Aphasia, Primary Progressive, Stuttering, Developmental
Conditions
Keywords
Stuttering, Developmental, Magnetic Resonance Imaging, Transcranial Direct Current Stimulation, Speech Motor Learning, Speech Disorders, Neurocomputational Modeling
Brief summary
Persistent developmental stuttering affects more than three million people in the United States, and it can have profound adverse effects on quality of life. Despite its prevalence and negative impact, stuttering has resisted explanation and effective treatment, due in large part to a poor understanding of the neural processing impairments underlying the disorder. The overall goal of this study is to improve understanding of the brain mechanisms involved in speech motor planning and how these are disrupted in neurogenic speech disorders, like stuttering. The investigators will do this through an integrated combination of experiments that involve speech production, functional MRI, and non-invasive brain stimulation. The study is designed to test hypotheses regarding the brain processes involved in learning and initiating new speech sound sequences and how those processes compare in persons with persistent developmental stuttering and those with typical speech development. These processes will be studied in both adults and children. Additionally, these processes will be investigated in patients with neurodegenerative speech disorders (primary progressive aphasia) to further inform the investigators understanding of the neural mechanisms that support speech motor sequence learning. Together these experiments will result in an improved account of the brain mechanisms underlying speech production in fluent speakers and individuals who stutter, thereby paving the way for the development of new therapies and technologies for addressing this disorder.
Interventions
BEHAVIORALLearning of non-native phoneme combinations: 1 training session
Each trial of the training sessions will follow a simple reaction time protocol in which a nonsense syllable containing novel consonant clusters (e.g., GDADK) is produced as quickly and accurately as possible after an auditory prompt presented via earphones. During the training session, the participant will practice producing a set of 3 stimuli (the Fully Learned stimuli). Each of the 3 Fully Learned stimuli will be produced 60 times.
BEHAVIORALLearning of novel multisyllabic nonwords
Each trial of the training sessions (total of 6 training sessions over 2 days) will follow a simple reaction time protocol in which a nonword stimulus formed by 2 or 3 syllables that are legal in American English is presented auditorily to the participant, who then produces the stimulus as quickly and accurately as possible. During training, each participant will repeatedly produce 6 nonwords, with each nonword produced a total of 60 times over the 6 training sessions.
OTHERAnodal tDCS
Continuous anodal tDCS is delivered to a speech processing area of the brain during a 19-minute speech training session. The tDCS stimulation will ramp up to its maximum value (2 milliamperes) in the minute prior to the training session and maintained at that level throughout the session.
OTHERSham tDCS
Sham tDCS stimulation is delivered to a speech processing area of the brain during a 19-minute speech training session. During the minute prior to training onset, the tDCS stimulator is ramped up to 2 milliamperes and then back down to 0.
BEHAVIORALLearning of non-native phoneme combinations: 8 training sessions
Each trial of the training sessions will follow a simple reaction time protocol in which a nonsense syllable containing novel consonant clusters (e.g., GDADK) is produced as quickly and accurately as possible after an auditory prompt presented via earphones. During each training session, the participant will practice producing a set of 3 stimuli (the Fully Learned stimuli). Each of the 3 Fully Learned stimuli will be produced 120 times over the 8 training sessions.
BEHAVIORALLearning of non-native phoneme combinations: 6 training sessions
Each trial of the training sessions will follow a simple reaction time protocol in which a nonsense syllable containing novel consonant clusters (e.g., GDADK) is produced as quickly and accurately as possible after an auditory prompt presented via earphones. During each training session, the participant will practice producing a set of 8 stimuli (the Fully Learned stimuli). Each of the 8 Fully Learned stimuli will be produced 60 times over the 6 training sessions.
Sponsors
Boston University Charles River Campus
National Institute on Deafness and Other Communication Disorders (NIDCD)
University of Michigan
Massachusetts General Hospital
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
6 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
* Healthy individuals with no history of neurological, speech, or hearing disorders (other than stuttering in studies that involve adults who stutter). * To maximize the uniformity of prior exposure to the speech stimuli that will be used, only native speakers of American English will be recruited, and only those with limited exposure to a second language will be enrolled. * All adult participants will also pass a standard pure-tone hearing screening at a 25dB hearing level threshold at 500, 1k, 2k, and 4kHz frequencies. * All participating children will pass a hearing screening at a 20 dB threshold at 500, 1k, 2k, and 4k Hz. * Participants in experiments that require them to read orthographic stimuli must have normal or corrected-to-normal vision (MRI-safe corrective glasses are available at the Boston University Cognitive Neuroimaging Center for use during neuroimaging). * Participating children will complete additional speech, language, hearing, and cognitive tests to ensure that they are within normal performance ranges for their age with the exception of stuttering for children in the children who stutter (CWS) group. * Persons who stutter will be evaluated formally by a speech-language pathologist to assess stuttering severity and to ensure the absence of other speech or language disorders. PWS will have no history of neurological disorder other than stuttering, and will demonstrate very mild to severe stuttering according to the Stuttering Severity Instrument for Children and Adults - 4th Edition (SSI-4: PRO-ED, Inc.), that is confirmed by clinical reports and expressed concern by the subject and/or guardian. * Participants with primary progressive aphasia (PPA) will have been diagnosed through the Massachusetts General Hospital Frontotemporal Disorders Unit (MGH-FTD) by an experienced neurologist in coordination with a speech-language pathologist. * Participants with PPA will have a score of 1.0 or lower on the Clinical Dementia Rating scale (i.e., mild cognitive impairment or mild dementia) to ensure cognitive levels are sufficient to complete the task. * All participants with PPA must have a recent clinical assessment and T1 structural neuroimaging scan through the MGH-FTD Unit for eligibility for this study.
Exclusion criteria
* Participants in studies that involve tDCS or MRI scanning will have no contraindications specific to those procedures. For the tDCS study, this includes individuals who have a metallic implant in the head or electrically sensitive devices implanted in the body, a history of seizures, significant scalp lesions, or pregnancy. * For MRI studies, this includes a history of seizures, severe claustrophobia, the presence of magnetically or mechanically active implant, ferromagnetic material embedded in any part of the body, or pregnancy). * All participants will perform a standardized nonword repetition pre-test (the Dollaghan and Campbell Nonword Repetition Task) to assess working memory performance. Participants who perform more than 2 standard deviations below the norm for their age range will be deemed to be unable to perform the experimental task and released from further participation. * Participating children will have no history of neurological disorder other than stuttering, and will demonstrate very mild to severe stuttering according to the Stuttering Severity Instrument for Children and Adults, 4th Edition, that is confirmed by clinical reports and expressed concern by the subject and/or guardian. * Children under the age of 6 and over the age of 8 will not enrolled in this study. * Participants with PPA will not be eligible for this study if they are taking any medications that would be expected to affect speech or language.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change from baseline in production error rate | Evaluated at Baseline and immediately following intervention | Investigators will compare mean error rates when producing newly learned speech sequences versus novel speech sequences of the same length in each arm. This measure will be used to test hypotheses regarding speech motor learning and brain activity and how these compare in persons with persistent developmental stuttering and persons with neurotypical speech. |
| Change from baseline in utterance duration | Evaluated at Baseline and immediately following intervention | Investigators will measure changes in utterance duration before and after speech sequence training to test hypotheses concerning differences in the neural mechanisms responsible for speed/duration improvements compared to improvements in accuracy (i.e., reductions in error rate). |
| Change from baseline in reaction time | Evaluated at Baseline and immediately following intervention | Investigators will measure the time interval between the prompt to begin speech and the subject's speech onset. Mean reaction time will be compared for learned and novel nonwords in persons with persistent developmental stuttering and persons with neurotypical speech. |
| Percentage of words stuttered | Evaluated at Baseline and immediately following intervention | Investigators will compare the percentage of words stuttered under different experimental conditions. This measure will be used to test hypotheses regarding the effect of speech motor learning on stuttering rate and the relationship between stuttering rate and brain activity. |
| Brain activity measured with functional magnetic resonance imaging | Evaluated at Baseline and immediately following intervention | Investigators will measure blood oxygen level dependent (BOLD) brain activity when producing speech utterances in different experimental conditions in adults with persistent developmental stuttering and those with neurotypical speech. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Cortical white matter connectivity | Evaluated during the MRI scanning procedure | Diffusion-weighted MRI will be collected and used to identify relationships between white matter connectivity and behavioral measures. |
| Cortical morphometry | Evaluated during the MRI scanning procedure | Structural MRI will be collected and used to identify relationships between cortical morphometry and behavioral measures. |
| Working memory test scores | Evaluated at Baseline | The Comprehensive Test of Phonological Processing (CTOPP) Second Edition working memory subtest scores for each participant will be used to identify correlations between working memory capacity, task performance, and brain measures in all studies. |
| Forward digit span | Evaluated at Baseline | Scores from the Forward Digit Span task from the Uniform Data Set neuropsychological test battery will be used for each participant with PPA to identify correlations between phonological working memory and task performance. |
| Stuttering Severity | Evaluated at Baseline | The Stuttering Severity Instrument, 4th Edition, will be administered to persons show stutter to identify correlations between stuttering severity and task performance and functional and structural brain measures. |
Countries
United States
Contacts
PRINCIPAL_INVESTIGATORFrank H Guenther, PhD
Boston University
PRINCIPAL_INVESTIGATORSoo-Eun Chang, PhD
University of Michigan
Outcome results
None listed