Stuttering and Genetics

Feb 24 2011 Published by under Brain & Behavior

Ever since the release of the award-winning movie The King's Speech, there has been a lot of discussion about stuttering in the media.

The movie is the fictionalized story of the struggle of King George VI - "Bertie" to his family - to overcome his stuttering with speech therapy.  That summary doesn't make it sound particularly interesting, but I found the story to be quite engaging. By the end I was rooting for Bertie to make it through his big speech.

It's estimated that almost 1% of adults stutter, just like Bertie. After decades of research, the underlying causes are only beginning to be understood.

At this past week's annual meeting of the American Association for the Advancement of Science (AAAS) in Washington DC, there was a symposium that focused on recent developments in cross-disciplinary stuttering research.  The most interesting study discussed in that session looked at how genetics may contribute to the speech disorder.

NIH geneticist Dennis Drayna and his colleagues have been studying closely-related families in Pakistan. They discovered three mutations associated with stuttering in those families. The three affected genes - GNPTAB, GNPTG, and NAGPA - are involved in directing glycoproteins to the lysosomes. Lysosomes are tiny organelles inside the cell that break down waste material and cellular debris. If the proper glycoproteins don't end up in the lysosomes, carbohydrates and fatty materials can build up to toxic levels in the body's cells.

It was already known that some mutations in GNPTAB and GNPTG cause mucolipidosis, a disease that affects both neurological and physical development.  In its severest form, mucolipidosis causes mental retardation and skeletal deformities. The people who carry the mutations in GNPTAB and GNPTG associated with stuttering don't have the severe neurological and physical problems associated with mucolipidosis.

It's not entirely clear how the mutations in genes involved in cellular metabolism might affect the development of the brain and cause speech problems, so there's still a lot of research to be done. But no matter what the mechanism is, finding these mutations provides support to the idea that the cause of stuttering is primarily physiological rather than behavioral or psychological.

But these genes are only a small part of the story.  Only about 6% of stutterers carry a mutation in GNPTAB, GNPTG or NAGPA.  Drayna's team and other research labs are searching for  additional associated mutations.  The hope is that the ongoing research into the genetics of stuttering will ultimately lead to new effective therapies.

Listen to the  AAAS Podcast on "The Mysteries of Stuttering" for more about the research presented at the symposium.

Additional reading:
• Michael Palin: "Stuttering: It's on everyone's lips now" Los Angeles Times (2011)

• Howell P. "Listen to the lessons of The King's Speech" Nature 470 (7) (2011) doi:10.1038/470007a

* Schenkman L. "First Gene Mutations Linked to Stuttering"  (Science NOW 2010)

• Willyard C. "Ancient Mutation to Blame for Stuttering" (Science NOW 2011)

• You can find more information about current research and resources for stutterers on the Stuttering Foundation of America's web site.   The National Institutes of Health also provides information on stuttering.

• Read the original research article: Kang C. et al. "Mutations in the Lysosomal Enzyme-Targeting Pathway and Persistent Stuttering" N Engl J Med 362:677-685 (2010)  doi: 10.1056/NEJMoa0902630 (free full text)

• Learn more about the research presented at the 2011 AAAS Meeting.

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The Neurochemistry of Love

Feb 14 2011 Published by under Brain & Behavior

Hearts (Explored!)My love is as a fever, longing still
For that which longer nurseth the disease,
Feeding on that which doth preserve the ill,
The uncertain sickly appetite to please.
My reason, the physician to my love,
Angry that his prescriptions are not kept,
Hath left me, and I desperate now approve
Desire is death, which physic did except.
Past cure I am, now reason is past care,
And frantic-mad with evermore unrest;
My thoughts and my discourse as madmen's are,
At random from the truth vainly express'd;
For I have sworn thee fair and thought thee bright,
Who art as black as hell, as dark as night.
~ Sonnet 147, William Shakespeare

The pursuit of romantic love is a greater driving force than the sex drive, according to Rutgers University anthropologist Helen Fisher, who studies the neuroscience of love.  As she describes it, symptoms of love are indeed quite powerful:

Romantic love begins as an individual comes to regard another as special, even unique. The over then intensely focuses his or her attention on this preferred individual, aggrandizing the beloved's better traits and overlooking or minimizing his or her flaws. Lovers experience extreme energy, hyper activity, sleeplessness, impulsivity, euphoria, and mood swings. They are goal-oriented and strongly motivated to win the beloved. Adversity heightens their passion [ . . . ] They reorder their daily priorities to remain in contact with their sweetheart , and experience separation anxiety when apart. And most feel powerful empathy for their amour; many report they would die for their beloved.

In fact, love can affect your brain like an addiction.  When love is reciprocated it's a constructive addiction, while rejection of love is a destructive addiction.  It's powerful effects have shaped and been shaped by evolution, and - Fisher argues - have even helped drive the development of human culture.

Here's an interesting lecture at UC San Diego where Fisher talks about the evolution and neuroscience of romantic love and the development of poetry and art (20 minutes):

If you are interested in more, also check out Fisher's 2008 TED talk about the brains in love (16 min.):

Happy Valentine's Day!

Technical reading:

Fisher HE et al. "Reward, Addiction and Emotion Regulation Systems Associated With Rejection in Love" J. Neurophysiol 104: 51-60 (2010)  (free pdf)

Fisher H "The Drive to Love: The Neural Mechanism for Mate Selection" in The New Psychology of Love, 2nd Edition. RJ Sternberg and K Weis (Eds.) New Haven: Yale University Press (2006) (free pdf)

Fisher HE et al. "Romantic love: a mammalian brain system for mate choice"  Phil Trans R Soc B 360: 2173-2186. (2006) (free pdf)

More of Fisher's publications.

Image: Hearts (Explored!) by qthomasbower, on Flickr

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Dance your PhD: How does your brain analyze incoming visual information?

Sep 24 2010 Published by under Art & Science, Brain & Behavior

The finalists in the 2010 Dance Your Ph.D. contest have been announced. The competition is open to all science PhDs (or soon-to-be-PhDs) willing submit a video of a dance interpretation of their PhD thesis. And yes, the author of the thesis has to be one of the dancers.

A finalist for each category - Physics, Chemistry, Biology, and Social Science - was announced last week. The finalist in biology was "How does your brain analyze incoming visual information?", by Utrecht University gradutate student Maartje de Jong.

She explains:

We tend to believe what we see with our eyes is real and accurate. What we often do not realize is that our eyes register only a reflection of the outside world. To reconstruct reality from this reflection we have to rely on inferences and assumptions. It is like putting together the pieces of a puzzle without any knowledge about the whole picture. Our brain does this without our conscious awareness. In a split second it organizes and interprets incoming visual information to form a stable and meaningful image of the world around us.

[. . . snip . . . ]

Our video explains the basics of how the brain analyzes visual information. You see a man (‘the observer’) watching a movie-clip on his laptop. The visual information presented on his laptop is registered by his eyes and translated into neural signals that enter his brain. Through dance we portray what happens inside the observer’s brain. The leading dancer in the video, who can be recognized by the brain depicted on his clothing, represents the observer’s internal neural factors, such as his goals and experiences. The dancers with an information-icon depicted on their clothing (‘the i-dancers’) represent the incoming visual information.

Read the rest of the explanation of her research - and the dance - here.

Check out the the finalists' videos and vote for your favorite at ScienceNOW. The overall winner will be announced on October 19th at the Imagine Science Film Festival in New York.

You can watch all the entries on the Gonzo Labs web site.

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