Ways of studying the brain

Question 1

How can post-moterm examination help in studying the brain

Answer 1

Ways of studying the brain of people with psychological abnormalities prior to their death in an attempt to establish the possible neurobiological cause of this behaviour
An example of this would be Tan a patient of Broce’s who exhibited speech problems when he was alive and was found to have lesion in the area of the brain known as the broce’s area
They have also helped identify some of the brain’s structure involved in memory HM’s inability to create long term memory was found to lesions in his hippocampus

Advantages:
- they allow for a more detailed examination of anatomical and neurochemical aspects of the brain than would be possible through non evasive scanning such as FMRI’s and EEg’s e.g it enables researchers to examine deeper into the hippocampus and hypothalamus.
Harison in 2000 claims that post-mortem studies have played a central role in our understanding of the origins of schizophrenia. They have discovered structural abnormalities

Disadvantages:
- limited in retrospect as the person is already dead. As a result the researcher is unable to follow up on anything that arises from the post-morterm concerning a possible relationship between brain abnormalities and cognitive functions

• because people die in a variety of circumstances and at varying stages of disease, these factors can influence the post-morterm brain. Similarly, the length of time between death and the post-morterm delay, drug treatments and age of death are possible confounding influences of any differences between cases and control

Question 2

How do FMRI’s link to ways of studying the brain?

Answer 2

it measures the change in activity in the brain when someone preforms a task
It measures the changes in blood flow in particular areas of the brain
If a particular area becomes more active there is an increased demand for oxygen in the brain
From this we learn about brain regions involved in the performance of specific tasks

Advantage:
- it is non invasive / it does not expose the brain to harmful radiation
- it is a more objective and reliable measure of psychological processes than is possible with verbal reports.

Disadvantage:
- it is not a direct measure of neural activity in particular brain areas as it measures the changes of blood flow in the brain
- critics argue that FMRI’s overlook the networked nature of brain activity as it only focuses on localised activity in the brain. They claim that it is communication among the different regions that is critical to mental function

Question 3

what are EEG’s?

Answer 3

a method of recording changes in electrical activity of the brain using electrodes attached to the scalp
When electrical signals from different electrodes are graphed over a period of time the resulting representation was an EEG

Advantages:
EEG’s provide a recording of the brain’s activity in real time rather than a still image of the passive brain. This means that the researcher can actively associate a region of the brain with an activity
EEG is a useful clinical diagnosis by recording the abnormal neural activity associated with epilepsy
they are caused by a disturbance in brain activity which means that EEG’s can measure them

Disadvantages;
they can only detect specific regions of the brain and not deeper regions such as the hypothalamus or hippocampus
electrodes can be implemented into non humans but this is unethical

electrical activity can be picked up by several neighbouring electrodes therefore it is not useful for pinpointing the exact source of activity

Question 4

what are event-related potentials

Answer 4

a technique that takes raw EEG data and uses it to investigate cognitive processing of a specific event. It does this by taking multiple readings and averaging them in order to filter out all brain activity that is not related to the appearance of the stimulus
ERP’s can be divided into two categories waves occurring within the first 100 milliseconds after presentation of the stimulus and those generated after the 100 millisecond stimulus

Strengths:
- ERP’s can measure the processing of stimuli even in the absence of behavioural response. ERP’s recordings make it possible to monitor ‘covertly’ the processing of a particular stimulus without requiring a person to respond to them
- ERP’s provide a continuous measure of processing in response to a particular stimulus, it makes it possible to determine how processing is affected by a specific experimental manipulation for example, during presentation of different visual stimuli

Weakness
- ERP’s are so small and difficult to pick out from other electrical activity in the brain. It requires a large number of trials to gain meaningful data. This places limitations on the types of questions that ERP’s can realistically answer
- Only strong sufficient voltage changes generated across the scalp are recordable. Important electrical activities occurring deep in the brain are not recorded meaning that the generation of ERP’s tends to be restricted to the neo-cortex