6
Sep

Are Deaf People’s Brains Wired Differently?

Not to Compare Apples and Oranges, But…: Someone asked us if it is true that Deaf and hearing people’s brains are wired differently. See below and decide for yourself.

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University College London

Above: Functional Magnetic Resonance Imaging (fMRI) pictures show different areas of the brain that are used by Deaf and hearing individuals when processing langauge. Yellow and red mark areas of increased blood flow.

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University of Massachusetts Medical Center

Above: These images related to face processing show that both Deaf and hearing people’s brains are activated in similar areas, but also reveal that for Deaf people, additional brain areas are activated. Researchers hypothesize that using visuospatial language may have an impact on face processing.

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University of Washington School of Medicine

Above: These are brain images of Deaf people watching sign language, and hearing people watching and listening to speech. Deaf people’s brains showed increased activity in the auditory cortex compared to those of hearing people.

10 Comments
  1. patti September 6, 2006

    Well, consider this source with the findings from MRI …

    The morphometry of auditory cortex in the congenitally
    deaf measured using MRI

    Virginia B. Penhune,a,c,* Roxana Cismaru,b Raquel Dorsaint-Pierre,c
    Laura-Ann Petitto,d and Robert J. Zatorrec

    Abstract
    The study of congenitally deaf individuals provides a unique opportunity to understand the organization and potential for reorganization of human auditory cortex. We used magnetic resonance imaging (MRI) to examine the structural organization of two auditory cortical regions, Heschl’s gyrus (HG) and the planum temporale (PT), in deaf and hearing subjects. The results show preservation of cortical volume in HG and PT of deaf subjects deprived of auditory input since birth. Measurements of grey and white matter, as well as the location and extent of these regions in the deaf showed complete overlap both with matched controls and with previous samples of hearing subjects. The results of the manual volume measures were supported by findings from voxel-based morphometry analyses that showed increased grey-matter density in the left motor hand area of the deaf, but no differences between the groups in any auditory cortical region. This increased cortical density in motor cortex may be related to more active use of the dominant hand in signed languages. Most importantly, expected interhemispheric asymmetries in HG and PT thought to be related to auditory language processing were preserved in these deaf
    subjects. These findings suggest a strong genetic component in the development and maintenance of auditory cortical asymmetries that does not depend on auditory language experience. Preservation of cortical volume in the deaf suggests plasticity in the input and output of auditory cortex that could include language-specific or more general-purpose information from other sensory modalities.
    © 2003 Elsevier Inc. All rights reserved.
    source:
    http://www.dartmouth.edu/~lpetitto/NeuroImage.pdf

    Reply
  2. Jenn September 6, 2006

    fMRI is a fanastic new technology that I’m very excited about because it has also helped identify how the brains are different in bipolar disorder.
    I think this technology will help analyze what’s going on in brains more.

    Studies also show that people can’t memorize as many random lists through watching sign as they can through speech (3-5 items signed vs 5-7 for speech)– the working memory for sign is shorter. They ruled out differences in signing/speaking rates.

    When the information is meaningful, the memory seem to be the same– people can listen and process sentences just as long in sign as in speech.

    I always suspected I was using my auditory cortex to process sign language (and some English too maybe), and looks like I am right. Can you refer me to the original URL sources of those fMRI readings?

    Because those images literally looks almost reversed to what I’d expect. Why do the hearing people’s auditory cortexes look almost dead in comparsion?

    Reply
  3. patti September 7, 2006

    Jenn says: “Studies also show that people can’t memorize as many random lists through watching sign as they can through speech (3-5 items signed vs 5-7 for speech)– the working memory for sign is shorter. They ruled out differences in signing/speaking rates.”

    I am skeptical of those studies because I know many deaf people that attended a lecture but didn’t write any notes, yet later in the evening or the following morning they were able to compile excellent synopses or summaries of the lecture.

    Reply
  4. Em September 7, 2006

    patti, i think jenny meant that studies show differences in memorizing random lists of signs or words. in her comment, she wrote: “when the information is meaningful, the memory seem to be the same– people can listen and process sentences just as long in sign as in speech.”

    it would be harder to remember a list of words that don’t tell a story or have a message. maybe hearing people can use auditory memory to remember a list of meaningless random words.

    so you are right, some deaf people can remember lectures with no problem because they make sense!

    Reply
  5. Jenn September 7, 2006

    Em has me interpreted correctly. I’m one of those people who can remember a lecture in considerable detail too because it all makes sense to me and I have the points.

    But if I ask my mom what she wants me to get at the store while I’m out, she’ll ramble and I’m thinking okay butter, eggs, and she throws in so many things and I listen for 3 minutes or so and I forget what she said originally because I am trying to make sense of her meandering conversation. I finally started asking her to write down the list for me and save me an headache– she never has a point to what she tells me.

    If it’s my own personal list I have no problems remembering it, though because I have a definite image of what I need to do and what things I need for that. If I forget anything it’s usually an irrelevant item peripheal to what I “need to do” that day, but definitely useful.

    Reply
  6. Lynn September 8, 2006

    What about hearing people watching BSL? Why just English? And why not Deaf people watching English? Wonder if it’d show the same or different parts of the brains being activated. hmmm

    Reply
  7. Robin September 26, 2006

    Jenn: I assume that hearing people’s brains look ‘almost dead’ in comparison because more lateralisation (specialisation) occurs with auditory communication processing. In deaf people, the brain rather creatively reassigns areas normally specifically involved in auditory communication processing to work with visual shape, movement and facial processing etc. to decode communication, so there is a more widespread, varied and less focussed activity pattern.

    Lynn: In hearing people using BSL, the same thing appears to happen: fMRI research has shown that while in deaf people there is a more specific, focussed involvement of language processing areas while watching/using BSL, hearing people have to additionally marshall the use of various visual and movement processing areas of the brain (BSL is _hard_ for us hearing dudes). In the case of BSL, it is the hearing brain that lights up like a christmas tree, while the deaf brain looks relatively inactive in comparison. 🙂 This does not change even for very experienced and accomplished hearing sign interpreters.

    Reply
  8. katie September 29, 2006
    Reply
  9. Betty Colonomos October 3, 2006

    I have been following research on Deaf brains for a long time, beginning with the work done by Ursula Bellugi on Deaf people who have had strokes. There is much evidence that Deaf people’s visual (occipital) region of the brain is more developed and larger than in hearing people. There are imaging results that show that the nerve connections spread out and move into the unstimulated auditory areas. That is one of the reasons that deaf people have such wide peripheral vision to process tbe stimulus ofthe world around them efficiently. Conversely, the auditory (parietal) region in hearing people is larger than in profoundly Deaf people.

    Here is the sad news. One of the goals of Cochlear Implants is to keep the auditory portions of the brain constantly stimulated (whether it works or not). When this happens the visual areas of the brain do not spread as widely because there is not room to do so. So not only are deaf children having invasive surgery, their ability to use their visual perception is diminished. If the CI doesn’t make them hearing, it will still interfere with them being visually as Deaf as non-implanted kids. Anyone think this was an accident?

    Reply
  10. Pingback: Deaf Brain | Deaf Technological Review

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