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Neuroscience
Techniques for studying brain structure and function
Question | Answer |
---|---|
Aneurism | a weakening of vessel wall. This leads to ballooning out effect. |
Vascular Malformation (VMF) | congenital abnormality. Cluster between vessels and arteries that pull blood from other parts of the brain or rupture. |
Angiogram | provides information on the structure of the cerebral blood vessels and the speed of blood circulation. Invasive. |
Computerized Tomography (CT) | provides static anatomical images of the brain. X-ray tube emits a series of narrow x-ray beams and rotates around the head. Reconstructs 3D image using mathematical techniques. |
Infarct | area of cell death |
What shows up light on a CT scan? | Bones and acute blood |
What shows up dark on a CT scan? | CSF, Brain tissue, infarct. cysts |
Four advantages of CT scan | provides structural image of brain vivo, can be used in healthy and clinical subjects, indicates areas of brain abnormality, relatively non-invasive |
Three disadvantages of a CT scan | poor spatial resolution, does not provide function information, expensive and requires highly trained staff |
What is an MRI | Like CT, MRI provides static "slice" images of brain, but in greater anatomical detail. Images result from effects of changing strong magnetic fields applied to brain tissue. |
What type of atoms found in the brain tissue align themselves with the orientation of field in the MRI? | Hydrogen atoms |
What are the two types of MRIs? | T1 and T2 |
Does CSF show up dark or light on a T1 MRI? | Dark |
Does CSF show up dark or light on a T2 MRI? | Light |
How do pathologies show up on an MRI? | They generally behave the same as CSF |
Four advantages of an MRI? | excellent spatial resolution, brain can be visualized in any plane, no x-rays or radio active material used, safe, painless, non-invasive |
What are four the disadvantages of an MRI? | even more expensive than CT, special housing required for magnetic field, cannot be used in patients with metallic devices (i.e. pacemakers), provides structure but not function |
Electroencephalogram (EEG) | Records electrical activity of brain by electrodes placed on scalp |
What are EEGs used to diagnose? | epilepsy and other brain abnormalities |
Event related potentials | Show change in EEG in response to sensory stimulus |
What are five advantages of an EEG? | non-invasive, excellent tempora resolution, can be used to recover 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 four disadvantages of an EEG? | poor at localizing function, activity is recorded from millions of groups of neurone, brain activity may fluctuate unpredictable, susceptible to movement artifact |
Positron Emission Tomography (PET) scan | Provides images of brain function, subject is injected with radioactive substance, which is transported by blood to brain, metabolically-active areas will use more glucose and become more radioactive |
What colour is most active in PET scan? | RED |
What colour is least active in a PET scan? | BLUE |
Three advantages of a PET Scan | measure of regional brain activity in vivo, can be used to measure brain activity during task performance, relatively good spatial resolution |
Four disadvantages of PET scans | Invasive, poor temporal resolution (blood flow is slower than neural transmission), tasks must take longer than 1 minute, expensive |
fMRI | Uses MRI technology, but measures brain activity. Active areas receive more oxygenated blood than inactive areas, concentration of oxygen in blood affects its magnetic properties. Thus, MRI can detect functionally induced changed in blood O2. |
What has better spatial resolution PET scan of fMRI? | fMRI |