What your doctor knows about neuroscience

I have nearly finished taking a first-year medical school course on neuroscience, though I am actually a graduate student myself. As a result I have a weird perspective on the course. So, the very first thing we learned is that the brain is made up of white matter and gray matter. When you dissect a brain (which was a surprisingly non-surreal experience) you can see parts that are lighter and parts that are darker. In general, the surface of your brain is grey matter, and then more towards the inside is a lot of white matter.

Now, scientists know exactly what white and gray matter are, but rather than get into the details, I'm just going to simplify by comparing to a computer. In the computer, there are chips, where information is processed, and then there are wires connecting the chips. So in the brain, the gray matter is like the chips, and the white matter is like the wires. There is white matter that goes from the top of your head all the way down to the bottom of your spinal cord, and some that goes from your toes all the way up to your brain in a single cell. Pretty cool, right? And of course, you need those long bits of white matter, otherwise how are you going to control your toes and feet? So all of this white matter is carrying pretty specific information. When you're outside of the brain, or in the brainstem, it is pretty easy to figure out what type of information all of those white matter wires are carrying. After all, you can see what they're connected to. Do those fibers go to a particular muscle? Do they come from sensors in your skin? Figuring that part out is pretty easy, so over the years scientists and doctors have figured out what goes were. In essence, they've figured out the wiring diagram of the body and brain.

For doctors, knowing that wiring diagram is great! With just a bit of knowledge about what areas of the brain are associated with what, they can then figure out what has become disconnected when you have a stroke, an aneurysm, hit your head, or whatever. This is particularly helpful when they scan your brain in an MRI machine and maybe they find two weird things in there at once. Is just one of them the problem? Maybe you only need one surgery, maybe you need two. If they know their wiring diagram well, then they can figure it out.

So I'm not trying to minimize how great it is that we know this wiring diagram, but given what I've learned I'm absolutely astounded at how little we have been taught about the computer chips! As an engineer, I'm picturing trying to learn about a computer by only being taught about the connections between the chips. That would gloss over everything that made it really a computer! You might figure out that the hard drive seems to store information if you looked on the signals on the wires. You might even figure out that the hard drive is long-term storage while the RAM is short-term storage. But you wouldn't have the faintest idea that a computer could run Word, Excel, and your game of Solitaire at the same time. That isn't to say that no one is working on figuring out what the gray matter does. A bunch of people are. I am. But to most medical doctors, they don't really have to care too much. And that's fine for them, just don't necessarily trust them to have deep insights about the brain.

I hope I have done justice to the wiring diagram. As a start, it is absurdly useful, especially to medicine, but from a perspective of trying to build a deep understanding of the brain, it does very little. It helps direct research a lot by telling us where we should stick our electrodes to study specific behaviors. Putting those electrodes in the wrong places would be a huge waste of money, so that is no small contribution, but the diagram also makes us miss connections sometimes when we're too focused on a specific area. For example, a lot of vision processing happens in the back of your brain (the occipital lobe), but if you focus too much on that area then you would miss how lip reading effects audio processing and how the associated sounds might also effect your vision.

One final endnote. No one in any neuroscience field that I've talked to has the slightest idea what is going on with Obama's BRAIN innitiative. In many senses we've already mapped out the brain (see above). In other senses we aren't even close (if you count the gray matter). And in some other senses (this is probably worth its own post) it doesn't even make sense to try to map out the brain because it's changing all the time. The initiative has the feel of Obama either trying to build a legacy out of nothing or just wanting to fund brain research and having no idea how to phrase it to sound intelligent to both the public and the scientists at the same time.