1 / 23

Stimulation-based state monitoring – new developments

Stimulation-based state monitoring – new developments S. Kalitzin  , D.Velis  , F. Lopes da Silva   Epilepsy Institute of The Netherlands (SEIN), Medical Physics Department  Epilepsy Institute of The Netherlands (SEIN), Department of Clinical Neurophysiology

jake
Download Presentation

Stimulation-based state monitoring – new developments

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. Stimulation-based state monitoring – new developments S. Kalitzin, D.Velis, F. Lopes da Silva  Epilepsy Institute of The Netherlands (SEIN), Medical Physics Department  Epilepsy Institute of The Netherlands (SEIN), Department of Clinical Neurophysiology  Swammerdam Institute of Life Sciences, University of Amsterdam, The Netherlands

  2. Phase clustering index (PCI) Complex Fourier amplitudes Triggered response Repetitive stimulus S. Kalitzin, J. Parra, D. Velis, F. Lopes da Silva, Enhancement of phase clustering in the EEG/MEG gamma frequency band anticipates transition to paroxysmal epileptiform activity in epileptic patients with known visual sensitivity, IEEE-TBME, v.49, 11 p 1279-1286, 2002

  3. Decision on stimulation sequence Monophasic Biphasic BiCAP Cyclic Alternating Pattern (CAP) Question 1: how to stimulate and measure the response ?

  4. Non-linear response to direct electric stimulation What is a linear response ? How can we test this ?

  5. Averaged triggered response analysis

  6. Linear Response Model

  7. CAP – polarity alternation For linear response model: total PCI=0

  8. BICAP: Separating PCI of the non-linear response

  9. Stimulation in conducting fluid (NaCl)

  10. Example from patient case –MONOCAP Stimulation frequency invariant response Stimulation frequency

  11. Application to interictal localization of the SOS Case: left TLE

  12. Robustness to stimulation frequency

  13. Question 2: where to stimulate and where to measure the response ? • Averaged rPCI • Collective PCI

  14. Processing features of the collective response to stimulation in one location Triggered response and correlation Partial correlation Collective phase clustering and bi-local phase coherence

  15. Application to interictal localization of the SOS Case: (predominantly) right TLE

  16. Collective Impact estimations

  17. Speculation: going beyond locality (bilateral case) rPCI of non-linear response

  18. What about Seizure prediction ?

  19. Summary & Conclusions: 1. rPCI feature successfully detected the SOS in six new TLE cases. 2 left, 2 right 2 bilateral. 2. BICAP stimulation solves the problem of high PCI due to linear conductance. 3. For interictal localization tasks, the best spatial coding so far is at the stimulation site and the best response measure is the collective response. 4. Bi-local rPCI spread studies deserve attention. 5. Seizure prediction in time remains a statistical observation at best. Electrode size, recording sites and stimulation protocol might be critical. Robustness is therefore crucial.

More Related