How do you imagine the line between life and death?

Maybe it's a long continuous process?

Or perhaps, it's a quick clear-cut transition?

This a question we've wondered about for a long time, from ancient philosophers to modern day doctors.

To Hollywood screenwriters producers who just write their own rules.

But it's only recently that we're discovering surprising facts about death.

We now know it doesn't happen in a single moment - rather, it's a continuous process that occurs in the brain.

Your brain is made of 86 billion neurons, or brain cells, making 100 trillion connections.

And your life depends on keeping these connections alive.

If your heart stops pumping blood even for just a few minutes, the brain slips into a state of frenzy.

Some neurons starve to death during the blackout.

And others fight for life.

Neurotransmitters, the chemicals that transmit your nerve impulses, spill out of neurons in high concentrations.

Uncontrollable electrical charges sweep across the brain.

Toxic chemicals pile up and literally burn holes in membranes of neurons.

All these events turn on programmed cell death - like a cell's suicide switch.

Eventually, neurons dies one by one, until the brain stops functioning altogether.

And that's what we call death.

So if dying takes so many steps, is it possible to halt or reverse the process?

This is a question that some scientists are working hard to answer.

Over just the past few decades we've seen huge progress in keeping people alive, by advanced surgical techniques, organ transplants, mechanical ventilators that can do the breathing for us.

We can even save a heart that has stopped beating.

So, what does it take to save an injured brain?

One of the trickiest things about the brain is that its neurons are irreplaceable.

All of the neurons you'll have for life, more or less, you are already born with.

But, scientists have recently discovered that our brain does have a small reservoir of stem cells that can generate new neurons.

Could we somehow coax these cells to turn into new neurons and self-repair the brain's injured tissue?

Or could we help a little bit by injecting neuronal stem cells into the brain of a patient?

Hypothetically, if it becomes possible to replace dead neurons, it should be possible to resurrect a person who has just died.

There are a few scientists who are planning to try.

Other experts, however, are really against it, calling it a bogus idea.

But, experts do agree that the idea of using stem cells to repair brain injury, in living patients, is promising.

But even this line of research is not without controversy.

Many experts believe that our understanding of stem cells is not yet at a point where we can apply it to humans and we may end up doing more harm than good to a patient.

What if the cells don't connect properly?

What if they grow uncontrollably, and like, give you cancer?

You may even see clinics that offer stem cell therapy for a variety of conditions, from stroke to paralysis.

But be warned, there's currently no FDA approved stem therapy for brain conditions.

But scientists are hopeful that one day we'll get there.

Scientists have shown that it is possible to plant stem cells in the brain of mice and help them grow into fully functioning neurons that make connections with their neighbors.

In the future, these methods could be used to repair the damage done to the brain by a stroke.

Right now, several trials are underway to transplant new neurons into the brains of people with Parkinson's disease.

Other scientists are taking a more direct approach by finding ways to turn other types of brain cells into neurons.

This approach has already worked in mice and one day, it might work for us too.

The cocktail of molecules that spurr neuronal growth could be even put in a pill.

These advances are exciting.

But they also raise a philosophical question.

If you agree that who you are is made by your brain cells and their connections, what happens to you when those neurons have been replaced?

Will you be a different person if your brand new neurons connect differently?

There are a lot of questions.

Would you receive a brain cell transplant?

Would you take a pill to grow new neurons?

Or would you give that pill to a relative?

And just how many cells do you think you can have replaced without fulling becoming a whole new person?

How far would you go to save your brain?