Brain Imaging

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  • Topic: Brain, Positron emission tomography, Electroencephalography
  • Pages : 3 (552 words )
  • Download(s) : 54
  • Published : December 8, 2012
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HOW CAN BRAIN IMAGING HELP STUDY COGNITION?

Intro
* involves analysing activity within brain while performing various cog tasks – allow us to link bhvr & brain function to help understand how info is processed * cog activity assoc w neural activity in brain regions:

* on scalp as electrical activity ie MEG, EEG (direct measures) * inside brain by measuring O2 consumption caused by neural activity ie PET, fMRI (indirect) * diff imaging techniques vary in their temp (time-based) and spatial (location) reso

Direct measures
Electrodes attached to head cap & amp – recordings of electrical activity (EEG) or change in mag field (MEG) – filter & statistically analyse – compare for diff tasks 1. Magnetoencephalography (MEG)

* magnetic brain measurements
* better spatial reso than EEG – mag fields x as blurred/attenuated 2. Electroencephalography (EEG)
* electrical – v high temp reso, relatively poor spatial

Indirect measures
Neural activity consumes O2, generate electrical signals – compensate for O2 consumption – more oxy blood pumped into region 1. Positron emission tomography (PET)
* radioactive isotopes (O2 15) injected – areas of brain which take up more = more active than other areas * measures blood flow
2. fMRI
* measures rel amount of oxy blood flowing to diff parts of brain - oxy blood = neural activity * put subject in big mag field – transmit radio waves – turn off waves transmitter – receive and record waves re-transmitted by subject – reconstruct 3D image * MRI: high reso, one image; fMRI: low reso, many images (2-3s for each, up to 50 mins)

Usefulness
Allows us to examine the dynamics of the whole brain – not just small region
Understand how many different brain regions interact
Examine processes impossible with lesion approach – e.g. memory encoding Understand the brain regions and networks involved in processes such as language

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