Biopsychology - Brain Imaging Techniques

Question 1

Intro to brain imaging

Answer 1

Allows us to study the living brain
Multiple techniques available to neuroscientists
fMRI
EEG
ERP
Post-mortem examination

Question 2

Functional Magnetic Resonance Imaging (fMRI)

Answer 2

1. Measures blood flow in the brain
2. If an area of the brain becomes more active, those neurones in the brain use the most energy and require oxygen
3. Oxygen is released for use by these active neurones at which point the haemoglobin becomes deoxygenated - different magnetic quality from oxygenated haemoglobin
   Based on energy use of active neurones
   Creates 3D map of brain activity
   Spatial resolution: 1-2mm (very accurate)
   Temporal resolution: 1-4 seconds delay.

Question 3

Electroencephalography (EEG)

Answer 3

1. Measures electrical activity via scalp electrodes
   Detects action potentials in neurones
2. Detects the size or intensity of electrical activity as well as the frequency or rate of electrical activity
3. Electrical signals from the different electrodes are plotted on a graph in the form of waves
   Produces wave patterns: Alpha, Beta, Theta, Delta
   Key properties: amplitude and frequency
   Gives a general reading of the brains activity

Question 4

EEG wave patterns

Answer 4

Alpha waves: light sleep, relaxation
Beta waves: normal waking state, focused attention
Theta waves: deeper sleep stages
Delta waves: deepest sleep
Synchronised vs desynchronised patterns

Question 5

Event-related potentials (ERP)

Answer 5

1. Uses EEG electrodes to measure very small voltage changes within the brain when presented with a stimulus
2. Averages responses over many trials to block out all the other background activity in the brain
3. Using a statistical averaging technique, all background brain activity from original EEG recording is filtered out so ERP is left
   Examines brains reaction to particular events
   Sensory ERPs: <100ms after stimulus
   Cognitive ERPs: >100ms after stimulus

Question 6

Comparing fMRI, EEG and ERP

Answer 6

Spatial resolution:
fMRI: high (1-2mm)
EEG/ERP: low (only superficial areas)
Temporal resolution:
fMRI: 1-4 seconds delay
EEG/ERP: Nearly real-time (1-10ms)
All non-invasive techniques

Question 7

Post-mortem examination

Answer 7

Studies physical brain after death
Allows detailed examination of brain structure
Can investigate deeper brain regions
1. Study individuals behaviour whilst they are alive - strange behaviour could suggest that there might be damage in the brain that is behind these problems
2. Study brain after death- researchers examine the brain to look for abnormalities and lesions in the brain
3. Analysis of the brain allows the researcher to form a correlation between the abnormal behaviour of the patient and a particular area of the brain
Limitations: can’t directly observe living brain function.
Correlation not causation

Question 8

Evaluating brain imaging techniques

Answer 8

Key factors to consider:
Spatial resolution
Temporal resolution
Invasiveness
Ability to show causation
No single “perfect” technique
Researches often use multiple methods

Question 9

Applications of brain imaging

Answer 9

Studying normal brain function
Investigating neurological disorders
Monitoring treatment effects
Advancing our understanding of cognition

Question 10

Evaluating EEGs and ERPs

Answer 10

Strengths:
Effective tools for diagnosing certain brain disorders - e.g. epilepsy x seizures identified through abnormal brain patterns
Cheaper than fMRIs - more accessible for a wide range of people + larger sample sizes from studiescan be used draw conclusions about the brain’s activity
Have high temporal resolution - take readings every millisecond - accurate measurement of when brain activity is occurring
Weaknesses:
Low spatial resolution - only detect the general activity of the cerebral cortex