Describe the methods and techniques that biological psychologists use to study the brain. Explain how these can help us understand the relationship between brain and behaviour.
In this essay, I aim to describe the methods and techniques that biological psychologists use to study the brain, as well as to describe how these methods have been used to help us understand the relationship between the brain and behaviour. In order to do this I have chosen to look at the works of Roger Sperry et al (1969), Penfield and Rasmussen (1968) and the more modern method of Positron Emission Tomography (PET) scanning. While all three of these methods are vastly different, they have all enabled us to gain a better understanding of the workings of the human brain.
In the state of California in 1969, Roger Sperry and associates (Mapping Psychology, p266) pioneered the first surgery of its kind, performed on a human brain, with the ultimate aim to prevent their patient from having further epileptic fits. Epileptic fits are caused by unusual and chaotic electrical activity amongst the neurons in a particular part of the brain, and can unfortunately influence the second half of the brain via several routes, the main one being the corpus callosum. The corpus callosum is used to combine information throughout the brain. During this surgery, Sperry cut through the corpus callosum, effectively severing one of the neurological ‘paths’ used by epilepsy. The operation proved successful, as it did indeed prevent the patient from further attacks. The patient’s everyday behaviour seemed to be unchanged to the behaviour shown prior to surgery.
Although successful, this surgery did have consequences. As the surgery was carried out on only one hemisphere, post operative training, or learning, was done using one hemisphere. During testing by the experimenters, it was found that this learning was not available to the other hemisphere, and that each hemisphere could be fed with different information. This information, although effectively assimilated, could cause patients to become conflicted in what to do. This pioneering surgery lead to a greater understanding of the roles the two hemispheres of the brain plays on our behaviour.
In 1968, Penfield and Rasmussen (Mapping Psychology, p267) studied humans who were undergoing surgery to remove diseased tissue from parts of their brain. Brain surgery is able to be performed on conscious humans, as the tissues of the brain does not hold any ‘pain receptors’ and the patients therefore cannot feel pain during surgery. Electrical stimulation was carried out on different regions of their brain, and the patients were asked to report on the sensations they felt. An example of this is that electrical stimulation on parts of the temporal lobe brought back memories of incidents that occurred earlier in their life. In a number of cases, patients experiencing chronic pain had electrodes implanted in regions of the brain associated with emotion. The patients were able to control the stimulation of the electrodes, and sometimes a decrease of pain was experienced. It was assumed that the stimulation altered the electrical activity in the area associated with positive emotion, and reduced the electrical activity in areas associated with pain.
One very important source of evidence of the brain/behaviour relationship is the study of damage to the brain, either by wounds, blood vessel damage or tumours. One relatively well known cause of damage is a ‘stroke’, during which a blood vessel on the brain becomes blocked or breaks, resulting in the loss of fuel and oxygen to that particular part of the brain. In brain injury accidents, the damage to the brain is rarely limited to one part of the brain and usually affects several different areas. One of the additional difficulties found in studying damage to the brain is that, circumstances dependant, other parts of