This summer my daughter spent a week at Astrocamp. She wasn’t allowed to have her phone, so we went a week wondering what she was up to.

Each night the camp staff would upload 200-300 pictures of that day’s activities, so every morning I’d go to their website and scan through them. I’d see her launching rockets, blowing things up, and doing blacksmithing. (I’m not sure how the last got in there, but she came home with a big piece of metal she calls “the brother poker.”)

It took me maybe 5 minutes to go click through all the shots. A few were of just one person, but most were of a group working on something.

While doing so I became fascinated with the brain’s ability to almost instantaneously sort faces into those that were familiar and those that weren’t, picking my daughter out quickly. We all read about these things in training, and see them in practice all the time, but it’s still a marvel when you realize how fast and precise the system is. Even when she was in the background I quickly identified her (although her habitual hat and jacket helped). After seeing other faces just one or two times I quickly recognized them in later pictures, too.

After she got back, we went on a cruise. I’m not prone to seasickness, and it’s impressive how quickly the vestibular system adjusts to the constant motion. The complex four-way rocking as the ship pushes through water quickly fades into the background. The semicircular canals and their input centers in the brain rapidly adjust to the moving world around you.

And when I return to land … the world keeps moving. For 3-4 weeks after a cruise, I continue to have a constant, mild rocking sensation. In my case, the “mal de débarquement” is more interesting than bothersome. Perhaps even a bit relaxing. My brain and vestibular apparatus, after syncing themselves to the constant motion of the ship, have trouble returning to the everyday stability of land. So my home and office slowly roll and pitch around me, gradually decreasing with each passing day.

Even as a doctor who specializes in the brain, its abilities still strike me as something to be marveled at. We take its 2-3 pounds of highly specialized nerve tissue for granted, not noticing its functioning as it guides our every activity (such as writing and reading this article). Yet, some innocuous events of this past summer again reminded me what an amazing thing it is.

Dr. Block has a solo neurology practice in Scottsdale, Ariz.