7 ways of studying the brain

name 5 ways of studying the brain

functional magnetic resonance imaging fMRI

electroencephalogram EEG

event related potential ERPs

post-martem examinations PMs

what is a fMRI and how does it work

• fMRI = functional magnetic resonance imaging.

• Measures changes in blood oxygenation and flow caused by brain activity.

• Active brain areas use more oxygen, causing increased blood flow (haemodynamic response).

• The change in oxygen levels alters the magnetic properties of haemoglobin, which the scanner detects.

• Produces 3D activation maps showing which brain areas are active during a task.

Key: More brain activity → more oxygen needed → increased blood flow → fMRI detects the change.

strengths of fMRI

• Non-invasive & virtually risk-free — unlike PET scans/X-rays, it doesn’t use radiation.

• High spatial resolution (~1 mm) → can identify the specific brain areas involved in a task.

• Produces detailed 3D images, making it useful for investigating localisation of function.

weaknesses of fMRI

• Expensive — around £1,200 per participant, meaning researchers may use small samples, reducing generalisability.

• Participants must remain very still → movement can affect the scan.

• Poor temporal resolution — activity isn’t measured in real time; images may be taken around every 5 seconds, so the scan may not accurately show exactly when brain activity occurred.

what is a EEG and what does it measure

• EEG (electroencephalogram) measures the brain’s electrical activity using electrodes attached to the scalp.

• Records brainwave patterns produced by the activity of millions of neurons.

• Four main waves:

  • Alpha: 8–13 Hz — relaxed/awake

  • Beta: 14–30 Hz — awake/mentally active

  • Theta: 4–7 Hz — light sleep

  • Delta: 0.5–3 Hz — deep sleep

• Amplitude = intensity/size of the wave.

• Frequency = number of waves per second.

• Can be used to diagnose conditions such as epilepsy and sleep disorders.

strengths and weakness of EEG

Strengths:

• High temporal resolution → records brain activity in real time.

• Cheap, allowing larger samples → greater generalisability.

• Useful for diagnosing conditions such as epilepsy and studying sleep stages.

Weakness:

• Poor spatial resolution → cannot pinpoint exactly where activity originates.

• Cannot detect activity from deep brain regions because electrodes are on the scalp.

what are ERPs

• event related potentials

• ERPs use the same equipment as EEGs, but measure brain activity in response to a specific stimulus/event.

• A baseline EEG is recorded first.

• A stimulus (e.g. sound/image) is presented repeatedly.

• Responses are averaged to identify activity specifically linked to the stimulus.

• Baseline activity is removed, reducing background/extraneous activity.

• ERPs can investigate processes such as attention and perception.

strengths and weaknesses of ERPs

Strengths:

• More specific than EEGs because they identify neural activity linked to a particular event.

• Can help investigate complex mental processes, e.g. people with phobias show greater ERP amplitude when viewing feared stimuli.

Weaknesses:

• Lack of standardisation between studies makes findings difficult to compare.

• Background activity may not be completely removed → could reduce validity.

• Still has poor spatial resolution, so the exact location of activity cannot be identified.

what is post martex examinations and its S and W?

What are they?

• Dissection and analysis of the brain after death.

• Usually involves people who experienced unusual brain damage, disorders or cognitive deficits.

• Damaged areas can be compared with a typical brain to investigate possible causes.

Strengths:

• Helped identify brain areas such as Broca’s and Wernicke’s areas.

• Can improve medical knowledge and generate hypotheses for further research.

Weaknesses:

• Causation: brain damage may not have caused the behaviour/deficit; damage could result from age, drugs or other factors.

• Ethical issues: obtaining consent before death can be difficult.

• Small samples → reduced generalisability.

• Cultural/gender bias: Western populations and males are overrepresented, limiting population validity.