Cortical Processing of Speech Sounds in Adverse Conditions

Supervising Professor: Dr. Michael P. Kilgard, Ph.D. The brain has an amazing capacity to accurately represent information about myriad complex stimuli from its surrounding environment. Problems with maintaining accurate representations of stimuli have harmful effects and are reflected behaviorally. Speech is one such complex stimulus. Normal hearing humans are adept at understanding speech in adverse situations. However hearing and learning impaired populations have great difficulty processing speech sounds in noise. Examining neural responses to speech sounds may provide a better insight into how the auditory system represents speech sounds. Previous studies with EEG and fMRI techniques have revealed much about how the brain responds to speech sounds. However, these techniques lack the spectral and temporal precision necessary to study the underlying neural representation of individual speech sounds. In this dissertation, microelectrode recordings of speech responses in rat primary auditory cortex provide high spatial and temporal precision. Previous studies have shown that animals have similar behavioral and neural responses to speech