1. R imager leftright  [...-Hb]/µM Studying NIRS from infancy

2. uses and abuses of optical topography hellmuth obrig

3. uses and abuses of optical topography hellmuth obrig!!!!!

4. Maybe there is some abuse in the literature

5. Taga et al 2003

6. condition 1 condition2 n=52 760 nm & 850 nm 7 detectors 8 sources 20s this is a boring experiment

7. the imaging result is redundant imager

8. the interesting result is the time course stim vs. stim stim vs. rest time /s concentration change / µM

9. data processing event related averaging artefact removal General Linear Model approach PCA removal of global effects

10. Thus we can check our hypothesis by an analysis procedure

11. Let‘s make things complicated Iadecola et al 04

12. ... or alternatively oversimplify the matter neuronal model blood-flow regulator oxygen- extractor venous balloon BOLD contrast

13. E E D D 3 s 0.01µM [deoxy-Hb] BOLD contrast ‚activation‘ is an operational term

14. likewise ‚deactivation‘ is an operational term

15. the time course is still conroversial

16. VEP NIRS the recoupling issue

17. There is a component not showing habituation

18. stimulusvascular-response neuronal activity vascular response flow velocity oxygenation  OD parameters want a break?

19. An early component of the VEP does not show habituation

20. transcallosal inhibition

21. NIRS tapping NIRS TMS Comparing excitation and inhibition of primary motor cortex

22. 10 0 - 10 1 0 motor TMS the vascular response is similar

23. mmol / l time / s mmol / l oxy deoxy The time courses are qualitatively similar

24. motorwithout with preactivation x3 activation and inhibition cannot be discriminated

25. EffectCBF Spiking (on target)(local)(output) Exitation Exitation+ Inhibition Deactivation Inhibition ? Disinhibition ? Lauritzen & Gold PNAS 2003 Inverse problem of the vascular response

26. EEG ssVEP source detector ISS NIRS Does background activity have an influence on the vascular response?

27. detector oxy-Hb emitter deoxy-Hb There is a focal hyperoxygenation over the occipital region

28. P3O1PzO2P4 EEG NIRS 2.5 cm 10 cm 2.5 cm 5 cm electrode detector NIRS-probe electrode emitter 591220861023... 5ms 45ms 5ms 45ms 15 s experimental setup

29.     Neurovascular coupling?

30. 8-12Hz 24-28Hz Alpha power is an inverse predictor of the haemodynamic response

31. stimulus Summation (EP /LFP) 1s ‚idling state‘ desynchronisation Modulation of evoked and spontaneous activity is mutually dependent

32. Use or abuse? There is a NIRS response closely linked to classical imaging methods There is changes which definitely are not related to the brain There is options to identify brain related signals Neurovascular coupling is a very general principle There are exceptions from the rule NIRS allows to investigate these deviations from a 1:1 translation