Inter-relation between quantum mechanics and higher brain functions: lessons from quantum computation and neurobiology

The relationship between quantum mechanics and higher brain functions is an entertaining topic at parties between a mixed, open-minded group of academics. It is, however, also a frequently asked question at international scientific conferences, in funding agencies and sometimes at the end of our lives, when thinking about ultimate truths. Therefore a well-founded understanding of these issues is desirable. The role of quantum mechanics for the photons received by the eye and for the molecules of life is not controversial. The critical questions we are here concerned with is whether any components of the nervous system - a 300° Kelvin wet and warm tissue strongly coupled to its environment - display any macroscopic quantum behaviors, such as quantum entanglement, and whether such quantum computations have any useful functions to perform. Neurobiologists and most physicists believe that on the cellular level, the interaction of neurons is governed by classical physics. A small minority, however, maintains that quantum mechanics is important for understanding higher brain functions, e.g. for the generation of voluntary movements (free will), for high-level perception and for consciousness. Arguments from biophysics and computational neuroscience make this unlikely.