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

Blood, brains and b-movies 4/10/2010 Kamitani & Tong (2005)

Blood, brains and b-movies 4/10/2010 Op de Beeck (2009) vs. Kamitani & Sawahata (2010)

Blood, brains and b-movies 4/10/ hyperacuity vs. coarse scale 2.voxel sampling of BOLD (compact support or spatio- temporal?) 3.relative sensitivity of mechanisms to High Frequency signal

Blood, brains and b-movies 4/10/2010 Kriegeskorte et al. (2010) Compact-kernel, SNR lower at high spatial frequency A multipronged sensor samples various spatial frequencies in a complex manner

Blood, brains and b-movies 4/10/2010 Kriegeskorte et al. (2010)

Blood, brains and b-movies 4/10/2010 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

Blood, brains and b-movies 4/10/2010 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

Blood, brains and b-movies 4/10/2010 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

Blood, brains and b-movies 4/10/2010 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

Blood, brains and b-movies 4/10/2010 Kriegeskorte et al. (2010)