For many people of a certain age, the PBS series Cosmos was a major event —a stunning love-letter to astronomy that provided a novel way of thinking about ourselves and our place in the universe, all the stranger and more inspiring because it was based on facts. The neuroscientist David Eagleman counts himself among those moved by Cosmos, and he sees it at as a model for his ambitious new PBS series. In “The Brain with David Eagleman,” he serves as tour guide for a lively 6-hour exploration of what has been called the most complex object in the known universe, the gelatinous mass that, somehow, makes us who we are. 

Eagleman answered questions from Mind Matters editor Gareth Cook.

Cook: What inspired you to do this series? What do you hope people will take away from it?
Eagleman: I grew up watching Carl Sagan’s Cosmos, and I always admired his endeavor to open up the beauty of a rarified field to everyone. I’ve been in neuroscience for 23 years now — this field is my home and my passion, and I wanted the opportunity to share the wondrousness of it with a wider audience. Not everyone is going to go into neuroscience as a profession (nor should they) but that doesn’t mean everyone shouldn’t get to delight in its magic to some degree. I hope viewers will gain a sense of the vastness of the insights in modern neuroscience, as well as the depth of the mysteries that still surround us.

Cook: Your first episode addresses the question of how the brain “creates” reality. Can you explain what you mean by this, and what is so interesting — and challenging — about trying to answer it?
Eagleman: Consider that whole beautiful world around you, with all its colors and sounds and smells and textures. Your brain is not directly experiencing any of that. Instead, your brain is locked in a vault of silence and darkness inside your skull. All it ever experiences are electrochemical signals coursing around through its massive jungle of neurons. Those signals are all it has to work with and nothing more. From these signals it extracts patterns, assigns meaning to them, and creates your subjective experience of the outside world. Your reality is running entirely in a dark theater. Our conscious experience of the outside world is one of the great mysteries of neuroscience: not only do we not have a theory to explain how private subjective experience emerges from a network of cells, we currently aren’t even certain what such a theory would look like. In the series I confront that mystery, and others, to give an indication of where the field is going, and how this might get solved.

Cook: The story you tell of Mike May is quite amazing. Can you tell me a bit about that, and what you think the lesson is?
Eagleman: Mike May was blinded in a chemical explosion at the age of three, and grew up entirely blind. In his 40s he underwent a surgery to repair his scarred corneas, thereby allowing light to pass through once again. The surgery itself was a success, but the amazing thing is that Mike still wasn’t able to see, at least not the way we think of vision. Although his eyes were now functioning perfectly well, his brain couldn’t interpret the signals. He stared at objects and people around them, but he couldn’t make sense of the jangling, buzzing data. Mike’s case reminds us that vision is not about the eyes but about the brain. Vision arises not simply from photons hitting the retina, but instead from the brain’s proper interpretation of the signals that result.

Cook: Those of us who are not psychologists or neuroscientists generally go through the day imagining that we consist of a unitary, conscious self, making decisions as we go. What are some of the ways that you see the series challenging this assumption?
Eagleman: Glad you asked: I’ve devoted a whole episode to the question of how we make decisions. In that hour it becomes clear that you, as an individual, are not single-minded. Instead, you are built of competing neural networks, all of which have their own drives and all of which want to be in control. This is why we’re interesting and complicated. We can argue with ourselves, we can get mad at ourselves, we can make contracts with ourselves. Who exactly is talking with whom? It’s all you, but it’s different parts of you. In another episode entitled “Who is in control?” I tackle the question of how much control your conscious mind actually has, as opposed to all the rest of the brain activity that chugs along without your acquaintance or your ability to access it. Collectively, over the course of the six episodes, I hope that viewers will find their assumptions about actions, beliefs, and reality put under the microscope.

Cook: What was the most challenging aspect of putting this series together?
Eagleman: Like so many things in life, the implementation of writing and filming a six-hour series was a far larger task than anticipated. It took almost a year and a half of constant work, and during that time I was running my full time research laboratory and finishing a textbook on Cognitive Neuroscience and launching two start-up companies out of my lab. The idea of downtime went the way of the mastodon.

On a shorter time scale, the most challenging moments involved writing and re-writing scenes on the fly while the camera was set up and the crew was waiting. Also, it’s surprisingly painful to film, say, a 2-day sequence that ends up on the cutting room floor, never to be seen again.

Cook: The final show is called “Who will we be?” What was the motivation behind that episode, and what can we expect to learn there?
Eagleman: I’m captivated by the ways that our technology is becoming married to our biology, thereby changing our trajectory as a species. I recently spoke about this issue at TED, where I unveiled a device we’ve invented in my lab to feed new information into the brain. This can expand the narrow human slice of perception. In the final series of The Brain, I extrapolate the technology-biology marriage into the distant future—exploring, for example, whether we can freeze brains and thaw them out a thousand years later to reboot you. Or whether we can circumvent our biology altogether and run a full, detailed simulation of your brain in a computer—and whether that would be you. If any of this turns out to be possible, it would open up possibilities for space travel, as the biology we come to the table with is not terribly useful for interstellar travel. What’s more, the future-looking question of whether we could someday live in a simulation circles back to a very old question, contemplated by philosophers from Chuang Tzu to Renee Descartes to the Wachowski brothers: how would we know if we were already living in a simulation?