1. MEG Data Analysis with Synthetic Aperture Magnetometry (SAM) Dr. Tom Holroyd NIMH MEG Core Facility

2. NIH's 275-channel MEG system

4. MEG Lab Features Stim computer (Ika) boots Win98 or WinXP, tasks are written using Presentation software (can also use Matlab, Linux, etc.). Stim computer (Ika) boots Win98 or WinXP, tasks are written using Presentation software (can also use Matlab, Linux, etc.). Visual stimuli via projection screen, driven by Ika. Auditory stimuli via pneumatic headphones, driven by Ika or arbitrary phono/RCA jack input. Visual stimuli via projection screen, driven by Ika. Auditory stimuli via pneumatic headphones, driven by Ika or arbitrary phono/RCA jack input. Secondary computer interface (e.g., laptop) including sound and light. Secondary computer interface (e.g., laptop) including sound and light. Other stimulators: Grass electrical stimulator, air-puff stimulator. Other stimulators: Grass electrical stimulator, air-puff stimulator. Response devices: optical button boxes (one handheld), dual motion sensors, eye tracker, pneumatic pads, x-y joystick. Response devices: optical button boxes (one handheld), dual motion sensors, eye tracker, pneumatic pads, x-y joystick. Optical sensor & auditory trigger for precise timing. Optical sensor & auditory trigger for precise timing. All devices interface both with Ika and the MEG system. All devices interface both with Ika and the MEG system.

5. CTF 151 Channel array

8. Flux transformers used to transport flux to the SQUID loop. (a) shows a simple one coil flux transformer, (b) a first order gradiometer.

10. Synthetic Aperture Magnetometry

21. Spatial resolution increases with the number of MEG channels

22. N-Back Working Memory Task Details Sixteen 22 sec blocks of alternating 0- back and 2-back Sixteen 22 sec blocks of alternating 0- back and 2-back Stim: one of four numbers (0.5 duration, 1.8 sec ITI) Stim: one of four numbers (0.5 duration, 1.8 sec ITI) normal volunteers strongly right handed normal volunteers strongly right handed 2-back accuracy greater than 65% 2-back accuracy greater than 65%

23. Methods: N-Back Task 1 23 4 1.8 s 1 23 4 3 1 23 4 1 23 4 1 2 4 3 Stimulus Response 0-BACK 1-BACK 1 none 4141 2424 4242 3434 Time

24. DataEditor window with marks in the stimulus and ADC channels

25. Data Analysis SAM: Synthetic Aperture Magnetometry SAM: Synthetic Aperture Magnetometry Optimum spatial filter for each.75 cm voxel calculated from dual state freq domain covariance matrix Optimum spatial filter for each.75 cm voxel calculated from dual state freq domain covariance matrix Time windows:block(14 sec), stim (500 msec), resp (500 msec) Time windows:block(14 sec), stim (500 msec), resp (500 msec) Theta, alpha, beta, gamma, freq bands Theta, alpha, beta, gamma, freq bands Group 3d map from Talairach aligned volumes using AFNI, n=18 NC Group 3d map from Talairach aligned volumes using AFNI, n=18 NC Blue=desynch; Red=power increase Blue=desynch; Red=power increase

26. Group Analysis MRI’s Talairach aligned in AFNI MRI’s Talairach aligned in AFNI SAM image z-score normalized by pooled variance SAM image z-score normalized by pooled variance AFNI 3dmean averaged warped SAM volumes AFNI 3dmean averaged warped SAM volumes Normalized t statistic (3dttest) to threshold group mean map Normalized t statistic (3dttest) to threshold group mean map

28. fMRI Processing 3T GE EPI-RT, 24 slices, TE 30, TR 2000, FOV 24 cm, voxel 3.75x3.75x6 mm, 64 x 64 matrix 3T GE EPI-RT, 24 slices, TE 30, TR 2000, FOV 24 cm, voxel 3.75x3.75x6 mm, 64 x 64 matrix Structurally aligned, smoothed and normalized to MNI space, SPM99 Structurally aligned, smoothed and normalized to MNI space, SPM99 Single subj block design contrast for 2back > 0back Single subj block design contrast for 2back > 0back Group second level analysis at approx p>.001 Group second level analysis at approx p>.001

29. SPM T map 2b>0b {SPM99 t ~ 4.0; Z ≡ ~ 3.10, p ~0.001, k > 10} CBDB and NIMH MEG Core MEG and fMRI 2-back vs 0-back memory task, Block design same 12 subjects, group map at p approx <.001 same 12 subjects, group map at p approx <.001 SAM 500 msec window on response, Beta desynchronization

30. Broadband clicks, 1 ms duration Broadband clicks, 1 ms duration Binaurally presented Binaurally presented Trains of 5 clicks with 250 ms ISI Trains of 5 clicks with 250 ms ISI Time-Frequency Analysis of Auditory Click Trains

31. Low frequency components Low frequency component High frequency component 5 Clicks – 250ms ISI4-6 seconds between click trains Stimuli

32. Beamformer Virtual Channels for an Auditory Metronome

33. Gamma Sources Time-Frequency plots using the Stockwell Transform

34. Advanced Signal Processing: FieldTrip

35. NIMH MEG Core Facility Dr. Richard Coppola, Director Dr. Richard Coppola, Director Dr. Tom Holroyd, Staff Scientist Dr. Tom Holroyd, Staff Scientist Dr. Fred Carver, System Analyst Dr. Fred Carver, System Analyst Judy Mitchell-Francis, Lab Mgr Judy Mitchell-Francis, Lab Mgr Cate Reynolds, Post-Bac IRTA Cate Reynolds, Post-Bac IRTA CBDB Neuroimaging J.H. Callicott B.A. Verchinsky S. Sust CBDB Sib Study M. Egan D.R. Weinberger