Ways of Studying the Brain (ERP and Post-mortem) Flashcards
1
Q
What do ERPs stand for?
A
Event-related potential
2
Q
What do ERPs measure?
A
- ERPs are small voltage changes in the brain that are triggered by specific events or stimuli. e.g. cognitive processing of a specific stimulus
- ERPs are difficult to pick out from other electrical activity being generated within the brain at a given time
3
Q
How do ERPs measure?
A
- Stimulus is usually presented hundreds of times as it’s difficult to isolate the activity
- Any extraneous neural activity that isn’t related to the stimulus will not occur consistently, but the activity linked to the stimulus will, making the specific response to the stimulus clearer.
4
Q
What are the two categories of ERPs?
A
- Waves occurring within 100ms after presentation of stimulus are termed ‘sensory’ ERPs as they show an initial response to physical characteristics of stimulus.
- ERPs generated after 100ms reflect how the subject evaluates the stimulus and termed ‘cognitive’ ERPs as they show information processing
5
Q
What is latency in ERPs?
A
Interval between presentation of stimulus and response
6
Q
Give advantages of ERPs
A
- Can monitor the processing of stimuli without a behavioural response. ERPs recordings can monitor ‘covertly’ the processing of a particular stimulus without requiring the person to respond to them
- As ERPs provide a continuous measure of processing in response to a particular stimulus, it determines how processing is affected by a specific experimental manipulation, e.g. during presentation of different visual stimuli
- Shows activity every millisecond, recording in nearly real time (great temporal resolution)
7
Q
Give disadvantages of ERPs
A
- Studies using ERPs have been critcised for a lack of standardisation in method
- As ERPs are so small, it’s difficult to pick up from other electrical activity in the brain. It requires a large number of trials to gain meaningful data. This limits the types of questions that ERP readings can answer
- A limit of the ERP technique is that only strong voltage changed are recordable. Important electrical actives deep in the brain aren’t recorded, meaning the generation of ERPs tends to be restricted to the neocortex
8
Q
Why are post-mortem examinations used?
A
- To establish the underlying biology of a particular behaviour
- e.g. researchers may study a person who displays a certain behaviour while they’re alive that suggests possible brain damage
9
Q
What are post-mortem examinations?
A
When a person dies, researchers can study the physical brain to look for abnormalities that might explain behaviour.
10
Q
What’s an early example of post-mortem examinations?
A
Broca’s patient (Tan) had a speech problem and was found to have a lesion in the posterior left frontal lobe in a post-mortem examination
11
Q
Give example of a disorder that has been found with post mortems
A
- Iverson found higher levels of dopamine in deceased schizophrenics brains (esp. in limbic system) compared to non-schizophrenic
- These allow detailed study of neurochemical and neuroanatomical aspects of the brain
12
Q
Give advantages of post-mortem examination
A
- Allows for a detailed examination as it enables researchers to examine deeper regions of the brain like the hypothalamus and hippocampus.
- Harrison claims post-mortem has played a central part in understanding the origins of schizophrenia. He suggests that due to post-mortem, researchers have discovered structural abnormalities of the brain
13
Q
Give disadvantages of post-mortem examination
A
- There are confounding variables. People die in various ways, at various stages of disease. Similarly, the length of time between death and post-mortem, drug treatments abd age at death can influence the post-mortem brain
- It’s limited as it’s retrospective because the person is already dead. As a result, the researcher can’t follow up on anything that rises from the post-mortem concerning a relationship between brain abnormalities and cognitive functioning
