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

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.

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.

Sensing Techniques-ERP Technique

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

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

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

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

PET Scans

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)

fMRI Method

MRI Scans

MRI Scans

fMRI Method

fMRI Comparisons

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

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