The human brain is really quite amazing. I've been thinking about that since last Thursday evening, when I got a minor concussion in karate class. It was an interesting experience; one moment I was in the midst of a warm-up fight, then I was on the floor, then I was sitting on a bench feeling very woozy and trying to figure out what exactly had happened. I didn't lose consciousness for more than a second or two, but I had some odd deja vu dreams, and it was probably about twenty minutes before I started to put together the sequence of events. All the while, of course, various instructors brought me water and talked to me as the class went on. An hour after the fall I was a bit headachy but quite able to make the two-minute drive home.
A concussion, as I understand it, is a fairly common injury caused by the brain being jolted and making contact with the inside of the skull, which can lead to bruising or nerve damage. I had a simple concussion, which does not require a brain scan and which usually heals within a week to 10 days. (I did go to the doctor on Friday to make sure I was okay for work.)
I found it particularly interesting to watch the effects of a brain injury as they manifested. Thursday night and all Friday I had a dull headache; by Saturday it was reduced to a soreness in my neck. It affected my mood as well. Though I suffered from clinical depression for years, now that I'm on a medication that works for me I'm generally a cheerful person who enjoys being alive; for two days after the injury, I felt like I was sinking again into my old state. Though I was functional enough to do the tasks required of me, being at work all day Saturday was hard; my coworker noticed it and said I didn't seem as sure of myself as I usually do. But it got better by the day, and today I went back to karate feeling just fine - though I'm not going to do any fighting till next week!
Tibetan Buddhists make the distinction between the ordinary mind, and the ultimate mind. (For a much better description than you'll find here, I'd refer you to the teachings of Sogyal Rinpoche.) As I understand it, the ordinary mind is that which is generated by the brain - an organ which, like all the others, is susceptible to aging, sickness, and death. It's not a sad thing, because much of the Buddhist path is realizing that "you" are far more than you realized - that's where the ultimate mind comes in. It just fascinates me how powerful and resilient this mass of grayish tissue can be - and makes me appreciate it all the more.