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Flashcards

Neuroimaging

Eleanor McShane Neuroscience Degree Inglês 25 flashcards

Flashcards do conjunto (25)

  1. 1What is Cognitive Neuroscience?The study of the neural basis of our mental states/cognition
  2. 2What is a EEG scan?An EEG measured voltage changes in synapses by placing electrodes on the scalp.
  3. 3Evaluate EEGGood - high temporal resolution which reveals differences in speed for different stimuli
    Bad - poor spatial resolution because activation from all over the brain will interfere with the waves, also can only place a certain amount of electrodes on scalp
  4. 4What does PET stand for?Positron Emission Tomography
  5. 5How does a PET scan work?Radioactive isotopes are injected (radioactive water or butanol) which will decay and produce a positron. The positron will annihilate with an electron and produce a pair of photons that will move in opposite directions. This is detected by scintillaor material which causes a huge wave of radioactivity. This is then picked up by a photomultiplier.
  6. 6Drawbacks of PET scans (4 points)X - Poor spatial resolution
    X - Poor temporal resolution
    X - Use of radioactivity not good for subject
    X - Takes a long time for radioactive substance to reach brain
  7. 7What does MRI stand for?Magnetic Resonance Imaging
  8. 8How does MRI work? (very short description)MRI uses magnetic field which makes protons in their hydrogen atoms to spin.
  9. 9What does the 'f' in fMRI stand for?Functional
  10. 10Why is hemoglobin used in fMRI?Hemoglobin has magnetic properties. When it is carrying oxygen it is not magnetic. When it is not carrying oxygen it is magnetic.
  11. 11Whats the difference between 'diamagnetic' and 'paramagnetic'?Diamagnetic = NOT magnetic (oxyhemoglobin)
    Paramagnetic = IS magnetic (deoyhemoglobin)
  12. 12Does deoxyhemoglobin make the fMRI scan brighter or darker?Deoxyhemoglobin is paramagnetic and therefore decreases the signal of the fMRI scan and subsequently makes the imagine DARKER.
  13. 13When the brain becomes active in fMRI the image becomes brighter. Why is this peculiar?If the image on an fMRI scan becomes brighter it implies that there is more oxygenated blood. This is peculiar because you would expect there would be a decrease in oxygenated blood because the brain will be using more oxygen.
  14. 14What increases when the brain becomes activated?Cerebral Blood Flow (CBF)
  15. 15Explain what the 'dip' is in fMRI.The 'dip' is the brief reduction of signal before the CBF reaches the brain. A reduction of signal implies there is an increase in deoxygenated blood.
  16. 16Which phenomenon increases the localisation of fMRI?The 'dip'. It shows the specific stimulated area within that region. For example, if you activate visual stimulus you see the visual cortex light up, the 'dip' shows specific, individual patches in the visual cortex.
  17. 17Because oxyhemoglobin and deoxyhemoglobin are different colours we are able to use...Imaging using light - optical imaging
  18. 18How does optical imaging using light work?The scalp is cut away and a light in shone into the brain. The subject is then give a stimulus to activate the brain. There is then a big flow of oxygenated blood. Because the oxygenated blood is a different colour to deoxy it will absorb and reflect the colour different. A camera then measures the colour of the light that is reflected and therefore we know if there is oxy or deoxyhemoglobin present.
  19. 19Explain the Rodent Whisker Barrel CortexIn the somatosensory (touch) cortex there are 'mini brains' for every whisker on a rodent. The whiskers on the right have the barrel left side of the brain and vice versa. This occupies a large part of their brain because they rely heavily on their whiskers to move around their environment.
  20. 20What in the blood absorbs light?Hemoglobin absorbs light. This is useful for optical imaging because it will tell us hemoglobin levels in the brain.
  21. 21How does the Laser Doppler Flowmetry work?A laser doppler probe of a certain colour is pointed at the brain. This light is either absorbed or bounces around in the brain and comes back out again. There are receivers on the probe that collect the light when it comes back out of the brain. If it changes colour that indicates that it has hit something moving i.e. blood cells. From this they can measure CBF.
  22. 22Marcus Raichle measure blood flow, glucose and oxygen consumption is brain activation. What did he find?Blood flow increased by 50%
    Glucose levels increased by 50%
    Oxygen hardly increased at all.
  23. 23Theories for the 'dip'Increased oxygen consumption
    Hypercapnia
    Diffusion Limited Theory
  24. 24What is hypercapnia and what happens when you have it?Excess CO2 in the blood. This increases blood flow to try and get rid of it. Only the parts of the brain associated with CO2 will activate when this happens therefore we use this as a control to look at CBF without the need to activate the brain.
  25. 25Explain Diffusion Limited Theory of Oxygen Delivery.A theory for why CBF is so large when the brain becomes active. Because the brain is so hungry for oxygen even at rest there is no extra oxygen for it to use when it becomes active so there is a huge CBF.

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Degree Neuroscience FlashCards sobre Neuroimaging, criado por Eleanor McShane em 29-05-2015.
Criado por
Eleanor McShane
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