Critically consider one invasive method and one non-invasive method of studying the brain

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he ablation technique involves surgically removing or destroying brain tissue. A study into this technique was conducted by Flourens (1820); who showed that the removal of thin slices of brain tissue; resulted in them displaying poor co-ordination and sense of balance but, they experienced no other difficulties.

Meanwhile, lesion production involves deliberately injuring a specific area of the brain and observing the behavioural changes that occur as a result. The aim of lesion studies is to tell us something about how different areas of the brain are connected. However, there are several flaws with this invasive method of studying the brain. One of these is that, since experiments of this type are carried out on animals, the results cannot really be generalised to humans. Also, there are ethical issues involved in the use of animals in experiments that could cause distress.

Other invasive methods of investigating the brain include; chemical stimulation of the brain and Electrical stimulation of the brain (ESB). One such investigation was conducted by Olds + Milner (54). In this experiment, they found that when they stimulated the hypothalamus of rats, they appeared to increase the frequency of whatever behaviour they were engaged in. Further research that they conducted on rats also hinted to the existence of both “pleasure centres” and “pain centres” within the brain. Again, as with all invasive methods; there are ethical considerations such as the possibility of distress being caused to the rats; the lack of an ability to generalise the results of the experiments to humans, (since the experiments were conducted on animals); and the issue of “localisation of function” against “distributed function”

An alternative to using an invasive method would be the use of non-invasive techniques such as an EEG, which records the electrical activity of the brain through the use of electrodes placed on a person’s skull. However, such a method is imprecise, not really showing the “activity” of the brain.

Alternatives to the EEG include scanning techniques such as a CAT or MRI Scan. A CAT scan is performed by x-raying the head and using a computer to produce a low resolution, 2D image of the brain (which, are the main disadvantages to a CAT). A MRI meanwhile, involves placing the head in a magnetic field and bombarding the head with radio waves. The main advantage of a MRI over a CAT is that a 3D image is produced. However, real time activity is still not shown. In order to see this, a PET scan would need to be used.

CAT’s, MRI’s and PET’s are all used within medicine to help diagnose diseases such as epilepsy/schizophrenia through analysis of the results that are obtained from the scans.

However, more recent techniques help to show brain function holistically e.g. fMRI, MEG etc. These provide a much clearer image of the structure of the brain thus providing more information about the brain for the “localisation of function” versus “distributed function” debate. They also show more clearly the individual functions of the brain. However, they are very expensive and difficult to access, as e.g. a MEG must be carried out in a magnetically shielded area to prevent inaccurate readings being obtained.

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