Investigating Individual Differences in Speech Motor Skills in Neurotypical Speakers and Persons With Disordered Speech

Официальное название

Brain Mechanisms Underlying Neurotypical and Disordered Speech

Обзор

This study aims to understand how people use different types of feedback to control their speech. When an individual speaks, the brain relies on several systems at the same time, such as sensory systems that monitor an individuals own voice and the movements of their speech muscles, and a motor system that builds and reads out learned motor patterns. The investigators are studying how these systems work together and how they differ across individuals. Investigators will test 90 adults between 18 and 50 years old, including people who stutter, people with dyslexia, and people with typical speech and reading development. Participants will complete several short speech tasks in which the sounds they hear or the movements of their jaw or larynx are briefly changed. These responses will be used to measure each person's speech motor skills and to estimate the settings of a computer model called "SimpleDIVA," which simulates how the brain controls speech. Participants will also complete an MRI scan so investigators can measure the structure and connectivity of different brain regions. These measures will help investigators understand how individual differences in the brain relate to the speech motor control skills we observe. Participants will also complete sessions with noninvasive brain stimulation (transcranial current stimulation, or tCS) to examine how stimulation of specific areas of the brain affects responses during the speech tasks. The knowledge gained from this study will help researchers understand why speech motor skills vary across people and how differences in neural function may contribute to conditions such as stuttering and dyslexia.

Вмешательства

• Поведенческое Unpredictable auditory feedback perturbation: 2 behavioral sessions
  Participants in Arms 1 and 2 will repeat consonant/vowel/consonant (/CVC/) words containing the vowel "eh" between two consonants that they hear over headphones. As they speak, vocal output from the participant will be transduced via a microphone and then played back to the participant over headphones at an undetectable delay. On a subset of (perturbed) trials, F0 or F1 in the auditory feedback presented to the participant will be shifted relative to their vocal output. On the remaining (baselin
• Поведенческое Unpredictable auditory feedback perturbation during tCS: 3 behavioral sessions
  Participants in Arms 1 and 2 will repeat /CVC/ words containing the vowel "eh" between two consonants that they hear over headphones. As they speak, vocal output from the participant will be transduced via a microphone and then played back to the participant over headphones at an undetectable delay. On a subset of (perturbed) trials, F0 or F1 in the auditory feedback presented to the participant will be shifted relative to their vocal output. On the remaining (baseline) trials, auditory feedback
• Поведенческое Sustained F1 auditory feedback perturbation
  Participants in Arms 1 and 2 will repeat /CVC/ words containing the vowel "eh" between two consonants that they hear over headphones. As they speak, vocal output from the participant will be transduced via a microphone and then played back to the participant over headphones at an undetectable delay. Over the course of each protocol, the first formant (F1) in the auditory feedback presented to the participant will be shifted relative to their vocal output. Trials will be organized in four phases:
• Поведенческое Sustained F0 auditory feedback perturbation
  Participants in Arm 1 and 2 will repeat /CVC/ words containing the vowel "eh" between two consonants that they hear over headphones. As they speak, vocal output from the participant will be transduced via a microphone and then played back to the participant over headphones at an undetectable delay. As they speak the fundamental frequency (F0) in the auditory feedback presented to the participant will be shifted relative to their vocal output. Trials will be organized in four phases: an initial b
• Поведенческое Reflexive somatosensory perturbation
  Participants in Arms 1 and 2 will repeat /CVC/ words containing the vowel "eh" between two consonants that they hear over headphones. While they speak, speech-shaped masking noise will be presented to participants at 85 dB. On a subset of trials (word productions), movements of the jaw will be perturbed (restricted) by the rapid inflation of a balloon placed between the upper and lower teeth shortly after voice onset. On another subset of trials, the position of the larynx will be perturbed by t
• Другое Anodal tCS targeting pSTG and vSSC
  Participants in Arm 1 will receive continuous anodal tCS targeting posterior superior temporal gyrus (pSTG) during a 20-minute reflexive auditory feedback task during one session and stimulation targeting ventral somatosensory cortex (vSSC) during the same task in another session. The tCS stimulation will ramp up to its maximum value (2 milliamperes) over the first 30 s of the session and will be maintained at that level throughout the remainder of the session.
• Другое Anodal tCS targeting left or right vPMC
  Participants in Arm 2 will receive continuous anodal tCS targeting left ventral premotor cortex (vPMC) during a 20-minute reflexive auditory feedback task during one session and stimulation targeting right vPMC during the same task in another session. The tCS stimulation will ramp up to its maximum value (2 milliamperes) over the first 30 s of the session and will be maintained at that level throughout the remainder of the session.
• Другое Sham tCS targeting pSTG or vSSC
  Participants in Arm 1 will receive Sham tCS stimulation targeting the pSTG or vSSC during a 20-minute reflexive auditory feedback task. During the minute prior to training onset, the tCS stimulator will ramp up to 2 milliamperes and then back down to 0 for the remainder of the session.
• Другое Sham tCS targeting left vPMC or right vPMC
  Participants in Arm 1 will receive Sham tCS stimulation targeting left or right vPMC during a 20-minute reflexive auditory feedback task. During the minute prior to training onset, the tCS stimulator will ramp up to 2 milliamperes and then back down to 0 for the remainder of the session.

Первичные конечные точки

• Reflexive compensatory response [Срок оценки: Day 1 and Day 2]
• Adaptive compensatory response [Срок оценки: Day 1 and Day 2]

Вторичные конечные точки (10)

• Stuttering Severity [Срок оценки: Baseline]
• Dyslexia Severity [Срок оценки: Baseline]
• Verbal and Nonverbal Intelligence [Срок оценки: Baseline]
• Receptive Vocabulary [Срок оценки: Baseline]
• Brain region volume [Срок оценки: Day 2]
• Brain region area [Срок оценки: Day 2]
• Brain region cortical thickness [Срок оценки: Day 2]
• Brain region cortical gyrification [Срок оценки: Day 2]
• Brain region functional connectivity [Срок оценки: Day 2]
• Brain region structural connectivity [Срок оценки: Day 2]

Критерии участия

Критерии включения

• Native speakers of American English
• Adults age 18-50
• Age-appropriate cognitive and receptive vocabulary skills
• Age-appropriate hearing
• Adults with dyslexia will have a history of dyslexia or report of ongoing reading difficulties that will be confirmed at the first screening visit
• Adults who stutter will have a history of stuttering that will be confirmed at the first screening visit

Критерии исключения

• History of neurological disorder, including a history of seizures
• Major brain injury, brain surgery, or stroke
• Orthodontia or atypical oral structure (e.g., cleft palate) that interferes with speech
• Fluency disorder (except those in the persons who stutter cohort), apraxia of speech, or dysarthria
• Language or reading disorder (except those in persons with dyslexia cohort)
• Standardized score below 80 on the Kaufman Brief Intelligence Test
• Standardized score below 1 standard deviation on the NIH Toolbox Picture Vocabulary Test
• Pregnancy
• Severe claustrophobia
• Presence of magnetically or mechanically active implant, or other ferromagnetic material embedded in any part of the body
• Significant scalp lesions that would prevent transcranial direct stimulation

Критерии приведены из реестра в оригинале (на английском). Окончательную оценку соответствия проводит исследовательский центр.

Здоровые добровольцы: Да

Дизайн исследования

Распределение

Рандомизированное

Модель

Параллельные группы

Маскирование

Простое слепое

Основная цель

Фундаментальное исследование

Центры проведения

США · 2 центра

• Boston University Charles River Campus — Boston
• Boston University — Boston

Идентификаторы

NCT: NCT07459803 · Guenther_8013 · R01DC022014-01

Первоисточники (государственные реестры)

• ClinicalTrials.gov (NIH, США)

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