Who am "I"?

Who am I?? Lets consider I is simply a hypothetical character generated by the brain. But why dont we give a damn about brain or the heart when the body loses that essence called life? The body is just another object without life. So what is this that make blood flows, stops it to stop flowing. Brain is the central organ of the human body, it somehow controls the heart beat, percieves the senses and does all the other small n big functions. Who runs the brain then? Can it take a decision which is not pre defined? Or it just acts upon the past experience and learning. What about the first experience?