8: NEUROIMAGING

Question 1

1. CT
2. MRI
3. ANGIOGRAM

Answer 1

3 STRUCTURAL/ANATOMICAL NEUROIMAGING TECHNIQUES

Question 2

1. ELECTRICAL (EEG)
2. METABOLICAL (PET + BOLD fMRI)

Answer 2

2 TYPES OF FUNCTIONAL NEUROIMAGING TECHNIQUES

Question 3

neuroimaging technique in which a device that uses a computer to analyze data obtained by passing XRAYS thru head at diff angles to produce a 2D pic of a “slice” of the brain

Answer 3

COMPUTERIZED TOMOGRAPHY (CT)

Question 4

to find the location of lesion in living brain

Answer 4

GOAL OF CT SCAN/MRI

Question 5

• bad spatial resolution
• lesions take long to show up on CT

Answer 5

CONS OF CT

Question 6

neuroimaging technique that involves interactions btwn RADIO WAVES + strong MAGNETIC FIELD to show a “slice” of the brain

Answer 6

MAGNETIC RESONANCE IMAGING (MRI)

Question 7

• good spatial resolution
• immediate imaging of lesions

Answer 7

PROS OF MRI

Question 8

neuroimaging technique that measures structure of CEREBRAL BLOOD SUPPLY by injecting bloodstream w contrast agent that makes blood black

Answer 8

ANGIOGRAM

Question 9

to image ANEURYSMS + other vast defects (ARTERIOVENOUS MALFORMATION)

Answer 9

GOAL OF ANGIOGRAM

Question 10

abnormal bulge in blood vessel wall that can lead to a brain bleed which can impair/kill smn

Answer 10

ANEURYSM

Question 11

knotting of blood supply

Answer 11

ARTERIOVENOUS MALFORMATIONS (AFV)

Question 12

• HYDROGEN PROTONS = most readily avail atoms in human body
• IN FREE SPACE: H atoms spin in all diff directions
• IN MAGNETIC FIELD (MRI): H atoms = aligned according to magnetic field (net magnetization)
• RADIO FREQ (RF) PULSE provides lil boost of energy to push protons out of alignment w magnetic field

Answer 12

What happens during an MRI?

Question 13

• protons process around MAIN MAGNETIC AXIS like a spinning top + frequency of procession around axis depends on STRENGTH OF MAGNET
• RF PULSE = used to push protons OUT of alignment
• protons flip back to OG position at end of RF PULSE

Answer 13

HYDROGEN PROTONS SPINNING

Question 14

neuroimaging technique in which electron cap = placed on scalp to record EVENT-RELATED POTENTIALS (ERP) + VISUAL EVOKED POTENTIALS (VEP)

Answer 14

ELECTROENCEPHALOGRAM (EEG)

Question 15

to diagnose EPILEPSY/SLEEPING DISORDERS

Answer 15

GOAL OF EEG

Question 16

ADV OF EEG

Answer 16

useful for examining LARGE POPS of neurons

Question 17

special cases of EEG that give overall picture of large area of brain activity

Answer 17

EVENT-RELATED POTENTIALS (ERP) + VISUAL EVOKED POTENTIALS (VEP)

Question 18

• good temporal resolution (gives info in msecs)
• good at linking specific physio markers to cog processes

Answer 18

ADVS OF ERP

Question 19

• poor spatial resolution
• difficult to get at some brain regions (temporal cortex/ventral regions)

Answer 19

CONS OF ERP

Question 20

2 TYPES OF FUNCTIONAL NEUROIMAGING TECHNIQUES THAT MEASUE METABOLISM

Answer 20

1. POSITRON EMISSION TOMOGRAPHY (PET)
2. BLOOD OXYGENATED LEVEL DEPENDENT (BOLD) fMRI

Question 21

functional neuroimaging technique that measures local changes in CEREBRAL BLOOD FLOW (CBF) by using radioactive tracers that rapidly decay + emit positrons

Answer 21

POSITRON EMISSION TOMOGRAPHY (PET) SCAN

Question 22

to measure neurochemicals in living human brain

Answer 22

GOAL OF PET SCAN

Question 23

• can localize any radioactive substance taken up in human brain
• can track multiple metabolic processes as long as emitted PHOTON can be detected (allows imaging of some NTs)

Answer 23

PROS OF PET SCAN

Question 24

• cost
• invasive (radioactive isotopes can only be administered every 4-5 years)
• not as good temporal resolution

Answer 24

CONS OF PET SCAN

Question 25

functional neuroimaging technique that measures metabolism in brain by detecting changes in BLOOD OXYGEN LEVEL

Answer 25

BLOOD OXYGENATED LEVEL DEPENDENT (BOLD) fMRI

Question 26

to record metabolic activity of regions in brain

Answer 26

GOAL OF BOLD fMRI

Question 27

- greater spatial resolution - greater temporal resolution (can detect activation of stimuli appearing for less than 1 sec) - measures regional metabolic acitvity of living/unanesthetized brain

Answer 27

PROS OF BOLD fMRI

Question 28

1. person receives injection of radioactive traces 2. person's head = placed in machine similar to CT scanner 3. when radioactive particles decay → they emit POSITRONS which meet nearby ELECTRONS 4. particles COLLIDE w each other + emit 2 PHOTONS which go in OPPOSITE directions 5. sensors around person's head detect PHOTONS + scanner plots location of collision

Answer 28

STEPS OF PET SCAN

Question 29

- run 2 conditions (STIMULATION w images vs CONTROL w blank screen) - measure diff in ACITVATION btwn 2 images (CONTROL - STIMULATION) - result = picture of REGIONAL CEREBRAL BLOOD FLOW relative to visual stimulation

Answer 29

MEASURING PET ACITVITY USING SUBTRACTION

Question 30

- very strong - 60K x Earth's magnetic field - heavy objects can fly into magnet

Answer 30

attributes of fMRI magnet

Question 31

neuroimaging method that uses modified MRI scanner to reveal bundles of MYELINATED AXONS in living brain

Answer 31

DIFFUSION TENSOR IMAGING (DTI)

Question 32

to measure microscopic mvmt of WATER in brain which makes it possible to visualize LOCATION/ORIENTATION/DIRECTION of brain's WHITE MATTER TRACTS

Answer 32

GOAL OF DTI

Question 33

neuroimaging method that applies magnetic pulse thru coil of wire to certain brain regions which either EXCITES/INTERFERES w functions of brain region stimulated

Answer 33

TRANSCRANIAL MAGNETIC STIMULATION (TMS)

Question 34

- good temporal resolution - can presumably disrupt individual processes within a task - potential combo w other imaging techniques

Answer 34

PROS OF TMS

Question 35

- poor spatial localization (stimulation = not v focused) - cant stimulate certain areas + can only stimulate cortical surface - distance effects (changed interactions due to stimulation) can induce SEIZURES

Answer 35

CONS OF TMS