Orch-OR
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 microtubules. The proposal was put forward in the mid-1990s by British theoretical physicist 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. [1] [2] [3] [4] [5] [6] [7] [8][9] [10] [11]
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.
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.[12] [13] [14] [15] [16]. [17] [18] [19] [20]
References
- ↑ Grush R, Churchland PS (1995). "Gaps in Penrose's toilings". J Consciousness Studies 2: 10–29.
- ↑ Penrose R, Hameroff SR (1995) What gaps? Reply to Grush and Churchland J Consciousness Studies 2:98-112
- ↑ McDermott D (1995) Penrose is wrong PSYCHE 2, October
- ↑ Chalmers DJ (1995) Minds, machines, and mathematics - a review of Shadows of the Mind by Roger Penrose PSYCHE 2 June
- ↑ Reimers JR et al. (2009). "Weak, strong, and coherent regimes of Fröhlich condensation and their applications to terahertz medicine and quantum consciousness". Proc Nat Acad Sci USA 106: 4219–24.
- ↑ Georgiev DD (2007). "Falsifications of Hameroff-Penrose Orch OR model of consciousness and novel avenues for development of quantum mind theory". NeuroQuantology 5: 145–74.
- ↑ Georgiev DD (2009). "Remarks on the number of tubulin dimers per neuron and implications for Hameroff-Penrose Orch". NeuroQuantology 7: 677–9.
- ↑ Georgiev DD (2009). "Tubulin-bound GTP cannot pump microtubule coherence in stable microtubules. Towards a revision of microtubule based quantum models of mind". NeuroQuantology 7: 538–47.
- ↑ McKemmish LK et al. (2009). "Penrose-Hameroff orchestrated objective-reduction proposal for human consciousness is not biologically feasible". Phys Rev E 80: 021912–6.
- ↑ Spier E, Thomas A (1998) A Quantum of Consciousness? A glance at a physical theory for a mind Trends Cog Sci 2:124-5
- ↑ Tegmark, M (2000), "Importance of quantum decoherence in brain processes", Phys Rev E 61: 4194–206
- ↑ Hameroff SR, Penrose R (1996) Orchestrated reduction of quantum coherence in brain microtubules: A model for consciousness. Mathematics and Computers in Simulation 40:453-480
- ↑ Hagan S et al. (2002) Quantum computation in brain microtubules? Decoherence and biological feasibility Phys Rev E 65:061901
- ↑ Hameroff SR, Penrose R (1996) Conscious events as orchestrated spacetime selections J Consciousness Studies 3:36-53
- ↑ Hameroff S (1998) Quantum computation in brain microtubules? The Penrose-Hameroff "Orch OR" model of consciousness Philos Trans R Soc Lond Ser A 356:1869-96
- ↑ Hameroff S (1998b) Funda-mentality": is the conscious mind subtly linked to a basic level of the universe? Trends Cog Sci 2:119-27
- ↑ Hameroff S (1998d) Did consciousness cause the Cambrian evolutionary explosion? In: Toward a Science of Consciousness II: The Second Tucson Discussions and Debates Eds. Hameroff SR, Kaszniak AW, Scott AC, Cambridge, MA: MIT Press pp.421-37
- ↑ Hameroff SR, Watt RC (1982) Information processing in microtubules J Theor Biol 98:549-61
- ↑ Hameroff SR et al. (2002) Conduction pathways in microtubules, biological quantum computation and microtubules Biosystems 64:149-68
- ↑ Hameroff SR (1998). "Quantum computation in brain microtubules? The Penrose-Hameroff "Orch OR" model of consciousness". Phil Trans R Soc Lond (A) 356: 1869–96.