1 / 21

Oscillatory phase synchronisation: A brain mechanism of memory matching and attention

Conjunct COST B27 and SAN Scientific Meeting, Swansea, UK, 16-18 September 2006. Oscillatory phase synchronisation: A brain mechanism of memory matching and attention. Paul Sauseng 1,2 , Wolfgang Klimesch 1 , Walter R. Gruber 1 , Niels Birbaumer 2. 1. 2. Top Down. Matching.

nuala
Download Presentation

Oscillatory phase synchronisation: A brain mechanism of memory matching and attention

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Conjunct COST B27 and SAN Scientific Meeting, Swansea, UK, 16-18 September 2006 Oscillatory phase synchronisation: A brain mechanism of memory matching and attention Paul Sauseng1,2, Wolfgang Klimesch1, Walter R. Gruber1, Niels Birbaumer2 1 2

  2. Top Down Matching Bottom Up • Introduction • Methods • - Exp. Pardigm • Data Processing • Results • Gamma Sources • cfPSI • PLI • Phase Coh. • Conclusions

  3. Busch et al. (2004) MUM Herrmann et al. (2004a) Herrmann et al. (2004a) Herrmann et al. (2004b) How is matching between top-down and bottom-up information implemented in the human brain? • Introduction • Methods • - Exp. Pardigm • Data Processing • Results • Gamma Sources • cfPSI • PLI • Phase Coh. • Conclusions

  4. Theta oscillations (around 5 Hz), fronto-parietal network and top-down activation • Introduction • Methods • - Exp. Pardigm • Data Processing • Results • Gamma Sources • cfPSI • PLI • Phase Coh. • Conclusions Sauseng et al. (2005) Sarnthein et al. (1998) von Stein & Sarnthein (2000): Integrative brain processes like top-down activation are reflected by long-range theta and/or alpha activity Sauseng et al. (2006)

  5. Interaction between GAMMA and THETA ? MUM local distributed Herrmann et al. (2004a) • Introduction • Methods • - Exp. Pardigm • Data Processing • Results • Gamma Sources • cfPSI • PLI • Phase Coh. • Conclusions

  6. invalid trial valid trial Experimental Paradigm + • Introduction • Methods • - Exp. Pardigm • Data Processing • Results • Gamma Sources • cfPSI • PLI • Phase Coh. • Conclusions 2500 ms + 34 ms + 600-800 ms 50 ms Time [ms]

  7. Time-frequency analysis Beamformer source analysis of 35-45 Hz activity Local sources (dipole clusters) into maxima of gamma sources Raw EEG at scalp level transformed into ongoing source activity using the dipolar model derived from gamma activity EEG data acquisition and analysis 22 healthy subjects 32-channel EEG at 250 Hz • Introduction • Methods • - Exp. Pardigm • Data Processing • Results • Gamma Sources • cfPSI • PLI • Phase Coh. • Conclusions

  8. Claims and measures Memory matching is reflected by gamma:theta interaction and amplified by attention => cross-frequency phase synchronisation index (cfPSI) consistency of phase differences between different frequencies over trials Is gamma:theta phase synchronisation phase locked to stimulus onset? And does evoked gamma activity reflect memory matching (MUM)? => phase locking index (PLI) consistency of phase angle of one frequency in respect to stimulus onset over trials Is top-down activation reflected by a fronto-parietal theta network? => phase coherence consistency of phase differences between electrode sites over trials at one frequency • Introduction • Methods • - Exp. Pardigm • Data Processing • Results • Gamma Sources • cfPSI • PLI • Phase Coh. • Conclusions

  9. Local Gamma sources (BESA) • Introduction • Methods • - Exp. Pardigm • Data Processing • Results • Gamma Sources • cfPSI • PLI • Phase Coh. • Conclusions

  10. + + + + + + Cross-frequency Phase Synchronisation Index (40 Hz : n Hz) D cfPSI (target right – target left) • Introduction • Methods • - Exp. Pardigm • Data Processing • Results • Gamma Sources • cfPSI • PLI • Phase Coh. • Conclusions

  11. Cross-frequency Phase Synchronisation Index (40 Hz : 4-8 Hz) • Introduction • Methods • - Exp. Pardigm • Data Processing • Results • Gamma Sources • cfPSI • PLI • Phase Coh. • Conclusions 4-way interaction F4,84 = 3.35, p<.05 no sign. effects in other frequency bands

  12. Valid condition Invalid condition Phase Locking Index • Introduction • Methods • - Exp. Pardigm • Data Processing • Results • Gamma Sources • cfPSI • PLI • Phase Coh. • Conclusions

  13. + + + Phase Coherence (on the scalp level) Theta • Introduction • Methods • - Exp. Pardigm • Data Processing • Results • Gamma Sources • cfPSI • PLI • Phase Coh. • Conclusions Gamma

  14. MUM gamma : theta phase synchronization 100 – 200 ms evoked gamma during first 100 ms poststimulus ATTENTION evoked theta between 100 and 300 ms Herrmann et al. (2004a) Conclusion: a cascade of brain oscillatory mechanisms of memory matching • Introduction • Methods • - Exp. Pardigm • Data Processing • Results • Gamma Sources • cfPSI • PLI • Phase Coh. • Conclusions Fronto-parietal theta network pre- and poststimulus

  15. This research was supported by the Deutsche ForschungsgemeinschaftDFG (Project BI 195/51-1)

  16. Cross-frequency Phase Synchronisation Index (cfPSI) µV t 2 pi 0 pi t µV t 2 pi 0 pi t

  17. pi -pi Cross-frequency Phase Synchronisation Index(cfPSI) 2 pi 0 pi t

  18. pi pi pi pi -pi -pi -pi -pi pi -pi Cross-frequency Phase Synchronisation Index(cfPSI)

  19. Cross-frequency Phase Synchronisation Index(cfPSI) difference

  20. Phase Locking Index(PLI) t stimulus onset

  21. Phase Coherence Phase locking value (PLV) Lachaux et al. (1999) Consitency of phase difference between 2 electrodes / sensors over trials cfPSI, PLI, Phase Coherence: 0 = no phase synchronisation / locking 1 = absolute phase synchronisation / locking

More Related