imported>Gareth Leng |
imported>Peter Schmitt |
| (15 intermediate revisions by 4 users not shown) |
| Line 1: |
Line 1: |
| {{subpages}} | | {{subpages}} |
| '''Orch OR (“Orchestrated Objective Reduction”)''' is the proposal that information processing in the brain involves complex computational processes within every [[neuron]], that involve co-ordinated changes in the conformational states of tubulin proteins within microtubules. The proposal was put forward in the mid-1990s by British theoretical physicist [[Roger Penrose|Sir Roger Penrose]] and American anesthesiologist [[Stuart Hameroff]]. | | '''Orch-OR''' (''Orchestrated Objective Reduction'') is the proposal that information processing in the brain involves complex computational processes within every [[neuron]], that involve co-ordinated changes in the conformational states of proteins within [[microtubule]]s. The proposal was put forward in the mid-1990s by British theoretical physicist [[Roger Penrose|Sir Roger Penrose]] and American anesthesiologist [[Stuart Hameroff]]. A few papers have been published criticising specific features of the theory, but |
| | largely it has been ignored by academic neuroscientists. |
|
| |
|
| Microtubules are cylindrical lattices of tubulin proteins that can act like "conveyer belts" inside cells to move [[vesicles]], [[granules]], organelles like [[mitochondria]], and [[chromosomes]] to different locations in the cell via special attachment proteins; they are also important components of [[cilia]] and [[flagella]] in motile cells, and are importany for [[mitosis]] in all cells. Structurally, microtubules are linear polymers of a globular protein, [[tubulin]] - these linear polymers are called [[protofilaments]]. | | Microtubules are cylindrical lattices of tubulin proteins that serve as structural elements inside a cell and can act like "highways" for the movement of [[vesicles]], [[granules]], organelles like [[mitochondria]], and [[chromosomes]] to different locations in the cell via special motor proteins; they are also important components of [[cilia]] and [[flagella]] in motile cells, and are important for [[mitosis]] in all cells. Structurally, microtubules are linear polymers of a globular protein, [[tubulin]] - these linear polymers are called [[protofilaments]]. |
|
| |
|
| Roger Penrose, a prominent theoretical physicist, argued in his 1989 book “[[The Emperor's New Mind]]” that human consciousness and understanding required a factor outside [[algorithmic computation]], and that the missing “non-computable” factor was related to a type of [[quantum computation]] involving what he termed “objective reduction” (“OR”).
| | Penrose argued in his 1989 book ''The Emperor's New Mind'' that human consciousness and understanding required a factor outside [[algorithmic computation]], and that the missing “non-computable” factor was related to a type of [[quantum computation]] involving what he called ''objective reduction'' (''OR''). Hameroff suggested to Penrose that microtubules within neurons might be involved in such quantum computation, and together they developed the theory of ''Orch OR''. |
| | |
| Hameroff suggested to Penrose that microtubules within neurons might be involved in such quantum computation, and together they developed a theory of ''Orch OR'' <ref>Hameroff SR, Penrose R (1996) [http://www.quantumconsciousness.org/penrose-hameroff/orchOR.html ''Orchestrated reduction of quantum coherence in brain microtubules: A model for consciousness''.] In: Toward a Science of Consciousness - The First Tucson Discussions and Debates. (Hameroff, S.R., Kaszniak, and Scott, A.C., eds.), pp. 507-540, MIT Press. Also published in Mathematics and Computers in Simulation (1996) 40:453-480</ref><ref>Hagan S ''et al.'' (2002) [http://arxiv.org/abs/quant-ph/0005025 ''Quantum Computation in Brain Microtubules? Decoherence and Biological Feasibility''.] ''Physical Rev E'' 65: 061901</ref> | |
| | |
| <ref>Hameroff SR, Penrose R (1996) [http://www.quantumconsciousness.org/penrose-hameroff/consciousevents.html ''Conscious events as orchestrated spacetime selections''.] ''J Consciousness Studies'' 3:36-53</ref>
| |
| <ref>Hameroff S (1998) [http://www.quantumconsciousness.org/penrose-hameroff/quantumcomputation.html ''Quantum computation in brain microtubules? The Penrose-Hameroff "Orch OR" model of consciousness''.] ''Philos. Trans. R. Soc. London Ser. A'' 356:1869-96</ref>
| |
| <ref>Hameroff S (1998b) [http://www.quantumconsciousness.org/penrose-hameroff/fundamentality.html ''"Funda-mentality": is the conscious mind subtly linked to a basic level of the universe?''] ''Trends Cognitive Sci'' 2:119-27</ref>.
| |
| <ref>Hameroff S (1998d) [http://www.quantumconsciousness.org/penrose-hameroff/cambrian.html ''Did consciousness cause the Cambrian evolutionary explosion?''] In: Toward a Science of Consciousness II: The Second Tucson Discussions and Debates. Eds. Hameroff, S.R., Kaszniak, A.W., & Scott, A.C., Cambridge, MA: MIT Press, pp.421-37</ref>
| |
| <ref>Hameroff SR, Watt RC (1982) [http://www.quantumconsciousness.org/documents/informationprocessing_hameroff_000.pdf ''Information processing in microtubules''.] Journal of Theoretical Biology 98: 549-561</ref>
| |
| <ref>Hameroff SR ''et al.'' (2002) [http://www.quantumconsciousness.org/pdfs/conduction%20pathways_hamerof.pdf ''Conduction pathways in microtubules, biological quantum computation and microtubules''.] ''Biosystems'' 64:149-168.
| |
| | |
| | |
| == References ==
| |
| | |
| <references/>
| |
| | |
| | |
| | |
| | |
| | |
| {{cite journal
| |
| | author = Grush, R., Churchland, P.S.
| |
| | title = Gaps in Penrose's toilings
| |
| | journal = Journal of Consciousness Studies
| |
| | volume = 2
| |
| | issue = 1
| |
| | pages = 10–29
| |
| | year = 1995
| |
| | url = http://mind.ucsd.edu/papers/penrose/penrose.pdf
| |
| | doi =
| |
| }}</ref>
| |
| | |
| * Penrose R, Hameroff SR (1995) [http://www.quantumconsciousness.org/penrose-hameroff/whatgaps.html ''What gaps? Reply to Grush and Churchland''.] J Consciousness Studies 2:98-112
| |
| <ref name="drew">[http://psyche.cs.monash.edu.au/v2/psyche-2-17-mcdermott.html Penrose is Wrong] Drew McDermott, PSYCHE, 2), October, 1995</ref>, <ref>[http://psyche.cs.monash.edu.au/v2/psyche-2-09-chalmers.html Minds, Machines, And Mathematics - A Review of Shadows of the Mind by Roger Penrose] David J. Chalmers, ''[[Psyche (journal)|PSYCHE]]'' 2(9) June 1995</ref>
| |
| | |
| </ref> In 1996 Penrose offered a consolidated reply to many of the criticisms of 'Shadows'.<ref name="reply">[http://psyche.cs.monash.edu.au/v2/psyche-2-23-penrose.html Beyond the Doubting of a Shadow - A Reply to Commentaries on Shadows of the Mind] Roger Penrose, ''[Psyche (journal)|PSYCHE]]'' 2 1996</ref>
| |
| ''"Cortical dendrites contain largely A-lattice microtubules"'' is one of 20 testable predictions published by Hameroff in 1998<ref name="Hameroff1998">
| |
| {{cite journal
| |
| | author = Hameroff, S.R.
| |
| | title = Quantum Computation In Brain Microtubules? The Penrose-Hameroff "Orch OR" model of consciousness
| |
| | journal = Philosophical Transactions Royal Society London (A)
| |
| | volume = 356
| |
| | pages = 1869–1896
| |
| | year = 1998
| |
| | url = http://www.quantumconsciousness.org/penrose-hameroff/quantumcomputation.html
| |
| | doi =
| |
| }}</ref> and it was hypothesized that these A-lattice microtubules could perform [[Topological quantum computer|topological quantum error correction]]. The latter testable prediction had already been experimentally disproved in 1994 by Kikkawa et al., who showed that all in vivo microtubules have B-lattice and a seam.<ref name="Kikkawa1994">
| |
| {{cite journal
| |
| | author = Kikkawa, M., Ishikawa, T., Nakata, T., Wakabayashi, T., Hirokawa, N.
| |
| | title = Direct visualization of the microtubule lattice seam both in vitro and in vivo
| |
| | journal = Journal of Cell Biology
| |
| | volume = 127
| |
| | issue = 6
| |
| | pages = 1965–1971
| |
| | year = 1994
| |
| | url = http://jcb.rupress.org/cgi/content/abstract/127/6/1965
| |
| | doi = 10.1083/jcb.127.6.1965
| |
| }}
| |
| </ref><ref name="Kikkawa2006">
| |
| {{cite journal
| |
| | author = Kikkawa, M., Metlagel, Z.
| |
| | title = A molecular "zipper" for microtubules
| |
| | journal = Cell
| |
| | volume = 127
| |
| | issue = 7
| |
| | pages = 1302–1304
| |
| | year = 2006
| |
| | url = http://dx.doi.org/10.1016/j.cell.2006.12.009
| |
| | doi = doi:10.1016/j.cell.2006.12.009
| |
| }}
| |
| </ref>
| |
| {{cite journal
| |
| | author = Reimers JR ''et al.'' | title = Weak, strong, and coherent regimes of Fröhlich condensation and their applications to terahertz medicine and quantum consciousness
| |
| | journal = Proc Nat Acad Sci
| |
| | volume = 106
| |
| | pages = 4219–24
| |
| | year = 2009
| |
| }}</ref>
| |
| <ref>
| |
| {{cite journal
| |
| | author = Georgiev, D.D.
| |
| | title = Falsifications of Hameroff-Penrose Orch OR model of consciousness and novel avenues for development of quantum mind theory
| |
| | journal = NeuroQuantology
| |
| | volume = 5
| |
| | pages = 145–174
| |
| | year = 2007
| |
| }}
| |
| </ref> an error in the calculated number of tubulin dimers per cortical neuron,<ref name="Georgiev2009a">
| |
| {{cite journal
| |
| | author = Georgiev, D.D.
| |
| | title = Remarks on the number of tubulin dimers per neuron and implications for Hameroff-Penrose Orch
| |
| | journal = NeuroQuantology
| |
| | volume = 7
| |
| | issue = 4
| |
| | pages = 677–679
| |
| | year = 2009
| |
| | url = http://precedings.nature.com/documents/3860/version/1
| |
| | doi =
| |
| }}
| |
| who showed that despite the fact that DLBs are stained by antibody against gap junctions, they are located tens of micrometers away from actual gap junctions. Also it was shown that the proposed tubulin-bound GTP pumping of quantum coherence cannot occur neither in stable microtubules<ref name="Georgiev2009b">
| |
| {{cite journal
| |
| | author = Georgiev DD
| |
| | title = Tubulin-bound GTP can not pump microtubule coherence in stable microtubules. Towards a revision of microtubule based quantum models of mind
| |
| | journal = NeuroQuantology
| |
| | volume = 7
| |
| | issue = 4
| |
| | pages = 538–547
| |
| | year = 2009
| |
| | url = http://www.neuroquantology.com/journal/index.php/nq/article/view/358
| |
| | doi =
| |
| }}
| |
| </ref>
| |
| {{cite journal
| |
| | author = McKemmish LK ''et al.'' | title = Penrose-Hameroff orchestrated objective-reduction proposal for human consciousness is not biologically feasible
| |
| | journal = Physical Review E
| |
| | volume = 80
| |
| | |
| | pages = 021912–6
| |
| | year = 2009
| |
| }}
| |
| </ref>
| |
| Spier, E. & Thomas, A. (1998) Trends in Cognitive Sciences, 2, 124-125.
| |
| | |
| A Quantum of Consciousness?
| |
| A glance at a physical theory for a mind
| |
| ref name=Tegmark2000>{{citation | last = Tegmark | first = M. | year = 2000 | title = Importance of quantum decoherence in brain processes | journal = Phys. Rev. E | volume = 61 | pages = 4194–4206 | doi = 10.1103/PhysRevE.61.4194 | url = http://arxiv.org/abs/quant-ph/9907009 }}</ref>
| |
