blood, brains, (b-movies) and mvpa
DESCRIPTION
Alejandro (Sasha) Vicente Grabovetsky. Blood, brains, (b-movies) and MVPA. Kamitani & Tong (2005). Op de Beeck (2009) vs. Kamitani & Sawahata (2010). hyperacuity vs. coarse scale voxel sampling of BOLD (compact support or spatio -temporal?) - PowerPoint PPT PresentationTRANSCRIPT
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Blood, brains, (b-movies) and MVPAAlejandro (Sasha) Vicente Grabovetsky
![Page 2: Blood, brains, (b-movies) and MVPA](https://reader030.vdocument.in/reader030/viewer/2022032804/56812a67550346895d8dea93/html5/thumbnails/2.jpg)
Blood, brains and b-movies
4/10/2010Kamitani & Tong (2005)
![Page 3: Blood, brains, (b-movies) and MVPA](https://reader030.vdocument.in/reader030/viewer/2022032804/56812a67550346895d8dea93/html5/thumbnails/3.jpg)
Blood, brains and b-movies
4/10/2010Op de Beeck (2009) vs. Kamitani & Sawahata (2010)
![Page 4: Blood, brains, (b-movies) and MVPA](https://reader030.vdocument.in/reader030/viewer/2022032804/56812a67550346895d8dea93/html5/thumbnails/4.jpg)
Blood, brains and b-movies
4/10/2010
1. hyperacuity vs. coarse scale
2. voxel sampling of BOLD (compact support or spatio-temporal?)
3. relative sensitivity of mechanisms to High Frequency signal
![Page 5: Blood, brains, (b-movies) and MVPA](https://reader030.vdocument.in/reader030/viewer/2022032804/56812a67550346895d8dea93/html5/thumbnails/5.jpg)
Blood, brains and b-movies
4/10/2010Kriegeskorte et al. (2010)
Compact-kernel, SNR lower at high spatial frequency
A multipronged sensor samples various spatial frequencies in a complex manner
![Page 6: Blood, brains, (b-movies) and MVPA](https://reader030.vdocument.in/reader030/viewer/2022032804/56812a67550346895d8dea93/html5/thumbnails/6.jpg)
Blood, brains and b-movies
4/10/2010Kriegeskorte et al. (2010)
![Page 7: Blood, brains, (b-movies) and MVPA](https://reader030.vdocument.in/reader030/viewer/2022032804/56812a67550346895d8dea93/html5/thumbnails/7.jpg)
Blood, brains and b-movies
4/10/2010Kriegeskorte et al. (2010)
Venule samples different regions at different times of the HRFThis gives it a unique spatio-temporal signatureThis may contain high-res information including small imbalances in sampling of neuronal populations
![Page 8: Blood, brains, (b-movies) and MVPA](https://reader030.vdocument.in/reader030/viewer/2022032804/56812a67550346895d8dea93/html5/thumbnails/8.jpg)
Blood, brains and b-movies
4/10/2010Kriegeskorte 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
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Blood, brains and b-movies
4/10/2010Kriegeskorte et al. (2010)
Power of MVPA before and after smoothing if we assume different types of filters:
•point (compact)•box (compact)•gaussian (compact)•complex
![Page 10: Blood, brains, (b-movies) and MVPA](https://reader030.vdocument.in/reader030/viewer/2022032804/56812a67550346895d8dea93/html5/thumbnails/10.jpg)
Blood, brains and b-movies
4/10/2010Kriegeskorte 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
![Page 11: Blood, brains, (b-movies) and MVPA](https://reader030.vdocument.in/reader030/viewer/2022032804/56812a67550346895d8dea93/html5/thumbnails/11.jpg)
Blood, brains and b-movies
4/10/2010Kriegeskorte et al. (2010)