Brain imaging.pdf
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Electrical S+mula+on ‐ ESB Involves using an electrode to deliver a precisely regulated electric current to the brain, thereby stimulating a specific area of the brain If electrical stimulation of a specific brain area initiates a behavioural response, then that specific area of the brain controls or is involved in that response
Extremely invasive – usually only conducted when other surgery is already necessary
Transcranial Magne+c S+mula+on TMS Delivers a magnetic field pulse through the skull stimulating the neurons closest to the point of entry
Only effects neurons to a depth of 2 – 3 centimeters\ Good for establishing how different brain regions control different functions Long term effects of repeated exposure are unclear Side effects can include localised pain or headache
Computerised axial tomography (CAT) Scan
A computer enhanced X‐ray of a slice (cross‐section) of the brain created from X‐rays taken from different angles.
CT is extremely useful for identifying the precise location and extent of damage to or abnormalities in various brain structures or areas. A CT scan can reveal the effects of strokes, tumors,
injuries and other brain disorders It does not provide information about the activity of the brain
POSITRON EMISSION TOMOGRAPHY (PET) Prior to the scan being taken, the person is given a sugar‐like
substance that contains a harmless radioactive element. When this substance enters the bloodstream it travels to the brain. As particular parts of the brain are activated, the substance emits radiation which is detected the PET scanner.
Great for examining brain function when performing different tasks As it involves radioactive element regular use is to be avoided
Single photon emission cpmputed tomography (SPECT) Similar to PET Radioactive tracer lasts longer Not as detailed as PET Can be combined with CT images to increase resolution
Much cheaper than PET
Magne+c resonance imaging (MRI) MRI uses a similar technique to the CAT scan, but instead of using an X‐ray, harmless radio frequencies are used to vibrate atoms in the neurons of the brain
The amount of vibration is detected and analysed by a computer
MRI can be used to detect and display extremely small changes in the brain. For example, MRI can more clearly distinguish between brain cells that are cancerous and those that are noncancerous. shows only brain structure not function
Func+onal magne+c resonance imaging (fMRI)
The technique is based on the standard MRI, and measures subtle changes in blood–oxygen levels in the functioning brain. When an area of the brain is active, there is increased blood flow to that area, as more oxygen is required by the active, functioning neurons
X‐RAY CAT
MRI
F‐MRI
PET
ESB