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Brain function means how the brain works. So experiments that investigate brain function, investigate how the brain works. Interestingly, after huge advances in other parts of medicine, we know relatively little about brain function.

Studying people with brain damage

Throughout history, studying people with brain damage has been the most common way of investigating brain function. Perhaps the most famous scientist to do this was Paul Broca (1824-1880). His work was so important that a part of the brain was named after him, Broca's area. This is a small part of the frontal lobe that is associated with language. He studied the brains of people who had speech difficulties that had arisen from head injuries. He found that they all had lesions on the same part of the frontal cortex in the cerebrum. Lesions are wounds, ulcers, abscesses or tumours. This was the first time that a part of the brain had been linked to any function.

Wernicke's area is another part of the brain. This is named after the German scientist Carl Wernicke (1848-1905). Shortly after Broca wrote about his findings, Wernicke began his own research. He found that not all issues with language developed after accidents came from the Broca area. He noticed that damage in another area resulted in people not being able to understand language.

Strokes

Strokes are a very common form of brain damage. They arise when a blockage reduces the blood flow to the brain. Commonly, people who have suffered a stroke lose control of their muscles on one side of their body causing it to droop. However, strokes cause other problems too. If the area of the brain without blood is at the back, then sufferers often have problems with their vision even if their eyes are working correctly. If the area of the brain with damage is at the front, then problems can arise with memory and maintaining attention.

Positron emission tomography

Recent developments in medical scanning technology have rapidly developed the understanding of brain function. In positron emission tomography (PET) scans, water containing radioactive oxygen is injected into the blood. This moves around the body and enters the brain. The radioactive water gives off gamma rays which can be detected. Parts of the brain that are working will give off more gamma rays. Medical researchers can therefore see what parts of the brain are working when patients complete certain activities.

Difficulties in studying brain function

There have been developments in the understanding of brain function since the work of Broca and Wernicke but these have not been quick. There are some real difficulties in studying brain function. These include:

• People suffering with brain damage may have reduced life expectancy.
• People who live with brain damage as a result of injury are thankfully rare and not always willing to take part in medical research.
• Some people with severe brain damage may be unable to agree to the experiments and so their closest relatives may face the difficult decision of agreeing. This is an ethical issue which means people may have religious or moral reasons for agreeing or disagreeing with it.