GAPS IN PENROSE ' S TOILINGS

Using the Gödel Incompleteness Result for leverage, Roger Penrose has argued that the mechanism for consciousness involves quantum gravitational phenomena, acting through microtubules in neurons. We show that this hypothesis is implausible. First, the Gödel Result does not imply that human thought is in fact non algorithmic. Second, whether or not non algorithmic quantum gravitational phenomena actually exist, and if they did how that could conceivably implicate microtubules, and if microtubules were involved, how that could conceivably implicate consciousness, is entirely speculative. Third, cytoplasmic ions such as calcium and sodium are almost certainly present in the microtubule pore, barring the quantum mechanical effects Penrose envisages. Finally, physiological evidence indicates that consciousness does not directly depend on microtubule properties in any case, rendering doubtful any theory according to which consciousness is generated in the microtubules.

[1]  K. Pribram,et al.  Quantum optical coherence in cytoskeletal microtubules: implications for brain function. , 1994, Bio Systems.

[2]  W. Sossin,et al.  Cellular and molecular biology of neuropeptide processing and packaging , 1989, Neuron.

[3]  C. Stevens,et al.  Changes in reliability of synaptic function as a mechanism for plasticity , 1994, Nature.

[4]  T. J. Walsh,et al.  Ganglioside AGF2 prevents the cognitive impairments and cholinergic cell loss following intraventricular colchicine , 1991, Experimental Neurology.

[5]  Philip Kitcher,et al.  The Nature of Mathematical Knowledge. , 1985 .

[6]  D. Bloor,et al.  Knowledge and Social Imagery , 1977 .

[7]  B. MacWhinney,et al.  Functionalism and the competition model , 1989 .

[8]  Hilary Putnam,et al.  Philosophy of mathematics : selected readings , 1984 .

[9]  A. Heyting,et al.  Intuitionism: An introduction , 1956 .

[10]  R. Llinás,et al.  Coherent 40-Hz oscillation characterizes dream state in humans. , 1993, Proceedings of the National Academy of Sciences of the United States of America.

[11]  E. Bennett,et al.  Uptake of [3H]colchicine into brain and liver of mouse, rat, and chick , 1980, Pharmacology Biochemistry and Behavior.

[12]  J. Conner,et al.  Distribution of nerve growth factor‐like immunoreactive neurons in the adult rat brain following colchicine treatment , 1992, The Journal of comparative neurology.

[13]  Turing Am.  Lecture to the London Mathematical Society on 20 February 1947. 1986. , 1995 .

[14]  Terrence J. Sejnowski,et al.  The Computational Brain , 1996, Artif. Intell..

[15]  R C Watt,et al.  Information processing in microtubules. , 1982, Journal of theoretical biology.

[16]  Carl B. Boyer,et al.  The history of the calculus and its conceptual development. : (The concepts of the calculus) , 1939 .

[17]  Images and subjectivity: Neurobiological trials and tribulations , 1996 .

[18]  Carver Mead,et al.  Analog VLSI and neural systems , 1989 .

[19]  T. Sejnowski,et al.  Thalamocortical oscillations in the sleeping and aroused brain. , 1993, Science.

[20]  Stuart R. Hameroff,et al.  QUANTUM COHERENCE IN MICROTUBULES: A NEURAL BASIS FOR EMERGENT CONSCIOUSNESS? 1 , 1994 .

[21]  Michael Dummett,et al.  The logical basis of metaphysics , 1991 .

[22]  R. Penrose,et al.  Shadows of the Mind , 1994 .

[23]  B. Libet.  Neurophysiology of Consciousness , 1993, Contemporary Neuroscientists.

[24]  P. Churchland,et al.  The Engine of Reason, The Seat of the Soul: A Philosophical Journey into the Brain , 1995 .

[25]  E. J. Ambrose,et al.  CELL MOVEMENTS. , 1965, Endeavour.

[26]  Michael I. Jordan.  Serial Order: A Parallel Distributed Processing Approach , 1997 .

[27]  F. Crick.  The Astonishing Hypothesis , 1994 .

[28]  H. Stowell.  The emperor's new mind R. Penrose, Oxford University Press, New York (1989) 466 pp. $24.95 , 1990, Neuroscience.

[29]  N. Logothetis,et al.  Neuronal correlates of subjective visual perception. , 1989, Science.

[30]  R. Llinás,et al.  Of dreaming and wakefulness , 1991, Neuroscience.

[31]  J E Bogen,et al.  On the neurophysiology of consciousness: I. An overview. , 1995, Consciousness and cognition.

[32]  DiVincenzo,et al.  Growing perfect quasicrystals. , 1988, Physical review letters.

[33]  Judith E. Dayhoff,et al.  Models for molecular computation: conformational automata in the cytoskeleton , 1992, Computer.

[34]  I. Lakatos.  PROOFS AND REFUTATIONS (I)*† , 1963, The British Journal for the Philosophy of Science.

[35]  G. Bensimon,et al.  Microtubule disruption and cognitive defects: Effect of colchicine on learning behavior in rats , 1991, Pharmacology Biochemistry and Behavior.

[36]  W. R. Lieb,et al.  Molecular and cellular mechanisms of general anaesthesia , 1994, Nature.

[37]  J. Gaddum,et al.  The Pharmacological Basis of Therapeutics , 1966 .

[38]  I. Székács.  [Introduction to molecular biology]. , 1966, Orvosi hetilap.

[39]  B. Kushner.  Descartes' error. , 1998, Journal of AAPOS : the official publication of the American Association for Pediatric Ophthalmology and Strabismus.

[40]  M. Carpenter.  The Fine Structure of the Nervous System , 1970, Neurology.