Describe and evaluate scanning techniques as a way of investigating the brain (16 marks)

There are many ways that biopsychologists can study the structure of the brain in a scientific way. The four main methods are functional magnetic resonance imaging (fMRI), electroencephalograms (EEG), event related potential (ERP) and post-mortem. fMRI is used whilst certain tasks are performed, which creates an image of the brain and shows which areas are most active during the task, as blood flow is increased in these areas - this helps with our understanding of localisation of function. EEG measures electrical activity in the brain and helps to diagnose certain conditions, especially those which are characterised by irregular neutron firing such as epilepsy. ERPs are useful in finding specific responses to certain stimuli, by ignoring extraneous data in EEGs and leaving just data relating to a specific stimulus. Post-mortems take place after death and allow psychologists to look at brain structure which would not be possible during life. 

A strength of fMRI scans is that they have high spatial resolution. They are able to pinpoint areas which are functioning to a millimetre accuracy, meaning that it is easy to tell which area of the brain (e.g Wernicke, Broca) is being utilised during a certain task. However, an issue with fMRI scans is it is extremely expensive (making it an inaccessible method for many) and it has poor temporal resolution, which means it does not show which areas are active in real time. This is important to consider as though fMRI can be effective when studying localisation of function, there are drawbacks for the method. 

A strength of EEG is that it has practical applications in diagnosis of sleep disorders and certain conditions, and also have high temporal resolution. EEGs are able to determine brain activity to an accuracy of a millisecond. Its ability to be used in diagnosis and further understanding of conditions is invaluable to the lives of some people who are affected by such conditions, and can contribute to the treatments and managements of them. However, EEG has poor spatial resolution, meaning it cannot tell which part of the brain is being used or is misfiring, possibly causing for treatments to be too general. This is important to consider as while EEG is effective in some ways, it may have some negative aspects which should be considered. 

A strength of ERP is that it addresses the weaknesses of EEG and is useful in research into cognitive functions and concepts such as the working memory model. ERP is able to be more specific and relate EEG data to certain stimuli, which allows biopsychologists to correlate cause and effect relationships. However, ERP also have drawbacks, mostly a lack of standardisation reducing reliability, and extraneous variables not being controlled adequately, reducing validity. This is important as though ERP may be useful, it should be considered that there are weaknesses of the technique. 

A strength of post-mortems is that they can improve medical knowledge as well as provide evidence for localisation of function. In some individuals who passed away with certain conditions, such as alcoholic dementia, (Korsakoff's syndrome), post-mortems can help medical professionals understand the areas damaged by the disease, how it affects structure and how it can be treated. However, individuals with severe terminal illnesses or low processing ability due to brain damage cannot effectively consent to post-mortem, raising ethical issues around the technique. It is important to weigh up the impact of this technique on scientific advancement, as well as ensuring ethics are met.