Ways of Investigating the Brain

Functional Magnetic Resonance Imaging

• Detects changes in blood oxygenation and flow that occur due to neural activity in specifc parts of the brain
• Parts that are more active use more oxygen so blood flow is directed there
• 3D images produced that shows which areas are more active during specific mental processes

Strengths:

• Doesn't use radiation, unlike a PET scan
• Virtually risk-free, non-invasive and straightforward to use 
• Images show detail of localisation in the brain

Limitations:

• Only measures blood flow, not specific neuronal activity so difficult to see type of activity
• Only get a clear image if person is completely still
• Expensive

Electroencephalogram

• Measures electrical activity via electrodes on a person's scalp
• Records brainwave patterns 
• Used to identify unusual patterns that may indicate neurological abnormalities, e.g. epilepsy

Strengths:

• Invaluable in diagnosing disorders, e.g. epilepsy, as it detects random bursts of activity
• Contributed to our understanding of ultradian rhythms, e.g. sleep
• Detects brain activity at an extremely high resolution - a single milisecond

Limitations:

• Too general - doesn't pinpoint the exact source of activity

Event-related potentials

• Types of brainwaves triggered by particular events
• Statistical averaging technique is used to remove extraneous brain activity from EEGs, leaving only the response to events such as the presentation of a specific stimulus or completing a specific task = ERPs

Strengths:

• More specific than EEGs
• Widespread use in looking at cognitive functions and deficits, e.g. P300 component (maintenance of working memory)
• Excellent temporal resolution

Limitations:

• Methodology isn't standardised so difficult to confirm findings
• Background noise/other extraneous variables have to be eliminated which is complicated to do

• Analysis of a person's brain after their death
• Likely to be someone with a rare disorder or unusual deficits

Strengths:

• Vital in providing a foundation for early understanding of key processes in the brain, e.g. Broca and Wernicke
• Help to generate hypotheses for further study

Limitations:

• Patients may not be able to give consent whilst alive, e.g. HM who lost his memory so couldn't give informed consent, but his brain was studied anyway
• Observed damage may not be due to the actual deficit of the individual - could be due to brain decay