Neural and perceptual correlates of closed-loop sensorimotor training: basic and applied studies

Thesis: Ph. D., Harvard-MIT Program in Health Sciences and Technology, 2016.Cataloged from PDF version of thesis.Includes bibliographical references.The global hearing healthcare field is faced with two principal challenges. First, the demand for basic audiometric testing services far exceeds the capacity of trained clinicians even in high income countries, and this supply/demand mismatch is expected to worsen secondary to population aging. Next, once patients are identified as having a hearing loss, the treatments that are provided (hearing aids) do not sufficiently address their primary complaint, namely that they have trouble hearing in noisy environments. To begin to address the first problem, we executed a proof-of-concept study to ask whether mobile consumer electronics could be used to replace manually performed clinic-based testing with self-directed hearing measurements from home. We found that self-administered home hearing measurements were largely equivalent to standard clinical measures. To begin to address the second problem (hearing in noise challenges of patients), we performed three additional experiments. Inspired by promising findings of enhanced visual attention following action videogame training, we developed a closed-loop audiomotor training application and asked if playing a game that focused on tone in noise discriminations would provide generalized benefit for speech recognition in noise abilities. In young normally hearing adults, closed-loop training for one month provided a 12 percentage point improvement in speech understanding in noise scores. Next, we recruited older adults who wore hearing aids to play a similar closed-loop training game and observed a 10 percentage point enhancement of speech recognition in noise abilities secondary to gameplay, suggesting that this training could be coupled with standard treatments to improve patient outcomes. Finally, we studied the neurophysiological correlates of audiomotor signal in noise training in a rodent model, where we observed enhanced resistance to noise suppression in auditory cortical neurons following three months of training, perhaps contributing to the perceptual benefits that we observed in human subjects.by Jonathon Whitton.Ph. D