Ways of Studying the Brain (fMRI and EEG)

Question 1

What are ways of studying the brain used for?

Answer 1

• Gives us important insight into underlying foundations of behaviour and mental processes
• Aid in medical diagnosis of illness
• Can be used to investigate localisation

Question 2

What does fMRI stand for?

Answer 2

Functional Magnetic Resonance Imaging

Question 3

Describe how fMRIs work

Answer 3

• Measure changes in brain activity while a person performs a task
• Detect change in blood oxygenation and flow that are caused by neural activity in specific brain areas.
• The more active a brain area is, the more oxygen it uses so blood flow is then directed to this area (haemodynamic response)

Question 4

What do fMRIs produce?

Answer 4

• A dynamic 3D map of the brain (activation map)
• Activation maps show which parts of the brain are involved in specific processes

Question 5

Give disadvantages of fMRIs

Answer 5

• fMRI images shows activity approx. 1.4s after it occurs (poor temporal resolution)
• As they measure changes in blood flow, it’s not a direct measure of neural activity in some brain areas. So it’s not a quantitative measure of mental activity in these brain areas
• fMRIs overlook the networked nature of brain activity, as it focuses on localised activity in the brain. So it doesn’t show communication among regions which is claimed to vital to neural function

Question 6

Give advantages of fMRIs

Answer 6

• They’re more objective and reliable than subjective reports by participants. It’s useful to investigate psychological phenomena that people wouldn’t be capable of providing in verbal reports
• It’s noninvasive as it doesn’t involve insertion of instruments into body, nor exposing the brain to harmful radiation.
• They are more accurate, within 1-2nm (high spatial resolution)

Question 7

What does EEG stand for?

Answer 7

Electroencephalogram

Question 8

Describe how EEGs work

Answer 8

• Measures electrical activity in the brain
• Electrodes placed on scalp detect small electrical charges, in the form of action potentials, resulting from the activity of brain cells
• When electrical signals from different electrodes are graphed over a period of time, the resulting representation is an EEG

Question 9

What can EEGs be used?

Answer 9

• To detect various brain disorders (epilepsy) or to diagnose other disorders that influence brain activity (Alzheimer’s)
• e.g. EEG readings in patients with epilepsy show spikes of electrical activity. EEG patterns in patients with brain disease or injury show slowing of electrical activity

Question 10

What are the 2 properties and patterns of EEGs?

Answer 10

• Properties: Amplitude (intensity or size of activity), frequency (speed or quantity of activity)
• Patterns: Synchronised (recognisable patterns - alpha, beta, theta, delta), desynchronsied (no pattern)

Question 11

Describe examples of the 4 EEG patterns

Answer 11

• When someone is awake but relaxed, alpha waves are recorded
• When someone is physiologically aroused, their EEG patterns shows low amplitude and fast frequency beta waves. Beta waves are also found in REM sleep when eyes move rapidly.
• Delta and theta waves occur during sleep.
• As persons moves to deep sleep, alpha waves decrease and replaced first by lower frequency theta waves and then by delta waves

Question 12

Give advantages of EEGs

Answer 12

• Provides a recording of the brain’s activity in real time, every millisecond so it has great temporal resolution, rather than a still image of a passive brain. This means that the researcher can accurately measure a task or activity with the brain associated with it
• An EEG is useful in clinical diagnosis, e.g. by recording the abnormal neural activity associated with epilepsy. Epileptic seizures are caused by disturbed brain activity, which means that normal EEG reading suddenly changes. This helps diagnose whether someone experiencing seizures has epilepsy

Question 13

Give disadvantages of EEGs

Answer 13

• As an EEG can only detect the activity in superficial regions of the brain, it can’t reveal what’s going on in the deeper regions e.g. hypothalamus or hippocampus. Electrodes can be implanted in non-humans to achieve this, but it’s not ethically permissible to do this with humans as this would be too invasive.
• Electrical activity can be picked up by several neighbouring electrodes, therefore the EEG signal is not useful for pinpointing the exact source of an activity. As a result, it doesn’t allow researchers to distinguish between activities originating in different but closely adjacent locations in the brain