What is depression? Why are brains able to slip into it? Is depression detectable in animals? Do animals have options beyond fight or flight? And what does any of this have to do with measuring depression medications in city water supplies, reward pathways in the brain, the prevalence of tuberculosis, and zapping the head with magnetic stimulation? Join today's episode with David Eagleman and his guest -- psychiatrist Jonathan Downar -- for a deep dive into the brain science behind depression and what new solutions are on the horizon.

Why can you hear some sounds two different ways, depending on which word you’re looking at? Why do electrical outlets sometimes look like a face? How can you have rich visual experience with your eyes closed? Are some crosswalk buttons fake? Why are some pictures interpretable only once you’ve been told what to look for? And although brains are often celebrated for their parallel processing, what should they really be celebrated for? Tune in to learn what happens when the raw facts of the world collide with your expectations.

When he was a child, Eagleman fell off a roof and time seemed to run in slow motion. When he became a neuroscientist, he grew curious about the experience and collected hundreds of similar stories from others. But is it true that your brain can actually see in slow motion, like Neo in the Matrix? And how would you test that? Hear how he dropped volunteers from a tower to put the science to the test, and what the answer reveals about our perception, memory, and experience of the world.

What would it be like to have a vastly better memory than you do now? What if you could remember what you were wearing on any day a dozen years ago? Or who you were with, what the conversation was, and whether it rained? Would it be a blessing or a curse? And if you’re forgetting a lot of your life, what might you do to better remember it? Join Eagleman with actress Marilu Henner, one of only dozens of people in the world diagnosed with highly superior autobiographical memory.

When you imagine something -- like the sun peeking over a mountain during an early morning rainstorm -- do you see it with rich visual detail, or instead with very little internal picture? In an earlier episode we tackled the spectrum of visual imagination, from hyperphantasia to aphantasia -- and in this episode we dive even deeper with guest Joel Pearson to surface the most surprising differences between people's internal lives. How does your experience differ from other people's, and how does your brain cobble together the skills you have to accomplish what you need?

Why do you see a unified image when you open your eyes, even though each part of your visual cortex has access to only a small part of the world?
What is special about the wrinkled outer layer of the brain, and what does that have to do with the way that you explore and come to understand the world? Are there new theories of how the brain operates? And in what ways is it doing something very different than current AI? Join Eagleman with guest Jeff Hawkins, theoretician and author of "A Thousand Brains" to dive into Hawkins' theory of many models running in the brain at once.

How do you define what things are living and dead? You might look at a sprinting cheetah and say it's clearly alive, whereas a chunk of rock is not -- but where do we draw the line? What might we expect extraterrestrials to look like, and would we even have the capacity to recognize them? And what does any of this have to do with Frankenstein, ancient Greek philosophers, or the possibility of finding a cell phone on Mars? Join Eagleman with guest Sara Walker, theoretical physicist at Arizona State University and author of the book “Life as No One Knows It”.

Do brains time travel? What is a prediction error? What does any of this have to do with the 2008 crash of the economy, how we keep internal price tags, or a rational approach to drug addiction in society? Join Eagleman to learn how your 3-pound universe spends its whole existence nailing down choices.