Blood, brains, (b-movies) and MVPA

1. Alejandro (Sasha) Vicente Grabovetsky Blood, brains, (b-movies) and MVPA

2. Kamitani & Tong (2005)

3. Op de Beeck (2009) vs. Kamitani & Sawahata (2010)

4. hyperacuity vs. coarse scale voxel sampling of BOLD (compact support or spatio-temporal?) relative sensitivityof mechanisms to High Frequency signal

5. Kriegeskorte et al. (2010) Compact-kernel, SNR lower at high spatial frequency A multipronged sensor samples various spatial frequencies in a complex manner

6. Kriegeskorte et al. (2010)

7. Kriegeskorte et al. (2010) Venule samples different regions at different times of the HRF This gives it a unique spatio-temporal signature This may contain high-res information including small imbalances in sampling of neuronal populations

8. Kriegeskorte et al. (2010) • Back to compact-kernels: • High spatial information could be aliased • But small head motion could completely modify the pattern of activity • Then MVPA should not work for train-test with head motion

9. Kriegeskorte et al. (2010) • Power of MVPA before and after smoothing if we assume different types of filters: • point (compact) • box (compact) • gaussian (compact) • complex

10. Kriegeskorte et al. (2010) As size decreases, partial volume effects become smaller Not only for GM, WM, CSF; but also for cortical columns Potentially, the power across voxels may increase with increased resolution, despite decreases in individual voxel SNR

11. Kriegeskorte et al. (2010)