Review of Damasio: Body and Emotion in Consciousness

Book of the Month:
JRSM 2000; 93: 99-101

Review of
The Feeling of What Happens:
Body, Emotion and the Making of Consciousness.
Antonio Damasio. Heinemann: London, 1999.
ISBN: 0 439 00773 0.

Bruce G Charlton MD
Reader in Evolutionary Psychiatry
Department of Psychology
University of Newcastle upon Tyne
NE2 4HH
England

Editor-in-Chief, Medical Hypotheses

Tel: 0191 222 6247
Fax: 0191 222 5622
E-mail: bruce.charlton@ncl.ac.uk

Antonio Damasio occupies an extraordinary position in the world of neuroscience. On the one hand, he is an internationally famous physician and scientist, publisher of many papers in the most prestigious journals, and author of the best-selling book Descartes' Error. On the other hand, his achievement is seriously under-rated.

In my view, Damasio is not ‘merely’ a successful career neuroscientist and popularizer; he is the major living figure in his field, possessor of the most profound understanding of higher human cognition: in short, a genius. If I was able to nominate one individual for the Nobel prize, it would be Antonio Damasio.

This may sound like wild over-praise, but it can be justified. If a genius is someone who has two ideas, then Damasio justifies the sobriquet. Firstly, he achieved the long sought-after integration of emotions into the mainstream explanatory schema of cognitive neuroscience; so we can now understand emotions in exactly the same way as we understand vision. And secondly he solved the problem of the nature of consciousness - a topic which forms the substance of his latest book The Feeling of What Happens. I will do my best briefly to outline these seminal theories.

Emotions are brain representations of body states

Damasio’s theories are based upon the standard neuroscientific conceptualization of brain function, a framework which originally derived from work on the visual system. Essentially, objects in the external environment cause patterns of activation of retinal receptive cells, and these retinal patterns are processed serially and in parallel to extract the visual aspects of the environment that we perceive. Patterns in the external world correspond with patterns of nerve cell activity in the brain, and these brain patterns are termed cognitive representations. So ‘thinking’ is done by means of patterns of nerve cell activation.

Damasio has suggested that while the senses of vision, hearing, touch, taste smell function by nerve activation patterns that correspond to the state of the external world; emotions are nerve activation patterns that correspond to the state of the internal world. If we experience a state of fear, then our brains will record this body state in nerve cell activation patterns obtained from neural and hormonal feedback, and this information may then be used to adapt behaviour appropriately.

For example, if we see the approach of an aggressive looking man, this image provokes sympathetic nervous system activation which affects the internal environment of the body by its action on smooth muscles and hormonal levels. This change in body state corresponding to the emotion that we call fear leads to patterns of nerve cell activation in the brain. Emotions are therefore cognitive representations of body states that are part of a homeostatic mechanism by which the internal milieu is monitored and controlled, and by which this internal milieu influences behaviour of the whole organism.

Emotions are based on internal body environment which act as inputs into the brain, just as visual or auditory information is an input to the brain from the external environment. Indeed, in evolutionary terms, the brain is primarily an organ for homeostasis - a centre which collects and collates feedback on body states, and acts to maintain constancy of the internal milieu. This concept vastly clarifies the role and nature of emotions, and allows them to be studied using the full force of integrated modern neuroscience.

Emotions and consciousness

Emotions are also vital to the higher reaches of distinctively human intelligence. Contrary to some popular notions, emotions do not ‘get in the way of’ rational thinking - emotions are essential to rationality.

Damasio’s group is probably best known for their case studies of reasoning in people with neurological damage to their emotional systems. For instance, people with damage to the ventro-medial part of the pre-frontal cortex (VMPFC) may be able to perform to a high level on most language and intelligence tests, but they display gross defects of planning, judgement and social appropriateness. Damasio’s group have shown that these defects in patients with VMPFC damage are caused by their inability to respond emotionally to the content of their thoughts.

For instance, using the above example, when thinking about an aggressive man, a normal person would physically experience the emotion of fear, because thoughts can lead to emotions. Thinking-about frightening events can activate the sympathetic nervous system, just as real life frightening events can cause activation (this is why people read ‘thrillers’ - to make themselves frightened). But when a person has VMPFC damage they will not activate the emotion of fear, hence they will not be able to make appropriate judgments of this individual, nor will their plans take into account his aggressive disposition. A person with VMPFC damage can not be frightened by reading about a murderer - although he would be frightened by meeting one in real life.

Somatic marker mechanism

Perhaps the most fertile of Damasio’s ideas, and one which has had a major influence upon my own work, is the idea of a ‘somatic marker’ mechanism which forms the basis of human consciousness. The somatic marker mechanism is the way in which cognitive representations of the external world interact with cognitive representations of the internal world - where perceptions interact with emotions.

Many animals display awareness of external sensory stimuli (eg. monkeys may be aware of specific aspects of the visual environment they see, as demonstrated in innumerable experiments). But what is unusual about humans is that we are also aware of our bodies, our ‘selves’, and this inner-directed attention forms the root of consciousness. Damasio argues that consciousness is based upon an awareness of the ‘somatic’ milieu, and that awareness of inner states evolved because this enables us to use somatic states (ie. emotions) to ‘mark’, and thereby ‘evaluate’, external perceptual information. And this interaction of cognitive representations occurs in working memory (probably located in the dorso-lateral prefrontal cortex).

For example, when registering the identity of an aggressive man, the body state of fear in response is also registered. In order to use this in planning future action, the brain needs to create a cognitive representation that contains both the external perceptual information (identity of the man) and the internal emotional information (fear in response to that particular man) - and this is achieved in working memory by the simple device of having evolved the ability to project body state representations into working memory where we can be aware of them.

The social nature of intelligence

The main incompleteness of Damasio’s theory at present is, I believe, an insufficient acknowledgment of the fundamentally social nature of human intelligence, as elucidated originally by Nick Humphrey.

The concept of social intelligence is the idea that the main problem which human ancestors faced, the problem that most affected human ancestors differential chances of reproductive success, was competition with other people. This means that human consciousness and human language evolved and are adaptive specifically for social tasks, and for those human social conditions which prevailed at the time of rapid frontal cerebral cortex expansion. Consciousness was ‘designed’ by natural selection for dealing with other people.

Comments here-and-there in Damasio’s work suggests that he has would go along with this idea, but his examples and explanations do not emphasize it. Some of my own work has been concerned to fill this gap in Damasio’s reasoning. For instance, I suggest that the somatic marker mechanism evolved specifically to perform the job of ‘strategic social intelligence’. Strategic can be contrasted with ‘Tactical’ social intelligence, which is found in many animals, and does not require large cognitive capabilities. Strategic social intelligence is the ability to perform internal cognitive modeling of social relationships, in order to understand, predict and manipulate the behaviour of others - and is found only in animals with a large pre-frontal cerebral cortex (humans and other apes and primates, dolphins, elephants and some other social mammals).

I believe that the somatic marker mechanism (SMM) evolved specifically to perform internal modeling of social relationships, and that the SMM is also the basis of what has been termed the ‘theory of mind’ mechanism. Theory of mind is the mechanism that enables us to interpret the mental states of other people - their dispositions, intentions and motivations. In other words, it seems that Damasio’s work stands at the very heart of our attempts to understand what it is to be distinctively human, and to be a human among other humans. His books lay the basis for an agenda for future research which could hardly be more exciting or important.

Damasio as writer

I hope I have sufficiently emphasized the richness of work here. But I must admit that neither Descartes' Error nor The Feeling of What Happens yield this interpretation easily. The books can be read on two levels. At one levels there are fascinating stories about fascinating patients - and it is this ‘Oliver Sacks’ level that has brought Damasio to public attention. There are purple passages, references to high (and low) art, personal anecdotes and engaging confessions. But when it comes to the ‘neuroscience’ parts of the books, we are - in my opinion - confronted by writing of extreme complexity and difficulty.

I read Descartes' Error four times, very slowly, in order to understand it. Clearly, it was well worth the effort; but this is much more concentrated attention than I am usually prepared to devote to a book. And most readers of Descartes' Error have not been so dedicated. Consequently, very few of Damasio’s readers - not even the professional neuroscientists - have followed him into the extreme ramifications of his arguments. This is, I suspect, why the depth of his achievement has not been grasped.

Damasio is a pioneer at the furthest reaches of understanding the human brain and human intelligence. He is sending back reports expressed as clearly as he can manage to make them - but the job is an immensely difficult one, this is unfamiliar territory. The parallel that springs to mind is the work of WD Hamilton and GC Williams on evolutionary theory in the early and mind 1960s in which they revolutionized our understanding of animal cooperation. However, the magnitude of their achievement was not appreciated for more than a decade until their work had been ‘translated’ by the brilliant communicator Richard Dawkins. Perhaps Damasio will need to wait for help from a ‘Dawkins’ before his achievement is properly recognized.

In the mean time, both Descartes' Error and The Feeling of What Happens are essential reading. Although they masquerade as ‘popular science’ they are ground-breaking classics of psychology and neuroscience on a scale that can be compared with William James immortal Principles of Psychology (which started life as an undergraduate text book). These are books to buy, keep and ponder. Do so, and you will be ahead of the ruck by at least a decade.

E-mail
bruce.charlton@ncl.ac.uk