  Recently, Tegmark pointed out that the superposition of ion states involved
in the superposition of firing and resting states of a neuron quickly decohere.
It undoubtedly indicates that neural networks cannot work as quantum computers,
or computers taking advantage of coherent states. Does it also mean that the
brain can be modeled as a neural network obeying classical physics? Here we
show that it does not mean that the brain can be modeled as a neural network
obeying classical physics. A brand new perspective in research of neural
networks from quantum theoretical aspect is presented.
