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- All Subjects: Speech Motor Learning
- All Subjects: Vowels
- Creators: Daliri, Ayoub
- Creators: Jones, Hanna Vanessa
Speech motor learning is important for learning to speak during childhood and maintaining the speech system throughout adulthood. Motor and auditory cortical regions play crucial roles in speech motor learning. This experiment aimed to use transcranial alternating current stimulation, a neurostimulation technique, to influence auditory and motor cortical activity. In this study, we used an auditory-motor adaptation task as an experimental model of speech motor learning. Subjects repeated words while receiving formant shifts, which made the subjects’ speech sound different from their production. During the adaptation task, subjects received Beta (20 Hz), Alpha (10 Hz), or Sham stimulation. We applied the stimulation to the ventral motor cortex that is involved in planning speech movements. We found that the stimulation did not influence the magnitude of adaptation. We suggest that some limitations of the study may have contributed to the negative results.
When we produce speech movements, we expect a specific auditory consequence, but an error occurs when the predicted outcomes do not match the actual speech outcome. The brain notes these discrepancies, learns from the errors, and works to lower these errors. Previous studies have shown a relationship between speech motor learning and auditory targets. Subjects with smaller auditory targets were more sensitive to errors. These subjects estimated larger perturbations and generated larger responses. However, these responses were often ineffective, and the changes were usually minimal. The current study examined whether subjects’ auditory targets can be manipulated in an experimental setting. We recruited 10 healthy young adults to complete a perceptual vowel categorization task. We developed a novel procedure where subjects heard different auditory stimuli and reported the stimuli by locating the stimuli relative to adjacent vowels. We found that when stimuli are closer to vowel boundary, subjects are less accurate. Importantly, by providing visual feedback to subjects, subjects were able to improve their accuracy of locating the stimuli. These results indicated that we might be able to improve subjects’ auditory targets and thus may improve their speech motor learning ability.