LITMIR.BIZ

       Chapter Two Understanding the Nature of Fear

       Brains and Minds

      The brain is the most complex object known to us. Perhaps there are more complex objects in other parts of the universe but we have yet to encounter them. Over the last fifteen years, how scientists talk about the brain has changed dramatically. Two words have entered their language - neuroscience and neuroscientist. Anyone called a neuroscientist could be a neurologist, a physiologist, a biologist, a chemist, a psychologist, an electrical engineer or even a quantum physicist. People skilled in all these different bodies of knowledge are needed in the attempt to understand this most complex object.

      There has been a subtle but important shift in how neuroscientists talk about the brain. They used to talk in terms of how the brain functions, in vision, hearing and the other senses - that is, in terms of perceiving the world. Now they talk, not in terms of the brain looking at reality, but in terms of how the brain creates a picture of reality. Our brain does not show us reality. It creates a picture of reality, and the kind of picture it creates depends on the kind of experiences we have each had. No two brains ever create exactly the same picture.

      The importance of experience in what individual brains do has led neuroscientists to look more closely at what individuals do. Neuroscientists used to be concerned with simple actions, such as how we distinguish different shades of colour or two different pitches of sound. Now scientists are interested in complex behaviour. They have even ventured to discuss the problem of consciousness, something which up till recently had been banned from scientific discourse because it was ‘subjective’, and scientists should always be ‘objective’. This was why psychologists and psychiatrists studied what people did, not what people thought about what they did and why they did it.

      The study of complex behaviour immediately raises the question of how humans and animals learn. Psychologists have always favoured very mechanical explanations. They described learning in terms of reward and punishment, and assumed that what they saw as a reward or a punishment would pertain for all their subjects, whether human or animal. They thought that for all rats a sweet substance would be a reward, sour a punishment. For all children a gold star would be a reward, being deprived of sweets a punishment. Rewards and punishments were seen as levers which propelled humans and animals in certain ways. It did not occur to these psychologists that a reward was a reward and a punishment a punishment only if the person or animal receiving them thought that this was so. Some children think that gold stars are rubbish, and some children do not like sweets. From his studies of how rats learn, Dr Anthony Dickenson, of Cambridge University, concluded that rats, though they are probably not self-aware, do operate with schemas - that is, ideas about what they want. These desires, said Dr Dickenson, have to be learnt. They are not innate mechanisms in the brain.¹

      One of the excuses which some people use when they do not want to take responsibility for their actions is that they cannot help doing something because they have been ‘conditioned’ to act in this way. Such an excuse has no scientific basis. Whatever we do follows from a wish, a desire, a need, perhaps to possess or to avoid something. We may not be consciously aware of these wishes, needs and desires, but they are ideas which we have learnt from our experience.

      Whenever we learn something, the structure of our brain changes - that is, the connections between some of the neurones in our brain change. Jack Challoner, in his fascinating book The Brain, explained:

      The neurone is the fundamental unit of the brain. Neurones produce or conduct electrical impulses that are the basis of sensation, memory, thought and motor signals that make muscles work to produce movement. There are other types of cell present but they only give support and nourishment to these cellular workhorses. Neurones are like other cells in many ways: they have a nucleus and a membrane, for example. However, they differ in the way they function. A neurone has long fibres, called axons, coming from its cell body. Emanating from the axons or from the cell body itself are other, smaller fibres called dendrites. Neurones communicate with each other: electrical signals pass along the axon and dendrites, and the brain is constantly buzzing with these signals.²

      These signals are actually both electrical and chemical, but just how they operate is not yet understood. This is why the statement, ‘Depression is caused by a chemical imbalance in the brain’ is a nonsense, or, as David Healy, Reader in Psychiatry, University of Wales, called it, ‘a myth’. He added in an endnote, ‘There are variations in serotonin levels and serotonergic receptors from person to person, and these may make us more or less sensitive to the effects of SSRIs [drugs] and even to stress. SSRIs do act on serotonin, but there is no evidence of a serotonergic abnormality in depression.’³ David Wallis, Professor of Physiology at Cardiff University, explained:

      Classical theory has it that the brain uses chemicals - neurotransmitters - to convey ‘information’ between nerve cells. These chemical messages have either a positive or negative effect on the nerve cell receiving them, dictating whether or not it will become momentarily excited.

      But over the past twenty years or so, we’ve discovered [that] chemical interactions between nerve cells are far more varied and subtle than we thought. A whole second level of communication exists, in which chemicals change the properties of nerve cells or synapses in ways other than simple fast excitation. For instance they might alter the protein in a nerve cell. These types of interaction, known as neuromodulation, are much harder to pin down than classical neurotransmission.⁴

      We are born with almost as many neurones as we are ever going to have but all these neurones have a vast array of possible connections with each other. What changes and develops over time is the connections between the axons and dendrites of the neurones. Just what connections are made, and whether a connection remains and strengthens or disappears, depends on our experience - that is, on what we learn. As Susan Greenfield wrote in her book The Private Life of the Brain, ‘The degree of meaning that we covertly apportion to each person, object, event as we blunder around in the outside world will, in turn, be matched by a corresponding degree of neurone connections.’⁵

      No two people ever have the same experience. Thus no two brains have identical patterns of connections between neurones. ‘It is the personalization of the brain,’ wrote Susan Greenfield, ‘crafted over the long years of childhood and continuing to evolve throughout life, that a unique pattern of connections between brain cells creates what might be called a “mind”.’ She went on, ‘My particular definition of mind will be that it is the seething morass of cell circuitry that has been configured by personal experiences and is constantly being updated as we live out each moment.’⁶

      This seething morass of cell circuitry is the physiological basis of what we experience as our thoughts and feelings, our memories, our desires, needs and fears, our beliefs, attitudes, prejudices and opinions. All of these are ideas, some of which we can put into words, some of which we know only as visual, auditory or bodily images. Some of these ideas are conscious, some are not. All of these ideas form a picture of ourselves, our world and our life in its past, present and future, and give us our sense

Скачать книгу