Flashcards in Studying the Brain Deck (19):
Why are scanning techniques used?
Often for medical purposes in the diagnosis of illness.
For psychologists to investigate localisation (determine which areas do what).
What are the four scanning techniques?
fMRI, EEG, ERP, post mortem.
fMRIs detect changes in blood oxygenation and flow that occur due to neural activity in specific brain areas.
When a brain area is more active it consumes more oxygen and so blood flow is directed to the active area (haemodynamic response).
What is haemodynamic response?
When a brain area is more active it consumes more oxygen and so blood flow is directed to this active area.
fMRI detects this.
What is a strength of fMRI?
+ produces images with a high spatial resolution, showing detail by the mm. Meaning fMRI can provide a clear picture of how brain activity is localised.
+ non invasive. Unlike other scanning techniques, it doesn't rely on the use of radiation and is safe.
What is a limitation of fMRI?
- expensive, and only captures a clear image if the person lays still.
- poor temporal resolution because of a 5 second time lad between initial neural activity and image. Meaning it may not truly represent moment to moment activity.
How does the process of EEG work?
EEG measures electrical activity within the brain via electrodes using a skull cap.
How does EEG work?
EEG measures electrical activity within the brain. And the scan recording represents the brainwave patterns generated from millions of neurons. This shows overall brain activity.
What is a strength of EEG?
+ extremely high temporal resolution; EEGs can detect brain activity at a resolution of a millisecond.
What's a limitation of EEG?
- because the EEG produces a generalised signal from thousands of neurons, it's difficult to know the exact source of neural activity. So EEG can't distinguish the activity of different but adjacent neurons.
What are ERPs?
They are types of brainwave that are triggered by particular events.
The scanning that's left when all extraneous brain activity from an EEG recording is filtered out.
How is an EEG done?
By using a statistical technique, leaving only those responses that relate to the presentation of a specific stimulus
What's a strength of ERPs?
+ Like EEGs, they have high temporal resolution. Especially compared to fMRI.
+ very specific measurement of neural processes than can be achieved using raw EEG data.
What's a limitation of ERPs?
- background noise and extraneous material must be completely eliminated, which may not always be easy to achieve.
Why are the strengths similar between EEGs and ERPs?
Because an ERP is just what's left when all extraneous brain activity from an EEG is filtered out.
What is a post mortem?
The analysis of a person's brain following their death.
How is the post mortem technique performed?
Areas of the brain are examined to establish the likely cause of a disorder that the person suffered in life.
This may include the comparison of a neurotypical brain.
What is a strength of post mortem examinations?
+ they provided the foundation for understanding he brain. For example, Broca and Wernicke relied on post mortem studies. Thus improving medical knowledge; and helping generate hypotheses for further study.