What Is the Language of the Brain?


by Guy McKhann, M.D.

February 27, 2014

What language does the brain use for its internal communication? That is a question posed in a New York Times article detailing the work of Clay Reid at the Allen Institute for Brain Science. In an attempt to answer that question, let me give you an example from my own family. My oldest son, now in his 50's, has always had a remarkable ability to recognize colors, remember them, and to reproduce them. Even when he was a small child, if we walked by a store's window display and I asked him what he saw, his answer would not involve the objects in the display but the colors. When we got home, he could reproduce those colors (and still could weeks later). He still possesses this ability, which surely helps in his career as an artist. How does his brain do it?

We know the outline of how color is perceived in the brain. Presumably there are networks of color-responsive nerve cells that involve the retina, way stations in the midbrain, and primary receptive cells in the visual areas of the cortex. From there the information is passed forward in the brain where it is integrated with information related to the colors such as source (a person, an animal, a tree-the list is almost endless). The color is then reproduced, requiring a motor act, but also requiring feedback to the memory or storage of the color.

If we could isolate the function of individual nerve cells in the networks for color in my son's brain, what would we find? How do they differ from mine, which have less "sense of color?" Are there more of them? Do they store color in a different way? How do they pass this information along? What is the language they use?

It is a little like the situation in genetics 50 years ago. Researchers wanted to know about the language used to store genetic information and how it was passed on to make a protein. Prior to the emphasis on DNA, the answer was considered to be in the proteins themselves. The recognition of the importance and structure of DNA changed everything. However, scientists were still left with a problem: If DNA was the genetic memory, how did it dictate the structure of a protein? The answer-the "genetic code"-turned out to be quite simple. DNA contains four nucleotide bases: cytosine (C), guanine (G), alanine (A), and thymine (T). How could four bases code for the 20 amino acids used in most proteins? The code works in combinations of three-three bases code for a specific amino acid. That is true for all cells in the body, and almost all species.

What does all of that have to do with how the brain processes information?

Currently scientists are studying small bits of the brain, looking at them with greater and greater discrimination. They are looking at the part of a nerve cell that passes on information, the synapse, and how this structure changes: What chemicals are involved? How do these chemicals change with nerve cell activity? Simultaneously, they are recording the electrical activity of these cells, trying to make some structural-functional correlations. We are getting a finer and finer idea of the wiring involved. But what is the message coming over these wires? That is the challenge!

Stay tuned! This subject, or question, is going to be coming up again.