The overall objective of this project is to elucidate neural mechanisms underlying cortical processing of speech by examining electrophysiological responses in monkey primary auditory cortex (A1). Structural anomalies in auditory cortex, and perceptual abnormalities in the processing of speech and other sounds, occur in people with developmental dysphasia. Relating these deficits to dysfunction of specific neural events requires an understanding of normal cortical processes that is best afforded by intracranial recordings. Many features of human phonetic perception occur in monkeys, indicating that these animals are a reasonable animal model for studying cortical responses to speech. Using multicontact electrodes, three complementary measures will examine the activity from neuronal ensembles, multiunit activity (MUA), evoked potentials (AEP) and the derived current source density (CSD). CSD delineates temporal and laminar distributions of current flow that reflect net synaptic excitation and inhibition, whereas MUA patterns define changes in the firing rate of neuronal ensembles. Through their relationship with the AEP, intracortical responses can be directly linked with homologous responses in humans. These procedures yield stable measures of the synchronized neural activity required for complex sound encoding. This project will clarify two key problems in phonetic perception: (1) the relationship between the acoustic signal of a speech sound and its phonetic representation and (2) how speech sounds are categorically perceived. These problems will be addressed by testing four hypotheses relating to the mechanisms underlying encoding of consonant place of articulation and voice onset time (VOT): (1) VOT is categorically encoded by temporal response patterns evoked by acoustic transients occurring at consonant onset and the onset of syllable voicing, (2) mechanisms of VOT encoding can be modeled through the use of simplified tone burst stimuli, (3) place of articulation is categorically encoded by responses to the onset spectra of consonants, and (4) place of articulation encoding in A1 is improved when dynamic spectral features embedded in the formant transitions are utilized. Testing these hypotheses will require that acoustic parameters of the stimuli be related to organizational features of A1, demonstrating that systematic changes in categorical response boundaries occur in parallel with stimulus modifications, and that prolonged formant transitions increase differences by increasing the duration of spectral disparity between the syllables. These studies will define normal mechanisms of A1 speech processing, and serve as a benchmark to evaluate dysfunctional mechanisms associated with abnormal language and language development.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
5R01DC000657-08
Application #
2683905
Study Section
Hearing Research Study Section (HAR)
Project Start
1990-08-01
Project End
2000-03-31
Budget Start
1998-04-01
Budget End
1999-03-31
Support Year
8
Fiscal Year
1998
Total Cost
Indirect Cost
Name
Albert Einstein College of Medicine
Department
Neurology
Type
Schools of Medicine
DUNS #
009095365
City
Bronx
State
NY
Country
United States
Zip Code
10461
Fishman, Yonatan I; Kim, Mimi; Steinschneider, Mitchell (2017) A Crucial Test of the Population Separation Model of Auditory Stream Segregation in Macaque Primary Auditory Cortex. J Neurosci 37:10645-10655
Wagner, Monica; Roychoudhury, Arindam; Campanelli, Luca et al. (2016) Representation of spectro-temporal features of spoken words within the P1-N1-P2 and T-complex of the auditory evoked potentials (AEP). Neurosci Lett 614:119-26
Davidson, Cristin D; Fishman, Yonatan I; Puskás, István et al. (2016) Efficacy and ototoxicity of different cyclodextrins in Niemann-Pick C disease. Ann Clin Transl Neurol 3:366-80
Fishman, Yonatan I; Micheyl, Christophe; Steinschneider, Mitchell (2016) Neural Representation of Concurrent Vowels in Macaque Primary Auditory Cortex. eNeuro 3:
Sussman, Elyse S; Steinschneider, Mitchell (2015) Advances in auditory neuroscience. Int J Psychophysiol 95:63-4
Nourski, Kirill V; Steinschneider, Mitchell; Rhone, Ariane E et al. (2015) Sound identification in human auditory cortex: Differential contribution of local field potentials and high gamma power as revealed by direct intracranial recordings. Brain Lang 148:37-50
Nourski, Kirill V; Steinschneider, Mitchell; Oya, Hiroyuki et al. (2015) Modulation of response patterns in human auditory cortex during a target detection task: an intracranial electrophysiology study. Int J Psychophysiol 95:191-201
Sussman, E; Steinschneider, M; Lee, W et al. (2015) Auditory scene analysis in school-aged children with developmental language disorders. Int J Psychophysiol 95:113-24
Fishman, Yonatan I; Steinschneider, Mitchell; Micheyl, Christophe (2014) Neural representation of concurrent harmonic sounds in monkey primary auditory cortex: implications for models of auditory scene analysis. J Neurosci 34:12425-43
Fishman, Yonatan I (2014) The mechanisms and meaning of the mismatch negativity. Brain Topogr 27:500-26

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