Comparison of brain scanning tecniques

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  • Created by: Georgia56
  • Created on: 04-04-18 19:44

MEHOD

DETAIL

ADVANTAGES

DISADVANTAGES

fMRI

Creates dynamic 3D map of the brain. Shows changes in brain activity as they actually happen by using really strong magnetic field and radio waves. Measuring blood flow of brain when performing tasks. Neurons most active require most energy, O2 released by active neurons, HB– deoxygenated, diff magnetic quantity from oxygenated HB. Temporal res– 1-4 secs, special res– 1-2 mm (accurate).

Haemodynamic approach– brain area more active will consume more oxygen and to meet this increased demand, blood flow is directed towards active area.

Shows which part of the brain is involved in particular mental processes and has important implications for out understanding of localisation of function.

Invasive or Non-Invasive: An advantage of fMRI is that is non-invasive. Unlike other scanning techniques, for example Positron Emission Tomography (PET), fMRI does not use radiation or involve inserting instruments directly into the brain, and is therefore virtually risk-free. Consequently, this should allow more patients/participants to undertake fMRI scans which could help psychologists to gather further data on the functioning human brain and therefore develop our understanding of localisation of function.

Spatial Resolution: fMRI scans have good spatial resolution. Spatial resolution refers to the smallest feature (or measurement) that a scanner can detect, and is an important feature of brain scanning techniques. Greater spatial resolution allows psychologists to discriminate between different brain regions with greater accuracy. fMRI scans have a spatial resolution of approximately 1-2 mm which is significantly greater than the other techniques (EEG, ERP, etc.) Provides clear picture of how brain is localised. Consequently, psychologists can determine the activity of different brain regions with greater accuracy when using fMRI, in comparison to when using EEG and/or ERP.

Non-invasive!- no radiation, no insertion of instruments directly into the brain, risk-free, unlike PET scans, enables more people to take part in scans, lead further understanding of brain.

Straight forward to use.

Temporal Resolution: fMRI scans have poor temporal resolution. Temporal resolution refers to the accuracy of the scanner in relation of time: or how quickly the scanner can detect changes in brain activity. fMRI scans have a temporal resolution of 1-4 seconds (5-second lag time) which is worse than other techniques (e.g. EEG/ERP which have a temporal resolution of 1-10 milliseconds). Consequently, psychologists are unable to predict with a high degree of accuracy the onset of brain activity.  Delayed response

Causation: fMRI scans do not provide a direct measure of neural activity. fMRI scans simply measure changes in blood flow and therefore it is impossible to infer causation (at a neural level). While any change in blood flow may indicate activity within a certain brain area, psychologists are unable to conclude whether this brain region is associated with a particular function.

In addition, some psychologists argue that fMRI scans can only show localisation of function within a particular area of the brain, but are limited in showing the communication that takes place among the different areas of the brain, which might be critical to neural functioning. 

Expensive compared to other methods

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