What are deja vue's? I don't get them very often, but when I do I get more than one in a day(?) Are they still unexplainable events of the mind?

Most people have had the experience of a tune "going round and round in the head", and not being able to stop it. What is going on in the brain to cause this phenomenon and is there a way to "stop the record playing"?

Does the fact of thinking, of having an intense cerebral activity, lead to more burning of calories? When one has a prolonged mental activity, especially involving concentration, one usually becomes tired and/or hungry... Does this mean that thinking is good "sport"? Is it coherent to imagine a small, non-sporty but intensively reasoning person needing and consuming as much calories as a stronger sportperson?

I remember hearing a while back, on a science podcast by Dr. Karl Kruszelnicki, that it is possible that memory is stored throughout the body aswel as in the brain. I'm not sure how correct this theory is, but if it is in fact true could it have any link to 'Phantom limbs'? I was thinking that maybe the body remembers how, an arm for example, moves or feels even when no longer there. This maybe sends signals to the brain (which knows the arm isn't there) but because the memory is stored elsewhere it causes confusion and leads you to interpret the memory as present truth. Could this be at all possible?

It can be argued that one of the reasons why humans love music with the same bpm as the human heart beat, is because it reminds us of being in the womb and can induce a relaxed state.

I have recently been reading up on self-sustaining criticality, the process by which the brain maintains a fine balance between boring and slow order, and exciting out of control thought propagation, to achieve a balance of speedy but stable thought / processing. A common example of self sustaining criticality in nature is the sand pile, where you can predict the average frequency and size of collapses, but where each one is still random and unpredictable.

There are similar events in nature that seem to be able to hold us humans in a trance, a burning fire, waves breaking, falling snow and of course avalanches in a sand pile. Do all of these events have an element of self-sustaining criticality to them?..and if they do, does our brain "enjoy" them because it fits in with its own processing system - similarly to how our body "enjoys" repetitive beats on the same frequency as our heartbeat?