Clinical Neuroscience Techniques Flashcards by Morariu Miruna

What are 6 techniques for studying brain structure and function?

Computerized Tomography (CT)
Magnetic Resonance Imaging (MRI)
Electroencephalogram (EEG) / Event Related
Potentials (ERP)
Positron Emission Tomography (PET)
Functional MRI (fMRI)

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When was Computerized Tomography develop?

Developed in 1970’s

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What images does CT scan provide?

Static anatomical images of the brain

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What does the X-ray source do in a CT scan?

X-ray source emits a series of narrow x-ray beams and
rotates around the head

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What positional information can we get from the CT scan?

Many positions and reconstructs a 3-D image of brain using mathematical techniques

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In computerize tomography image is produced because different substances ______________________________________.

absorb different amounts of X-rays

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CT scan shows that dense tissue:

absorbs a lot of rays -> light image
e.g. Bones
Acute blood

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CT scan shows that soft tissue:

absorbs fewer rays -> dark image
CSF
Brain tissue (density of gray matter > white matter)
Infarct
Cysts

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What can be used in CT scan to increase contrast for the images?

Intravenous injection of dye may be used to increase contrast (may allow blood vessels, tumors to be seen)

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What are the advantages of CT scan? (4)
* Provides what?
* Can be used in?
* Indicates?
* Invasiveness?

Provides structural image of brain in vivo
Can be used in healthy and clinical subjects
Indicates areas of brain abnormality
Relatively non-invasive

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What are the disadvantages of CT scans? (3)
* Resolution?
* Doesn’t provide what?
* Price and requires what?

Relatively poor spatial
resolution
Provides measure of
structure, not ongoing
activity
Expensive and requires
highly trained specialist
staff

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MRI and CT scans have in common that they provide:

Static “slice” images of brain,
but in even greater anatomical detail

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In MRI, the images result from effects changing __________________________________________________.

strong magnetic fields applied to brain tissue

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What happens with the nuclei of certain atoms in brain tissue in MRI?

Nuclei of certain atoms in brain tissue
(usually hydrogen) align themselves in
orientation of field when the subject is placed in the magnetic field.

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What happens with hydrogen atoms when specific radio frequency (RF) is INTRODUCED during the procedure?

Causes hydrogen atoms to
resonate and change axis of alignment

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What happens with hydrogen atoms when specific radio frequency (RF) is REMOVED during the procedure?

Hydrogen atoms
“relax” and return to original alignment

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What occurs in MRI with hydrogen atoms and RF? (3)

During realignment, hydrogen atoms discharge the RF energy that they had absorbed
Because hydrogen (i.e., H2O) composition of different brain structures varies, the RF energy
given off is distinct for different structures
Computer analyses construct 3-D image of brain based of differential energy emissions

Rate at which hydrogen atoms realign and return to a lower energy state is called __________ in MRI.

relaxation

What are the two types of relaxation in MRI?

T1 and T2 which result in 3 main types of images

In MRI T1 images provide: (2)

Dark CSF, light tissue
Pathologies generally behave like CSF (i.e., dark on T1 and bright on T2)

In MRI, T2 images provide: (2)

Light CSF, dark tissue
Pathologies generally behave like CSF (i.e., dark on T1 and bright on T2)

What are the advantages of an MRI? (4)
*Resolution?
* Visualization of brain?
* No use of what material?
* invasiveness?

Excellent spatial resolution (about 1 mm; determined
mainly by magnet strength)
Brain can be visualized in any plane
No X-rays or radioactive material used
Safe, painless, non-invasive

What are the Disadvantages of an MRI? (4)
* Price?
* Where?
* Can’t be used with who?
* What measure does it not provide?

Even more expensive than CT
Special housing required for magnetic field
Cannot be used in patients with metallic devices (e.g.,
pacemakers, vessel clips)
Provides measure of structure not ongoing activity

What does EEG stand for?

Electroencephalogram (EEG)

What does the EEG record?

Records electrical activity of brain by electrodes placed on scalp

In EEG, the signal is generated by ________________ activity of millions of _____________ cells of layer V and Vl . Signal is amplified and seen as ____________.

Post-synaptic activity of millions of pyramidal cells Seen as waveforms

In EEG, beta rhythm of an alert participant (_____________, ________________) will have waveforms of _____________________ amplitude

Awake, Excited Low amplitude

In EEG, alpha rhythm of an calm participant (_____________, ________________) will have waveforms of _____________________ amplitude

Relaxed, Resting high amplitude

Why do we use EEG?

Used to diagnose epilepsy and other brain abnormalities

Event-Related Potentials ERP show:

change in EEG signal in response to sensory or cognitive stimulus

What are the advantages of EEG? (5) * Non-invasive or invasive? * Resolution? * Record of brain activity? * Can measure what? * Price?

* Non-invasive * Excellent temporal resolution * Can be used to record brain electrical activity in real time * Can be used to measure brain’s response to a number of sensory or cognitive variables * Relatively cheap

What are the Disadvantages of EEG? (4) * Localizing functions? * Record of neurons? * Brain activity? * Susceptible to what?

* Poor at localizing function * Activity is recorded from millions of groups of neurons * Brain activity may fluctuate unpredictably * Susceptible to movement artifact

What does Positron Emission Tomography (PET) provide?

images of brain function

What is the subject injected with for the PET scan?

radioactive substance (e.g., 2-deoxyglucose)

In PET scan, ________________ transported by blood to brain and metabolically-active areas will use more ________________ and become more ____________

Glucose Glucose Radioactive

In PET scan, amount of gamma radiation is represented in ____________ images which indicate those regions which are__________ in metabolism

color-coded high or low

Which method is used in PET and other functional techniques to make conclusions on brain activity?

Subtraction method (Brain is always active so need to subtract normal background activity (i.e., control) from activity measured during task (i.e., stimulation))

What are the advantages of PET? (3) * Measure of? * When can we use it? * Resolution?

* Measure of regional brain activity in vivo * Can be used to measure brain activity during task performance * Relatively good spatial resolution (3-8 mm)

What are the disadvantages of PET? (4) * Invasive or non ? * Resolution? * Tasks? * Price?

* Invasive * Poor temporal resolution (blood flow is slower than neural transmission) * Tasks must take longer than 1 minute * Expensive

What does fMRI measure?

Uses MRI technology, but measures brain activity

What happens in fMRI? (3)

* Active brain areas receive more oxygenated blood * Concentration of oxygen affects magnetic properties * MRI can detect functionally induced changes in blood oxygenation

Compare fMRI to PET and EEG. (2)

* Compared to PET, fMRI has better spatial and temporal resolution * Poorer temporal resolution than EEG)