Behavioral and Neural Responses to External Alterations of Speech Variability

Behavioral and Neural Measures of Speech Motor Control

The purpose of this research study is to understand how the brain processes and controls speech in healthy people. The investigators are doing this research because it will help identify the mechanisms that allow people to perceive their own speech errors and to learn new speech sounds, which may be applied to people who have communication disorders. 15 participants will be enrolled into this part of the study and can expect to be on study for 3-4 visits of 2-4 hours each.

The overall study (Establishing the clinical utility of sensorimotor adaptation for speech rehabilitation) aims to understand how cognitive, perceptual, and motor processes are integrated in the control of speech movements. The investigators study how this complex skill is performed in healthy speakers to understand how this system functions, how this skill relates to the perception of speech, and what role different parts of the brain play in this process. Different studies look at how speech motor control is executed, maintained, and changed. Overall, the study will recruit 329 participants over the course of 5 years. Participants can expect to be on study for up to 3 weeks.

The entire study is composed of 8 experiments and 6 interventions. The present record represents the experiments involving magnetoencephalographic (MEG) imaging, i.e. Experiment 5: Behavioral and neural responses to external alterations of speech variability.

This paradigm modulates the perceived speech variability of participants through three different altered auditory feedback sessions: an inward-pushing feedback perturbation that decreases perceived variability by playing back participants' speech closer to the center of their vowel distributions, an outward-pushing feedback perturbation that increases perceived variability by playing back participants' speech farther from the center of their vowel distributions, and a normal feedback condition in which speech feedback is played back without perturbation. Participants will complete this paradigm during MEG imaging, which will noninvasively measure auditory cortical activity evoked during speech production and playback.

Inclusion Criteria (Patients):

• English-speaking adults

• diagnosed communicative disorder, target populations may include:

  • stroke survivors with aphasia
  • individuals with cerebellar ataxia
  • individuals with parkinson's disease
  • individuals who use cochlear implants to hear
  • adults who stutter

Inclusion Criteria (Control):

• English-speaking adults
• normal hearing and speech
• no history of stroke or neurological conditions

Exclusion Criteria:

• Native language other than English

• Any neurological disorders other than the disorder of interest

• Any history of hearing disorders

• Uncorrected vision problems that prevent participants from seeing visually-presented stimuli

• Significant cognitive impairments that prevent participants from carrying out the task or from giving informed consent

• Vulnerable populations (minors and prisoners)

• Additional exclusionary criteria if participating in neuroimaging:

  • Implanted paramagnetic materials (metal clips, plates, pacemakers, etc.)
  • Head too large for MEG recording helmet
  • Claustrophobia or intolerance of MRI scanner noise
  • Low signal to noise ratio in pilot MEG recordings
  • High levels of artifacts (eye-blinks, etc.)
  • Inability to produce the speech sounds proposed with minimal movement
  • Left-handedness

• Additional exclusionary criteria if participating in transcranial magnetic stimulation (TMS):

  • Implanted paramagnetic materials (metal clips, plates, pacemakers, etc.)
  • Increased risk in the event of a seizure
  • Serious heart disease
  • Increased intracranial pressure
  • Pregnancy
  • History of seizures
  • Family history of epilepsy
  • Epileptogenic medications
  • Chronic or transient disruption of sleep (including jet lag)
  • History of fainting
  • Chronic or transient increase in stressful experiences
  • Use of illegal drugs