ways of studying the brain

Question 1

what does fMRI measure?

Answer 1

fMRI measures blood flow in the brain when a person performs a task.

Question 2

how does it work? what does it detect?

Answer 2

• Neurons in the brain that are the most active use the most energy.
• Energy require glucose and oxygen.
• Oxygen is released for use by these active neurons at which point the haemoglobin (which carries the oxygen) becomes deoxygenated
• Deoxygenated haemoglobin has a different magnetic quality from oxygenated haemoglobin. An fMRI can detect these different magnetic qualities to create a dynamic (moving) 3D map of the brain.

Question 3

what is the temporal resolution of fMRI?

Answer 3

fMRI images show activity approximately 1-4 seconds after it occurs.

Question 4

what is the spatial resolution of fMRI?

Answer 4

fMRI images are thought to be accurate within 1-2 mm.

Question 5

what are EEG?

Answer 5

EEG (Electroencephalogram) scanners measure electrical activity through electrodes attached to the scalp.

Question 6

how do EEG work?

Answer 6

• Information is processed in the brain as electrical activity in the form of action potentials or nerve impulses
• Small electrical charges are detected by the electrodes and graphed over a period of time, indicating the level of activity. There are four types of EEG patterns: alpha, beta, theta and delta waves.

Question 7

what can EEG be used to detect?

Answer 7

Used to detect illnesses like epilepsy and sleep disorders, and to diagnose other disorders that affect brain activity, like Alzheimer’s disease.

Question 8

what are ERP’s?

Answer 8

ERP (Event-Related Potentials) use similar equipment to EEG (electrodes attached to the scalp).

Question 9

how do ERP’s work?

Answer 9

• A stimulus is presented to a participant (for example a picture/sound) and the researcher looks for activity related to that stimulus (event-related).
• The stimulus is present many times (usually hundreds), and an average response is graphed. (‘Averaging’).

Question 10

what is the temporal resolution of EEG/ERP?

Answer 10

Show activity every millisecond, recording activity in (nearly) real-time.

Question 11

what is the spatial resolution of EEG/ERP?

Answer 11

EEG/ERPs only detect activity in superficial, general areas of the brain.

Question 12

what is post mortem examination?

Answer 12

Researchers study the physical brain of a person who displayed a particular behaviour while they were alive. E.g. Paul Broca and Patient ‘Tan’.

Question 13

are post mortem examinations useful?

Answer 13

yes - post-mortems have contributed to our understanding of many disorders

they allow for a more detailed examination of anatomical and neurochemical aspects of the brain than would be possible with other techniques.

Question 14

evaluation 1 - spatial resolution

Answer 14

spatial resolution - the smallest feature (or measurement) that a scanner can detect, and is an important feature of brain scanning techniques.

good - fMRI = 1-2mm
bad - EEG/ERP = Superficial/General Regions Only

Question 15

evaluation 2 - temporal resolution

Answer 15

Temporal resolution refers to the accuracy of the scanner in relation of time: or how quickly the scanner can detect changes in brain activity.

bad - fMRI = 1-4 seconds
good - EEG/ERP = 1-10 ms

Question 16

evaluation 3 - invasive vs non-invasive

Answer 16

fMRI, EEG and ERP all invasive unlike other scanning techniques e.g. PET scans, fMRI, EEG and ERP don’t use radiation or involve inserting instruments directly into the brain, and is therefore virtually risk-free.

Question 17

evaluation 4 - causation

Answer 17

bad - fMRI scans do not provide a direct measure of neural activity. fMRI scans simply measure changes in blood flow.

bad - Post Mortem: The deficit a patient displays during their lifetime (e.g. an inability to speak) may not be linked to the deficits found in the brain (e.g. a damaged Broca’s area).

bad - EEG: Electrical activity is often detected in several regions; it can be difficult pinpoint the exact region of activity.

good - ERP: ERPs enable the determination of how processing is affected by a specific experimental manipulation.