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Language-specific phoneme representations revealed by electric and magnetic brain responses

Language-specific phoneme representations revealed by electric and magnetic brain responses. By:Rito Naatanen, University of Helsinki Published in: Nature (1997), vol 385, pp. 432-434. Two Key Definitions:.

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Language-specific phoneme representations revealed by electric and magnetic brain responses

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  1. Language-specific phoneme representations revealed by electric and magnetic brain responses By:Rito Naatanen, University of Helsinki Published in: Nature (1997), vol 385, pp. 432-434.

  2. Two Key Definitions: • Mismatch Negativity (MMN): a neurophysiological index of the detection of a change in the acoustic environment that can be elicited in the absence of focused attention • Sinusoidal Tone: a single frequency tone with no harmonic content. It corresponds to a sine wave.

  3. Main Question of Investigation • Does the processing of sounds depend on whether they are parts of speech?

  4. The Subjects • Finns: 13 (4 female, 9 male), normal-hearing, age 18-29, and right-handed. • Estonians: 11 (6 female, 5 male) normal-hearing, age 19-31, and right-handed.

  5. Determining the vowel phoneme prototypes • For /e/, /Õ/, and /Ö/, subjects were asked to categorize stimuli of varying F2 frequency while the F1, F3 and F4 remained constant.

  6. Stimuli Presentation - /e/ is used as the standard stimulus • All other prototypes are the deviant stimuli • They are presented in an oddball paradigm.

  7. Näätänen et al. (1997) e e/ö ö õ o Fin    Est     F2

  8. The Oddball Paradigm • Blocks of /e/ stimuli presented (75 dB with 400 ms duration each) • 1400 ms onset-to-onset intervals. • 15% of stimuli were randomly appearing deviant sounds (one per block) and presented approximately 30 times.

  9. Simple sinusoidal stimuli blocks • In later trials they replaced the prototypical stimuli with corresponding simple sinusoidal tones.

  10. Responses to simple tone with varying F2

  11. Magnetic Responses to Deviant Stimuli

  12. Findings • Cortical traces of speech sounds exist. • Left-Hemisphere dominance of the MMNM to phoneme prototypes.

  13. Future Questions The authors believe that the MMN paradigm they have discovered in this study could help to unravel the experience-dependent neural memory traces for phonemes of any given language.

  14. Thank you!Have a Great Weekend!

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