Biopsychology Chpt 5 Flashcards
How do contrast x-rays work
something is injected that absorbs x-rays less or more than surrounding tissue
What is a CT scan also called? How does it work?
> x-ray computed tomography
>uses combinations of many x-ray images from different angles to produce cross-sectional (tomographic) 3D images
How does MRI work?
Magnetic Resonace imaging uses the NMR signal from hydrogen nuclei > magnetic field causes nuclei to align with field and a radio wave causes nuclei to respond and an image is captured from the response
What are three pros for MRI?
- Great spatial resolution
- Can create images in any plane
- Little side effects
What are two cons for MRI?
- Expensive
2. Unpleasant, noisy, not good for claustrophobic people
How does DTI work?
> Type of MRI
Identifies pathways water diffuse along
Shows MAJOR tracts
How does a functional MRI work?
> measures blood flow increase and decrease
BOLD signal recorded (Blood-Oxygen-level-dependent signal)
Hemoglobin has different properties when oxygen is bound or not
Why would MRI not show ALL brain activity?
Action Potentials last 2 milliseconds > MRI takes 2-3 seconds so info could be missed
What are two pros for MRI?
- Provides structural and functional info
2. good spatial resolution
What are two cons for MRI
- False positives > dead fish brain activated
2. Poor temporal resolution
How does PET work? (positron emission tomography)
> Radioactive tracer injected into carotid artery
identifies distribution of different molecules in the brain with radioactive ligands
radioactive Deoxyglucose is taken up by active cells
Activity shown but NOT anatomical data
shows distribution of receptors in nervous system
How does fluorodopamine signal issues with dopamanergic pathways?
> Cells in substantia nigra take up Fluoro-L-dopa and convert it to fluorodopamine
shows degeneration in this area
if it does not create fluorodopamine it tells us there is no dopamine to take it up
Why is fMRI often more useful than PET?
- gives structural and anatomical info in one image
- nothing injected
- better spatial resolution
- can create 3D images of activity over entire brain
How does Transcranial Magnetic Stimulation (TMS) work?
-magnetic wires disrupts activity of neurons underneath it
-either increased activity or decreased
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Why does TMS provide an important role in identifying neural functions?
- allows us to make causal inferences
- allows us to narrow parts of the brain truly responding to stimuli
