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A book by
William H. Calvin
The Cerebral Symphony
Seashore Reflections on the
Structure of Consciousness

Copyright ©1989 by William H. Calvin.

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As with my previous books, this one has benefited greatly from the comments of a number of volunteer readers who have endured the early drafts. As other writers surely know, it is quite difficult (outside the framework of writers' workshops) to get forthright criticism of what one has included (and left out), before the manuscript is shipped off to one's publisher. I thank my wife, Katherine Graubard, for many of our discussions that have made their way into print, and for suggestions on the drafts. But she knows too much, being a neurobiologist, and scientists writing for general readers need "guinea pigs" outside the field, preferably both scientists and nonscientists, to flag the difficult spots. Few writers are so fortunate as to have a mother-in-law experienced at encyclopedia editing (Blanche Kazon Graubard), an ex-wife trained in the law who teaches writing (Kathryn Moen Braeman), and a cousin whose Ph.D. is actually in philosophy (Beatrice Bruteau). If there are any remaining passages where the author sounds pompous or muddled, it is because I have occasionally ignored their forthright advice. John DuBois, Dean Falk, Seymour Graubard, John Pfeiffer, and Christine Phillips have also kindly suggested improvements and flagged stumbling blocks. My editors at Bantam, the late Tobi Sanders and subsequently Leslie Meredith, were enthusiastic and helpful with both structure and detail. I thank them all, together with my many colleages and readers who have kept an eye open for articles of interest to me.


Woods Hole, Massachusetts
Seattle, Washington
(Summer 1986 -- Winter 1989)

Chapter Notes

Prologue: Finding Mind Amid the Nerve Cells


2 T. H. Huxley, Methods and Results (Appleton, New York, 1897), p.191.

1. Making Up the Mind:

Morning on Eel Pond

Page (in Bantam 1989 edition)
8 Loren Eiseley, from The American Scholar (1960), reprinted in the posthumous Eiseley collection The Star Thrower (Times Books, 1978), p. 37.

10 I am indebted to Harvey Pough for a description of the second-skunk scenario.

13 "The will...." H. H. Kornhuber, "Attention, readiness for action, and the stages of voluntary decision -- some electrophysiological correlates in man." In Sensory-motor integration in the nervous system, edited by Otto Creutzfeldt, Richard F. Schmidt, and William D. Willis (Springer, 1984), pp. 420-429.

14 For the three Primal Questions, I am indebted to Jef Poskanzer -- who reports that his sister heard those lines in a Harvard commencement address!

18 J. Z. Young, Philosophy and the Brain (Oxford University Press, 1987), p. 107.

19 Eugen Herrigel, Zen in the Art of Archery (Pantheon 1953), pp. 31-32.

20 Susan Allport, Explorers of the Black Box: The Search for the Cellular Basis of Memory (Norton, 1986), p. 28.

21 Ferryboat collision with piers: James M. Shreeve, "Seawater system keeps MBL organisms alive." The [Falmouth] Enterprise (8 August 1988), p. 13.

23 Deceptions, see Machiavellian Intelligence: Social Expertise and the Evolution of Intellect in Monkeys, Apes, and Humans, edited by Richard Byrne and Andrew Whiten (Oxford University Press, 1988). The story in the text doesn't appear there as such, but each of the elements of the story (omission of food cry when small quantities, leading other chimps away from food and then circling back) have been described by various researchers in the last two decades. I appear to have picked up this particular story, combining those elements in sequence, from conversations that I had with a variety of chimpanzee researchers in the summer of 1988.

25 T. H. Huxley, speech at the 1894 Royal Society dinner, London Times; reprinted in G. de Beer, ed., Charles Darwin-Thomas Henry Huxley, Autobiographies (Oxford University Press, 1983), pp. 110-112.

2. The Random Road to Reason:

Off-line Trial and Error


28 Herbert A. Simon, The Sciences of the Artificial (MIT Press, 1969), p. 97.

28 Paul Valéry, quoted by Jacques Hadamard, in The Psychology of Invention in the Mathematical Field (Princeton University Press, 1949), p. 30.

29 Portions of this introduction are adapted from my article "The Brain as a Darwin Machine" which appeared in Nature 330:33-34 (6 November 1987).

30 Friedrich Nietzsche, The Birth of Tragedy (Doubleday Anchor, 1956), pp. 84, and pp. 107-108.

30 T. E. Lawrence letter, quoted by Robert Jay Lifton and Nicholas Humphrey, In a Dark Time (Harvard University Press, 1984), p. 99.

31 Bacterium's tumbling path: See J. E. Segall, S. M. Block, and H. C. Berg's article in Proceedings of the National Academy of Sciences (USA) 83:8987-8991 (1986).

35 Shaping up via selection stories: See Richard Dawkins, The Blind Watchmaker (Norton, 1986).

36 William Smith (1817), quoted by Loren Eiseley, Darwin's Century (Doubleday, 1958), p.117.

36 Donald T. Campbell, in The Philosophy of Karl Popper, edited by Paul A. Schilpp (LaSalle IL: Open Court, 1974), pp. 413-463.

37 Peter Ashley, letter quoted by Daniel C. Dennett, Brainstorms (MIT Press, 1981), pp. 274-5.

37 Jacob Bronowski, The Origins of Knowledge and Imagination (Yale University Press, 1978, transcribed from 1967 lectures), p. 33.

38 Bronowski (1978), p. 18.

41 G. M. Goldbaum, et al. "Failure to use seat belts in the United States: The 1981-1983 behavioral risk factor surveys," Journal of the American Medical Association 255:2459-2462 (1986). See also letter to editor by Gary Goldberg in JAMA 257:1473 (20 March 1987): "[By buckling his seat belt], a driver reduces his likelihood of severe injury or death by at least 50%, if he should be involved in a serious collision... [and] the average American has a one in three chance of being involved in such a collision during his lifetime." Studies of emergency-room patients suggest that seat belts reduce the severity of injuries by more than 60 percent, e.g., New York Times story "Seat belt study..." (12 January 1989).

Since reason has clearly failed to persuade half of the American public that seat belts should be routinely worn, perhaps we should try embarrassment instead -- perhaps some bumper stickers such as:

Don't be caught dead without your seat belt!

Your life insurance company will think
you committed suicide and not pay your family.

42 Roger Sessions on Music, edited by Edward T. Cone (Princeton University Press, 1979). Originally published in The Intent of the Artist by S. Anderson et al, A. Centeno, editor (Princeton University Press 1941, 1969). Quoted in William Zinsser, Writing to Learn (1988), p.230.

42, 124 Konrad Lorenz. Foreword to Niko Tinbergen, The Herring Gull's World (Harper and Row, 1960).

3. Orchestrating the Stream of Consciousness:

Prefrontal Cortex Performances


? Edward O. Wilson, On Human Nature (Harvard University Press, 1978).

48 Mid-Cape Highway: Judging from the signs erected to warn approaching drivers, they have had a lot of trouble with this pre-Hyannis rest area over the years. The rest rooms have been removed (people still stop and disappear into the bushes), though no signs warn people not to cross the highway. Why they do not simply close the rest area is only slightly less puzzling than why anyone ever designed such a lethal combination in the first place. Then there's the story of the national guardsman during 1987 summer training who lobbed a mortar shell onto the Mid-Cape Highway, just missing a school....

48 I suppose that I sympathize with the politicians a little: After all, it was the Massachusetts voters who overturned the life-saving seat-belt requirement that the legislature passed. Massachusetts has long led the nation in damaged cars (see the New York Times story Auto Insurers Sue..., 18 October 1987), having an insurance claims rate 67 percent higher than the national average; for most of the last decade it has also led the nation in stolen cars. "About 60 percent of the state's drivers are now in a high risk pool." A psychiatrist who trained in a Boston hospital observed, "I was accustomed to parents who were anxious about the safety and achievement of their children. In contrast, Irish parents (at least some [in Boston]) were proud of their sons' heroic risk-taking. For example, one fourteen-year-old boy was stealing cars and racing them on Boston's most hazardous local expressway where his best friend had been killed in a similar escapade. The parents were proud of him. They were expressing, of course, the Irish fondness for near suicidal courage and, implicitly, the feeling, fatalistically, that death and God's mercy might be preferable to life." John K. Pearce, p.576 in Ethnicity and Family Therapy, edited by Monica McGoldrick, John K. Pearce, and Joseph Giordano (Guilford, 1982).

51 For an appreciation of Limulus, see William Sargent's The Year of the Crab: Marine Animals in Modern Medicine (Norton, 1987). "I had run-ins with shellfish wardens, town fathers, and narcotics agents. Can you imagine trying to explain to a federal agent that you are in your wetsuit, skulking about the marshes before sunrise, in order to keep your horseshoe crabs from getting wet?" (p. 16).

53 J. Allan Hobson, The Dreaming Brain (Basic Books, 1988), pp. 212-213.

54 Confabulation: Donald T. Stuss and D. Frank Benson, The Frontal Lobes (Raven Press, 1986), pp. 225-226.

56 Supplementary motor area: Mario Wiesendanger, "Organization of secondary motor areas of cerebral cortex." In Handbook of Physiology. Section 1: The Nervous System. Volume II: Motor Control, Part 2, (American Physiological Society, 1981), Chapter 24, pp. 1121-1147.

57 Switching back and forth between temporal patterns: Stuss and Benson (1986), pp. 77ff. A premotor lesion does not result in paralysis or paresis, or loss of general intention to perform, or general plan. However, speed, smoothness, and automaticity are disturbed. Luria described several neuropsychological tests that he considered particularly sensitive to pathology of premotor: Complex rhythm tapping, requiring changes in the number or intensity of beats, becomes discontinuous and fragmented and may be replaced by a stereotyped response. Even the rhythmical repetition of simple tapping may be disrupted. If required to alternate between square and sawtoothed line drawing, preservation may result.

58 Jelle Atema, "To sense the world as others sense it." MBL Science 3(1):2-3 (Winter 1988).

59 In ordinary mortals, left premotor cortex is said to dominate the sequencing of both right and left sides of the body. In a violinist, it might make some sense for right premotor cortex to handle the left hand's fingering, while the left premotor ran the bowing and orchestrated everything -- but until some expert violinists are studied with sophisticated techniques, all we have to go on is the story about ordinary mortals. Left hemisphere is widely specialized for serial-sequential activities (it isn't just premotor):

J. L. Bradshaw and N. C. Nettleton, "The nature of hemispheric specialization in man." Behavioral and Brain Sciences 4:51-92 (March 1981).

George A. Ojemann, "Brain organization for language from the perspective of electrical stimulation mapping." Behavioral and Brain Sciences 6(2):189-230 (June 1983).

Doreen Kimura, "Neuromotor mechanisms in the evolution of human communication." In: Neurobiology of Social Communication in Primates, edited by H. D. Steklis and M. J. Raleigh, Academic Press, New York, pp. 197-219 (1979).

George A. Ojemann and Otto D. Creutzfeldt, "Language in humans and animals: contribution of brain stimulation and recording." In Handbook of Physiology. Section 1: The Nervous System, Volume 5 part 2, The Higher Functions of the Brain, edited by Vernon B. Mountcastle, Fred Plum, and Steven R. Geiger (American Physiological Society, 1987).

59 A more conventional definition of prefrontal would be the cortex to which the mediodorsal nucleus of the thalamus projects. The history of the term prefrontal in comparative anatomy is much more complicated; see Ivan Divac's "A note on the history of the term `prefrontal'" in IBRO News 16(2):2 (1988), the newsletter of the International Brain Research Organization. Adding to the confusion is the use of "frontal cortex" to designate the areas sandwiched between premotor and prefrontal, as well as the cortex of the entire frontal lobe more generally.

59 Prefrontal role in strategy: Joaquin M. Fuster, "Prefrontal cortex in motor control." In Handbook of Physiology. Section 1: The Nervous System. Volume II: Motor Control, Part 2 (American Physiological Society, 1981), chapter 25, pp.1149-1178.

60 Neuropsychologists check for frontal-lobe injury using a variety of subtle diagnostic tests, such as the Wisconsin Card-sorting Task. There are now many good neuropsychology texts; A simplified introduction is William H. Calvin and George A. Ojemann, Inside the Brain: Mapping the Cortex, Exploring the Neuron (New American Library, 1980).

60 Unfolding proper sequence of actions, see Stuss and Benson (1986), p. 80. Luria suggested prefrontal cortex affects 1) maintenance and control of cortical tone; 2) regulation of the scheme or program of the action itself; 3) unfolding of the motor program is impaired (the patient cannot raise a hand that is initially under the bed covers without being given two separate commands, first to remove the hand from beneath, and then to raise it); and 4) deficit in comparing execution with original intention and correcting (they can see errors in others, indicating problem is not conceptual).

61 Prefrontal cortex monitors narratives: B.L.J. Kaczmarek, "Neurolinguistic analysis of verbal utterances in patients with focal lesions of frontal lobes." Brain and Language 21:52-58 (1984). Suggested that the left dorsal-lateral frontal cortex is important for sequential organization and that the left orbital frontal lobe is important for direction of a narrative through monitoring.

For another view of the lesion and prepotential literature, see H. H. Kornhuber, "Attention, readiness for action, and the stages of voluntary decision -- some electrophysiological correlates in man." In Sensory-motor integration in the nervous system, edited by Otto Creutzfeldt, Richard F. Schmidt, and William D. Willis (Springer, 1984), pp.420-429. He says (p. 427) that `When to do it' is the function of the supplementary motor area. And that "the supervision of the task `what to do' may be a function mainly of the orbital cortex with its hypothalamic, limbic, and mnestic afferents. `How to do it' is in novel situations probably mainly a task for the frontolateral cortex with its afferents from the parietal and temporal teleceptive association areas."

61 "Our need for chronological...": R. Scholes, "Language, narrative, and anti-narrative." In On Narrative, edited by W. J. T. Mitchell, p.207. University of Chicago Press, 1981. See also Misia Landau, "Human evolution as narrative," American Scientist 72:262-268 (May/June, 1984).

61 Quote from Nancy C. Andreasen, "Brain imaging: Applications in psychiatry." Science 239:1381-1388 (18 March 1988).

63 Twins and ventricular sizes: Nancy C. Andreasen, talk at psychiatry grand rounds, University of Washington (14 April 1988). See also: Nancy Andreasen et al, "Structural abnormalities in the frontal system in schizophrenia. A magnetic resonance imaging study," Archives of General Psychiatry 43(2):136-144 (February 1986).

63 Threefold variation in the size of primary visual cortex among normal adult humans: Suzanne S. Stensaas, D.K. Eddington, and W.H. Dobelle, "The topography and variability of the primary visual cortex in man," Journal of Neurosurgery 40:747-755 (June 1974).

66 Hobson (1988), pp. 10-11.

67 Ralph Barton Perry, "Conceptions and misconceptions of consciousness," Psychological Review 11:282-296 (1904). For a more recent collection of the many things called consciousness, see Ronald S. Valle and Rolf von Eckartsberg, eds., The Metaphors of Consciousness (Plenum, 1981).

4. Varieties of Consciousness:

From Coma to Reverie


70 Henry Beston, The Outermost House (Penguin, 1962; originally published 1928), pp. 220-221.

70 Henry David Thoreau, The Maine Woods (1864), p. 71.

71 Walking distance of a beach: "All around the country, the various coastal states are finally beginning to view beaches as the national treasures they truly are. There is no question that the time will come when our remaining beaches will be like national parks, protected forever for the benefit of the public at large. They won't be like Yellowstone Park, however, where one can be sure that Old Faithful will be in the same location 50 years from now. Instead, our beach management policy will have to take into account that the sea level is rising and that the beaches are moving [like rivers of sand]. Thus the beaches of the future may become mobile national parks!" Thomas A. Terich, Living with the Shore of Puget Sound and the Georgia Strait (Duke University Press, 1987), p. 37.

72 Beston (1928), p. 2.

73 Foamlike boxes and ozone depletion: Gary Taubes in Discover 8(8):66 (August 1987).

74 Charles R. Morris, "Our muscle-bound Navy," The New York Times Magazine (24 April 1988), p. 102.

75 Morris Berman, The Reenchantment of the World, (Cornell University Press, 1981), pp. 16, 72.

77 L. Weiskrantz, Blindsight: A Case Study and its Implications (Oxford University Press, 1986).

77 Karl R. Popper and John C. Eccles, The Self and Its Brain (Springer International, 1977), p.125. See also Donald R. Griffin, Animal Thinking. (Harvard University Press, 1984); a view of animal consciousness, though lacking in any comparison of sequential planning skills amongst animals. Not many of the commentators on human consciousness have widely informed themselves about the many specialties relevant to the problem, e.g., animal behavior, human evolution, neurophysiology, philosophy, psychology, etc. The reader may find the following books particularly rewarding:

Patricia Smith Churchland, Neurophilosophy (MIT Press, 1986).

Daniel C. Dennett, Brainstorms: Philosophical Essays on Mind and Psychology (Bradford Books, 1978). And his recent The Intentional Stance (MIT Press, 1987).

John C. Eccles, Evolution of the Brain: Creation of the Self (Routledge, Chapman and Hall, 1989).

Nicholas Humphrey, Consciousness Regained, (Oxford University Press, 1983).

79 Australian stewards of the land: Bruce Chatwin, Songlines (Viking, 1987).

80 Beston (1928), pp. 43-44.

80 Benjamin Libet, "Unconscious cerebral initiative and the role of conscious will in voluntary action." Behavioral and Brain Sciences 8:529-566 (December 1985).

81 Cautionary poem from John Maynard Smith, The Problems of Biology (Oxford University Press, 1986), p. 128.

82 Marvin Minsky, The Society of Mind (Simon and Schuster, 1986), p. 151.

82 Heinz Pagels, The Dreams of Reason (Simon and Schuster, 1988), pp. 222-223, and p.225.

83 Albert Szent-Györgyi, quoted by Sidney Tamm, "Imagination in science," MBL Science 2(2):9-13 (Summer 1986).

84 Oliver Sacks, A Leg to Stand On (Harper and Row, 1984), p. 131.

86 Minsky, p. 50.

86 Bennett G. Braun, editor, The Treatment of Multiple Personality Disorder (American Psychiatric Press, 1986). Multiple personalities are one of the occasional outcomes of child abuse, apparently an attempt by the child to protect himself against the pain of the abuse. One of the most striking findings is that each of the multiple personalities is associated with different allergies, susceptibilities to drugs or epilepsy, and even switches in visual acuity. See Daniel Goleman's story in The New York Times (28 June 1988).

88 Peter Medawar and Jean Medawar, The Life Science (Wildwood House, 1977).

5. The Electrically Exciting Life

of the Inhibited Nervous Cell


92 Rodolfo Llinás, quoted in Susan Allport's Explorers of the Black Box (Norton, 1986), pp.166-167.

94 Albert Szent-Györgyi, in The Scientist Speculates, ed. by I. G. Good, 1962.

96 The Spanish neuroscientist Santiago Ramón y Cajal, with a ten-year blaze of discoveries starting in 1888, is credited with most of our modern concepts of the organization of the vertebrate brain, though many parallel discoveries in invertebrate nervous systems were made in 1888 by the Norwegian zoologist Fridtjof Nansen. My colleague John Edwards tells me that Nansen had the neuron doctrine right even before Cajal (both used the Golgi method), but was forgotten by nervous system historians because he did not continue working on the nervous system. Instead Nansen merely made the first crossing of the Greenland ice cap, did pioneering research in oceanography, led the 1895 Arctic expedition, became Norway's first ambassador to Great Britain, and won the Nobel Peace Prize in 1922 for his work with refugees, e.g., the "Nansen passport"!

Charles Sherrington coined the word "synapse" in 1897, and was one of the people who demonstrated the synaptic delay (which we now know is associated with secretion of the neurotransmitter). The reticulated notions started with Gerlach back in 1858, though Hess and Forel realized by the 1880's that a cell should be considered a unit in and of itself. Cajal's beautiful pictures of axon terminals in the cerebellum (the basket cell endings and the climbing fiber endings on the Purkinje cells, in particular) were what convinced him that the axon came to an end, and he associated it with the one-way valve needed in the reflex arc. But the reaction of the histologists to Cajal's synapse postulates starting about 1900 served to make the reticular theory stronger than ever for a while.

98 Actually, it probably wasn't a dream that inspired Otto Loewi but rather nocturnal mentation; see J. Allan Hobson, The Dreaming Brain (Basic Books, 1988), pp. 4 ff. Not only does dreaming occupy about two hours of each night, but there is another two hours of mentation such as thinking. Such mentation is not accompanied by sensory illusions and is not bizarre as dreaming may be; it is rather commonplace, banal, repetitive, and usually uncreative.

100 Though the reticular theory came to a dead end, the aftermath of Loewi's 1921 discovery was not, however, the firm establishment of chemical transmission for central nervous system. Physiologists continued their attempts to have graded electrical signals propagate across the synapse -- though by 1949, when microelectrodes were introduced, they realized that this alternative would not work in mammalian spinal cord. But of course it is nonetheless utilized at what we now call "electrical synapses" found elsewhere, so both synaptic mechanisms were correct in the end. The vesicles that Palay saw in 1953 were identified with the miniature synaptic potentials at the nerve-muscle synapse by del Castillo and Katz in 1955. Thus the synapse concept, from the false reticular theory that denied synapses to the modern establishment of chemical transmission, took almost a century -- though the correct principles of operation were mostly set forth halfway through the period, between 1888 and 1904. From Sanford Palay's lecture, "The history of the synapse", Toronto, 15 November 1988. See also Marco Piccolino, "Cajal and the retina: a 100-year perspective." Trends in Neurosciences 11(12):521-525 (December 1988).

100 See the Loewi biography by Gerald L. Geison in Dictionary of Scientific Biography 8:451-7 (1973) and Walter Cannon's "The story of the development of our ideas of chemical mediation of nerve impulses," American Journal of Medical Sciences 188:145-159 (August 1934).

101 Blood pressure of 60/45: The brain stops working very quickly if not kept supplied with oxygen via the blood. A low blood pressure in the head is what causes someone to faint. But most cases of fainting can be easily reversed by simply laying the victim flat on the floor (not a chair!); that's because blood pressure decreases with height above the heart. Eliminating the hydrostatic pressure effect by laying the victim horizontal usually increases the head's blood pressure by one-third; propping up the legs will even make hydrostatic pressure work to increase blood pressure. The victim often recovers so quickly that he wonders why he is lying on the floor, is embarrassed and tries to sit up, and promptly faints again (try to keep the victim flat for a few minutes and, should he get up, protect the back of his head from a fall). Such is the potent difference made by upright posture.

102 The mischief that temporary demyelination can cause is demonstrated in a paper of mine published only a half year prior to this little episode: William H. Calvin, Marshall Devor, and John F. Howe, "Can neuralgias arise from minor demyelination? Spontaneous firing, mechanosensitivity, and afterdischarge from conducting axons," Experimental Neurology 75:755-763 (March 1982).

104 U. J. McMahan and S. W. Kuffler, "Visual identification of synaptic boutons on living ganglion cells and of varicosities in postganglionic axons in the heart of the frog," Proceedings of the Royal Society (London) B177:485-508 (1971). See also the three papers that follow this one.

105 For more on thalamotomy for Parkinson's disease, see W. H. Calvin and G. A. Ojemann, Inside the Brain: Mapping the Cortex, Exploring the Neuron (NAL, 1980), Chapter 5.

6. Making Mind from Mere Brain:

Taking Apart the Visual World


110 Virginia Woolf, To the Lighthouse (Harcourt Brace, 1927), p. 301.

112 Stanislaw M. Ulam, in a conversation quoted by Heinz Pagels, The Dreams of Reason (Simon and Schuster, 1988), p. 94.

114 Schemas: Michael A. Arbib, "Schemas," in The Oxford Companion to the Mind (Oxford University Press, 1987), pp. 695-697. Piaget's schemas are mostly movements (of which, more later); there are a number of variations on the schema theme: Minsky uses the word frames; Schank uses the word scripts; Lorenz and Tinbergen talk of innate releasing mechanisms, Peirce of habits, there are semantic nets, and so forth. See Michael A. Arbib, In Search of the Person (University of Massachusetts Press, 1985), pp. 11-16. And from Michael A. Arbib, E. Jeffrey Conklin, and Jane C. Hill, From Schema Theory to Language (Oxford University Press, 1987), p. 7: "Each schema roughly corresponds to a domain of interaction, which may be an object in the usual sense, an attention-riviting detail of an object, or some domain of social interaction. Just as programs may be combined to yield larger programs, so may schemas be combined to form new schemas.... Note that a schema is both a process and a representation. It combines the declarative information with a program for action." Particularly relevant to schemas is Categorical Perception: The Groundwork of Cognition, edited by Stevan Harnad (Cambridge University Press, 1987).

115 S. W. Kuffler, "Discharge patterns and functional organization of mammalian retina." Journal of Neurophysiology 16:37-68 (1953).

115 H. K. Hartline, "The response of single optic nerve fibers of the vertebrate eye to illumination of the retina." American Journal of Physiology 121:400-415 (1938).

117 See Robert Barlow's appreciation of H. Keffer Hartline (1903-1983) in Trends in Neurosciences, 9:552-555 (November-December 1986).

121 Key papers of the "frog's eye era" of neuroethology can be found in Sensory Communication, edited by Walter A. Rosenblith (MIT Press, 1961).

122 Steven P. R. Rose, The Conscious Brain, updated edition (Vintage 1976) p. 27.

127 Center-surround organization disappears: Blue light anywhere in the round receptive field will excite; yellow or red light anywhere in the field will inhibit. Yet all of such a cell's inputs have a center-surround arrangement; thus, these cells have just the right mixture of inputs so that one input's blue surround and another input's blue center combine to give a uniform blue circular field. These cells become very good at reporting the color of the uniform middle of a patch, while other cells respond primarily to the boundary lines between patches. For modern expositions regarding receptive fields, see Chapters 2, 3, and 20 of Stephen W. Kuffler, John Nicholls, and Robert Martin, From Neuron to Brain, 2d edition (Sinauer, 1984).

127 Best stimuli for cortical cells are straight edges and lines: This isn't quite true; the cells in layer IVc still have center-surround receptive fields. See Chapter 12 in W. H. Calvin and G. A. Ojemann, Inside the Brain (1980).

127 The initial Hubel-Wiesel model for receptive fields is the easiest to teach, but there are other ways of looking at the matter, e.g., R. M. Shapley and P. Lennie, "Spatial frequency analysis in the visual system," Annual Reviews of Neuroscience 8:547-583 (1985). These use the average firing rate of a cell as their measure of cell output; looking in more detail at the spike train, Barry Richmond and Lance Optican find that the elementary forms of organization are more abstract; see news article "A new view of vision" in Science News 134:58-60 (23 July 1988).

129 Hans-Lukas Teuber, Perception, Voluntary Movement, and Memory (1967).

129 Torsten Wiesel, "A life of excellence and style: a short account of the career of Stephen W. Kuffler (1913-1980)," Trends in Neurosciences 4(1):1-3 (January 1981).

129 Hubel, Wiesel, and Roger Sperry shared the 1981 Nobel Prize for Physiology or Medicine; Sperry was cited for his work on split-brain patients, though his earlier work on what controls development of visual pathways is considered at least as significant.

130 Training in neurobiology: See Neuroscience Training Programs, published yearly by the Society for Neuroscience, 11 Dupont Circle NW, Washington DC 20036 U.S.A., and available in most college libraries.

131 E. H. Gombrich, Art and Illusion: A Study in the Psychology of Pictorial Representation (Phaidon Press, 1959). Quoted in William Zinsser's Writing to Learn (Harper and Row, 1988), pp.122-123. At the time that Gombrich wrote, it was still thought that photoreceptors "fired" nerve impulses to send messages; a decade later, we discovered that they usually do not, nor do the bipolar cells that are next in the chain between photoreceptor and brain. What the photoreceptors (rods and cones) instead do is surprising beyond anyone's wildest imaginings: They instead leak neurotransmitter molecules all the time, decreasing the leakage rate when light intensity increases, by amounts proportional to light intensity. Thus their output is greatest in the dark!

7. Who Speaks from the Cerebral Cortex?

The Problem of Subconscious Committees


134 Michael A. Arbib, In Search of the Person (University of Massachusetts Press, 1985), pp.52-53.

135 Maps are generally orderly: Yet sometimes the cortical representations simply don't make any sense, in the usual sense of neighbors on the skin being neighbors in the cortex. The somatotopic map in Crus II of cerebellar cortex has now been shown to be a series of disconnected fragments: "fractured somatotopy," as James Bower calls it. In the Edelman example at the end of Chapter 10, one can imagine disorderly maps arising from spotty stimulation regimes rather than smooth stroking of skin during the tuning-up phase.

136 Cape Cod as a terminal moraine: The so-called "Falmouth moraine" extends from Woods Hole north and east, across the north shore of the arm to the elbow near Orleans (where similar boulders are found to those in Woods Hole); the forearm and hand are likely deposited by ocean currents, as the forearm follows the edge of the Continental Shelf drop off. I hope that geologists will forgive my overly broad use of moraine to include hills of glacial till carved by meltwaters: Properly speaking, moraines refer only to the piles created at the very margins of a glacier, not the glacial sediments underneath a glacier carried along by runoff channels.

138 Organization of visual cortical columns: David H. Hubel and Torsten N. Wiesel, "Functional architecture of macaque visual cortex," Proceedings of the Royal Society (London) 198B:1-59 (1977).

138 A visual cortical map goes to the center of the retina, rather than the far side, because the left half of the brain handles everything to the right of where you're looking, the left visual world going to the right brain instead. It is not a matter of everything seen by the left eye, but everything seen by either eye from the left half of the center, where you're looking at the time. See Figure 6-3 on page 120.

140 Some mechanisms of depth perception can be found in S. M. Zeki, "Cells responding to changing image size and disparity in the cortex of the rhesus monkey." Journal of Physiology 242:827-841 (1974).

140 "Converge eyes until receptive fields overlap" isn't quite true. What the arrangement suggests is disparity differences, not convergence differences. If looking down a sidewalk row of parking meters and "looking at" the third one (such as the further target in Figure 7-1 on page 141), such a cell might be optimally sensitive to the second one (such as the nearer target in Figure 7-1).

141 W. H. Calvin, "Fine discrimination as an emergent property of parallel neural circuits." Society for Neuroscience Abstracts 10:218.11 (1984). And "A stone's throw and its launch window: timing precision and its implications for language and hominid brains." Journal of Theoretical Biology 104:121-135 (September 1983).

143 The receptive fields should probably be thought of as serving as a vector basis set. Though just two receptive field types, a horizontal specialist and a vertical specialist, could serve to represent any intermediate angle by the vector's decomposition into cartesian components, the individual cells are noisy, and that restricts the interpretation of the line's angle in space. But with vector components spaced at about 10, any intermediate angle can be easily represented in terms of the relative activation of the two closest members of the basis set. Thus, "labeled lines" for lines aren't needed, just about eighteen basis vectors at 0, 10, 20,...,170 from the horizontal; combinations of their activity seems to be sufficient to allow discrimination of line tilt to a fraction of a degree.

144 Thomas Young, "On the theory of light and colours." Philosophical Transactions of the Royal Society of London 95:12-48 (1802). Color mixing is nicely demonstrated in Richard L. Gregory, Eye and Brain: The Psychology of Seeing, 2d edition (McGraw-Hill, 1973), p.120.

145 Actually, Helmholtz went even further in his 1860 Physiological Optics, representing the three cone outputs as a vector, and the just-noticeable difference in hue as the difference vector between the two hues.

146 Young's patterning principle is also relevant to the perception of line orientation: Those eighteen types of specialized line-orientation neurons (each responds over about a 10 range of orientations) found by Hubel and Wiesel can be thought of as just another example of the principle. Any line (say, at 37) stimulates one type of cell best (say, the one at 40) and weakly stimulates two others (say, the ones centered on 30 and 50). The ratio of the latter's activity can be used to estimate that the line is oriented somewhat less than the favorite's 40. If there were only two orientation types, horizontal and vertical, the ratio of their activity could theoretically be used to estimate 37 -- but nerve cells are noisy, and so the estimate would many times rougher than when one uses eighteen specialists spaced every 10 throughout the 180 range. If you're ultimately going to do a vernier estimate, its precision will depend on how fine the final scale is.

147 Humberto Maturana and Francisco Varela, Autopoesis and Cognition: The Realization of the Living (Reidl, 1980), p.47.

147 Robert P. Erickson, "On the neural bases of behavior." American Scientist 72:233-241 (May-June 1984). Covers both Young's theory for color and the taste data.

147 William H. Calvin, "Why `Grandmother's Face' and `Command' Neurons Are Rare (Answer: The Fireworks Finale)." Society for Neuroscience Abstracts 14:260 (1988).

148 Inhibition is also important in triggering motor programs because it is the committee pattern that counts: Major pathways of the cerebellum (one of whose major functions is coordinating motor programs) operate on downstream neurons only via inhibition.

149 Actually, what Terrence Sejnowski said at MBL's Computational Neuroscience course on 2 September 1988 was "It is humans who categorize, but to distribute is divine," but I converted it to Alexander Pope's phraseology.

152 Joaquin M. Fuster, "Prefrontal cortex in motor control." In Handbook of Physiology. Section 1: The Nervous System. Volume II: Motor Control (American Physiological Society, 1981), Part 2, Chapter 25, pp. 1149-1178 at p. 1167.

152 Four decades later, I revisited the scene. The barbershop is still there, but is smaller than I remembered; it is only four chairs deep from the front of the shop (the house I lived in then, and the school I went to, also look much smaller than I remembered -- but then I was considerably shorter than I am now). There is still the padded board that fits across the arms of the old-fashioned barber chair, worn by several more generations of little boys. And the plate-glass mirrors are still there, perfectly positioned. The trolley car was discontinued long ago, and the turnaround is now a parking lot.

154 Daniel C. Dennett, Brainstorms (Bradford Books, 1978), p. 123.

8. Dynamic Reorganization:

Sharpening Up a Smear with a Mexican Hat


158 J. Z. Young, "Hunting the homunculus", New York Review of Books 35(1):24-26 (2 February 1988).

158 J.-P. Changeux, "Concluding remarks on the `singularity' of nerve cells and its orthogenesis." Progress in Brain Research 58:465-478 (1983).

159 J. Z. Young, A Model of the Brain (Claredon Press, 1964). His "The organization of a memory system," Proceedings of the Royal Society (London) 163B:285-320 (1965) introduces the mnemon concept in which weakened synapses serve to tune up a function. A later version is "Learning as a process of selection," Journal of the Royal Society of Medicine 72:801-804 (1979).

161 Lewis Thomas, "A long line of cells." In Inventing the Truth: The Art and Craft of Memoir (Houghton Mifflin, 1987). Quoted by William Zinsser in Writing to Learn (1988), pp. 169-170.

161 Charles Darwin, The Descent of Man (London: John Murray, 1871), p. 100.

162 The songwriter John Barlow, quoted in David Gans and Peter Simon, Playing in the Band: an Oral and Visual Portrait of the Grateful Dead, (St. Martin's Press, 1985), p. 21.

163 Marian Diamond, in a book review in Ethology and Sociobiology 5:67-68 (1984), says there is little evidence for cortical neuron loss after early adulthood.

163 Evolutionary version of the carving principle: Sven O. E. Ebbesson, "Evolution and ontogeny of neural circuits," Behavioral and Brain Sciences 7:321-366 (September 1984).

164 See Warren S. McCulloch, Embodiments of Mind (MIT Press, 1969).

165 Gained connections until eight months after birth: P. R. Huttenlocher, "Synapse elimination and plasticity in developing human cerebral cortex." American Journal of Mental Deficiency 88:488-496 (1984). For monkeys the data is more extensive: Ronald G. Boothe, William T. Greenough, Jennifer S. Lund, and K. Krege, "A quantitative investigation of spine and dendrite development of neurons in visual cortex area 17 of Macaca nemestrina monkeys," Journal of Comparative Neurology 186:473-490 (1979); and using electron micrographs, P. Rakic, J.-P. Bourgeous, M. F. Eckenhoff, N. Zecevic, and P. Goldman-Rakic, "Concurrent overproduction of synapses in diverse regions of the primate cerebral cortex," Science 232:232-234 (1986).

? A.-S. LaMantia and P. Rakic, "The number, size, myelination, and regional variation of axons in the corpus callosum and anterior commissure of the developing rhesus monkey," Society for Neuroscience Abstracts 10:1081 (1984).

165 Daniel C. Dennett, Content and Consciousness (Routledge and Kegan Paul, 1969; page references to 1986 paperback edition), pp. 52-59. This is Dennett's D. Phil. dissertation at Oxford in 1965 (just imagine having the neurobiologist J. Z. Young and the philosopher A. J. Ayer as your examiners!). Dennett's formulation for brains seems analogous to the convergent selection (shaping towards species "type") envisaged by some of Darwin's predecessors, e.g., Edward Blyth. See Loren Eiseley's posthumous book, Darwin and the Mysterious Mr. X (Harcourt Brace Jovanovich, 1979). As in biology, selection's creative role ("divergent selection") in neural darwinism was only recognized later.

166 The synapse elimination literature is rapidly developing; to find more recent news, I would suggest searching Science Citation Index for articles that cite some of the key papers prior to 1989. In addition to previous citations, these should be useful:

M. F. Bear, L. N. Cooper, and F. F. Ebner, "A physiological basis for a theory of synapse elimination." Science 237:24-28 (1987).

J.-P. Changeux, "Neuronal models of cognitive functions," Cognition (in press).

S. Clarke and G. Innocenti, "Organization of immature intrahemispheric connections," Journal of Comparative Neurology 251:1-22 (1986).

G. M. Innocenti and R. Caminiti, "Postnatal shaping of callosal connections from sensory areas," Experimental Brain Research 38:381-394 (1980).

D. J. Price and C. Blakemore, "Regressive events in the postnatal development of association projections in the visual cortex," Nature 316:721-723 (1985).

D. Purves and J. W. Lichtman, "Elimination of synapses in the developing nervous system," Science 210:153-157 (1980).

166 Favored sites for sprouting in cortex: It has been suggested, as part of the explanation of binocularity "fixing" at the end of its critical period, that the myelination of the thalamocortical axons reduced the side branches -- simply by covering up 99 percent of the axon surface. One might modify this speculation to read: Once myelination occurs, the possible sites for a new side branch are reduced to a few per millimeter. Still, most of the new branching probably occurs from the unmyelinated terminal arbor of the axon, and thus to near neighbors of the neurons to which connections already exist.

167 Ludwig Wittgenstein, Last Writings on the Philosophy of Psychology, vol. 1, 504 (66e) (University of Chicago Press, 1982).

167 David E. Rumelhart and Donald A. Norman, "A comparison of models." In: Parallel Models of Associative Memory. edited by G. Hinton and J. Anderson (Erlbaum, 1981), p.3.

168 Little black lines between your fingers: Floyd Ratliff, Mach Bands: Quantitative Studies on Neural Networks in the Retina (Holden-Day, 1965). This book is not only a nice review of lateral inhibition and Mexican-hat-like organization, but also relates the neurophysiology to such philosophical issues as knowledge.

169 Retina's lateral inhibition turned off during dark-adaptation, see Horace B. Barlow, Richard FitzHugh, and Stephen W. Kuffler, "Change of organization in the receptive fields of the cat's retina during dark adaptation," Journal of Physiology (London) 137:338-354 (1957).

173 Lateral inhibition's uses for contrast enhancement may be one of those pesky cases of a secondary utility; John DuBois points out that network stability may be the most essential function of such inhibition, and I would add that range-shifting might also be a more primitive use, as in the need to shift from daylight to moonlight intensity levels with their millionfold differences. And so contrast enhancement might be a sidestep, a functional change in anatomical continuity (see Chapter 9).

174 Reorganizing finger maps: Michael M. Merzenich et al, Neuroscience 10:639-665 (1983); Annual Reviews of Neuroscience 6:325-356 (1983); Journal of Comparative Neurology 224:591-605 (1984); Journal of Neuroscience 6:218-233 (1986); Nature 332:444-445 (31 March 1988). For a recent review, see J. T. Wall, "Variable organization in cortical maps of the skin as an indication of lifelong adaptive capacities of circuits in the mammalian brain," Trends in Neurosciences 11(12):549-557 (December 1988).

177 Sprouting in peripheral nerve: P. A. Redfern, "Neuromuscular transmission in newborn rats." Journal of Physiology 209:701-709 (1970).

9. Of Arms Races in Church Gardens:

Sidesteps and Evolution's Other Byways


182 Theodore Melnechuk, "Network notes from Cape Cod," Trends in Neurosciences 3(5):8-9 (May 1980).

183 Mahendra Jumar Jain and Rafael Apitz-Castro, "Garlic: molecular basis of the putative `vampire-repellent' actions and other matters related to heart and blood." Trends in Biochemical Sciences 12(7):252-254 (July 1987).

184 Edible plants: G. A. Rosenthal, "The chemical defenses of higher plants." Scientific American 254(1):94-99 (1986).

184 Guam and Rota Island story: Peter S. Spencer, Peter B. Nunn, Jacques Hugon, Albert C. Ludolph, Stephen M. Ross, Dwijendra N. Roy, and Richard C. Robertson, "Guam amyotrophic lateral sclerosis-Parkinsonism-dementia linked to a plant excitant neurotoxin." Science 237:517-522 (31 July 1987). See also Roger Lewin's news article in the same issue, pp.483-484.

185 Gregory Bateson, Mind and Nature: A Necessary Unity (Bantam, 1979), p.193

186 For aquatic references, see Mile 136 of my book, The River that Flows Uphill: A Journey from the Big Bang to the Big Brain (Macmillan, 1986).

187 Ultradarwinists are discussed by M. Grene and N. Eldredge, Interactions (Harvard University Press, forthcoming).

187 The new-niche concept tends to be associated with Emile Durkheim, The Division of Labor in Society (Glencoe IL: Open Court, 1947), Book II, Chapter 2. But the same concept can be found in Darwin.

187 Herbert A. Simon, Reason in Human Affairs (Stanford University Press, 1983), p.73.

188 Thomas H. Jukes, "The fight for science textbooks," Nature 319:367-368 (30 January 1986).

187 Some of the cultural-evolution analogies first appeared in my article "The evolutionary sidestep," Whole Earth Review 60:4-9 (Autumn 1988).

189 Calvinist combination: Jacob Bronowski and Bruce Mazlish, The Western Intellectual Tradition (Harper and Row, 1960), p. 94. Though I would happily claim him, John Calvin is an ancestor of mine only by family tradition (no one seems to have noticed that his only children died in infancy).

190 Ernst Mayr, Toward a New Philosophy of Biology (Harvard University Press, 1988), pp. 2-3.

191 Behavior innovates, anatomy follows: This observation is often credited to Konrad Lorenz, but it goes back several centuries to Lamarck. See also Alister C. Hardy, The Living Stream (London: Collins, 1965).

191 Jane Goodall, The Chimpanzees of Gombe (Harvard University Press, 1986).

192 Biology facilitating cultural practices: James L. Gould and Peter Marler, "Learning by instinct." Scientific American 256(1):74-85 (January 1987).

193 Loren Eiseley, The Immense Journey (Knopf, 1957), p. 47.

193 Accommodation in middle age and other vision topics: R. A. Weale, Focus on Vision (Harvard University Press, 1982).

193 Absurd evolutionary `designs' also include the female reproductive system of mammals, especially the connection (or lack of it!) between the ovary and the uterine tube. It isn't so bad if the ovum misses its narrow channel into the uterus, and thus a possible opportunity to meet a sperm; what's so absurd is that a fertilized ovum can escape back out the tube into the abdominal cavity to cause a life-threatening ectopic pregnancy. Or that the endometrium which is shed at the end of each menstrual cycle can also escape backwards and take up residence in the abdomen (the `reflux' theory for endometriosis). Or that vaginal infections can cause widespread pelvic infections.

196 Ernst Mayr, Toward a New Philosophy of Biology (Harvard University Press, 1988), p. 95.

196 Conversions of function obscured by subsequent streamlining: Charles Darwin, The Origin of Species (London: John Murray, 1859), p. 182. "Metamorphosis of function" term coined on p. 204; "So important to bear in mind the probability of conversion from one function to another...." (p. 191).

197 Biological underpinning of morality, or lack thereof: Richard Alexander, The Biology of Moral Systems (Aldine 1987).

198 Other genetic disorders such as the glucose-6-phosphate dehydrogenase deficiency common in Mediterranean populations are also associated with resistance to malaria ("G6PD" is an enzyme in one of the metabolic pathways that converts glycerol to glucose).

200 Tension between scientific reductionists and holists: See, for example, the exchange between Ernst Mayr and Steven Weinberg in Nature 331:475-476 (11 February 1988). A more complete treatment is in Mayr's Toward a New Philosophy of Biology (Harvard University Press, 1988), chapter 1.

201 Richard Dawkins, The Extended Phenotype (Freeman, 1982), p. 113.

Deborah L. French, Reuven Laskov, and Matthew D. Scharff, "The role of somatic hypermutation in the generation of antibody diversity." Science 244:1152-1157 (9 June 1989).

203 Karl R. Popper, "Critical remarks on the knowledge of lower and higher organisms, the so-called sensory motor systems." In Sensory-Motor Integration in the Nervous System, edited by Otto Creutzfeldt, Richard F. Schmidt, and William D. Willis, (Springer-Verlag, 1984), pp. 19-31, at p. 28

10. Darwin on the Brain:

Self-organizing Committees


206 François Jacob, The Statue Within: An Autobiography (Basic Books, 1988).

207 Glynn Ll. Isaac, talk at University of Washington (31 January 1984).

208 Eugène Marais, The Soul of the Ape (about 1927; Penguin, 1969), p. 56, has an account of chacma baboon nut-cracking: "On reaching the hills, the [coconut-sized hard] fruit was placed on a flat rock and smashed with stones.... Great efforts were first made to break the fruit by hammering it on the rock by hand before a stone was used as a tool."

The classic accounts in chimpanzees are C. Boesch and H. Boesch, "Sex differences in the use of natural hammers by wild chimpanzees: a preliminary report," Journal of Human Evolution 10:585-593 (1981); "Optimization of nut-cracking with natural hammers by wild chimpanzees," Behaviour 83:265-286 (1983); "Mental map in wild chimpanzees: an analysis of hammer transactions for nut cracking," Primates 26:160-170 (1984).

210 This brief explanation omits, of course, the serious problem of self-recognition: how we tell friend from foe. There is a tuning-up period during development when the immune system learns about its host's own characteristic molecules, and so doesn't play this game with them. Autoimmune diseases are what happens when the system fails. Sometimes the immune response to an infecting antigen also develops antibodies for one's own molecules, in which case all sorts of things can happen.

210 Immune-system examples of darwinism and networks: A. Coutinho and F. Varela, "Immune networks: A review of current work," Immunology Today (in press, 1988); and N. Jerne, "Idiotypic networks and other preconceived ideas," Immunology Reviews 79:5-24 (1984).

210 Marvin Minsky, The Society of Mind (Simon and Schuster, 1986), p. 73.

211 Hand-moving quotes are from a computer-mediated discussion on the Well, the Whole Earth Review's conferencing system, in 1987.

214 Daniel K. Hartline, in The Crustacean Stomatogastric System, edited by A. I. Selverston and M. Moulins, (Springer, 1987), pp.181-204.

214 Graham Hoyle, quoted in Susan Allport's Explorers of the Black Box (Norton, 1986), p.57.

216 Stanislaw M. Ulam, Adventures of a Mathematician (Scribners, 1976), p. 13-14.

217 J. Z. Young, Philosophy and the Brain (Oxford University Press, 1987) p. 216

222 Sounds overlap as when pronouncing 675, so that you have to detect 7 in the midst of the final sounds of 6. There is a reading equivalent to this problem, very much what has slowed down the development of good text scanners to convert printed pages into letter strings; it is the "kerning" that printers favor to reduce the space between letters, as when the a may nestle under the T in Tap.

222 Terrence J. Sejnowski and Charles R. Rosenberg, "NETtalk: a parallel network that learns to read aloud," Johns Hopkins University Electrical Engineering and Computer Science Technical Report JHU/EECS-86/01 (1986).

224 David E. Rumelhart, Geoffrey E. Hinton, and Ronald J. Williams. "Learning representations by back-propagating errors," Nature 323:533-536 (9 October 1986). This was for feed-forward networks only.

224 A most interesting new field is unfortunately named: neural networks. It seems absurd for neurobiologists to have to start talking about "real neural networks" just because the physics-math-AI folk didn't learn their lessons. And I'm not referring to ignorance of neurobiology, though that too is a sore point: Remember the hyperbole in the old days when the fledgling digital computer got called a "brain"? And how soon no self-respecting computer person would call a computer a "brain" for fear of being thought a beginner? So why are we now seeing this nonsense of calling any plastic network of pseudoneurons a "neural network"? For some simulations, it seems appropriate to use "neural network" in referring to the computer model: Those simulations of lobster networks, the simulations of the retina using state-of-the-neurobiological-art parameters, etc. But most so-called "neural networks" in AI don't even have the ambition to simulate a real neural circuit: They are seeking shortcuts around formal programming, a plastic network that can be shaped up by training until it performs a desired task (and perhaps then cloned). They should be called "neurallike networks" or "connectionist models."

225 Gerald M. Edelman, Neural Darwinism (Basic Books, 1987), p. 241.

225 Ulam (1976), p. 13.

226 "Connectionism" is what neurallike networks are often called in the literature; see the special issue of Daedalus (Winter 1988) for some excellent introductory essays.

227 Portions of this section are adapted from W. H. Calvin, "A global brain theory (review of Neural Darwinism)", Science 240:1802-1803 (24 June 1988).

227 Glutamate receptor at synapse: I am referring here to a particular subtype, usually called "NMDA" because N-methyl-D-aspartate is the molecule to which it is most sensitive. But glutamic acid is the neurotransmitter normally used at such synapses.

229 Gerald M. Edelman, in How We Know (Nobel Conference, 1985), p. 24.

230 W. Ross Ashby, Design for a Brain (1952), p. vi.

230 Richard Dawkins, The Blind Watchmaker (Norton, 1986).

11. A Whole New Ball Game:

Bootstrapping Thought Through Throwing


234 Rodolfo Llinás, quoted in Susan Allport's Explorers of the Black Box (Norton, 1986), p.170.

237 Sand is always imported: See Thomas A. Terich, Living with the Shore of Puget Sound and the Georgia Strait (Duke University Press, 1987), Chapters 1-3. There is actually a sand cycle, for the sand that gets swept away from the shore each winter and deposited in offshore depressions in the ocean bottom.

237 John Kenneth Galbraith, A Life in Our Times (Houghton Mifflin, 1981), p. 43.

238 Arm-back-to-arm reaction time: Paul J. Cordo, "Mechanisms controlling accurate changes in elbow torque in humans," Journal of Neuroscience 7(2):432-442 (February 1987). "A corrective adjustment in torque [occurred] within roughly the first 100 msec of responses. This mechanism incorporated target torque information provided by the stimulus into the response."

239 J. L. Leavitt, R. G. Marteniuk, and H. Carnahan, "Arm movement trajectories and movement control strategies of expert and non-expert dart throwers," Society for Neuroscience Abstracts 13:713 (1987).

239 For an introduction to reaction times, see Ernst Pöppel, Grenzen des Bewußtseins (Deutsche Verlags-Anstalt, 1985) -- English translation Mindworks: Time and Conscious Experience (Harcourt Brace Jovanovich, 1988).

240 Denis Diderot, "Locke," Encyclopédie, IX, cited in R. Desné, Les matérialistes français de 1750 à 1800 (Paris: Buchet-Chastel, 1965), p. 179.

240 Artur Schnabel, quoted in Chicago Daily News (11 June 1958).

241 William H. Calvin and Charles F. Stevens, "Synaptic noise and other sources of randomness in motoneuron interspike intervals," Journal of Neurophysiology 31:574-587 (1968).

242 William H. Calvin, "A stone's throw and its launch window: timing precision and its implications for language and hominid brains," Journal of Theoretical Biology 104:121-135 (1983). Sequencing as the neural predecessor of language is also discussed by Ovid J.L. Tzeng and William S.-Y. Wang, "Search for a common neurocognitive mechanism for language and movements," American Journal of Physiology 246:R904-R911 (1984).

244 John R. Clay and Robert DeHaan, "Fluctuations in interbeat interval in rhythmic heart-cell clusters," Biophysical Journal 28:377-389 (1979). A similar existence proof for the temporal precision enhancement by averaging large numbers of jittery cells is James T. Enright's "Temporal precision in circadian systems: a reliable neuronal clock from unreliable components?," Science 209:1542-1544 (1980).

246 Eightfold reduction in jitter for throwing twice the distance: Essentially, a target twice as far away subtends only one-quarter the solid angle. But to throw with a fairly flat trajectory, you also have to throw twice as fast, which halves the time scale. So the "launch window" shrinks to one-eighth of what sufficed at the shorter distance.

247 Cell can be assigned to different tasks at different times: See Shaul Hochstein and J. H. R. Maunsell, "Dimensional attention effects in the responses of V4 neurons of the macaque monkey," Society for Neuroscience Abstracts 11:364.6 (1985).

247 Redundancy in memory: Suppose that your telephone's battery was running down and the memories were a little flaky: 223-9077 sometimes was recalled as 324-9077 and sometimes as 223-9079, etc. Solution: Put the same phone number in all ten memories and somehow reprogram the little computer inside the phone to examine all ten memories before dialing the first digit: Whatever digit is most frequent, dial that one (2 most of the time). Next digit, survey again. With this redundancy, the right number will usually be dialed even though none of the memories was 100 percent correct on all seven digits. But the Law of Large Numbers operates by averaging, not by majority rule; either way, redundancy buys much more than just backup systems in case of failure.

252 Ulam (1976), pp. 180-181.

12. Shaping Up Consciousness with a Darwinian Dance:

Emergence from the Subconscious


? Oliver Sacks, quoted in Jonathan Cott, Visions and Voices, (Doubleday, 1987).

256 Jean-Paul Sartre, Nausea (tr. Robert Baldick), Chapter "Saturday noon."

256 Peter Brooks, Reading for the Plot: Design and Intention in Narrative (Random House, 1984), pp. 1-2.

257 Child development: "Life's First Feelings", NOVA television program (1988); and Jerome Kagan, J. Steven Reznick, and Nancy Snidman, "Biological Bases of Childhood Shyness," Science 240:167-171 (8 April 1988).

258 Exploit others through understanding them: See introduction to Machiavellian Intelligence: Social Expertise and the Evolution of Intellect in Monkeys, Apes, and Humans, edited by Richard W. Byrne and Andrew Whiten (Clarendon Press, 1988). See also Behavioral and Brain Sciences 11:233-273 (1988).

258 David Ballin Klein, The Concept of Consciousness (University of Nebraska Press, 1984), pp. 22-23.

259 R. B. Cattell, "Animal intelligence," in Encyclopaedia Britannica, 12:345-347 (1970).

260 Alf Brodal, "Self-observations and neuro-anatomical considerations after a stroke," Brain 96:675-694 (1973).

260 William James, "Great men, great thoughts, and the environment," The Atlantic Monthly 46(276):441-459 (1880) at p. 456. James apparently started discussing the idea in letters to friends about 1874; see Robert J. Richards, Darwin and the Emergence of Evolutionary Theories of Mind and Behavior (University of Chicago Press, 1987), pp. 440 ff.

261 Paul Souriau, Théorie de L'Invention (Paris: Hachette, 1881).

261 Kenneth J. W. Craik, The Nature of Explanation (Cambridge University Press, 1943), p.61.

261 Darwin Machine: Term introduced in W. H. Calvin, "Bootstrapping Thought: Is Consciousness a Darwinian Sidestep?", Whole Earth Review 55:22-28 (Summer 1987).

261 Idea of randomness as basis of thought: Donald T. Campbell lists twenty-six previous statements of same idea: "Evolutionary epistemology" in The Philosophy of Karl Popper, edited by P.A. Schilpp (Open Court, 1974) pp. 413-463. See also Nicholas Humphrey, Consciousness Regained, (Oxford University Press, 1983), pp. 178-179; and Douglas R. Hofstadter, "Variations on a theme as the crux of creativity," in his Metamagical Themas (Basic Books, 1985).

262 Shaping up by selection: See the examples in Richard Dawkins, The Blind Watchmaker (Longman, 1986), Chapter 3.

266 George A. Miller, "The magical number seven, plus or minus two: Some limits on our capacity for processing information," Psychological Reviews 63:81-97 (1956).

267 Chunking: Herbert A. Simon, Models of Thought (Yale University Press, 1979), p. 41.

271 For an example of a neurophysiological view of consciousness that is also oriented to time-series such as speech, poetry, and planning -- but without the Darwin Machine at the center of things -- see Ernst Pöppel's Mindworks: Time and Conscious Experience (Harcourt Brace Jovanovich, 1988 translation from the 1985 German original), especially Chapter 19.

271 "The artificial intelligentsia" term is credited to Louis Fein by J. Weizenbaum, Computer Power and Human Reason (Freeman, 1976), p. 179.

272 Linkages such as is-a and is-contained-in are used in LISP, the AI programming language.

274 Alfred North Whitehead, Adventures of Ideas, part III, 15.

13. The Trilogy of Homo seriatim:

Language, Consciousness, and Music

Portions of this chapter and the next appeared in Reality Club #3, edited by John Brockman (Lynx, 1989).

278 Robert Frost, in Selected Prose of Robert Frost, edited by H. Cox and E. C. Lathem (Collier, 1986), pp. 33-46.

278 Stanislaw M. Ulam, Adventures of a Mathematician (Scribners, 1976), pp. 180-181.

279 Martin E. P. Seligman, "A reinterpretation of dreams," The Sciences 27(5):46-53 (September 1987). Argues visual bursts are random elements that mind finds ways of stringing together in attempt to make coherent story. Subconscious sequences rising to the level of consciousness and action without the usual censorship are particularly well illustrated by some of the phenomena seen in Tourette's syndrome. See Oliver Sacks, "Tics," New York Review of Books, pp.37-41 (29 January 1987).

279 William H. Calvin, The River that Flows Uphill (Macmillan, 1986), p. 365.

281 George Johnson, The Machinery of the Mind: Inside the New Science of Artificial Intelligence (Times Books, 1986), pp. 3-4.

282 Herbert A. Simon, Reason in Human Affairs (Stanford University Press, 1983), pp. 12-13. Simon goes on to note at p. 17 that "in typical real-world situations, decision makers, no matter how badly they want to do so, simply cannot apply the SEU model. [Human beings] have neither the facts nor the consistent structure of values nor the reasoning power at their disposal that would be required... to apply SEU principles." See A. Tversky and D. Kahnermann, "Judgment under uncertainty: Heuristics and biases," Science 185:1124-1131 (1974).

287 I am grateful to Paul Ryan for noting that Darwin Machines do not solve the problem of value and reminding me of Warren McCulloch's model, and to Michelle DuBois for the information on naming horses (those are indeed the names and lineages of actual horses).

291 Oscar Saenger, The Oscar Saenger Course in Vocal Training (The Victor Talking Machine Company, 1915). Quoted by William Zinsser, Writing to Learn, (1988), p. 227.

291 Gerald Weissman, The Woods Hole Cantata: Essays on Science and Society (Houghton Mifflin, 1985), p. 2.

294 Ear worm is one of the gems to be found in Howard Rheingold, They Have a Word for It (J. Tarcher, 1988).

294 Jacob Bronowski, The Origins of Knowledge and Imagination (1967 lecture; Yale University Press, 1978), p. 9.

295 Rain dance, see Jane Goodall, The Chimpanzees of Gombe (Harvard University Press, 1986).

298 Heinz Pagels, The Dreams of Reason (Simon and Schuster, 1988), p. 88.

298 Gregory Bateson, Mind and Nature: A Necessary Unity (Bantam, 1979), p. 191.

14. Thinking about Thought:

Twilight at Nobska Lighthouse


302 Heinz Pagels, The Dreams of Reason (Simon and Schuster, 1988), pp. 138-139.

304 Species occupying same niche competing to extinction: This is called the Competitive Exclusion Principle or Gause's Principle (after G. F. Gause, The Struggle for Existence, 1934), though Charles Darwin also recognized it eight decades earlier in The Origin of Species' discussion of extinction (p. 110). An interesting ecological discussion of it relating to the competition between monkeys and chimpanzees for fruit trees can be found in Michael P. Ghiglieri, East of the Mountains of the Moon (Macmillan, 1988), Chapter 9; since it appears that the monkeys are winning, it demonstrates (to supplement the warning in Ecclesiastes about the race not always being to the swift) that the race is not always to the clever, at least in a rain forest!

306 Henry Beston, The Outermost House (1928; reference to 1962 Penguin edition), p. 211.

308 Peter Brooks, Reading for the Plot, (Knopf, 1984), p. 3.

310 "leak in heater hose....": Like most theories, this one was wrong. It was really the usual water pump hose. Some leaks are simply intermittent. But the inspiration still illustrates subconscious problem-solving while you go about other business.

311 Daniel C. Dennett, Brainstorms: Philosophical Essays on Mind and Psychology (Bradford Books, 1978). Dennett's Chapter 15 is a particularly good reference on free will and the generate-and-test hypothesis for mental acts.

311 Carl Sagan, in Skeptical Inquirer, (Fall 1987), pp. 41-42.

312 "Nietzsche said....": See also Francis Bacon in Novum Organum: "Truth comes out of error more readily than out of confusion."

312 François Jacob, The Statue Within (Basic Books, 1988), p. 15.

312 Pagels (1988), p. 328.

313 "lobbing discus-shaped rocks into the midst of a tightly-packed herd....": At least, that's my interpretation of what the Acheulian "hand axe" was primarily used for.

313 "noise window in hominid evolution": See William H. Calvin, The River that Flows Uphill: A Journey from the Big Bang to the Big Brain (Macmillan, 1986), p. 407.

314 The first collection of papers on neural-like networks was D. E. Rumelhart, J. L. McClelland, & the PDP Research Group, Parallel Distributed Processing (MIT Press, 1986, 2 vol.).

315 Italo Calvino, in Corrierre della Sera (August 10, 1975), quoted in Calvino's The Uses of Literature (tr. Patrick Creagh), (Harcourt Brace Jovanovich, 1986), p. 138.

15. Simulations of Reality:

Of Augmented Mammals and Conscious Robots


318 Anne Sexton, "The poet of ignorance," in The Awful Rowing Towards God (Houghton Mifflin, 1975).

323 Richard Dawkins, The Blind Watchmaker (London: Longmans, 1986), pp. 46-49.

328 Mary Midgley, Evolution as a Religion: Strange Hopes and Stranger Fears (Methuen, 1985), p. 38.

329 Jane Goodall, "A plea for the chimps," New York Times Magazine, pp. 108-120 (17 May 1987).

329 Big machines protecting their niche need not occur for any sinister reason: There was some danger of niche domination in the U.S. back before the microcomputer ascendancy of the late 1970's. At large universities and in many state governments trying to cope with rising expenditures for computers, one could not buy a piece of computing equipment without going through a computer committee, usually chaired by the head of the biggest computer center around. These experts naturally wanted to expand their operations and make them more efficient; they usually discouraged small, inefficient operations. When lab instruments needed computing power, they encouraged tie-lines from labs to the central computer. But some of us had data-acquisition requirements that required wider band-pass than telephone lines, and so we began to escape the dominance of the central computer setup. Eventually, we learned to phrase our purchase orders to avoid any mention of "computer" and to piece together computers from components whose purchase orders escaped the purview of such committees. And because these "data-acquisition devices" could also do word-processing and statistical manipulations, we neurophysiologists (and some chemists and physicists as well) had stand-alone single-user computers much like the present microcomputers, but a decade before Apple et al came on the scene and swamped the computer committees into impotence (before then, there were about fifty-thousand computers in the whole world; now that many are produced every day). See my letter "The Missing LINC" in Byte 7(4):20 (April 1982). In other cases, central authorities dominated, most notably in Eastern Europe and the U.S.S.R., but that central domination too started to erode when the cheap "clones" of popular U.S. computers became available from the Far East.

331 Ralph Wendell Burhoe, "What specifies the values of man-made man?" Zygon 6:224-246 (1971).

331 Downloading brains into work-alike computers, see Hans Moravec and Daniel Hillis quotes in Grant Fjermedal's The Tomorrow Makers (Macmillan, 1986), pp. 4-5, p. 96. Chaos studies are nicely summarized in James Gleick, Chaos: Making a New Science (Viking, 1987).

335 "the most strongly right-handed actions....": A useful news article by Bruce Bower on handedness and brain organization is in Science News (7 January 1989).

338 Darwin Machine not especially suitable for depiction: That doesn't mean that you couldn't use a massively serial device to help out with what is basically a large parallel representation. After all, you can reduce a three-dimensional house to a stack of two-dimensional blueprints, reduce the blueprint page by scanning in a Fax machine to a one-dimensional string of bits -- then reconstruct the blueprint on the other end (and indeed the house). Many parallel-like phenomena seem to happen too rapidly for such serial reconstructions to assist, but depiction is often spread out over time when dealing with a novel construct, either in creating a depiction or in deciphering it. For a discussion of depiction's role in hominid evolution, see Iain Davidson and William Noble, "The archaeology of perception: Traces of depiction and language," Current Anthropology 30(2):125-155 (April, 1989).

338 Power requirements: The fourfold larger brain now consumes about one out of every four calories, so the hominid enlargement probably ran into some problems. One of the constraints was likely overheating, when engaging in a long chase under the hot sun. Brain cells are far more sensitive than the rest of the body to an episode of overheating, and so hominid brain enlargement may have been selected against until some improvements in the cooling arrangements were made to protect the brain against the heat arriving in the arterial blood. Dean Falk argues (Behavioral and Brain Sciences, to appear 1990) that the head's venous drainage system altered in parallel with the enlargement over the 2-million-year encephalization process, with the emissary veins bringing sweating-cooled venous blood from the scalp into the cranial cavity. The robust Australopithecine lineage lacked such an arrangement, suggesting that they could either run or have a bigger brain, but not both.

339 Freeman Dyson, interview in U.S. News and World Report (18 April 1988), p. 72.

339 Mental evolution of everyone in Woods Hole: Well, at least if they're not in coma. But then there are no hospitals or nursing homes in Woods Hole, only up in Falmouth. Does everyone else, awake or asleep but at least not in coma, share this evolutionary property? Certainly there are individuals who are locked into patterns (obsessive-compulsives, and perhaps some of the senile) that probably prevent new patterns from ever winning. But then there is stasis in biological evolution too, such as the horseshoe crabs, and we often label such long-lasting species as extraordinarily successful.

342 Pagels (1988), p. 331.

The Cerebral Symphony (Bantam 1989) is my book on animal and human consciousness, using the setting of the Marine Biological Labs and Cape Cod. AVAILABILITY is limited.

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