Quantum Models of Mind: Are They Compatible with Environment Decoherence?

Quantum models of mind associate consciousness to coherent superposition of states in the brain. Some authors consider consciousness to be the result of a kind of internal quantum measurement process in the brain. In this paper we discuss the ideas of Hameroff Penrose and Tegmark and their calculation for an estimate of decoherence time. We criticize the Hameroff Penrose model in the context of quantum brain model by gravitational collapse orchestrated objective reduction (orch. OR), assumed by Penrose, and we propose instead that the decoherence process is caused by interaction with the environment. We consider it useful to exploit this possibility because of the growing importance of decoherence theory in quantum measurement, and also because quantum mechanics can be applied to brain study independently of the Hameroff -Penrose model for mind and consciousness. Our conclusion is that the Hameroff-Penrose model is not compatible with decoherence, but nevertheless quantum brain can still be considered if we replace gravitational collapse orch .OR with decoherence. However our result does not agree with Tegmark ́s conclusion of refuting not only the Hameroff-Penrose gravitational collapse but also quantum brain, based on decoherence time calculations in specific cases in the brain. In spite of this fact we also disagree with some points of the response to Tegmark ́s article given by Hagan, Hameroff and Tuszynski.