Has anyone ever conducted a study that checked the influence of quantum mechanics on our brains? I am asking because sometimes this is used as a leeway out of the deterministic universe problem - if everything follows physical laws, then the inital setup of the big bang has determined how the universe would look like ad infinitum. So then someone mentions quantum mechanics - it makes anything but sense and works on probabilities rather than predetermined outcomes. So my question is really twofold: Firstly, do quantum fluctuations affect our brain? Do they decide whether I will choose an apple over an orange? Personally I find this a bit hard to digest, because everything that occurs in our brains is ultimately random how can we be thinking clear thoughts, unless we are not affected by these quantum effects? Secondly, do we know if the behaviour of particles once they are measured is random as a whole, but predetermined for each particle, or just completely random? Let's ake the double-slit experiment for example, and send one photon at a time. We send a photo and see that it hits a certain spot, if we were to go bac in time (which we can't) and send the same photon again, would it hit the same spot (i.e its behaviour is predetermined) or would it hit a completely different spot (random behaviour)? Perhaps the answer to the second question is that the particles' behaviour is predetermined, it's just that we can't predict it (as opposed to classical physics which enable us to predict the outcome given complete details of the inital setup). If that's the case, then the answer to the first question doesn't matter - the universe is deterministic, and everything we do results from a single moment in time in which the universe came to be. Thank you for reading and I'm sorry if this sounds like a layman's ramblings - it is.