1 / 20

Structural and Functional Imaging

Structural and Functional Imaging. This is a Functional MRI Image !?. Structural and Functional Imaging. This is a structural MRI image (an “anatomical” image). Structural and Functional Imaging. What you really want is both images co-registered. Structural and Functional Imaging.

shina
Télécharger la présentation

Structural and Functional Imaging

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Structural and Functional Imaging • This is a Functional MRI Image !?

  2. Structural and Functional Imaging • This is a structural MRI image (an “anatomical” image)

  3. Structural and Functional Imaging • What you really want is both images co-registered

  4. Structural and Functional Imaging • What you really want is both images co-registered • Why? What’s wrong with the functional image alone?

  5. Structural and Functional Imaging • Functional images tend to be lower resolution and fail to convey spatial information Pixels

  6. Structural and Functional Imaging • Structural images have finer (smaller) pixels Pixels

  7. Structural and Functional Imaging • Brain scan images (CAT, PET, MRI, fMRI) are all made up of pixels (stands for picture elements) Pixels

  8. Structural and Functional Imaging • “Slices” are assembled into “volumes” Pixels

  9. Structural and Functional Imaging • Volumes are composed of “volume elements” or voxels Voxels

  10. Structural and Functional Imaging • Another thing you want: the ability to tell other people where something is • “the activity was centered on voxel #653” will not work in a scientific journal

  11. Structural and Functional Imaging • MRI anatomical spaces • Talairach Space: • Based on detailed analysis of one elderly woman • Talairach & Tournoux (1988) • Montreal Neurological Institute Template (MNI) • based on average of 152 different brains, each normalized to Talairach space • advantage: gyri and sulci are more representative • disadvantage: it’s blurry • MNI “Representative Brain” • the one brain from the 152 in the MNI Template set that is most like the average • advantage: it’s not blurry • disadvantage: it’s still just one person’s brain

  12. Structural and Functional Imaging • Reasons for normalizing to standard stereotaxic space (templates) • two levels: within-subject and between-subjects

  13. Structural and Functional Imaging • Within-Subject Reasons: • structural and functional volumes may not be coregistered due to • movement • distortion • results can be described in standard coordinates • data across sessions can be averaged

  14. Structural and Functional Imaging • Between-Subject Reasons: • Volumes will not match because of variability across individuals • results can be described in standard coordinates • data across participants can be averaged

  15. Preprocessing of Structural and Functional Images • Normalizing images to fit a standard template (e.g. Talairach) • Define Coordinate System using easily recognizable landmarks • Origin in the Anterior Commissure • y-axis connects AC and PC • x-axis perpendicular interhemispheric plane and through AC • z-axis perpendicular to x and y

  16. The Talairach Coordinate System PC AC

  17. The Talairach Coordinate System -y AC - PC line defines y-axis +y

  18. The Talairach Coordinate System -y +x x-axis perpendicular to interhemispheric plane -x +y

  19. The Talairach Coordinate System +z -y +x z-axis perpendicular to x-y plane -x -z +y

  20. Structural and Functional Imaging • Cortical Flattening • Software such as BrainVoyager can “inflate” the cortex like a balloon so that sulci and gyri are “flattened” • functional data can be transformed with the same complex function • functional and structural data can be overlaid so that distribution on cortical sheet can be visualized

More Related