The Feeling of What Happens: Body and Emotion in the Making of Consciousness by Antonio Damasio 385pp, Heinemann, £20
The nature of consciousness is a traditionally lofty subject, which has long seemed the province of philosophers rather than scientists or doctors. In this book, the eminent neurologist Antonio Damasio tries to show the general reader how consciousness can be explained by experimental science. He guides us through his life's work: to understand not only how the brain forms mental images, but how we have a sense of a self-knowing that we are doing so.
Damasio's previous book, Descartes' Error , was named after the Western thinker who is often held responsible for the dualism of mind and body that Damasio challenges. The Feeling of What Happens elaborates upon his theory that "the part of the mind we call the self" is grounded on a "collection of nonconscious neural patterns standing for a part of the organism we call the body proper".
Damasio finds the roots of the singularity of self in the simple observation that we each have one body. This is not a new idea. He finds precedents in Kant, Nietzsche, Freud and Merleau-Ponty, and sees some reassuring efforts in contemporary philosophy to establish a close relationship between cognition and the representation of the body.
Scientists tend to be wary of investigating the self-consciousness that is the habitual concern of philosophers. Damasio cites Francis Crick's caution in his The Astonishing Hypothesis: The Scientific Search for the Soul that "there are many forms of consciousness, such as those associated with seeing, thinking, emotion, pain and so on . . . Self-consciousness - that is, the self-referential aspect of consciousness - is probably a special case of consciousness. In our view, it is better left to one side for the moment". In Damasio's opinion, the omission of self-reference may hamper efforts to understand consciousness as a whole.
Behind this book lies an ongoing research project, which aims to devise testable hypotheses regarding the neuroanatomy of consciousness. Until recently, advances in the area of brain function were made by observing peo ple with sites of brain damage called lesions. Damage to circumscribed regions gives rise to particular deficits and behavioural change. A small blockage to an artery feeding part of the brain which organises the production of speech can lead to a person becoming incomprehensible, whilst still able to understand everything around them. It was often necessary to wait until autopsy to fit the symptoms of neurological illness to the cause. In this way, over the years, a large number of brain functions have been traced to specific areas of the brain.
In the last 20 years, new techniques in imaging have enabled neurologists to examine 3D pictures of the living brain, while cognitive and/or behavioural tests are performed. The information is displayed on a computer screen. Brain activity levels can be assessed using PET (positron emission tomography) or fMRI (functional magnetic resonance imaging). Changes in electrical potentials can be measured from scalp, skin and brain surface and can indicate areas of abnormal brain activity.
Damasio is utterly convincing in his contention that there will one day be an anatomy of conscious ness. However, there may not be one site or "seat" of consciousness. Damasio divides consciousness into "core consciousness" and "extended consciousness". Core consciousness is not exclusively human. Its scope is the "here and now". Extended consciousness is individual identity, providing a sense of past and future. Extended consciousness can be damaged, without affecting core consciousness, but damage to core consciousness spells disaster for consciousness as a whole.
Damasio illustrates this theory with fascinating examples from his clinical work. He describes a man called David, who developed encephalitis at the age of 46, sustaining major damage to his left and right temporal lobes. From this time on, he was unable to learn any new facts. Each time he sees a member of his family, it is as if he is seeing them for the first time, although, once he establishes who they are, he has some knowledge of their names and relationship to him. David manages to keep up with the social conventions of a conversation, but lacks autobiographical memory to inform his social behaviour. His extended consciousness is impaired. Damasio draws two conclusions from this: that factual knowledge is not a prerequisite for core consciousness, and that those regions of David's brain that are damaged cannot be responsible for core consciousness.
The link between emotion and consciousness is Damasio's central theme. For him, consciousness develops from emotions, and emotions inform our reasoning and decision-making. Evidence for this is drawn from the investigation of people, who were entirely rational until they sustained neurological damage either by stroke, tumour or head injury. Although logical thinking remained intact, they would make irrational decisions, which were disadvantageous to themselves and others. Damasio suggests that it is the emotional input to the nervous system that affects the mechanism of reasoning. He concludes that a reduction of emotion is as prejudicial to rationality as excessive emotion. Clearly emotions are no substitute for reason, yet reason is curiously handicapped without them.
The story of a woman called S shows how a damaged emotional response can affect the very ability to survive. S suffers from a rare condition, Urbach-Wiethe disease, which is characterised by abnormal deposition of calcium in the skin, throat and brain. In the case of S, a part of her brain - the amygdala - was damaged bilaterally. S could learn new facts, had no problems with language or movements and had normal basic intelligence. However, it was as though she were devoid of negative emotions such as fear and anger. She was unable to attribute correctly the emotion of fear in the face of others, or to mimic an expression of fear. If all faces appear trustworthy and approachable, it is hard to appreciate social risks, and this leads to increased vulnerability to environmental dangers.
The Feeling of What Happens comes to life when Damasio writes about neurology. The case histories are beautifully crisp and simple. While his explanations will be understood by a variety of readers with a scientific background, some of the more abstract discussions may be difficult, though not impossible, for the general reader to comprehend. While he acknowledges the work of contemporary philosophers of consciousness, it can be hard, without prior knowledge of this area, to see what their arguments are in relation to his own, and thus to assess how radical his own research has been. He relies on a basic knowledge of books like Daniel Dennett's Consciousness Explained (1994), Thomas Nagel's The View from Nowhere (1986) and John Searle's The Rediscovery of the Mind (1992). Whilst he describes consciousness studies as having been devised "by a handful of philosophers and scientists, independently, unwittingly and unexpectedly", in fact he makes this field seem rather clubbable.
Yet, daunting though this theme might seem, there are rewards for those who are willing to meet the challenge of reading Damasio's book. There are few more interesting subjects in the world than the source and workings of consciousness and rarely has there been an author better qualified to explain them.
