Electrodes are placed on the scalp and they measure the AP of the neurons directly beneath them
Limited to the cortex
Temporal resolution is in real time
What is the difference between static and functional imaging?
Static- visual picture of structural tissue
Functioning- looks at function of the tissue
How does a CAT scan work?
like an x-ray but the image is in 3D, camera goes all the way around body and takes images then pieces them together
spatial resolution is 1cm
temporal resolution is real time
How does an MRI work?
The MRI machine has 1.5-3 T magnets inside that rotate. The magnetic field spins protons on their axis and a radio frequency interrupts them 90 degrees away from their original axis. The amount of time it takes for the protons to return to their original axis
Spatial resolution is 1 mm
Temporal resolution is a few minutes
What are the differences between a PET scan and an fMRI?
PET scans-
measures glucose levels in the brain
has lower spatial resolution/ temporal resolution
Invasive method, requires injection of radioactive material
fMRI-
measures oxygen levels in the brain.
Higher spatial resolution/ temporal resolution
Noninvasive but more expensive
How does a PET scan work?
Measures glucose levels in the brain
Patients are injected with glucose with radioactive tags
Imaging detects the brain regions that are using the most glucose
Spatial resolution- 10mm.
Temporal resolution- 30 secs
How does an fMRI work?
Measures oxygen levels in the blood. Uses BOLD symbol to find hemoglobin and detect if the Fe ions have bonded with O2 or not
Spatial resolution- 1mm
Temporal resolution- 5 secs
ERP
Event related potential
How is a depth electrode placed?
Using a stereotaxic frame, the doctor can align the needle with the part of the brain that he wants to see and then lowers the needle through the skull and into the brain. It stays outside the electron and uses an electrode in the tip to measure AP
What is TMS?
A magnetic field is induced over the cranium which causes the neurons to fire randomly. The neurons are more active than normal but because they have been interrupted they fire randomly and cannot function in an organized manner
Spatial- 1-5 cm
Temporal- microseconds
What are the types of mechanical lesions?
Transection- cutting
Aspiration- vacuuming
What does an EEG recording show?
Measures brain activity by recording the AP of many neurons at once
What is the subtraction method?
When during imaging the patients brain is first recorded at baseline and then during the stimulus so the researchers know what is due to manipulation and what is due to normal activity