6.6: Functional magnetic resonance imaging (fMRI)

Question 1

Describe and evaluate scanning techniques as a way of investigating the brain (16 marks).
fMRI (functional magnetic resonance imaging) is a method used to measure brain activity while a person is performing a task that uses MRI technology (detecting radio waves from changing magnetic fields).
This enables researchers to detect which regions of the brain are rich in oxygen and thus are active.

An electroencephalogram (EEG) is a record of the tiny electrical impulses produced by the brain’s activity.
EEGs measure electrical activity within the brain via electrodes that are fixed to an individual’s scalp using a skull cap.
The scan recording represents the brainwave patterns that are generated from the action of millions of neurons, providing an overall account of brain activity.

ERPs (event-related potentials) are how the brain’s electrophysiological response to a specific sensory, cognitive or motor event can be isolated through statistical analysis of EEG data.
ERPs are types of brainwave that are triggered by particular events.

The first AO3 paragraph is that one key strength of fMRIs are that unlike other scanning techniques such as PET, it does not rely on the use of radiation.
If administered correctly, it is virtually risk-free, non-invasive and straightforward to use.
It also produces images that have very high spatial resolution, depicting detail by the millimetre and providing a clear picture of how brain activity is localised.
For example, Peterson found that Wernick’s area was active during listening tasks using brain scans, supporting this.
However, fMRI is expensive compared to other neuroimaging techniques and can only capture a clear image if the person stays perfectly still, which is difficult for the person, especially because it can be uncomfortable for them.
In addition, fMRI has poor temporal resolution, because there is around a 5 second time lag behind the imagine on screen and the initial firing of neuronal activity, so you can’t see activation of the brain.

The second AO3 paragraph is that one major strength of EEGs is their practical application.
They have proved invaluable in the diagnosis of conditions like epilepsy, a disorder characterised by random bursts of activity in the brain that can easily be detected on the graph.
Similarly, EEGs have contributed very much to our understanding of the stages involved in sleep (research into ultradian rhythms).
As well as this, unlike fMRIs, EEG technology has extremely high temporal resolution.
Today’s EEG technology can accurately detect brain activity at a resolution of a single millisecond and even less in some cases.
This is important, because in the case of epilepsy, you can identify neurons misfiring and pinpoint when an epileptic episode starts.

The third AO3 paragraph is that there are different techniques used to investigate brain activity, because all are flawed in some way.
For example, to find out if a person has epilepsy you could use an EEG to see if there is faulty neuronal transmission leading to irregular brainwaves.
If you wanted to see how this individual responds to bright lights, you would need to use an ERP.
If you want to locate the very specific area of the brain that may be damaged you could use an fMRI.
However, what?

Answer 1

However, none of the techniques can see activity at a cellular level and to see that we would need to look at the brain in a post-mortem