F.C. Donders Centre for Cognitive Neuroimaging

1. MR-Scanner F.C. Donders Centre for Cognitive Neuroimaging

2. MR-Scanner F.C. Donders Centre for Cognitive Neuroimaging

4. b) Protonen im Magnetfeld N a) Protonen außerhalb des Magnetfeldes Z

6. Gradiëntspoelen Rf antenne Components of MRI-scanner Supergeleidende magneet Rf ontvanger Rf zender Gradiëntversterkers Pulsprogramma Computersysteem

7. Anatomische MR-Aufnahme • Angeregte Protonen kehren in verschiedenen Gewebearten (weisse, graue Substanz, Liquor) unterschiedlich schnell in den Ruhezustand zurück • 160-180 sagittale Schichten • Auflösung: 1 x 1 x 1 mm • Dauer: +/- 10 Minuten

8. Structural MR scan: sagittal slices

9. Functionele MRI PET Blutstrom Rust fase Hämoglobin radioaktives Wasser Sauerstoff Actieve fase

10. Menon and Kim (1999)

11. Funktionelle MR-Aufnahme • Blutfluss zu aktivem Hirngewebe nimmt stärker zu, als für die Sauerstofversorgung nötig • Sauerstoffsättigung des Hämoglobins im venösen Blut nimmt zu • Magnetische Störung durch venöses Blut nimmt ab • Angeregte Protonen drehen sich länger synchron. Ihr elektrisches Signal dauert länger/ist stärker.

12. Data collection, fMRI • Terminology I • Volume = 1 brain image = 1 set of slices (typically 16-24) • Run = 1 set of volumes measured continuously (typically 80 – 120) • Session = 1 set of runs without subject leaving the scanner (typically 2 – 16)

13. Functional MR scan: 16 horizontal slices (1 ‘volume’)

14. Data collection, fMRI • Terminology II, Design types • Blocked = continous presentation of several stimuli of the same type (advantage: stronger signal) • Event-related = measurement of response to single stimuli (advantage: randomization possible, analysis can be based on behaviour) • Measurement can be stimulus-locked (fixed temporal relation between stimulus and scan), jittered (average relation fixed but for every stimulus slightly varying), or temporally unrelated to the stimulus

15. fMRI Design Options BLOCKED: SPACED EVENT-RELATED: EVENT-RELATED: MINI-BLOCKS: Instead of one event a small and varying number of events of the same condition

16. TIME TRANSIENT BOLD RESPONSE TO EVENTS SUSTAINED BOLD RESPONSE TO SET TIME MEASURED BOLD RESPONSE

17. Menon & Kim, 1999

19. functional MR scan: movement correction

20. PETPRONUNCIATION OF PSEUDOWORDSvs.PRONUNCIATION OF WORDS Hagoort, P., Indefrey, P., Brown, C., Herzog, H., Steinmetz, H., and Seitz, R.J. (1999).

21. fMRIPSEUDOWORDS vs. WORDS (0.001; 0.05 corr.)

22. fMRISingle subject analyses: PSEUDOWORDS vs. WORDS

23. Gazzaniga, Ivry, and Mangun (1998)

24. Functional studies: PET – MR decision • Default: MR • Consider PET if: • ROI inferior temporal lobe • Overt continuous speech production during scans necessary • High quality acoustic stimuli necessary • ERP registration during scans necessary • TMS during scans necessary • Claustrophobic subjects • Subjects with intracorporeal metal

25. Encoding Delay Response Words Pseudowords False font strings 12 time series (runs) of 125 volumes, TR = 2338 sec Stimulation protocol of one run Baseline (rest)

26. yes GRAGEL BEURAL no ‘What’-task BEURAL DIESTE 2 TR 6 TR 2 TR TR=2338 ms

27. GRAGEL BEURAL

28. BEURAL

29. no GRAGEL BEURAL yes ‘Where’-task BEURAL BEURAL 2 TR 6 TR 2 TR TR=2338 ms

30. BOLATI DIESTE

31. DIESTE

32. Delay Encoding/Response where what

33. where Delay Encoding/Response what

34. lat.occ non-verbal ITG p.orb p.operc MTG verbal Encoding period of ’what’-trials