Brain imaging Flashcards
Structural imaging
MRI, CAT, DTI
Dynamic imaging
Functional
PET, fMRI, DBS, EEG, ERP, single/multi cell recording
Indirect measures of brain activity
Dynamic usually
Blood oxygenation
Blood flow
Etc
Single cell recording
Electrode inserted next to or into an individual neuron and measures activity of the person with the firing pattern of the neuron
Best used in PNS because neurons are usually longer and larger
EEG recording
Electrodes on scalp to measure output of a group of neurons and can be used to map the origin of the signal based on where electrode locations and recordings
Partial vs generalized seizures
One area of brain affected vs over entire brain
States of consciousness
Beta - awake and alert - high freq, low amp
Alpha - relaxed, low freq, med amp
Delta - sleeping, low freq, high amp
Neural convergence vs neural divergence
Rods and cones relate to less cells and then to one vs a few synapse into many
Theta waves
Stage 1 of sleep, low freq and mid amp
Stage 2 sleep is k complexes and sleep spindles
High coherence
Low freq high amp
Coordinated activity of neurons but low cognitive load
Low coherence
High freq low amp
Many neurons firing at diff times actively processing info
ERP
Event related potential
Repeatedly present stimulation to someone with an EEG on and then take the average of their brainwaves from the repeated stims
Magnetoencephalography
MEG
Use SQUIDS to map the movement of electrical charges through the magnetic fields of neurons
Very expensive and hard to use
DBS
Implant an electrode into brain region and emit electrical charges
Used for therapy and treatment
TMS
Transcranial magnetic stimulation
Strong magnetic field to surface of skull to knock out or activate adjacent neurons
Pneumoemcephalograohy
Replaces CSF in spinal cord with air and increases contrast on an X-ray
Angiography
Inject a tracer into blood to increase contrast on an xray for the circulatory system
CT scan
Computed tomography
Narrow beams of x ray passed through brain at diff angles to create a 3D image of brain made up of 1mm cube voxels
Good for locating bleeding in brain
PET imaging
Positron emission tomography
Inject or ingest radiotracer to get into your blood brain barrier and then emits positrons that annihilate electrons to emit a photon
Looks at bloodflow
MRI
Subject goes into strong magnetic field that aligns all protons in body up with the field and then knocks them 90 degrees sideways
Then times how long it takes to realign and how long it takes to desynchronize
Used to map diff tissues in the brain
Diffusion tensor imaging
DTI
Maps movement of water through axons in the brain using MRI (hydrogen in the water)
fMRI
Looks at magnetic field diff between oxygenated and de hemoglobin in the blood
BOLD contrast reveals activity in brain regions
rs-fMRI
No task being performed and can be used to characterize disease states
Optical tomography
Functional near infrared spectroscopy fNIRS
shines NIR light through skull and detects light reflected from blood to measure oxygenation
Subtraction in brain imaging
Subtraction of control experiment from activity condition will leave you with the task activity
Then average across diff individuals to find the mean diff image
Invasiveness from most to least
DBS/TMS
Single/multi cell
PET
fMRI
EEG
Temporal resolution best to worst
EEG and ERP
Single multi cell
PET
fMRI
MRI, CAT, DTI have none
Spatial resolution best to worst
Single multi cell
MRI, CAT, DTI
fMRI
PET
EEG and ERP
