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Recent Advances in Voice, Speech, and Language Research

Transformative Genetic Studies

  • Scientists continue to discover new genetic and genomic alterations (including the role of copy number variants) associated with speech and language disorders using new methods such as next-generation whole-exome sequencing.209-213 For example, a new gene, GRIN2A, was identified for focal epilepsies with speech and language disorders, reinforcing an important role for this gene in motor speech function.214, 215 These discoveries are likely to improve the classification, diagnosis, and treatment of speech and language disorders.
  • Researchers are learning how reflux from the stomach to the throat and vocal fold tissue harms the larynx. They have demonstrated that reflux significantly alters the expression of 27 genes that are associated with malignant changes of the larynx.216, 217 Understanding how changes in gene expression lead to laryngeal injury provides a comprehensive model for identifying novel diagnostic and therapeutic targets to treat reflux-related injury.
  • Researchers generated a transcriptome dataset to capture the complexity of genes responsible for wound healing of the vocal folds. This dataset serves as a resource in developing new studies that would accelerate the identification of novel therapeutic targets to treat reflux-related injury.218

Behavioral Phenotyping

  • Studies demonstrated that children with developmental speech and language problems are at a considerable risk for learning disabilities and other psychosocial problems that emerge during adolescence or adulthood.219-221
  • Some families with high incidence of stuttering may also have high incidence of other fluency disorders and other speech production difficulties. This finding can lead to new genetic studies across multiple families to define the characteristics of stuttering.222
  • Scientists are using new imaging technology to study structural and mechanical characteristics of laryngeal scarring.223 This could provide the foundation for developing improved treatments for one of the most common causes of voice disorders.
  • Researchers have identified distinct and viable characteristics of language disorders, extending the research to new populations, such as children who are deaf or minimally verbal children with autism, and to language disorders shared across different populations that may be used in future genetic and treatment studies.224-226 The development of these classification systems will guide future investigations into the genetic, neurologic, and other causal factors that contribute to voice, speech, and language impairments.

Interventions

  • Researchers suggest that self-administered computer therapy with single word production improved chronic apraxia of speech. This method shows promise for delivering high-intensity speech and language rehabilitation for individuals recovering from stroke.227
  • Scientists have developed a wearable monitoring device to accurately measure voice disorders during daily activities and provide real-time feedback.228, 229 When combined with knowledge of gene expression changes related to vocal fold vibration exposure230, ambulatory monitoring has shown the potential to revolutionize treatment that could facilitate healthier vocal function and enhance diagnosis and treatment options.
  • Studies have demonstrated the clinical benefit of speech and language therapy for school-age children who have pragmatic and social communication problems231 and for minimally verbal children with autism.232
  • Scientists have extended behavioral treatment research to explore the use of a virtual speech clinician for individuals with aphasia.233 Other studies have shown that spelling therapy combined with supplemental treatments such as transcranial magnetic and direct electrical stimulation of the brain enhances treatment outcomes in individuals with aphasia.234, 235
  • Pairing vagus nerve stimulation with a speech sound can improve how the brain processes spoken language.236 These discoveries leverage existing knowledge, inform the development of new treatment paradigms, and improve outcomes for individuals with speech and language disorders.

Bioengineering Advances

  • Researchers have expanded the range of augmentative and alternative communication through widely available technologies, such as tablets, for individuals with ASD and related communication disorders.237, 238
  • Researchers have developed a model, which can detect and correct speech production errors prior to articulation. This model showed a potential for the development of a brain computer interface (BCI) that uses auditory feedback to allow profoundly paralyzed users to learn to produce speech using a speech synthesizer.239
  • Scientists have made significant advances in replacing, engineering, and regenerating vocal fold tissue through the use of stem cells.240 In one study, researchers bioengineered vocal fold tissue using human cells that could produce sound when transplanted into animals.241 Also, investigators have built computational simulations of vocal fold vibrations242-246 that could provide essential information for designing biomaterials that will help restore injured vocal folds. These studies help advance the understanding of normal and disordered vocal function in order to restore vocal fold structure and function and develop improved treatment options.

Imaging Correlations

  • Brain imaging technology has identified differences in the white matter of the brain in disorders, such as autism spectrum disorder (ASD) and specific language impairment247, 248, and have demonstrated that common neuropathology tied to shared specific characteristics (e.g., non-word repetition) may be found across different developmental language disorders.249
  • Advanced imaging technology has improved our understanding of the complex actions that take place in the part of the brain controlling human speech95 and has allowed for mapping of the functional connections of the brain (connectome) that are responsible for speech control250 and mapping the neural interactions involved in critical elements of the speech motor system.251-254 Similarly, other imaging studies have shown that the brain is organized in specific patterns to perceive speech93, 255-262, including processing vocal tone occurring in the left and right sides of the brain263, and to simultaneously perceive spoken and signed language.264
  • Significant advances were made in understanding the anatomical differences of the brain in neurological disorders that impair speech production, such as stuttering265-268 and spasmodic dysphonia.222, 269-271 In addition, scientists can better explain the neural organization of language in a range of acquired language disorders272, 273 and how language networks change as a result of treatment in individuals who have had a stroke.274
  • Imaging of the larynx and vocal folds have been refined by ultrasound275 to characterize the relative concentration of collagen and elastic fibers, which are key factors influencing the biomechanical properties of the vocal folds, and by nonlinear laser scanning microscopy and atomic force microscopy-based indentation223 to characterize scarred vocal folds. These imaging techniques are likely to enhance diagnostic capabilities and help evaluate bioengineering techniques used to simulate vocal fold tissue.

Developmental Timing

  • Longitudinal studies have documented the predictors and risk factors that are associated with behavior and brain development underlying speech and language in children with or without speech and language disorders.276, 277 This research is now being used to identify early behavioral and neural risk factors that predict later language disorders.278-280
  • Studies identified that the quality of caregiver-child interaction is one of the factors that influences how quickly infants process speech.281 Variations in early language experience (early vs. late bilingualism) shape patterns of functional connectivity in the human brain.282 Further, researchers found that the auditory brainstems of adolescents are immature and speech development can be altered.283 Another study helped scientists understand the differences in how the brain perceives vowels and consonants, which may explain some aspects of developmental and acquired speech processing disorders.284
  • The first systematic determination of the cellular and molecular progression of vocal fold epithelium development documented five developmental events of the progression from vocal fold initiation in the embryonic anterior foregut tube to fully differentiated and functional adult tissue. The study serves as the necessary foundation for future functional investigations of vocal fold formation.285
  • For the first time, a series of high-speed digital imaging studies have compared vocal fold vibration between children and adults. Researchers have demonstrated vocal fold vibration in children is complex and not easily predicted from an adult.286, 287 Further, precise characterization of age-related changes in the larynx paves the way for scientists to design biomaterials with the potential to restore voice to elderly individuals with vocal fold atrophy.288-292

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Last Updated Date: 
January 27, 2017