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DH Wilkinson once calculated, rather whimsically, that an average human life lasts about 10 9 seconds whereas an average sensory trace lasts less than one second pace Buddha, St John of the Cross and an extremely select group of others. Confined though I am within my own solipsistic nutshell, I know I am more than the sum of a billion-odd parts, and suspect that the same might be true of my fellow humans as well.
But between sensation and experience yawns a dreadful gap, long lamented by philosophers, and latterly by neuroscientists too. His book is a well-written and commendably comprehensive survey of many of the big ideas in modern neuroscience.
It is manifestly not an answer to the question posed by its title. LeDoux's central concern is nothing less than the synaptic interface between the ancient emotional circuitry of the limbic brain and the neocortical apparatus of cognition and motivation.
The operation of this interface in emotional and goal directed behaviours and the mechanisms by which it is changed by experience are the great themes of his book. His expositions have an easy charm that belies their author's eminence.
As one of the pioneers of emotional cognition, LeDoux is entitled to his dauntless vision of the brain as the canvas of our evolutionary and personal past. He has stripped away the filmy varnish of our sentience to reveal the ancient triptych of cognition, emotion and motivation.
Neuroanatomy, cellular neurophysiology, neurotransmitter pharmacology, systems physiology, behavioural psychology, functional brain imaging, clinical neurology and psychiatry are all duly painted in.
And yet, when all's said and done, our intricate inner lives are very probably unique, quite different in kind as well as in degree from those enjoyed by the many animal species that populate LeDoux's book. In his final chapter, LeDoux rightly rejects the notion of a coordinating homunculus, crouched somewhere inside the skull, in favour of a set of seven organizational principles that confer plasticity on parallel synaptic networks and permit the brain to reinvent itself as it learns.
And yet, his principles leave oddly untouched the central paradox of our experience of the grainy and chaotic world—its seamless perceptual unity in time and space. It may indeed turn out that a sense of extension in time is fundamental to the idea of self, at least as far as human brains go; it is not at all clear that animals possess such a sense, for it anticipates a future no less than it reanimates a past.
It is evidently not dependent on any single memory mechanism, as we now understand them. For the present, it remains a true mystery; and to his credit LeDoux refuses to explain it away by resorting to neurophysiological legerdemain. The problem is, this mystery lies at the very core of human selfhood; it is the biological sine qua non upon which the existential angst of Sartre and friends is built. Our own existence cannot fill us with nausea, ecstasy, or perverse and peculiarly human mixtures of both, unless we first apprehend that we exist.
The neural machinery that LeDoux describes would be blind and mute if something about the human brain did not insist on this ontogenetic Catch The problem is no less acute in the case of our perceived spatial integrity. For LeDoux, the paradigm of a self divided is the schizophrenic patient, or perhaps the callosotomy patient with inter-manual conflict; but the clinical neurologist might point to wards filled with stroke patients who refuse even to own their left arms.
To paraphrase JBS Haldane, the brain is surely queerer than we imagine, though I trust not queerer than we can imagine. Turn to any page of Wilder Penfield's neurosurgical ancient history and you will quickly reacquaint yourself with the appalling strangeness of an organ that has stored a faithful record of all the banalities it has ever suffered, alongside all its transports of delight.
LeDoux's magnificently intelligible joining of parts is most seductive; but I am still bothered by niggling doubts.
All the same, his book has a refreshing humility. He acknowledges at the outset that his is not the whole story. Like the Danaids of Greek myth, neuroscientists may never finish this particular job with the tools they now have at their disposal: the leaking vessels of our present paradigms cannot contain the self in its brain.
Getting inside our own qualia is proving much more difficult than getting inside the atom, but that is no reason to abandon the attempt—or worse still, to convince ourselves that we have already succeeded. Non intellego, ergo sum. National Center for Biotechnology Information , U. J R Soc Med. Reviewed by Jason Warren. Author information Copyright and License information Disclaimer.
Synaptic Self: How Our Brains Become Who We Are
The brain is a wonderful territory for scientific exploration but those who study it are only a little way in from the frontier. There is an enormous area of unexplored territory. To be blunt, there is a great deal that we don't understand about the way it works. The bottom line of Joseph Ledoux's Synaptic Self is that we are our synapses.
The author of The Emotional Brain elaborates on the theory that the particular patterns of synaptic connections in our brain provide the keys to who we are. He follows that with a discussion of brain development, explaining how nature and nurture together shape the synaptic organization of the brain. Genes make the proteins that determine how the neurons are wired together, and experiences create changes in these arrangements. Synapses, the junctions between neurons, encode and store information, which is accessible to us through memory. Without learning and memory, LeDoux points out, the self would be an empty expression of our genetic constitution. He sets himself the technical task of explaining just how neuronal circuits are modified by what we learn and remember; he considers how the brain systems that underlie thinking, emotion, and motivation develop, interact with, and influence each other to make us who we are.
Synapses encode the essence of personality, enabling each of us to function as a distinctive, integrated individual from moment to moment. Exploring the functioning of memory, the synaptic basis of mental illness and drug addiction, and the mechanism of self-awareness, Synaptic Self is a provocative and mind-expanding work that is destined to become a classic. Synaptic SelfAcknowledgments 1. The Big One 2. Seeking The Self 3. The Most Unaccountable Of Machinery 4.
Love is a many-moleculed thing
The author of The Emotional Brain elaborates on the theory that the particular patterns of synaptic connections in our brain provide the keys to who we are. Many will readily concede that the activities of the mind result from physical process in the brain, but Joseph E. Ranging widely through philosophy, literature, and the history of science, LeDoux examines how we have conceptualized the relationship between brain and self through the centuries. His own contribution, based on two decades of research, begins with the startlingly simple premise that the self-the essence of who a person is-intricately reflects patterns of interconnectivity between neurons in the brain.