Ways of investigating the brain

Question 1

What is a fMRI?

Answer 1

• fMRI works by detecting the changes in blood oxygenation and flow that occur due to neural activity
• when a brain area is more active it consumes more oxygen and blood flow is directed to the active area (haemodynamic response)
• produces 3D images showing which parts of the brain are involved in particular mental processes

Question 2

What is an EEG?

Answer 2

• EEGs measure electrical activity within the brain via electrodes that are fixed to an individual’s scalp using a skull cap
• the scan shows the brainwave patterns that are generated by neurons, providing an overall account of brain activity

Question 3

What is an ERP’s?

Answer 3

• EEG data are contained all the neural responses associated with the specific sensory, cognitive and motor events
  -as such, researchers have developed a way of teasing out and
  statistical averaging techniques, are used to filter out and isolate these responses
  -what remains are event-related potentials: types of brainwave that are triggered by particular events

Question 4

What are post-mortem examinations?

Answer 4

• a technique involving the analysis of a person’s brain following their death
• used on 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
• this may also involve comparison with a neurotypical brain in order to ascertain the extent of the difference

Question 5

What are the strengths of the functional magnetic resonance imaging?

Answer 5

• one key strength of fMRI is, 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 produced images that have very high spatial resolution, depicting detail by the millimetre and providing a clear picture of how brain activity is localised

Question 6

What are the weaknesses of functional magnetic resonance imaging?

Answer 6

• fM|RI is expensive compared to other neuroimaging techniques and can only capture a clear image if the person stays perfectly skill
• it has poor temporal resolution because there is around a 5-seconnd time-lag behind the image on the screen ad the initial firming of neuronal activity of individual neurons and so it can be difficult to tell exactly what kind of brain activity is being represented on screen

Question 7

What are the strengths of electroencephalogram?

Answer 7

• EEG has proved invaluable in the diagnosis of conditions such as epilepsy, a disorder characterised by random bursts of activity in the brain that can easily be detected on screen
• similarly it has contributed much to our understanding of the stages involved in sleep
• unlike fMRI EEG technology has extremely high temporal resolution.
• to days EEG technology can accurately detect brain activity at resolution of a single millisecond and even less in some cases

Question 8

What are the weaknesses of the electroencephalogram?

Answer 8

• the main drawback of EEG lies in the generalised nature of the information received that of many thousands of neurons
• the EEG signal is not useful for pinpointing the exact source of neural activities originating in different but adjacent locations

Question 9

What are the strengths of event-related potentials?

Answer 9

• the limitations of EEG are partly addressed through the use of ERP’s
• these bring much more specificity to the measurement of neural processes that could eber be achieved by using raw EEG data
• As ERP’s are derived from EEG measurements, they have excellent temporal resolution, especially when compared to neuroimaging techniques such as fMRI and this has led to their widespread use in the measurement of cognitive functions and deficits
• researchers have been able to identify many different types of ERP and describe the precise role of these in cognitive functioning; for instance, the P300 component is thought to be involved in the allocation of attentional resources and the maintenance or working memory

Question 10

What are the weaknesses of the event-related potentials?

Answer 10

• critics have pointed to a lack of standardisation in ERP methodology between different research studies which makes it difficult to confirm findings
• a further issue is that, in order to establish pure data in ERP studies, background noise and extraneous material must be completely eliminated and this may not always be easy to achieve

Question 11

What are the strengths of post mortem scans?

Answer 11

• post-mortem evidence was vital in proving a foundation for early understanding of key processes in the brain
• Boca and 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 improve medical knowledge and help generate hypotheses for further study

Question 12

What are weaknesses of post mortem scans?

Answer 12

• causation is an issue within these investigations, however observed damage to the brain may not be linked to the deficits under review but to some other unrelated trauma or decay
• a further problem is that post-mortem studies raise ethical issues of consent from the patient before death
• patients may not be able to provide informed consent e.g. 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

Question 13

How are fMRIs used in lie detection?

Answer 13

• one i9nnovative and recently emerging application of fMRI has been in the field of lie detection
• many have claimed that fMRI is an ideal tool for detecting truthfulness or lack of it due to its ability to effectively see inside the brain
• supporters of its use argue that the analysis of neural blood flow is preferable to tracking peripheral measures of anxiety - such as changes in pulse, skin temperature or respiration - that would be recorded by more traditional lie detectors or polygraphs such as those employed by police detectives or on daytime talk shows
• traditional lie detectors are widely acknowledged as beatable but neural activity is much more difficult to fake
• two US companies Cephos and the catchily-named no lie MRI, claim to predict with over 90% accuracy whether its clients are spinning a lie
• no lie MRI suggests that the technique may even be used for risk reduction in dating
• many neuroscientists and legal scholars doubt such claims - and some even question whether brain scans for lie detection will ever move beyond the research lab into the real world