They are mainly made of stem cells and move around to create memories and other things like muscel function, it's hard to explain how they work because the brain does so many jobs. Stem cells are unspecialised/partially unspecialised cells which can develop to be any kind of cell (to some degree) they are vital in the growth of babies and the maintanence of the spinal cord and brain as the reproduce to form entirely new things! Scientists are currently experimenting with them to grow new organs and stem cells are used to grow skin to treat third degree burns. So to condlude, the brain is basically a living organism which is controlled by many different stem cells
