Free Inventing Iron Man by E. Paul Zehr

any given moment. You probably also recognize that your brain doesn’t exactly work like your computer or even your car engine. So, there isn’t a little port just sitting there ready to have something plugged into it so it can directly relay commands to a computer. Is it even possible to get specific and useful information from all the activity in the brain? Let’s investigate that “brain-computer interface” concept I mentioned a bit earlier. Get ready and hold on because we are about to dig deep into your gray matter.
    Your brain contains about 100 billion neurons, and there are about 1 billion more living in your spinal cord. As I write this sentence there are about 7 billion people on earth. So, the number of neurons in your nervous system is about 15 times more than all the people on earth right now. If we think of activity of the neurons in the brain like individual people trying to talk to each other, we can ask ourselves this question: what—if anything—can we extract from a conversation among 101 billion people? Luckily all our neurons speak basically the same “language” and communicate in the realm of electrical signals. And, they don’t all talk at once and aren’t literally all connected to each other. Despite the fact that there are so many neurons with different levels of activity, amazingly we can get something consistent and resembling certain patterns.
    Why is it that we can get anything to use as a signal to control things? When we make a purposeful movement, the commands start way up in our brains. Literally at the top, because the part of your brain that helps initiate movement really is at the physical top of your brain. (We will come back to this in more detail later in the chapter.) It is a bit oversimplified to say that areas of the brain are set up completely separate from other areas like isolated little kingdoms. However, different areas of the brain have very specialized functions, and it is usually shown as divided into frontal, parietal, occipital, and temporal lobes (also called “cortices”; figure 3.4 ). The labels in the figure within each lobe are meant to generally indicate the functions for those brain areas. When speaking about commands for movement, we are in the “motor system.”
    A common story in physiology and neuroscience is that many of the discoveries about function of parts of the brain and nervous system have come from observing what happens when things don’t work well or when there are injuries. In other words, much of what we knew before imaging technology came from descriptions of how movement control was disordered after brain or spinal cord injury. The “Edwin Smith Surgical Papyrus” described motor control problems after head injuries in ancient Egypt—over 5,000 years ago. Even though people have known about the connection between brain injuries and motor control for millennia, for quite some time there were many controversies about how the nervous system itself worked. For example, it took a long time to establish that the cells in the nervous system were “excitable tissue.” That is, they convey information using electrical signaling (see chapter 2 ). This is very important for the issues involved with Inventing Iron Man, since many of the things we are discussing in this book have to do with interfacing electrical devices (like computers) with the basic signaling within the nervous system (which is electrical). However, in classical medicine, Galen (AD 129–199) suggested that nerves were hollow and worked in a kind of pump or pipelike system to convey commands in the body. The substance relaying commands to activate muscle would then flow into the muscles and make them go. This idea was also favored by famous French philosopher René Descartes (1596–1650)—he of “I think therefore I am” fame. However, cutting to the heart of the matter (there is a pun