1. Sensing Techniques-Cat Scans
Cat Scans use x-rays to show structures
Really precise maps
Hard to determine functions

2. Sensing Techniques-Cat Scans
ordinary x-rays look at bone, other matter
its a composite picture- doesn’t isloate a single slice
To isolate a single slice, trangulate in using lots of scans and use a computer to reconstruct the slice.

3. Sensing Techniques-Cat Scans
ordinary x-rays look at bone, other matter
its a composite picture- doesn’t isloate a single slice
To isolate a single slice, trangulate in using lots of scans and use a computer to reconstruct the slice.

4. Sensing Techniques-ERP Technique

5. Sensing Techniques-PET
Radioactive element decays, gives off positron
Positron moves a short distance and gives off two gamma rays in opposite directions

6. Sensing Techniques-PET
Because 180 degrees apart, can isolate a slice of the brain
Detectors detect arriving gamma rays, and because of the timeing involved they can figure out where the original decay was
Radioactive materials carried by glucose- used by brain when it it working
More glucose = more brain activity
An indirect measure of brain functioning- but studies brain functioning none-the-less

7. PET Scans Eyes Closed White Light Complex Scene Left scan: Eyes closed
Middle scan: White light
Right scan: Complex scene
See increasing activity in Occipital lobes
Eyes Closed
White Light
Complex Scene

8. PET Scans Episodic Task Semantic Task Difference
Episodic Task: remembering an experience that happened 40 years ago
Semantic task: thinking about the history of astronomy that was learned 40 years ago
Red:above-average blood flow, yellow: average blood flow, green: below-average blood flow.
Difference: Red: greater activation during episodic task, Green: greadter activation during semantic task
Difference

9. PET Scans

10. Sensing Techniques-fMRI
Functional Magnetic Nuclear Resonance Imaging
Similar to Pet, uses radio frequency information given off by water
Gives better time (6 seconds) and spatial (2 mm) resolution than Pet or Cat scans
Technology still under revision
Slight danger to subjects
Expensive ($300 an hour)

11. fMRI Method

12. MRI Scans

13. MRI Scans

14. fMRI Method

15. fMRI Comparisons

16. Question At what level should we study the brain?
Depends on the research question
Information should be combined at all levels

17. Summary Appropriate technology depends on question
ERP has good temporal resolution
CAT, Pet, MRI have good spatial resolution
fMRI has both, but is expensive