Presented by Viktor Kharlamov September 27, 2006 University of Ottawa

1. Näätänen et al. (1997) Language-specific phoneme representations revealed by electric and magnetic brain responses. Presented by Viktor Kharlamov September 27, 2006 University of Ottawa

2. Introduction • The study of: • Selective listening and event-related brain potential • Language-dependent memory traces • Language-specific phoneme representations as revealed by electric and magnetic brain responses.

3. Finnish vs. Estonian • Similar sound inventories, but: • Finnish - 8 vowels • Estonian - 9 vowels • The vowel /õ/ only occurs in Estonian

4. Finnish vs. Estonian • Vowel inventories:

5. Behavioral task • “Good phoneme” judgements • Subject is presented with sets of phonemes that differ only in the second-formant frequency • Subject is asked to press /e/, /ö/ or /o/ when the phoneme sounded as a “good” one (i.e., prototypical in their language.) Estonians also had an /õ/ response button.

6. Results • Both Finns and Estonians judged vowels common to both languages similarly, but: • Estonians also had /õ/ which is a prototype phoneme in Estonian • Finns could perceive /õ/ (there’s a drop in “goodness”), but didn’t consider it a “good phoneme”

7. Results • Good phoneme responses (%)

8. EEG Experiment • 13 Finnish and 11 Estonian subjects • Presented with /e/ as the standard stimuli; /e/ was randomly replaced by deviant stimuli that differed from the standard only in F2 (/ö/, /õ/) • Mismatch paradigm: e e e e ö e e õ e e e e õ e e e ö e e … • Attention-independent change-detection process (reading a self-chosen text)

9. Results • Standard stimuli elicited a P1-N1-P2 waveform • Deviant stimuli showed MMN • Larger MMN with greater F2 deviation, but: • Finns: /ö/ (prototype in Finnish) elicited a larger MMN than /õ/ (non-prototype in Finnish), although /ö/ deviated acoustically less from /e/ than /õ/ • Estonians: no drop in amplitude

10. Results (2) • MMN Amplitude: • Claim: existence of neural traces of language-specific phoneme representations

11. MEG Experiment: • 9 Finnish subjects • Same experimental paradigm as the EEG experiment, but: measuring MMNM • Same pattern of response in the left hemisphere (the diminished /õ/ response) (non-prototype in Finnish), although /ö/ deviated acoustically less from /e/ than /õ/ • Larger MMNM in the left hemisphere for prototypical deviant stimuli

12. MEG Experiment (2): • MMNM originated at the left auditory cortex • MMNM strength (dipole moment) was considerably greater for the prototype deviant (/ö/, a phoneme in Finnish) than for the non-prototype deviant /õ/ (not a phoneme in Finnish) • Right-hemisphere responses were weak

13. MEG Experiment (3):

14. Discussion: • Found cortical, language-dependent memory traces of speech sounds (Finns don’t treat /õ/ as a phoneme as it’s not a prototype in Finnish) • The traces are activated only in the processing of speech and they act as recognition patterns • Recognition patterns develop gradually with exposure to language (1st year of life)

15. Discussion (2): • MMNM results indicate that the left auditory cortex is involved in phonemic discrimination • Both left/right cortices are used in acoustic discrimination

16. The end!!! p.s. Elämä on epävarmaa, syö jälkiruoka ensin.