Collaborative Study Shows Therapy Results Among Mutant Gene Carriers for Stuttering

In collaboration with a research team from the National Institute on Deafness and Other Communications Disorders (NIDCD), Hollins Communications Research Institute (HCRI) recently published a study to evaluate the effectiveness of the institute’s 12-day, behavioral therapy among a group of stutterers who possess one or more of the mutant genes for stuttering compared to the outcomes of a group of stutterers who do not carry any of the mutant genes.

The abstract is presented below.


We sought to determine whether outcomes of therapy for persistent developmental stuttering differ in individuals who carry a mutation in a known stuttering gene compared to individuals without such mutations.


We studied outcomes of an intensive fluency shaping-based therapy program in individuals with persistent developmental stuttering. We evaluated a cohort of 51 stuttering individuals with who carried a mutation in either the GNPTAB, GNPTG, NAGPA, or AP4E1 gene. We compared therapy outcomes in these individuals with outcomes in 51 individuals matched for age, gender, and ethnicity, who underwent the same therapy program and did not carry a mutation in any of these genes.

Fluency pre- and post-therapy was evaluated using blinded observer-based quantitative stuttering dysfluency measures (Dysfluent Words Score, DWS), and by subjects’ self-reported measures of struggle, avoidance and expectancy behavior associated with speaking (Perceptions of Stuttering Inventory, PSI). The difference between pre- and post-therapy fluency scores was taken as the measure of near-term therapy efficacy.


Comparison of fluency measures showed a strong effect of therapy overall. Mutation carriers achieved significantly less resolution in PSI following therapy, with PSI scores showing significantly less improvement in individuals who carry a mutation (RR=1.75, OR=2.92, p = 0.0157). There was a trend toward poorer outcomes in mutation carriers measured by changes in DWS.


These results suggest stuttering is more resistant to therapy in individuals who carry a mutation in one of the known stuttering genes.

. . . . . . . . . . .

Reference: Carlos E. Frigerio-Domingues1, Zoi Gkalitsiou2, Alexandra Zezinka1,#, Eduardo Sainz1, Joanne Gutierrez1, Courtney Byrd2, Ronald Webster3, Dennis Drayna1*. (2019) Genetic factors and therapy outcomes in persistent developmental stuttering. Journal of Communication Disorders, 80, 11-17.


Click for a summary of all HCRI research on the genetics of stuttering >>


About HCRI

Virginia-based HCRI, a 501(c)(3) charitable organization, opened its doors in 1972. Since that time, the insititute has become a leader in stuttering research and the development of innovative, scientifically derived therapy approaches. HCRI clinicians have treated more than 7,000 individuals who stutter. Clients come from all walks of life and include broadcasters, teachers, engineers, musicians, students, doctors, military personnel, business professionals, police officers, actors, a supreme court nominee, and even royalty.

HCRI is located at 7851 Enon Drive, Roanoke, Va. 24019. For more information, visit or contact HCRI at (540) 265-5650 or

Results Announced for Pioneering Research on the Effect of Mutant Genes on HCRI Stuttering Therapy

NEWS ALERT:  Roanoke, Va (September 12, 2019) – Hollins Communications Research Institute (HCRI), a national center for stuttering research and therapy innovation, just completed another research initiative in collaboration with the National Institutes of Health (NIH). The study is the first to evaluate stuttering therapy outcomes among a group of stutterers who possess one of four mutant genes for stuttering in comparison to a group who do not carry the same mutant genes.

Findings revealed significant fluency outcomes for both groups following participation in HCRI’s 12-day stuttering therapy program. At the same time, results suggested stuttering is slightly more resistant to therapy in individuals who carry a stuttering gene mutation. While dysfluency measures after therapy were similar for both groups, personal perceptions of fluency among the carrier group were weaker. The results of the study are published in the 2019 July/August issue of Journal of Communications Disorders.

HCRI has treated thousands of stuttering cases that range from mild to severe.
HCRI’s specially trained clinicians have treated thousands of stuttering cases that range from mild to severe.

For this research, HCRI President Ronald L. Webster, Ph.D. and his team worked in collaboration with Dennis Drayna Ph.D. of NIH’s National Institute on Deafness and Other Communication Disorders (NIDCD).

The two organizations have partnered for two decades on research to advance the scientific understanding of stuttering. HCRI was a member of the NIDCD team that discovered the genetic link to stuttering ten years ago.

HCRI stuttering therapy was used for the study because of the treatment’s quantitative, systematic methodology. In addition, HCRI clinicians have treated thousands of individuals who stutter with consistently positive results.

“At HCRI, we are in a strong position to facilitate genetics research because of our objective, physically based approach to therapy, as well as the large number of clients we have successfully treated,” Dr. Webster said.

HCRI research demonstrates that 93% of clients achieve normal levels of fluency by the end of their 12-day therapy. When evaluated two years post therapy, data indicates 75% maintain fluent speech. An additional 15% of individuals remain with improved fluency; however, they did not fall into the normal range.

Each group of stutterers was comprised of 51 individuals matched on age, gender and ethnicity. Speech samples before and after HCRI therapy were scored using detailed disfluency measures. Also, participants provided self-reported scores of their speech, based on perceived measures of struggle, avoidance and expectancy when speaking.

While therapy can be effective for mutant gene carriers, according to Dr. Webster, findings from this study provide a springboard for fine-tuning treatment when there is a genetic factor involved.

“We need to delve further into the physical details of speech, with emphasis on the carrier group,” Dr. Webster added. “Additional research will enable us to more precisely define the effects of therapy and may set the stage for customizing treatment for those individuals who carry mutant genes. And, we are working on that at HCRI right now.”

About Stuttering

Approximately 66 million people worldwide suffer from the effects of stuttering, with three million in the U.S, according to NIDCD. The condition is characterized by repeated or prolonged sounds, syllables, blocks and words that disrupt speech. Stuttering can impair social growth, educational attainment, and career potential.

About HCRI

HCRI was founded by Ronald L Webster, Ph.D. in 1972 to investigate stuttering through scientific discovery and treatment innovation. A 501(c)(3) nonprofit organization, HCRI is a leader in stuttering research and scientifically derived therapy. More than 6,500 people from across the U.S. and 50 countries have come to HCRI for stuttering treatment. HCRI is located at 7851 Enon Drive, Roanoke, Va. 24019. To learn more, visit or contact HCRI at (540) 265-5650 or

New Research at HCRI Designed to Advance the Understanding and Treatment of Stuttering

Hollins Communications Research Institute (HCRI) is recognized nationally for providing advanced treatment for stuttering, along with extensive post-therapy support to alumni from across the country and around the globe. Yet, as our institute name reflects, research is inherent to our mission. We are committed to furthering the understanding of stuttering and how to treat the condition most effectively.

HCRI Research We continually work on the frontiers of knowledge and technology to improve the analysis and treatment of stuttering.

The outcomes of recent research include the rollout of our remote-access refresher program for HCRI alumni and a new children’s stuttering therapy program.

In addition, we have exciting, new research endeavors underway that are summarized below. Much of this groundbreaking research can only be conducted at HCRI. The scope and depth of our experience makes such work possible.

Genetics of Stuttering and HCRI Stuttering Therapy Efficacy

We have partnered with Dr. Dennis Drayna and his team at the National Institute on Deafness and Other Communication Disorders to evaluate the impact of HCRI therapy on individuals who have mutant genes for stuttering and those who do not possess such genes. The research is now complete and we are awaiting publication of the findings. Once the article is published, we will be in a position to discuss the results and implications for our treatment of stuttering.

Quantitative Measurement of Fluent and Stuttered Speech

One of the great challenges with stuttering treatment lies in the subjective scoring of disfluent speech events. To address this, we are working on the first ever system to quantitatively measure and track stuttered vs. fluent speech through multidimensional acoustic analysis. Through the real-time scoring of critical speech parameters, we will be able to advance the effectiveness of both the assessment and treatment of stuttering.

These and other research initiatives are made possible through ongoing support from HCRI alumni and friends. As a 501(c)(3) nonprofit organization, HCRI relies on gifts to continue changing lives through fluency. By donating to HCRI, individuals help…

  • Fund important new research to enhance the understanding of stuttering and its treatment, with the ultimate objective of finding a cure.
  • Provide essential operational support that enables HCRI to continue providing life-changing stuttering therapy.
  • Make therapy scholarships possible for individuals in need.

Donors may designate their tax-deductible gift to be used for research, scholarships and/or HCRI’s operating fund. One hundered percent of donation dollars are used to advance the understanding and treatment of stuttering.

If you are interested in helping individuals who stutter through a gift to HCRI, please click here: Donate to HCRI >>

About HCRI Stuttering Therapy

HCRI’s stuttering therapy is a science-based, immersion program that teaches individuals how to control stuttering by replacing faulty muscle movements that give rise to stuttering with new muscle behaviors that generate fluent speech.

For 12 days, therapy participants work in a small group setting and are guided by specially trained clinicians who teach skills that help individuals overcome stuttering and speak fluently. HCRI’s therapy technology is used in the treatment process to help individuals acquire fluency with greater ease and precision. Therapy takes place in the clinical environment, as well as in real-world settings.

By the end of 12 days, research demonstrates that 93 percent of participants achieve fluent speech. Follow-up studies reveal that 75 percent of clients maintain their fluency skills when evaluated two years post therapy.

Watch before-and-after therapy videos >>

To learn more about HCRI’s stuttering therapy approach, call (540) 265-5650 or send an email to



HCRI Stuttering Therapy – Client Survey Results

At HCRI, we are committed to staying in contact with our stuttering therapy participants once they return home. This includes phone and email contact with clinicians, as well as providing a host of post-therapy practice tools to support long-term fluency.

Recently we surveyed our alumni to determine their perspectives about the impact of HCRI stuttering therapy participation on their lives. The feedback we received from the survey is highlighted in the infographic below.

Infographic - 2016 Alumni Survey Results - Border




How HCRI Responds to the Need for More Knowledge About Stuttering and Effective Fluency Training

HCRI President’s Message

The following message from Ronald L. Webster, Ph.D., president of the Hollins Communications Research Institute (HCRI) appeared in the non-profit institute’s 2011 spring newsletter, which was distributed to past stuttering therapy clients and HCRI supporters. A national leader in stuttering research and therapy innovation, HCRI has treated nearly 6,000 people who stutter from around the globe.

It is very clear to me that stuttering involves tremendously subjective reactions that are important to the person who stutters. In addition, the disfluencies produced during stuttering are observed subjectively by outside people who witness these behaviors.

One of our goals is to create new technologies that increase the objective measurement of the speech events that occur when a person stutterers. Of course, most of you know that we have developed tools for measuring voice onset characteristics during therapy. These tools are represented within our therapy program, our FluenceyNet home practice system, and our iPhone/iPod Touch apps. There is no question that these tools make the acquisition of targets more reliable and improves their retention.

We are working on exciting new tools for measuring speech in real time. Our newest development is the “speech microscope.” This system allows us to slice speech into hundreds (or thousands) of samples, each one of which can be quantified and examined independently or in relationship to other samples.

One of the first findings during the testing of this new technology was that we could clearly differentiate stuttered speech from fluent speech. There was no question about the clarity and reliability of these results – every stuttered speech sample, no matter how slight the stuttering, was seen to be quantitatively different from the fluent speech samples.

There are two next steps with the HCRI Speech Microscope: the first deals with automating the scoring of disfluencies; the second deals with developing the analysis system so all relevant speech targets in our therapy can be taught with guidance from the system.

There is no question that we can better measure, understand, and use in treatment the objective information generated by our new tool. And, there is a great deal to be learned as we move ahead; however, each step creates a platform of understanding that sets the stage for further advances.

I believe that we need to invent new ways of seeing and understanding stuttering. When we do this, everything gets better for our clients – and that is the ultimate goal for our organization.

About HCRI

Hollins Communications Research Institute was founded by Ronald L. Webster in 1972 to investigate stuttering through scientific discovery and treatment innovation. Under Dr. Webster’s direction, Roanoke, Virginia-based HCRI, a 501 (c) (3) charitable organization, has become an international leader in stuttering research and the development of innovative, scientifically based therapy approaches.

The Institute offers 17 stuttering therapy programs annually, each of which lasts 12 days. HCRI clinicians have treated nearly 6,000 people, aged 10 to 73, from across the U.S. and 47 other countries. Clients include broadcaster John Stossel of Fox News; Annie Glenn, wife of Senator and Astronaut John Glenn; as well as athletes, teachers, engineers, students, doctors, military personnel, business professionals, police officers, actors, and others from all walks of life.

For more information, visit or call HCRI at 540-265-5650.

HCRI Offers Hope to People Who Stutter

The following front page story about Hollins Communications Research Institute ran in The Roanoke Times on February 23, 2010:

Not many people know about the little lab in Roanoke County (Virginia), but for stutterers from around the globe, it’s a center of hope for a new life. When news spread earlier this month that scientists had discovered mutations in three genes that appear to cause stuttering, the phones began ringing at Hollins Communications Research Institute (HCRI).

“They call on a regular basis,” said Candy Smith. “But people wanted to make sure we’d heard.”

Smith, a nurse, is one of two clinicians at Hollins Communications Research Institute, an internationally recognized leader in stuttering research and therapy located across from Walrond Park in Roanoke County.

The institute, which is most commonly called HCRI, was founded in 1972 by Ronald Webster, who at the time was a psychology professor at Hollins University. He remains a professor emeritus with the university, but devotes his time as president of HCRI.

“This is the first time a genetic linkage has been found,” he said about the research, which was reported in the New England Journal of Medicine on Feb. 10. “For years we’ve known it tends to run in families. A little more than half [of people who stutter] can point to someone in their family background. … Really this research is pretty much a breakthrough.”

So, yes, the workers at HCRI had heard about the latest findings, and were celebrating.

“The more times that people can understand that science is really important in treating people who stutter, the better,” said LuAnn Yates, a speech pathologist and the other HCRI clinician.

For Shannon Taylor of McKenny, who attended HCRI in 2003 and again in 2009, the research findings offered hope.

“There is an incorrect status or impression people have that folks who stutter are dumb, just that they cannot hold down a good job, and that is so far from the truth,” said Taylor, 33. “To see that there is an actual connection there, just that you are not dumb, that there is a root cause that can be addressed at some point … I guess that brings excitement, because once you have a cause then you have something to work toward for a cure.”

Currently there isn’t a cure for stuttering, which affects about 1 percent of the population. The research did point to a possible enzyme treatment for stuttering someday.

“While this study is the first to identify specific genes associated with stuttering, the findings apply to about 5 percent of the total cases studied,” Dr. Jody Hershey, a member of the HCRI board of directors, said in an e-mail. “There is much more to be learned here; however, the door to further discoveries has been opened.”

But for now, the focus at HCRI is on teaching skills and techniques to improve speech.

HCRI has developed an intense 12-day therapy course to teach people how to control their voice, respiration and facial muscles so they can speak without stuttering. It’s not the only treatment available, but it is one that is widely known among people who stutter.

Nearly 5,800 people have gone through the HCRI treatment, traveling from 23 countries and all 50 states. HCRI has helped famous people such as TV journalist John Stossel and Annie Glenn, wife of astronaut and former U.S. Sen. John Glenn.

“People from all walks of life in all 50 states know exactly where Roanoke, Virginia, is because of what we do,” Yates said. “And yet there are people down Plantation Road who don’t know we are here.”

Hershey, who is the health director of the New River Health District and a graduate of the HCRI therapy course, said the institute has had a major influence on stuttering research.

“I’m not sure that many people in the Roanoke Valley are aware of HCRI’s national and international accomplishments and successes,” he said.

Stuttering Research Commentary #4 by HCRI

Genetic Studies: Possibilities and Limitations Related to Stuttering

Commentary by Ronald L. Webster, Ph.D., Founder and President of Hollins Communications Research Institute (HCRI), a nonprofit center dedicated to the investigation and treatment of stuttering.

The issue of genetics in stuttering is important and it deserves to be understood in terms of what genetic analyses can and cannot do in improving our understanding of stuttering. The scientific and popular enthusiasm for modern DNA analyses is generating a possibly problematic situation with the seemingly magical expectation that the human condition can be understood almost solely through genetic analyses.

It is clear, however, that the information resulting from genetic analyses must be integrated with other forms of knowledge about how organisms are organized and how they function.

The coherent formulation of knowledge about fundamental properties of organisms will lead to better understanding of the specific mechanisms that are embodied within them and the activities accomplished by these mechanisms. This will be true for the disorder identified as stuttering.

A few recent studies illustrate the nature of research being conducted on genetics and stuttering.  Following are links to abstracts.


These reports show scattered and inconsistent results when different types of genetic linkage studies are conducted. The main point is that there is still relatively little evidence for specific genetic factors in the broad population of stutterers. Evidence improves slightly when more closely related samples are examined.

There is the long-standing general observation that stuttering tends to run in families. Approximately half of the people who stutter can identify someone in their family background who stuttered. That finding implicates the notion that genetic factors are relevant in some way to the problem of stuttering.

There is preliminary evidence that aspects of stuttering within family members can be accounted for by advanced genetic models. However, when geneticists have conducted genetic linkage studies in which they searched for genetic markers that differentiated family groups with stuttering represented with family groups without stuttering represented, only weak relationships were found.

One of the conclusions that can be drawn about the probable role of genetics in stuttering is that slightly more that 50 percent of the cases will have a genetic component present. That means there will be a considerable proportion of stuttering cases where a genetic component will not be present. There is considerable importance to this interpretation when it comes to searching for the cause or causes of stuttering.

It seems likely that there is a mechanism or mechanisms that can produce stuttering in a individual even when there is no specific genetic element present. If this is indeed the case, then, in those instances of stuttering where a genetic component is identified, it would be expected that the physical manifestations of the genetic material are acting upon components of an existing body system that is primarily responsible for the disfluent speech events.

The implication that I draw from the genetics research is that we should intensify the search for physical mechanisms within the body that govern speech motor output. A good place to begin the search is to examine the broad array of physical variables that enhance fluency in stutterers and degrade fluency in normal speakers. Nature is presenting us with sets of clues that are almost certainly pointing to the arena where the causal factors in stuttering will be found.

For information about HCRI’s 39 years of research and therapy delivery, visit

HCRI Research Study Commentary – An Introduction

Stuttering: Generating Fluent Speech as a Tool for Discovering the Cause(s) of Stuttering

By Ronald L. Webster, Ph.D., Founder and President
Hollins Communications Research Institute (HCRI)

There are a number of observations regarding stuttering and manipulations of physical conditions that reliably generate fluent speech. It would seem reasonable to state that, with these observations on conditions that generate fluent speech, nature is pointing clearly and strongly to a way to advance our understanding of stuttering as a physically based disorder.

This type of information also has special significance for understanding stuttering because it is based specifically upon the direct manipulation of physical variables and not upon studies that merely seek relationships between and among nonmanipulated variables.

Inferences drawn from experiments have the potential for being stronger and more useful than inferences drawn from simple associations. That is, they have to power to permit the correct inference of causal relationships.

We here at HCRI understand that physical facts and the patterns among them represent the foundation information upon which the eventually discovery of the cause or causes of stuttering will emerge. Identification of cause in stuttering will, in turn, generate work that will have potential for curing the disorder.

We note, for purposes of clarity, that we shall be focusing only on developmental stuttering. We will not be addressing stuttering associated with physical damage to the central nervous system induced by insult, disease or drugs.

On this site, we have provided and will continue to add representative studies, along with commentary, that have demonstrated reliable links between specific physically manipulated conditions and the propagation of fluent speech in persons who stutter.

After all, one of the major tasks of the scientific analysis of events in nature is to discover patterns of lawfulness among those events. Another major task is to develop a parsimonious network of constructs that organizes this information and suggests next steps in research. We shall indicate the properties of the patterns we see and will also discuss the scientific implications that can be drawn from this work. Click on the links below for specific studies and commentary by HCRI:

If you would like information about HCRI’s scientifically based stuttering treatment program, visit or call 540-265-5650.

Stuttering Research Commentary #3 by HCRI

As research scientists focus on determining the cause of stuttering, it is important to examine how the brain is involved in stuttering. Yet, it is premature to rush to the simple conclusion that the brain is “causing” stuttering.

The brain operates as a complex set of physiological systems that are, in turn, provided with an array of inputs and outputs. The research task is to develop an understanding of the complex context within which the brain functions.

The following research abstract is the third in a series es provided as a service by Hollins Communications Research Institute (HCRI).  HCRI is a nonprofit Institute based in Roanoke, Virginia that has been at the forefront of stuttering research and treatment innovation since 1972.

The commentary provided following the abstract is provided Ronald L. Webster, Ph.D., HCRI’s Founder and Director.


Structural and functional abnormalities of the motor system in developmental stuttering.

Brain. 2008 Jan;131(Pt 1):50-9. Epub 2007 Oct 10. Watkins KE, Smith SM, Davis S, Howell P. Department of Experimental Psychology, University of Oxford, Oxford, UK.


Though stuttering is manifest in its motor characteristics, the cause of stuttering may not relate purely to impairments in the motor system as stuttering frequency is increased by linguistic factors, such as syntactic complexity and length of utterance, and decreased by changes in perception, such as masking or altering auditory feedback.

Using functional and diffusion imaging, we examined brain structure and function in the motor and language areas in a group of young people who stutter. During speech production, irrespective of fluency or auditory feedback, the people who stuttered showed overactivity relative to controls in the anterior insula, cerebellum and midbrain bilaterally and underactivity in the ventral premotor, Rolandic opercular and sensorimotor cortex bilaterally and Heschl’s gyrus on the left.

These results are consistent with a recent meta-analysis of functional imaging studies in developmental stuttering. Two additional findings emerged from our study. First, we found overactivity in the midbrain, which was at the level of the substantia nigra and extended to the pedunculopontine nucleus, red nucleus and subthalamic nucleus.

This overactivity is consistent with suggestions in previous studies of abnormal function of the basal ganglia or excessive dopamine in people who stutter. Second, we found underactivity of the cortical motor and premotor areas associated with articulation and speech production. Analysis of the diffusion data revealed that the integrity of the white matter underlying the underactive areas in ventral premotor cortex was reduced in people who stutter.

The white matter tracts in this area via connections with posterior superior temporal and inferior parietal cortex provide a substrate for the integration of articulatory planning and sensory feedback, and via connections with primary motor cortex, a substrate for execution of articulatory movements.

Our data support the conclusion that stuttering is a disorder related primarily to disruption in the cortical and subcortical neural systems supporting the selection, initiation and execution of motor sequences necessary for fluent speech production.

HCRI Comment:

This study found evidence for anomalous cortical and subcortical activation in stutterers. While the authors  refer to these systems in terms of motor activation and control, the door remains open to the question of sensory involvement in motor execution. That is, a flaw in sensory return associated with speech initiation would have significant implications for motor functions.

For more information about HCRI’s work in the field of stuttering and treatment programs, visit .

Stuttering Research Commentary #2 by HCRI

All human behavior is associated with brain functioning of one type or another — including stuttering.

As research scientists focus on determining the cause of stuttering, it is important to examine how the brain is involved in stuttering. Yet, it is premature to rush to the simple conclusion that the brain is “causing” stuttering.

The brain operates as a complex set of physiological systems that are, in turn, provided with an array of inputs and outputs. The research task is to develop an understanding of the complex context within which the brain functions.

The following research abstract is the second in a series provided as a service by Hollins Communications Research Institute (HCRI).  HCRI is a nonprofit Institute based in Roanoke, Virginia that has been at the forefront of stuttering research and treatment innovation since 1972.

HCRI commentary follows the abstract and is provided Ronald L. Webster, Ph.D., HCRI’s Founder and Director.


Common features of fluency-evoking conditions studied in stuttering subjects and controls: an H(2)15O PET study.

J Fluency Disord. 2003 Winter;28(4):319-35; quiz 336.  Stager SV, Jeffries KJ, Braun AR.  Language Section, Voice Speech and Language Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA.

Educational Objectives:

1. Compare brain activation patterns under fluency- and dysfluency-evoking conditions in stuttering and control subjects;

2. Appraise the common features, both central and peripheral, of fluency-evoking conditions; and

3. Discuss ways in which neuroimaging methods can be used to understand the pathophysiology of stuttering.


We used H(2)15O PET to characterize the common features of two successful but markedly different fluency-evoking conditions — paced speech and singing — in order to identify brain mechanisms that enable fluent speech in people who stutter. To do so, we compared responses under fluency-evoking conditions with responses elicited by tasks that typically elicit dysfluent speech (quantifying the degree of stuttering and using this measure as a confounding covariate in our analyses).

We evaluated task-related activations in both stuttering subjects and age- and gender-matched controls. Areas that were either uniquely activated during fluency-evoking conditions, or in which the magnitude of activation was significantly greater during fluency-evoking than dysfluency-evoking tasks included auditory association areas that process speech and voice and motor regions related to control of the larynx and oral articulators.

This suggests that a common fluency-evoking mechanism might relate to more effective coupling of auditory and motor systems — that is, more efficient self-monitoring, allowing motor areas to more effectively modify speech. These effects were seen in both PWS and controls, suggesting that they are due to the sensorimotor or cognitive demands of the fluency-evoking tasks themselves.

While responses seen in both groups were bilateral, however, the fluency-evoking tasks elicited more robust activation of auditory and motor regions within the left hemisphere of stuttering subjects, suggesting a role for the left hemisphere in compensatory processes that enable fluency.

HCRI Comment

This article hints at problems in auditory sensory and motor activation relationships. These results are consistent with the idea that there is a flaw in sensory/motor feedback relationships.

For more information about HCRI’s work in the field of stuttering and treatment programs, visit