It is very difficult to do research on the processes that take place in our brains. This is because it is not possible to take the brain apart and study it, as you would do with the engine of a car. But even if we did have the ability to do this, we would not know what the different parts of the brain are involved in. In that case, we could only say something about the structure of the brain.
Fortunately, over the years other ways of researching the functions of brain areas have been developed. These ways are divided into different categories, because you can measure different things with them.
Correlating anatomy with behavior
This involves looking at whether people with unusual behaviors also possess unusual features in the brain. The oldest method in this category is phrenology. This method was used in the 19th century, and consisted of explaining behavior through the shape of the skull. Intelligence, according to this method, was determined by the circumference of your head, and language ability by a spot just above the eyes (the language tubercle). The findings of phrenology turned out not to be entirely accurate, since skulls differ from person to person, and in this sense have nothing to do with what lies beneath the surface!
In the period that followed, brains of deceased people were used to examine the anatomy of the brain. The results of these studies made a great contribution to the knowledge of the anatomy of the brain, but unfortunately no conclusions could be drawn about the function of the different areas.
Nowadays we can also study the anatomy of the brain in living people. In this way a lot of people can be examined. This not only makes the results of the studies more reliable, but also allows many people with the same behavioral abnormality to be studied. Thus, a statement can be made about the relationship between anatomy and behavior. The methods used to do such research are CT and MRI.
Recording brain activity during behavior
Some methods look at which brain areas become active during certain actions, such as sleeping, fighting or problem solving. In animals, it is easy to examine this, by placing electrodes in the brain. These electrodes are sensitive to the electrical changes that occur when the brain is active. Substances can also be injected into the brain that cause certain neurotransmitters to be affected. This allows us to see which areas are using this neurotransmitter.
In humans, the above methods cannot be used because there is a high chance of damage to the brain. There are other methods that can measure and record brain activity during a certain action. These methods are called EEG, MEG, PET and fMRI.
Research into the effects of brain damage
Research can also be done on people with brain damage. This involves looking at the exact location of the damage, and how the damage affects certain functions. Perhaps there are actions that the patient cannot perform since the damage occurred. A very well-known application of this method is that of neurologist Paul Broca and his patient Tan... This patient could no longer talk, and was found to have damage to an area that has since become known as Broca's area.
One problem with this method is that all patients have different brain damage. The issue is not only the location of the damage, but also the extent and the severity of the damage. Because of this problem, it is never possible to properly test whether a theory is certainly correct.
With animals, this problem does not exist. In animals, controlled damage can be done to a specific part of the brain. This can be done in many animals simultaneously, so that it can be seen which actions are really disrupted by the removal of this area. Of course we cannot intentionally cause damage to human brains, but there is a method of causing temporary lesions. This method is called TMS, and it can be used to see what happens when you "turn off" an area for a while.
Researching the effects of brain stimulation
Instead of looking at what happens when a brain area is turned off, it is also possible to look at what happens when you artificially activate a brain area. In animals, this is done by implanting electrodes in the brain, which deliver short shocks that activate neurons. In humans, brain stimulation can be done with TMS, a method that thus has various applications.
Author: Myrthe Princen (translated by Melanie Smekal)