Evaluations - A03

• Strength of post mortem examinations - evidence from post mortem research crucial in building first understanding of key brain processes. EG Broca relied on this technique to separate links between language and the brain decades before neuroimaging was possible. This method helped add scientific credibility before scans and helped generate hypothesis for future research and added scientific credibility.
• Strength of post mortem examinations - post mortem research allows for more detailed examination of anatomical and neurochemical aspects that wouldn't be possible with just non invasive methods like scanning techniques. This allows us to physically access the brain rather than seeing it through scans on monitors.
• Limitation of post mortem examinations - limited approach because the data is retrospective. As a result, the researcher is unable to follow up on anything that arises from post mortem concerning a possible link between brain abnormality and cognitive functioning.
• Limitation of post mortem examinations - research can lack causation because observed damage in brain may not always lead to deficit the individual had suffered. It could be due to unrelated trauma or brain injury which is not possible to deduce after death, this means that post mortem methods have a weak cause and effect relationship.
• Strength of fMRI - fMRIs avoid the use of radiation unlike PET scans. This means that it is risk free, non invasive and a straightforward method to use. Additionally, it also produces images that provide a clear picture of how brain activity is localised.
• Limitation of fMRIs - fMRI scans lack temporal resolution (delayed). This is because fMRIs measure changes in blood flow and this flow of blood is not a direct measure of neural activity in particular areas. Blood flow passing through a part of brain does not always translate to higher level of activity in these areas. This means that it is not a truly quantitative measure of mental activity in brain areas in comparison to other methods such as EEGs.
• Strength of EEG - EEG has high temporal resolution as it provides a recording of the brains activity in real time rather than a still image of a passive brain. Unlike fMRIs, EEGs do not have a lag in reporting activity because it can detect brain activity a single millisecond later, this allows it to be possible to determine how processing is affected by a specific stimulus.
• Strength of EEG - this technique has helped diagnose disorders by identifying unusual brain activity. It has helped in the diagnosis of disorders such as epilepsy and it can also be used to understand the sleep wake cycle which shows the usefulness of EEGs.
• Limitation of EEG - EEGs only provide a general picture by combining activity from thousands of neurons. Since it detects activity on the surface of the brain, we cannot pinpoint the exact source of neural activity and we cannot reveal the activity in deeper regions of the brain such as hippocampus. Therefore we do not get a complete picture of the brains functions as it doesn't allow us to distinguish between the area where the activity originated from and its surrounding areas.
• Strength of ERPs - since ERPs produced using EEG signals they also have excellent temporal resolution and they provide a recording of the brains activity in real time rather than a single still image of a passive, this allows it to be possible to determine how processing is affected by specific stimulus especially compared to fMRIs.
• Strength of ERPs - ERPs help overcome limitations of EEGs by giving specific details on the measurement and by showing where original neural processes are coming from.
• Limitation of ERPs - because the voltage signals are so small and difficult to pick up from between other electrical activity of the brain, it requires a large number of trials to gain meaningful data limiting its usefulness and practicality.