3. Ways of studying brain

fMRI (Functional Magnetic Resonance Imaging)

It’s a method used to measure brain activity while person is performing a task.

Measures: changes in blood oxygenation and blood flow.

Works: when a brain area becomes active, it requires more oxygen, which creates a haemodynamic response, where blood flow increases to the active brain area. The scanner detects these changes in blood oxygenation and blood flow.

Produces: 3D images (brain maps) showing which brain areas are involved in a particular mental process.

EEG (Electroencephalogram)

A method used to record electrical, activity in the brain.

Measures: Brainwave patterns produced by the activity of thousands of neurons.

Works: Electrodes are attached to the scalp. The electrodes record electrical activity generated by the brain.

Used for: can identify patterns of activity associated with epilepsy, sleep disorders

ERP (Event related potentials)

A technique derived from EEG recordings.

Measures: specific brain responses linked to a particular sensory, cognitive or motor event.

Works: researchers use statistical averaging to isolate responses related to a specific stimulus or task. This removes background brain activity and leaves only the neural response to the event.

Used for: to investigate cognitive processes.

Postmortem

Examinations of the brain after death.

Investigating: the relationship between brain structure and behaviour.

Works: researchers analyse the brains of individuals who experience cognitive, behavioural or neurological abnormalities during their lifetime. Areas of damage or abnormality are identified and linked to observed behaviour.

Useful: as allows researchers to investigate brain structures that can’t be examined in living pp.

Spatial resolution (evaluation)

-accuracy of identifying the exact location of neural activity within the brain

fMRI: +, as it has spatial resolution of approximately 1-2 mm and can detect activity in very small brain regions. So psychologists can accurately identify which specific brain areas are active during a task or behaviour, leading to more accurate conclusions about localisation of function.

EEG/ERP: -, as records activity from superficial/general regions of the brain through electrodes attached to the scalp. This means that the scanner only measures activity from the outer layer of the brain and can’t accurately identify the precise sources of neural activity, so conclusions about localisation of function are less accurate.

Temporal resolution (evaluation)

-refers to the accuracy of identifying the timing of neural activity.

fMRI: -, as scans produce an image approximately every 1-4 sec, which means that there is a delay between neural activity and image produced. So psychologists are less ble to identify the precise timing of neural activity, reducing the accuracy of conclusions about when brain processes occur.

EEG/ERP: +, as records every 1-10 seconds, which allows psychologists to measure brain activity in real time, rather than looking at a passive brain. So more accurate conclusions can be drawn about the timing of neural processes.

Invasive vs Non-Invasive (evaluation)

fMRI: +, as non-invasive and doesn’t require instruments to be inserted into the brain. Pp experience very little physical risk or discomfort, which makes procedure safer and more ethical than invasive techniques.

EGG/ERP: +, as electrodes are attached to the scalp rather than inserted into the brain, so non-invasive. The procedure is virtually risk-free and can be used safely with a wide range of pp.

Causation (evidence)

fMRI: -, as doesn’t directly measure neural activity, instead, it measures changes in blood oxygenation and blood flow. Because blood flow is only associated with neural activity, psychologists can’t be certain that observed brain activity caused a particular behav. So cause and effect conclusions can’t be established.

EGG: -, as electrical activity is often detected across several brain regions simultaneously. Researchers can’t always identify the exact region responsible for the activity, so it’s is difficult to establish cause and effect relationship between a specific brain area and behav.

ERP: +, as involves presenting a specific stimulus and statistically averaging responses to remove background noise. As neural responses can be linked directly to a known stimulus, psychologists can’t make stronger causal inferences about how particular cognitive processes are affected by experimental manipulations.

Postmortem: -, as researchers identify abnormalities after death and attempt to link them to behav shown during life. The observer deficit may not have been caused by the damaged area. Other illnesses, trauma may also have contributed, so causation can’t be firmly established.