E-mail exchange with Dennis Drayna

Me:

"Dr. Drayna,

Excuse the intrusion on your time. I teach an undergrad linguistics course
and a student brought in a back issue of Science News in which you are
quoted:

"The exciting thing here is that it's now possible to begin picking apart
language, one of the highest-order cognitive functions, one gene at a time,"
comments geneticist Dennis Drayna of the National Institute...."

I find that very exciting and I wonder if you might briefly tell me and my
students what the current state of your optimism is and perhaps where we can
turn to for up-to-date information."

"The current state of my enthusiasm for understanding speech and
language at the molecular level in the brain is unchanged. On the one
hand, it's clear that progress will be slower than we'd like, since our
genetic approaches rely on very rare families with very unusual inherited
disorders. Finding these families and getting them studied properly will
require an extended effort. On the other hand, a number of new lines of
evidence seem to be converging on the concept that many language and
communication disorders are intimately involved with deficits in sound
processing within the brain. Since these sorts of deficits are quite
accessible to study, I suspect progress will be even more rapid than I
expected over the next couple of years.

The work referred to in the Science News article is an article that
appeared in the journal Nature Genetics last year, describing a family
studied in Britain. The senior (last) author was Dr. Marcus Pembrey, and
the study demonstrated that a single gene, designated speech-1, is the
cause of an inherited speech/language disorder in this family. A number of
additional studies of specific language impairment are underway. Many of
these disorders appear to have at least partially genetic etiology,
although none of these studies is as advanced as the British study. So,
while I can't show you a paper describing a particular gene which causes a
particular language disorder, these sorts of things are most certainly in
the works.

My own work deals with finding the genes which predispose
individuals to stuttering. In this disorder, individuals know precisely
what they wish to say, but are unable to say it, even though they are
capable of normal speech at times. There doesn't appear to be anything
wrong with their ability to construct correct sentences or with their
vocabulary of words, nor is there anything fundamentally wrong with the
speech producing muscles. Instead, they seem to have a problem accessing
the neural command to produce particular speech sounds. Stuttering clearly
has at least some genetic causes, and we are in the midst of a search to
identify the location of these causative genes. Ultimately, we hope to
isolate the genes themselves and to study precisely what is wrong with
them.

That, in a nutshell, is what's going on. Not much is published
yet, but it will be. You can keep track of research developments via the
homepage of the American Speech-Language-Hearing Association, which has a
regularly updated section on Research News."

>they [stutterers] seem to have a problem accessing
>the neural command to produce particular speech sounds...<

Is it just something I read in the popular press, or is it actually the case
that at least some stutterers don't seem to have problems when they sing
speech sounds? How does that fit it?

"Yes it is true that most stutterers are unaffected when they sing.
They also tend to be fluent when they speak in unison, read a prepared
text, when they whisper, or when they vocalize speech sounds in a number of
non-typical forms of communication. I believe the simplest unifying
hypothesis to explain this is that anything that distracts the stutterer
tends to increase fluency. The harder they concentrate on saying
something, the worse stuttering tends to be. I also believe this is the
basis for the little efficacy that most stuttering therapy provides. Most
of these therapy methods tend to distract the speaker from the usual speech
production process. There are other explanations, of course, but people
haven't had much luck sorting these out in past research."