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Describe and critically assess one invasive and one non-invasive method of investigating the brain.

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Psychology Exam Questions 1. Describe and critically assess one invasive method of investigating the brain. (12) There are many different invasive ways of investigating thee brain including chemical stimulation, ablation and lesioning. All invasive methods artificially stimulate, and actually affect the brain. For my example I am going to look at electrical stimulation. The first person to study electrical stimulation on the brain was by Olds and Milner in 1954. They applied a weak current to the pleasure centre of the brain to a number of rats using small electrodes. The rats themselves could trigger the electrical stimulation themselves by pressing a lever. They found that apart from eating and sleeping the rats would press the lever for hours of end. This was very important research at the time and showed how electrical impulses affect the brain, but it has a number of weaknesses. It is difficult to generalise these findings to humans. ...read more.


These discoveries where quite magnificent at the time and led the way for more research into the brain and then later development of PET and MRI scans. But there are still a great number of problems in this research and any research using electrical stimulation. For a start in the above experiment there was a very small sample of people used and therefore the results cannot be generalised to the rest of the human population. Also all of the patients had either brain tumours or epilepsy and therefore their brains were "abnormal" anyway. So none of the findings can be generalised to people with "normal" functioning brains. All experiments using electrical stimulation on the brain also lack ecological validity due to the fact that the impulses are abnormal and artificial. Therefore they may not reflect the actual function of the cortex. Also no one really knows what affect theses impulses are having on the brain, i.e. ...read more.


Most epileptics have normal brain structure and no brain damage yet suffer serious brain defects which can only be seen in the electrical functioning of the brain and hence be seen on the EEG scans. EEG's can explain whether an epileptic has focal (one part of the brain affected) or multifocal (several areas affected). This can help a doctor decide if drugs are an appropriate treatment or whether neurosurgery might help. Other people have used EEG in similar ways to the above. Othmer et al (95) used EEG as a biofeedback for improving Attention Deficit Hyperactivity Disorder (ADHD) and specific learning difficulties. Although EEG are a very useful and important way of investigating the brain there are a number of disadvantages and problems. The scans can only measure the surface electrical activity of the brain and not the deeper activity (which may be important in a number of syndromes such as epilepsy). Also it is a very broad and wide-ranging scan. Although it can show whether a persons brain activity is normal or not, it cannot specifically pinpoint the region of the brain producing this activity. ...read more.

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