Look into what others have said. However, my addition would Information systems theory, specifically noise within systems and signal processing. Dynamic Systems Theory. A note on what you find out could be helpfull to many.
Hi! i have a colleage that published a measure -based on fractals- for characterizing the structural complexity of the human brain. However, the input data are anatomical datasets, so i don´t know if there is any work quantifying complexity in functional data!
Article Robust estimation of fractal measures for characterizing the...