How Does Your Brain Know Where You Are?

Although some of us are certainly directionally challenged, a claim my wife makes about me that I staunchly deny, we can easily navigate spaces with which we are familiar. When, late at night, you wake up needing a drink of water (or an illicit sandwich), you can make your way to your kitchen without having to turn on a single light. You can also form a mental picture of the streets you normally take to get to your office, having driven the route more times than you’d like to remember. How is this possible? How does your brain know where you are?

Older theories about the answer to this question essentially came in two different flavors. One theory held that the cognitive map in our brains was egocentric, that is, centered on the self. This mental map would have your brain at its center at all times, therefore continually changing as you move in the real world. The second theory had an allocentric cognitive map, a map based on an external frame of reference completely independent of the observer, in which the self moves as if it were a token moving across a game board.

Researchers believed that both theories could be tested because each cognitive map would show up in the neurons that were responsible for creating it. Years of research did not live up to these optimistic expectations, however, and researchers are still searching for a definitive answer. How are we able to form our mental images, or maps, of familiar places and routes? As I sit here tying this article, I can close my eyes and go back to my childhood home, moving through each room and hallway as if it were just yesterday that I lived there, when in fact my family moved away from that home when I was only 15. I can move not only through the house, but also outside the house, up and down our street, into our backyard, just about anywhere that I navigated in reality. What’s really interesting is that I can picture where I am now, in Central Florida, in relation to that childhood home, though it is quite far away. (I may owe that ability more to Google Earth than anything else, however.)

The human brain has been described as the most complex thing in the universe. Some have speculated that we will never be able to fully understand it because the brain would be attempting to understand itself. According to one scientist, “If the human brain were simple enough for us to understand, we would be too simple to understand it.” The most difficult obstacle we now face in our efforts has to do with the fact that we cannot ethically penetrate a living person’s skull for the purpose of study and experiment. This means that we are limited to the use of sensory equipment to measure brain activity from the outside, which is obviously extremely imprecise.

A new development may be in the works, however, that would allow researchers to survey, down to the level of individual neurons, exactly what is going on in the human brain. Dr. Rodolfo Llinas, in an interview for the PBS show 22^nd Century, describes his research with nanowires, and his belief that such wires can eventually be implanted in the brain down to the neuronal level. Here’s a brief part of that interview:

“The possibility occurred to me that it would be very intriguing to use the holes that are already present in the brain… without actually having to go through the skull. And the, the holes that I’m talking about are the holes produced by the fact that the brain has vessels and the vessels, which basically bring oxygen to the brain, may be used as pathways into the brain.

“Clearly you cannot direct one nano wire anywhere. If you, on the other hand, have bundles of nano wires… you can do a very good job of directing bundles into certain areas of the brain by going to well known points in the vascular system. So what does this mean? Can one go up the vessel in, in the brain and get to a particular point? The answer is yes. It is done every day. Interventional neurologists do that when there are problems with the vessels.

“So the technology is there. Now the question would be, can you actually put nano wires exactly at the place you want? The answer is no, you can’t. But nano wires are very small. So what you do is you actually send a certain number of them… So the idea would be to have a bundle and then the bundle would be allowed to, to float into the bloodstream until it can go no further. That is, they would be tethered. So some of them are short, some of them would be long.

“You will end up then, seeding or wiring a particular part of the brain. Let’s say you want to go to the anterior part of the brain, so you take the anterior cerebral artery and you go to the right side or the left side and so on. Because the wires are so small, you can put a very a large number of them.”

If Dr. Llinas’ nanowires, or some other new technology, work, we may know a great deal more about our minds than we do today. Hopefully that will be a positive development.