This research is studying the use of low-intensity focused ultrasound (LIFU; a mild, noninvasive acoustic stimulation technique) in a small number of people to learn about its safety as a treatment for stuttering. LIFU is a small, safe sound signal that produces a gentle, pulsing flow of acoustic waves to help different parts of the brain communicate with each other. Researchers want to understand how the mild, non-invasive brain stimulation affects speech relevant brain areas, which may in turn affect speech fluency and speaking-related brain activity in people who stutter.
have normal language, hearing and cognition
speak English as their primary language
currently stutter
score at least 10 (very mild) on the Stuttering Severity Instrument (SSI-4) or exhibit greater than 3% stuttered syllables during at least one of the first 3 speech samples
History of seizures
Major medical or neurological illness (e.g., stroke, serious head trauma, brain infection, Parkinson's disease, etc.)
History of closed head injury with loss of consciousness (e.g., concussion)
Metal or electronic implants such as cochlear implants and pacemakers
Crossover
High DC LIFU
DeviceStimulation parameters and target location. Stimulation will be delivered using the BrainSonix BXPulsar 1002 System (BrainSonix Corporation, Sherman Oaks, CA, USA). Sonication Parameters will be as follows. Fundamental frequency: 650 kHz; pulse repetition frequency: 10Hz; pulse duration: 100ms; DC: 70% (yielding pulse width of 70 ms); sonication duration: 30 s; inter-sonication interval: 30s; LIFU-ON epochs per block: 12 epochs (Jang et al., 2025). During active stimulation a total of 4.2 min stimulation will be applied across all LIFU-ON epochs. Both active and sham stimulation sessions will last \~12 mins each. The researchers will be targeting ventral intermediate nucleus (VIM) region of the thalamus for the active stimulation.
Sham
DeviceStimulation parameters and target location. Stimulation will be delivered using the BrainSonix BXPulsar 1002 System (BrainSonix Corporation, Sherman Oaks, CA, USA). Sonication Parameters will be as follows. Fundamental frequency: 650 kHz; pulse repetition frequency: 10Hz; pulse duration: 100ms; DC: 70% (yielding pulse width of 70 ms); sonication duration: 30 s; inter-sonication interval: 30s; LIFU-ON epochs per block: 12 epochs (Jang et al., 2025). During sham stimulation a total of 4.2 min stimulation will be applied across all LIFU-ON epochs. Both active and sham stimulation sessions will last \~12 mins each. The researchers will be reversing the direction of the transducer placed on the head such that no active stimulation will be applied to the participant's head. But the neuronavigation procedures (targeting VIM) and stimulation parameters will be kept identical such that the participant experiences the same procedure across active and sham conditions.
Percentage of stuttered syllables produced during speech sample
The study will calculate the percentage of stuttered syllables (out of total syllables) in two speech samples (one before LIFU and one sample after LIFU) per each stimulation session. Decreased stuttered syllables represents better outcomes (greater reduction in stuttering). Two samples are collected during session 1 and two samples are collected during session 2. An additional baseline sample is collected at the baseline session (on a separate day before the two stimulation sessions).
Stop signal response time (SSRT)
The study will measure the Stop signal response time (SSRT) from the stop signal fMRI task (one before LIFU and one sample after LIFU) per each stimulation session. Two SSRT outcomes are collected during session 1 and two SSRT outcomes are collected during session 2. An additional baseline SSRT is collected at the baseline session (on a separate day before the two stimulation sessions). SSRT will be measured 5 times total.
Rhythm discrimination score (d')
The study will compare the rhythm discrimination behavioral task from before and after LIFU during both session 1 and 2 for a total of 4 measurements. This is measured by the signal direction measures d' that will be calculated to quantify perceptual sensitivity (d'). Apart from the stimulation sessions, the baseline session will also collect this measure. Thus, assessed 5 times in total, considering the baseline session and stimulation sessions 1 and 2.
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University of Michigan
Lead sponsor
Michigan Pioneer Fellowship
Collaborator
