Biopsychology: Studying the Brain - Post-Mortem Examination

Another method of investigating the brain is post-mortem examination, where researchers will study the physical brain of a person who displayed a particular behaviour while they were alive that suggested possible brain damage.

An example of this technique is the work of Broca, who examined the brain of a man who displayed speech problems when he was alive. It was subsequently discovered that he had a lesion in the area of the brain important for speech production. This later became known as Broca’s area. Similarly, Wernicke discovered a region in the left temporal lobe, which is important for language comprehension and processing, which is now known as Wernicke’s area.

This method of investigation has successfully contributed to the understanding of many disorders. Iverson examined the brains of deceased schizophrenic patients and found that they all had a higher concentration of dopamine, especially in the limbic system, compared with brains of people without schizophrenia, highlighting the importance of such investigations.

Furthermore, post-mortem studies allow for a more detailed examination of anatomical and neurochemical aspects of the brain than would be possible with other techniques. They also enable researchers to examine deeper regions of the brain such as the hypothalamus and hippocampus, something that is not as easy with other methods of investigation.

Evaluation of Post-Mortem Examination

Causation: One of the main limitations of post-mortem examination is the issue of causation. 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). The deficits reported could have been the result of another illness, and therefore psychologists are unable to conclude that the deficit is caused by the damage found in the brain.

Another issue is that there are many extraneous factors that can affect the results/conclusions of post-mortem examinations. For example, people die at different stages of their life and for a variety of different reasons. Furthermore, any medication a person may have been taking, their age, and the length of time between death and post-mortem examination, are all confounding factors that make the conclusions of such research questionable.

However, one strength of post-mortem examinations is that they provide a detailed examination of the anatomical structure and neurochemical aspects of the brain that is not possible with other scanning techniques (e.g. EEG, ERP and fMRI). Post-mortem examinations can access areas like the hypothalamus and hippocampus, which other scanning techniques cannot, and therefore provide researchers with an insight into these deeper brain regions, which often provide a useful basis for further research. For example, Iverson found a higher concentration of dopamine in the limbic system of patients with schizophrenia which has prompted a whole area of research looking into the neural correlates of this disorder.

While post-mortem examinations are ‘invasive’, this is not an issue because the patient is dead. However, there are ethical issues in relation to informed consent and whether or not a patient provides consent before his/her death. Furthermore, many post-mortem examinations are carried out on patients with severe psychological deficits (e.g. patient HM who suffered from severe amnesia) who would be unable to provide fully informed consent, and yet a post-mortem examination has been conducted on his brain. This raises severe ethical questions surrounding the nature of such investigations.