as his bullet-beating velocity and steel-bending strength. But it seems Superman isn't the only being with the gift of quickness. Neuroscientists reported in November at the Society for Neuroscience's annual meeting in San Diego that they have found an interesting group of real individuals with such superhuman mental abilities—blind people. Moreover, functional brain imaging now reveals how they achieve their extraordinary cerebral feats.

A popular notion is that blind people sharpen their remaining senses to compensate for lost vision. Blind musicians, such as Stevie Wonder and Ray Charles, may excel in music because of their highly developed sense of hearing. Researchers from the Hertie Institute for Clinical Brain Research at the University of Tübingen in Germany have found scientific support for this belief. Blind people can easily comprehend speech that is sped up far beyond the maximum rate that sighted people can understand. When we speak rapidly we are verbalizing at about six syllables per second. That hyperactive radio announcer spewing fine print at the end of a commercial jabbers at 10 syllables per second, the absolute limit of comprehension for sighted people. Blind people, however, can comprehend speech sped up to 25 syllables per second. Human beings cannot talk this fast. The scientists had to use a computerized synthesizer to generate speech at this speed. "It sounds like noise," Ingo Hertrich, one of the scientists involved in the research told me. "I can't understand anything…maybe it sounds like some strange foreign language spoken very rapidly." (To hear what speech at 16 syllables per second sounds like, listen to a sample recording the scientists used in their experiments.)

Hertrich and his colleagues Hermann Ackermann and Susanne Dietrich wanted to find out what was going on inside the brains of blind people that gives them this "superpower" to understand speech at ultrafast rates.  Examining brain regions activated by blind and sighted people while they listened to ultrafast speech and laid inside a (functional magnetic imaging, or MRI) brain scanner revealed that in blind people the part of the cerebral cortex that normally responds to vision was responding to speech.

No wonder blind people seem to have superhuman powers of high-speed listening comprehension. Normally, this brain region, situated at the back of the skull and called V1, only responds to light. Vision is such an important sense for humans that a huge portion of the brain is devoted to visual processing—far more gray matter than is dedicated to any other sense. In blind people all this brain power would go to waste, but somehow an unsighted person's brain rewires itself to connect auditory regions of the brain to the visual cortex.

Ackermann explained that the age at which a person loses sight is likely to be critical in rewiring brain regions controlling hearing to the region that normally processes vision. In people who are born blind the visual cortex is completely unresponsive to any auditory or visual stimulation. This region of the brain becomes functionally disconnected because visual input is necessary early in life to wire up visual brain circuitry properly. Younger people who lose sight after these connections formed, however, are able to reroute them to process auditory information after becoming blind. On the other hand, people who lose sight late in life are also less able to rewire their brains, because the critical period during which visual experience can influence this process is limited to earlier years in life. (All the subjects in this study had lost their sight between two and 15 years of age.)

But how do brain regions connected to the ears get rewired to brain regions that are normally connected to the eyes? The fact is that most of our senses have some interacting circuitry between them, which is called cross modality. There are some connections between the brain's auditory and visual regions, because the two senses must work together. Seeing a person's lips move helps comprehension of speech. We also need to orient our visual and auditory attention to the same events and to the same place in space, so there is an exchange of information between the auditory and visual cortices. Nerves from muscles that control our eye movements, for example, connect to the brain's hearing centers as well. These connections between visual and auditory regions of the brain become strengthened after losing sight. Also, some regions of cerebral cortex that border visual and auditory cortices—the left fusiform gyrus, for example—expand territory in blind people to make use of the idle circuitry in visual cortex.

Interestingly, the researchers found that blind people only use the right visual cortex for understanding ultrafast speech. Ackermann suspects that this may be because the right brain is specialized for processing low-frequency information, which is typical of speech, but this theory is still unproved. What blind people might use the left visual cortex for is something the group is investigating and hopes to report at next year's meeting.

The main interest of the researchers is in brain stroke. By investigating how the blind brain rewires itself to compensate for lost function, the researchers hope to discover new information that can be helpful to patients recovering from stroke. But Ackermann also stresses that an important outcome of this research is the help it can provide the blind. Whereas it is always better to be sighted than not, people who have lost vision do have certain extraordinary abilities that can give them advantages over sighted people. He finds that blind people are able to turn up the rate of text-to-speech converting computer programs to read three books in the time it would take a sighted person to read one. This extraordinary ability will benefit blind people in processing large amounts of written information in textbooks for study at school, and perhaps open new job opportunities to exploit their high-speed reading skills for translation or other auditory comprehension at blazing speeds that to Lois Lane and the rest of us mere mortals sounds like babble.

20 Comments

1. 1. jtdwyer 06:32 PM 12/13/10

   Some of the more interesting findings were explained using an unfortunate analogy:
   "Ackermann explained that the age at which a person loses sight is likely to be critical in rewiring brain regions controlling hearing to the region that normally processes vision. In people who are born blind the visual cortex is completely unresponsive to any auditory or visual stimulation. This region of the brain becomes functionally disconnected because visual input is necessary early in life to wire up visual brain circuitry properly. Younger people who lose sight after these connections formed, however, are able to reroute them to process auditory information after becoming blind. On the other hand, people who lose sight late in life are also less able to rewire their brains, because the critical period during which visual experience can influence this process is limited to earlier years in life. (All the subjects in this study had lost their sight between two and 15 years of age.)"
   
   While everyone likes to think that they understand computer hardware and software, neurons are not CMOS and copper hardware. I think it would be much clearer and more meaningful to explain that brain structures that have never been used most likely atrophy, having never developed circulatory support to deliver the nutrients necessary for their physical development. Once developed, neural networks may be reallocated to other processes have have some prior neural access and processing support.
   
   Perhaps these researchers are intent on surgically imbedding computer hardware to establish connectivity to brain regions now rendered inaccessible by stroke damage. If so they may also discover that firmware device support may be required in addition to the 'hardware hookup'.

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2. 2. Davy in reply to jtdwyer 08:36 PM 12/13/10

   jtdwyer, you suggest an inaccurate analogy but you don't explain where that is (although the single word in the long passage you quote that may apply is "circuitry"). The point the researchers are making has nothing to do with computer hardware, as far as I can tell; are you offended by the use of the word "wiring"? Neurons really do wire the brain; this is not a metaphor. The point of this study is not to suggest future cybernetic therapies, but to describe how neurons in the visual cortex, after they have made functionaly connections, are later able to make new functional connections across two sensory systems.
   

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3. 3. jtdwyer in reply to Davy 03:43 AM 12/14/10

   I felt certain that anyone reading the second paragraph of my comment would have no question as to the nature of my objection. I'll try to provide you with additional explanation. As I understand, neurons are more than just wiring connecting functional components of the brain - they are the functional components of the brain.
   
   I specifically object to the statements including the phrases: "rewiring brain regions", "visual input is necessary early in life to wire up visual brain circuitry properly" and "rewire their brains", regardless of the point you think these researchers were trying to make with their research. I think these phrases clearly indicate a simple process much like connecting your computer to a network, for example, that casual readers may be able to relate to but hardly convey the processes that are required to 'rewire brains'.
   
   As I understand brain components operate more than just an electronic switchboard, involving complex chemical processes and signal amplification functions that lie at the heart of the complex processes performed.
   
   I'm no neuroscientist but I can hook you up with Wikipedia:
   http://en.wikipedia.org/wiki/Neuron

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4. 4. dougfields 09:19 AM 12/14/10

   This wording is not an analogy. Neuroscientists use the word “wire” as a verb, not a noun. It is the process of connecting neurons into circuits. How the brain gets wired up properly is a fascinating question. One neuron can have as many as 100,000 synaptic connections on it, and the human brain is estimated to have 100 billion neurons in it. How do each of these connections get wired together properly? They can’t each be specified by a chemical label—we only have 30,000 genes in our entire genome. Functional activity guides the wiring and re-wiring of the brain. This is one of the processes that I study in my own lab at the NIH. Hubel and Wiesel showed in their Nobel Prize winning research that if you put a patch on a kitten’s eye during the critical period when connections from the eye are wiring up to the visual cortex, and remove it weeks later, the kitten will be permanently blind in that eye. There is nothing wrong with the eye; visual experience was necessary to guide the proper formation of connections from the eye to the correct neurons in the brain.

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5. 5. meijerpb 09:49 AM 12/14/10

   Recruitment of visual cortex for processing complex and rapidly varying sounds also lies at the basis of visual-to-auditory sensory substitution for the blind, where live images from a camera are converted into sounds that encode much of the visual content. Visual cortex activation by sound then raises the hope that meaningful visual information can be non-invasively passed on to the visual cortex of blind persons.

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6. 6. dougfields 09:50 AM 12/14/10

   For technical reasons, Scientific American was not able to provide the audio clip of what speech at 16 syllables a second sounds like. Have a listen at my science blog: http://rdouglasfields.wordpress.com. Dr. Hertrich and Ackermann provided this recording, which they used in their experiments, to share with Sci. Am. readers. It is amazing!

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7. 7. meijerpb in reply to dougfields 10:09 AM 12/14/10

   @dougfields That 16 syllables a second sample is a very nice illustration. A few months ago I did a back-of-the-envelope calculation in the context of sensory substitution, relating the high reading speeds of blind people (some of whom set their screen readers up to about 600 words per minute, or 10 per second) to visual reading, assuming a width of some 20 pixels per word on average: http://www.seeingwithsound.com/acuity.htm
   Of course these are all crude estimates, but it all sort of fits together.

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8. 8. meijerpb in reply to dougfields 11:47 AM 12/14/10

   I just discovered that your 16-syllables-a-second sample plays a German speech sample *backwards*! No wonder that even the blind people that I asked could not make any sense of it. :-) When I reverse the sample I can hear the speaker talk about "ein Großes Potential sagte der Umwelt Minister" or something like that.

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9. 9. Robin Lloyd 01:08 PM 12/14/10

   We've added the direct link, from Dr. Fields' blog, to a clip of what speech at 16 syllables/second sounds like. The link is now added to the end of the story's second paragraph. Thanks.

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10. 10. meijerpb in reply to Robin Lloyd 01:16 PM 12/14/10

    The new link is also for the time-reversed German speech sample, so not quite a good example to "hear what speech at 16 syllables per second sounds like", because even normal rate human speech sounds weird when played backwards.
    
    Thanks

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11. 11. dougfields 02:03 PM 12/14/10

    Interesting. I will try to contact Dr. Hertrich and find out if I received the wrong clip. The researchers did use reversed speech as a control in their experiments to be sure that they were imaging brain changes involved in comprehension rather than just hearing sound. But this proves the point. If you are sighted you can't tell the difference.

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12. 12. dougfields 02:06 PM 12/14/10

    Interesting. I will try to contact Dr. Hertrich and find out if I received the wrong clip. The researchers did use reversed speech as a control in their experiments to be sure that they were imaging brain changes involved in comprehension rather than just hearing sound. But this proves the point. If you are sighted you can't tell the difference.

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13. 13. jtdwyer in reply to dougfields 05:27 PM 12/14/10

    Since there is no metal wire in the brain, the use of this term, yes, even by the entire community of neuroscientists, is an analogy drawn from electrical and electronics engineering.
    
    I suggest that the use of this term for the purpose of describing the electrical connections that grow between neurons infers that these connections can be engineered as you pointed out, to help stroke victims.
    
    You asked, "How do each of these connections get wired together properly?" - I suggest that the connections are grown as a result of the increased blood supply grown as a result of increased nutritional demand, but in accordance with a structure that is determined by, I presume, genetic instruction.
    
    Otherwise, young mice could be trained to develop superior intellectual capabilities, through functional activities.
    
    I suggest that functional regions of undeveloped young brains can effectively atrophy if not used, since blood supply will not be delivered to tissues that do not extract nutrients. This (lay described) process can account for the inability to later develop vision in a patched eye.
    
    I further suggest that the part of the cerebral cortex that normally responds to vision contains neural networks that perform specific pattern matching functions normally used primarily for vision processing. I predict that even in sighted persons there would also be some activation of this brain region when processing language.
    
    I suggest that young people who have lost their vision early can then allocate the pattern matching neural networks previously developed for support of vision for increased support of language processing, which was also previously connected.
    
    I doubt that there is much physical 'rewiring' going on to produce the observed enhanced language capabilities and regional blood flow within the brain.
    
    Of course that just how I envision that these effects are produced, from the perspective of a successful, highly experienced information systems analyst, very large systems configuration manager, etc. You see, while you may see my comments about neuroscience as severely lacking, I view your analogous referrals to computer electronics to be misapplications.
    
    I would suggest that fMRI studies be undertaken to confirm that no activation of any of the regions of the brain that have been associated here with vision occur when sighted people process language. In that case I would agree that some kind of physical functional reconnection has occurred.

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14. 14. dougfields 06:33 PM 12/14/10

    Wire vt: to predispose, determine, or establish genetically or innately. Webster Collegiate Dictionary

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15. 15. jtdwyer in reply to dougfields 11:14 PM 12/14/10

    Whoa - you consider the dictionary entry sufficient to dismiss the entirety of my objection?
    
    Apparently Neuroscience has no need to understand how "wiring" is biologically accomplished - it appears to be mysteriously produced by "functional activity". I'm certainly disappointed.

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16. 16. dougfields 10:10 AM 12/15/10

    Dear meijerpb Thank you for the link to the interesting research on converting vision to sound for blind persons. All of this research is very interesting with respect to the power of the human brain to accommodate to injury through rewiring circuits driven by environmental experience. These learned extraordinary abilities raise the question of the untapped potential of the human brain. Savants, who often have neurodevelopmental problems, are an example. But does such extraordinary ability come at a cost? This work is also interesting with respect to synesthesia. Do blind people see speech since auditory pathways get rewired to visual cortex?

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17. 17. WildKatCa 06:19 PM 12/15/10

    I always wondered why my blind friends and I could understand very fast speech on our computers and other devices, but had to turn the rate down to what seemed like a very low setting for our sighted friends and teachers.
    
    It leaves me thinking about something though. I was born with Cerebral Palsy and also under-development of my optic nerves and absence of the septum pellucidum (a midline part of the brain). So, with all of the "damage" and missing parts, how can I still understand speech that is so much faster than what the average person can understand?

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18. 18. dougfields 08:49 PM 12/15/10

    Wildcatca Thank you for sharing your experience. It is wonderful to realize how adaptable the human brain is and that coping with “disability” makes us stronger in some ways. Most of us will experience disability at sometime in our life. You may be interested in reading my experience from 2007 http://www.washingtonpost.com/wp-dyn/content/article/2007/09/04/AR2007090401785.html) The reason for your extraordinary ability is that the human brain, unlike the brain of most animals, develops after birth. A baby’s brain is so feeble it takes years for us to become functional—years to learn to walk and read and communicate, and decades for personality and skills to develop. But this is the reason for our success as a species! The human brain develops according to the environment and experience we have through childhood and adolescence. In a sense, our species cheats evolution in this way. We develop our brain after birth for maximum success in the environment we are born into, rather than the environment of our caveman ancestors coded in our genes. So if a brain happens to develop differently because of a developmental problem, it re-wires itself to the extent possible for maximum success in the environment and situation that we find ourselves. Your brain is different, but then so is everyone else’s. Don’t think of it as damage and missing parts. I understand, but think of it as building upon what you were born with. Sometimes that can lead to abilities that others simply cannot attain.

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19. 19. dougfields in reply to dougfields 08:48 PM 12/20/10

    The clip in the article is indeed reversed speech from the experiment that was used as a control to distinguish comprehension from simple sound stimulation of the brain. Dr. Hertrich has kindly provided three sound clips in English at 14, 21, and 24 syllables/sec for readers to hear. These can be heard on my website:
    http://rdouglasfields.wordpress.com/2010/12/14/extraordinary-ability-of-blind-people-to-hear-ultrafast-speech/
    
    They all sound like reverse speech in German to me.

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20. 20. creuzerm 06:09 PM 12/21/10

    I did some web-design work for a company that employed blind people. One lady did telephone order support using the website I worked on. She had the speech reader speed cranked way up and so quite. The one chance I got to see her work in person, she had to turn up the volume and turn the speed way down so I could follow along with the screen reader.
    
    Turned out that I was putting a table header at the top of a data table and the screen reader was reading each heading. She knew what the headings where, she had memorized the tab order of the entire page. I moved the data heading to the bottom of the table so us mere mortal sighted people knew what the data table was about and it didn't get in her way.
    
    I am pretty sure that most people who interacted with her on the phone never realized that she couldn't see the computer screen and was listening to both them and the computer at the same time. It's been 7 years or so, and I am still impressed with her abilities.

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