Everyone knows the expression ‘a broken heart’. But nobody knows yet why people have a greater chance of dying in the period following the death of a loved one.
Science has always tried to link body and mind. Character was formerly attributed to fluids in the body, whereas today scientists are inclined to believe that physical disorders can be caused by a particular mental state. It is thought, for example, that people with a certain type of character have more chance of having a heart attack or an ulcer.
Knowledge of how the body and the mind interact is, however, largely speculative. It is difficult, for example, to explain precisely how an ulcer develops, even though it is known that it is a psychosomatic complaint – that is, physical disorder largely caused by tension. Much more difficult are the physical complaints, such as pain in the back, which are not accompanied by any visible abnormality. The body and mind lie very close together in these cases. Often, tension is found to underlie the complaint and drugs are of little help. Oriented as it is to abnormalities that are clearly demonstrable and can be treated by means of drugs or other forms of intervention, the medical profession does not really have any answer.
It is only in recent years that people have begun to realize that mental processes play a part in nearly every physical disorder, and that many complaints should be approached with both body and mind in view.
Body and mind
Philosophers have been interested in the relationship between body and mind since the time of the ancient Greeks. The French philosopher Rend Descartes (1596-1650) believed that matter (body) and mind were separate things. The body was what we could see by dissection, for instance, but no amount of dissection could demonstrate the presence of mind. Descartes also placed great stress on the reality of mind; in some ways he thought it more ‘real’ than matter. That is probably why he made the famous statement: ‘I think therefore I am.’ Although body and mind can be thought of as separate things, our everyday experience teaches us that there certainly is a unity. Descartes claimed that the interaction between the body and the mind occurred in the pineal body, a gland in the brain now known to have an influence on many time-based changes in the body. In the years since Descartes a vast amount has been learned about the functioning of the brain. But scientists tend to have a very simplified view of the body. Sometimes our body is described as being just a – very intricate – machine. This point of view has brought us far from even the beginning of an answer to the question how the unity of body and mind can be explained. For example, there is much evidence that mental events are based on chemical processes in the brain – a view that was once described by the saying ‘no phosphorus, no thoughts’. Today some psychiatrists explain depression by assuming an excess or a shortage of certain chemical substances in the brain. Such knowledge, however, does not make clear what it is like to be a person: it does not tell what the experience of swimming feels like, nor what it is to be sad.
How the brain works
The human brain is the body’s control centre. It occupies most of the inside of the skull, and from the age of about six years weighs about 1.4 kilograms. It consists of about 50 billion nerve cells or neurons. Each of these cells is interconnected with dozens or even thousands of other neurons. It is a large information-processing system: nerve cells can influence the activity of each other by sending impulses along their offshoots and by releasing chemical substances called neurotransmitters. All this activity requires energy so that, although the brain comprises only two per cent of one’s body weight, it consumes 20 per cent of the total oxygen supply when at rest. Cutting of the oxygen supply (by interrupting the blood supply) results rapidly in brain damage or brain death. Mental processes are based on the activation of specific interconnected neurons. Scientists can now say at what place in the brain such mental processes occur. This approach must not be confused with phrenology, which tried to localize such mental characteristics as reticence, cunning and eroticism. These are really personality traits.
The modern approach, called neuropsychology, tries to localize cognitive functions within the brain. It has had most success with simple functions. For example, the response to light is transmitted from the retina to the back part of the brain (the occipital area). Here cells react to simple retinal stimulations such as those from a strip of light on a dark background. In nearby areas are cells that respond only to specific more complicated visual signals, such as an empty square. This is how the brain builds up moving pictures of the world outside. What you ‘see’ is a mental event as well as a process of activation of brain cells. Speech is located for most people on the left side of the brain. Parts of the temporal lobe (the area of the brain protected by the side of the skull) receive sound signals from the nerves of the ear in the same way as the occipital lobe receives light signals. Sound signals recognized by the brain as speech activate cells in a particular area at the top of the left temporal lobe. Close to this and to the left in the frontal lobe is the area responsible for generating speech. Strokes that destroy these areas destroy the power of understanding speech, speech itself or both. Nerve fibres from the surface of the body travel to an area just behind a line down the centre of the brain which is responsible for the sensation of touch. Just in front of this line is the area responsible for movements of the body.
In between these main areas are parts of the cerebral cortex that put all the information together to make coherent pictures of the world. In the very front of the brain is the area where forwardthinking occurs. The destruction of this area leaves people unable to make the complicated decisions we all need to cope with life in society.
Deep structures of the brain
Deep in the brain are areas responsible for mood and memory, and others that regulate processes in the rest of the body by influencing the autonomic nervous system that governs reflex action. In this way emotions (mental events that are also brain processes) can influence events in the body. For example, during arousal or excitement the pupil of the eye increases in diameter. This occurs because the events in the brain activate the sympathetic nervous system. The impulses pass down the brain stem and out along nerves going to the eye. There they are connected to the muscles which open up the iris and make the pupil look larger. Fashionable ladies in the nineteenth century used to put drops of the narcotic atropine (belladonna) in their eyes to make this happen ar-tificially, because men were thought to find it attractive.
The brain has a logical structure. The parts that most need to ‘talk’ to each other are closest to each other; for example, the sound-receiving area and the speech-receiving area. There is also a specialization between the two halves of the brain. The left side is concerned with sequential patterns – speech, logic and calculation – whereas the right side is concerned with spatial patterns – drawing, music and ‘aesthetic’ experience. It will be clear that a well-functioning mind implies an intact brain. This relation can even be expanded as is shown by the saying: ‘a healthy mind in a healthy body’. Mental dysfunctioning can be caused by a brain disease, but also by other conditions such as a simple influenza or by alcohol abuse. It is possible too, to look at the relationship between body and mind the other way round. The development of psychosomatic disorders, such as a type of high blood pressure or gastric ulcers, is strongly influenced by a person’s mental condition.