Importance of quantum decoherence in brain processes.
Based on a calculation of neural decoherence rates, we argue that the degrees of freedom of the human brain that relate to cognitive processes should be thought of as a classical rather than quantum system, i.e., that there is nothing fundamentally wrong with the current classical approach to neural network simulations. We find that the decoherence time scales ( approximately 10(-13)-10(-20) s) are typically much shorter than the relevant dynamical time scales ( approximately 10(-3)-10(-1) s), both for regular neuron firing and for kinklike polarization excitations in microtubules. This conclusion disagrees with suggestions by Penrose and others that the brain acts as a quantum computer, and that quantum coherence is related to consciousness in a fundamental way.
Tegmark
M
M
Institute for Advanced Study, Olden Lane, Princeton, New Jersey 08540, USA. max@physics.upenn.edu
D001699:Biometry; D055592:Biophysical Phenomena; D001703:Biophysics; D001921:Brain / Q000502:physiology*; D003071:Cognition / Q000502:physiology; D019277:Entropy; D006801:Humans; D008870:Microtubules / Q000502:physiology; D008959:Models, Neurological; D016571:Neural Networks, Computer; D009474:Neurons / Q000502:physiology; D011789:Quantum Theory