As a neuroanatomist at Harvard, I studied how our brain creates our perception of ­reality. And then one morning, I woke up with a sharp pain directly behind my left eye. In the course of four hours, I lost the ability to walk, talk, read, write, or recall any of my life. I was experiencing a major hemorrhage, bleeding in the left half of my brain, which rendered me an infant in a woman’s body.

The perception of time is, of course, controlled by cells inside our brains. Cells in the left hemisphere allow us to think linearly, to recognize that things happen in a certain order. My stroke completely shut down those cells, leaving me dependent on my right hemisphere, which doesn’t register anything beyond the present. I had no perception of the past or future. What I was seeing and smelling and experiencing at that instant was my entire existence.

It’s hard to put that feeling into words, but consider this situation: Your clothes are in a pile. You use your linear brain—the left half—to figure out what goes on first and what goes on last. You’re going to put on your underwear before you put on your pants. Without that sense of ­linearity, all you have are the individual pieces. It’s hard to relate to people when you think that way; it’s not good when a storyteller tells you the punchline before the joke.

A couple of weeks after the hemorrhage, surgeons pulled a golf-ball-size blood clot out of my left cerebral cortex. I immediately felt brighter and more present—even with a hole in my head. Brain cells, and a lot of my memories, started to come back online. I began to relearn skills. And I learned to work with time: I had a watch, and I understood the concept. But my experience remained very much in the present moment for a good six years. You could teach me how to put my socks and shoes on, yes. But if you put them down in front of me, I wouldn’t know which to put on first.

Eventually, time came back. Some abilities I had to learn all over again, and some just returned on their own. I remember some things I forgot, but I have no clue what parts of myself I’ve lost forever. I still can’t remember, say, what my 10th birthday cake looked like. Can you?

Source: Popular Science