Joel S. Snyder - US grants

DESCRIPTION (provided by applicant): One theory of auditory dysfunction in schizophrenia posits a decreased capacity to form distinct representations for different sounds, which is supported by numerous behavioral findings that show impaired ability to discriminate tones of different frequencies. The purpose of the proposed study is to identify the neural mechanisms of this auditory coding imprecision in schizophrenia by measuring event-related brain potentials (ERPs) related to auditory sensory processing in chronic schizophrenia patients compared with healthy matched controls. The ERP paradigm will assess the capacity of the auditory system to suppress activity of neurons adjacent to those previously stimulated, which results in sharper stimulus representations. In the same participants, we will also correlate frequency discrimination ability and gray matter volumes of brain regions containing primary and secondary auditory cortex with ERP measures of auditory processing. Finally, in patients we will correlate clinical measures with ERP measures of auditory processing. Associating deficient physiological mechanisms of sensory coding imprecision with brain substrates and clinical measures will potentially enable a better understanding of how to treat perceptual and cognitive problems in schizophrenia. PUBLIC HEALTH RELEVANCE This project seeks to identify mechanisms of auditory processing dysfunction and their substrates in auditory cortex in schizophrenia that contribute to difficulty in sound perception, from discriminating the frequencies of pairs of simple tones to identifying the vocal affect of speech. Identifying mechanisms and anatomical substrates of auditory perception difficulties may lead to more specific therapeutic targeting of perceptual and cognitive dysfunction in schizophrenia.

Human and non-human animals alike rely on a set of abilities that allow them to segregate sounds of interest from noisy background sounds, for example, when we listen to someone talking on a crowded, noisy bus. These abilities, collectively called 'auditory scene analysis,' have been the focus of several decades of laboratory research. However, recent research has pointed out the need for more empirical and theoretical work to explain the diversity of phenomena that occurs during sound segregation. Joel Snyder from the University of Nevada, Las Vegas, focuses on context effects because they show promise for significantly advancing our theoretical understanding of the mechanisms and levels of processing necessary to explain auditory scene analysis. Key issues to be addressed include 1) What features of sound patterns influence context effects? 2) Are sensory or decision levels of processing best suited to explain context effects? 3) Do attention or awareness influence context effects?

The findings from this project may have technical and health applications such as prosthetic design of hearing aids, speech and music recognition devices, and amelioration of auditory impairments that occur in normal hearing, hearing impairments, developmental disorders, and schizophrenia.