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  • Created by: 10dhall
  • Created on: 17-05-19 22:20
Describe the energy demands of the brain
The brains resting energy levels are most of the energy it consumes, even though it is energy conserving. Tasks only increase energy demands by a small amount - less than 5%. The brain gets energy by receiving glucose and oxygen from blood stream
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who made the point that the brain only changes 5% during tasks??
Smith - 2002
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What did Shelman find in MRS in rats?
80% of brains energy is used to cycle glutamate - suggesting active signal processing at synapses constantly, which use the majority of energy
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Describe PET - positron emission tomography
Radioligand is an active radioactive substance that binds to areas of the brain and releases positrons.react with spec areas of the brain and release photons.these speed out and are traced back to specify area of activity.determines no of photons
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contine
released from every area of the brain to feedback levels of activity. the scans require upto 45mins of stillness
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What radioligand is used to determine activity/metabolism? explain
Fluoro-2-deoxyglucose is the radioligand used to react with glucose, a metabolic supplier of the brain
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What other radioligands can be produced?
metabolism, measure+map densities of NT receptors, can see spatial distr of specific chemicals/NT e.g. sero/opium
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epilepsy+PET?
the epileptic focus usually has less activity, therefore in diagnosing epilepsy can see whether the focus has less energy. cannot study seizures due to the time in machine
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insomnia +PET? Nofzinger 2004
compared insomnia to healthy- found increased cerebral glucose levels in insom- also smaller decline in metabolism in areas of the brain that promote wakefulness when travelling from wake to sleep states. shows pet can be used to accurately measure
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Manuyama - 2010?
In alziemers- Tau and amyloid beta proteins tangle non-neuronal tissue which cause cell death and dementia- began to develop radioligands to measure- allows tracking and imaging in AD
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Metabolic cascade of function? activity timeline?
Interaction of photon(measured by pet), =increased neutron activity(measured by eeg), =increased energy consumption(measured by pET)=increased oxygenation from blood(measured by fmri)
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Pos of PET?
shows metabolic resting state differences between groups
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negatives?
temporal resolution is slow, give subjects radiation dose(invasive), need radioligand(fresh, close lab), fuzzy images(poor spatial)
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explain how MRI works
measures hydrogen in water molecules, unaligned hydrogen atoms are given a pulse of radio frequency=tips them+excites= when realigning with MRI's MF emit energy which is used to create image. diff tissue emits diff signal e.g. white/grey matter etc
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fmri?
de-oxygenated blood is magnetic- fmri sensitive to the amount of oxygenated haemoglobin in blood- Bold signals are measured to map changes in activity in the brain
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Logothesis - 2001 - depth and fmri
simultaneously measured BOLD, LFP, AP by fmri and depth. BOLD closely followed LFP but not AP, with a delayed 8 second onset. showing successful measurement of brain processes
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Rauch- 2008- drug
Injected a drug to prevent AP's. AP inhib. LFP and BOLD correlated- shows BOLD measures underlying intracortical processes not spiking activity
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What else can affect BOLD?
Numerous things so don't count on findings- heart rate, drugs, disease etc
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how long is haemodynamic bold lag?
8 seconds
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What is CBF (Cerebral blood flow) and its importance?
Cerebral blood flow is the blood flow= activity in areas of the cerebral cortex- this can be measured using MRI- its important because it shows activity in brain areas= pp by pp comparison can show differences and deficits in areas of under activity.
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Card 2

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who made the point that the brain only changes 5% during tasks??

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Smith - 2002

Card 3

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What did Shelman find in MRS in rats?

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Card 4

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Describe PET - positron emission tomography

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Card 5

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contine

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