NeuroImaging Flashcards
What are the three structural imaging techniques?
- CAT SCAN
- MRI SCAN
- DTI
These scans can tell us about structural integrity but nothing about function
Structure won’t change unless substantial injury
What are the techniques provide Functional and Metabolic Images?
- PET Scans
- FMRI Scans
What Techniques measure the Brain’s Electrical/Magnetic Activity?
- EEG
- ERPs
- MEG
- ERF
Do not provide a lot of information on neuroanatomy but a lot about temporal Activity
What techniques alter Brain Activity?
- TMS
- TEM
Note: Changes are temporary
Skull X-ray
STRUCTURAL IMAGE
-NO information on brain
CAT SCAN
- Uses X Ray Technology to provide Horizontal 2D Scans
- Shows variation of density in tissue
- Injuries will show density alterations in to the brain
What are some Advantages and Disadvantages to CAT SCANS
ADVANTAGES
- Visualize brain structure
- Visualize Cortical and subcortical areas
- Visualize pathological changes that alter density
DISADVANTAGES
- Exposure to Radiation
- Spatial Resolution is not that great “average”
- Only shows pathological changes that alter density
What are some ADVANTAGES to MRI SCAN?
- Fast
- No radiation
- Better spatial resolution than Cat Scan
- Can differentiate between Gray and White matter.
- Provides more visual angles
- Can visualize cortical atrophy
What is an MRI SCAN?
STRUCTURAL IMAGE
A structural 3D image that uses water’s magnetic properties to provide spatial information of the brain.
Changes in Relaxation time of atoms can provide pathological measurement
What are some disadvantages to an MRI SCAN?
- It’s a loud, narrow unpleasant tube,
- Claustrophobia
- Can trigger seizures
- GIANT MAGNET: not safe for metals and pacemakers
- EXPENSIVE
- Not available in all hospitals
DTI
Diffusion Tensor Imaging
STUCTURAL IMAGE
Reveals structures of the white matter pathways
Measures diffusion of water molecules
What are some advantages/disadvantages of DTI
Advantages
-Provides direction and integrity of the white matter pathways.
DISADVANTAGE
-Can give false positives/negatives
What is the principle of Metabolic Measures?
Greater neural activity leads to higher metabolic function
Metabolic techniques provide Indirect measurements of brain activity.
PET SCANS
METABOLIC/FUNCTIONAL IMAGE
Requires injection or inhalation of a radioactive isotope.
What are some PET SCAN Advantages?
- localize metabolic activity
- look @ different substances
- View functional lesions
What are some DISADVANTAGES to PET SCANS?
- INVASIVE
- RADIOACTIVE
- Temporal resolution is not great
- Spatial resolution is not great
FMRI
Functional Magnetek Resonance Imaging
METABOLIC/FUNCTIONAL IMAGE
- Shows brain areas whose activity change together during a task.
- Temporal Resolution: 1 second
- Detects BOLD
What is BOLD?
Ratio of oxygenated/deoxygenated blood.
oxygenated blood increases to more activated areas
What are some advantages to FMRI?
- Good measure of brain activity
- Not invasive
- Widely Available
- Spatial & Temporal Resolution better than PET
- Allows exploration of brain networks
What are some disadvantages to FMRI?
- Temporal resolution is not as great as we want it
- Not safe for metal and pacemakers
- Takes about an hour
- Need cooperation of patients
What is EEG?
Electrical Measurements
Electrodes mesure electric and cortical activity
Changes is person is sleeping or awake.
Not Invasive
What are ERP
(Event Related Potentials?
A rather boring test that provide EXCELLENT TEMPORAL RESOLUTION.
“Average” of many trails gets rid of randomized activity
What are some Advantages/Disadvantages to ERP?
ADVANTAGES
- Great Temporal Resolution (over ms))
- Measurements can be done without activity.
DISADVANTAGES
- Time locked to stimulaus
- Prone to artifacts
- Do not know localization.
MEG (megnetoencephalograpy)
ELECTRICAL MEASUREMENTS
Active neurons produce small magnetic fields.
Magnetic fields not distorted
Good source of localization.
EXPENSIVE
