If you are considered brain dead, what makes your heart still beat

The aunomic nervous system (ANS) does not require conscious cntrol. Autonomic nervous system - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Autonomic_nervous_system)

You don't require consciousness to eat, breathe, digest food etc.

With biofeedback you can train your brain to have an effect on things normally controlled by the ANS. Example: A temperature sensor can be placed on the fingertips and you can be asked to raise the temperature. With training you may be able to do so and eventually can do it without the thermometer.

If you ever studied optics, you would realize that the image seen by the eye/brain is upside down. The baby 'learns' to invert the image in his brain.