Studying the Brain Flashcards
What is a post-mortem examination?
This is a technique involving the analysis of a person’s brain following their death.
In psychological research, whose brains are likely to be examined? What is examined? Why?
Those who have a rare disorder and have experienced unusual deficits in mental processes or behaviour during their lifetime.
Areas of damage within the brain are examined after death as a means of establishing the likely cause of the affliction the person experienced.
This may also involve comparison with a neurotypical brain in order to ascertain the extent of the difference.
What are 3 strengths of a post-mortem?
Post-mortem evidence was vital in providing a foundation for early understanding of key processes in the brain.
Paul Broca and Karl Wernicke both relied on post-mortem studies in establishing links between language, brain and behaviour decades before neuroimaging ever became a possibility.
Post-mortem studies were also used to study HM’s brain to identify the areas of damage, which could then be associated with his memory deficits.
What are 3 limitations of post-mortems?
Causation is an issue. Observed damage to the brain may not be linked to the deficits under review but to some other unrelated trauma or decay.
Post-mortem studies raise ethical issues of consent from the individual before death.
Participants may not be able to provide informed consent, for example in the case of HM who lost his ability to form memories and was not able to provide such consent - nevertheless post-mortem research has been conducted on his brain. This challenges the usefulness of post-mortem studies in psychological research.
What does fMRI stand for?
Functional magnetic resonance imaging.
What are 2 strengths of fMRI?
fMRI does not rely on the use of radiation. If administered correctly it is virtually risk-free, non-invasive and straightforward to use.
Produces images that have very high spatial resolution, depicting detail by the millimetre, and providing a clear picture of how brain activity is localised. This means that fMRI can safely provide a clear picture of brain activity.
What are 2 limitations of fMRI?
fMRI is expensive compared to other neuroimaging techniques.
It has poor temporal resolution because there is around a 5-second time-lag behind the image on screen and the initial firing of neuronal activity. This means fMRI may not truly represent moment-to-moment brain activity.
How does fMRI work?
Works by measuring the energy released by haemoglobin (Hb - the protein content of blood – this is the part of the red blood cell that binds with O₂).
When Hb is bound to O₂ it reacts differently to when it is without O₂.
When an area is more active, blood flow is directed to that area (haemodynamic response).
The difference in the amount of energy released by the Hb is detected by the moving scanner and the change measured.
This gives us a dynamic (moving) image of the brain and shows us a 3D image which allows us to map which parts of the brain are involved in particular mental processes – this has important implications for our understand of localisation of function.
What is the temporal duration of fMRI? At what distance does is it accurate?
fMRI shows activity about 5 seconds after it occurs.
It is also accurate within 1-2mm in the brain.
Outline fMRI use with lie detectors
Analysis of neural blood flow is preferable to tracking peripheral measures of anxiety that would be measured by more traditional lie detectors or polygraphs.
Traditional lie detectors are widely acknowledged as being “beatable” but neural activity is much more difficult to fake.
What is a strengths of using fMRI as a method of lie detection?
Specificity in lie detection may be higher than that of the polygraph.
What are 2 limitations of using fMRI as a method of lie detection?
Most scientists currently agree that fMRI research evidence is still weak and lacks both external and construct validity (Spence, 2008).
The current state of the science does not, at this time, meet the legal standards in court proceedings.
What does EEG stand for?
Electroencephalogram
What are 2 limitations of an EEG?
Main drawback lies in the generalised nature of the information received.
The EEG signal is not useful for pinpointing the exact source of neural activity. Therefore it does not allow researchers to distinguish between activities originating in different but adjacent locations. (Low spatial resolution).
What are 3 strengths of an EEG?
Useful in studying the stages of sleep and in the diagnosis of conditions such as epilepsy - can easily be detected on screen.
EEG technology has extremely high temporal resolution.
Today’s EEG technology can accurately detect brain activity at a resolution of a single millisecond or less. This shows the real-world usefulness of the technique.
This technique is much cheaper than others (such as fMRI) so are more widely available.
They require a level of expertise in order to interpret the data gathered.
