What *will* cause branching of the wave function in your body is radioactive decay of isotopes in your body, since those occur randomly. But that isn't the same thing as rolling the dice at every human-scale possibility (like giving n to the power of a gogol permutations of this discussion). The relative amplitude of wave function interactions between a radioactive decay and interactions that would cause those changes in your brain is *insanely* low, relative to that not happening.