The basic mechanisms underlying comprehension of spoken language are unknown. We do not understand, for example, how the human brain extracts the most fundamental linguistic elements (consonants and vowels) from a complex and highly variable acoustic signal. An investigation of the cortical representation of speech sounds during categorical perception can likely shed light on this fundamental question. Categorical perception occurs when a change in a variable such as phonem ic contrast along a continuum is perceived, not as a gradual function but rather as a discrete category change. Previous research has implicated the superior temporal cortex in the processing Of speech sounds. However, how the cortex actually represents (i.e. encodes) phonemes is undetermined, mainly due to limitations of non-invasive recording techniques. The recording of neural activity di rectly from the cortical surface is a promising approach si nee it can provide both high spatial and temporal resolution. Here, I propose to examine the mechanisms of categorical speech processing by utilizing neurophysiological recordings obtained during ne urosurgical pnacedures. The principal focus of the independent ROO phase wil I be to elucidate the emergent invariant representation of phonemes in the superior tem poral gyrus that underiies categorical perception. High-density electrode anays, advanced signal processing, and direct eiectrocortical stim ulation will be utilized to unravel both local population encoding of speec h sounds in the lateral temporal cortex as well as global processing across multiple sensory and cognitiv e areas.

Public Health Relevance

The ainn of this research is to reveal the fundamental mechanisnns that underlie comprehension of spoken language. An understanding of how speech is coded in the brain has signifieant implications for the development of new diagnostic and rehabilitative strategies for language disorders (e.g. aphasia, dyslexia, autism, et alia). Abnormal perception of phonemes is a central component to language disability in all of these conditions.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Transition Award (R00)
Project #
5R00NS065120-04
Application #
8322157
Study Section
Special Emphasis Panel (NSS)
Program Officer
Babcock, Debra J
Project Start
2009-09-25
Project End
2013-08-31
Budget Start
2012-09-01
Budget End
2013-08-31
Support Year
4
Fiscal Year
2012
Total Cost
$239,255
Indirect Cost
$70,297
Name
University of California San Francisco
Department
Neurosurgery
Type
Schools of Medicine
DUNS #
094878337
City
San Francisco
State
CA
Country
United States
Zip Code
94143
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Dichter, Benjamin K; Bouchard, Kristofer E; Chang, Edward F (2016) Dynamic Structure of Neural Variability in the Cortical Representation of Speech Sounds. J Neurosci 36:7453-63
Cheung, Connie; Hamiton, Liberty S; Johnson, Keith et al. (2016) The auditory representation of speech sounds in human motor cortex. Elife 5:
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Leonard, Matthew K; Bouchard, Kristofer E; Tang, Claire et al. (2015) Dynamic encoding of speech sequence probability in human temporal cortex. J Neurosci 35:7203-14
Cibelli, Emily S; Leonard, Matthew K; Johnson, Keith et al. (2015) The influence of lexical statistics on temporal lobe cortical dynamics during spoken word listening. Brain Lang 147:66-75
Wilson, Stephen M; Lam, Daniel; Babiak, Miranda C et al. (2015) Transient aphasias after left hemisphere resective surgery. J Neurosurg 123:581-93
Bouchard, Kristofer E; Chang, Edward F (2014) Control of spoken vowel acoustics and the influence of phonetic context in human speech sensorimotor cortex. J Neurosci 34:12662-77
Conant, David; Bouchard, Kristofer E; Chang, Edward F (2014) Speech map in the human ventral sensory-motor cortex. Curr Opin Neurobiol 24:63-7

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