Inside Salk; Salk Insitute

Insider's View

William R. Brody

William R. Brody

The ‘Decade of the Brain’ has finally arrived

Ever since I was in medical school (as many decades ago as the number of fingers on one hand, at least), I have been hearing “this is the decade of the brain,” meaning that in the next ten years, scientists will unlock the manifold secrets of the brain.

In the late 1950s, the famous mathematician John von Neumann wrote a book The Computer and the Brain in which he pointed out that when we don’t understand something–in this case the introduction of digital computers–we use a more familiar term by analogy–i.e., the brain–as a way of making the new concept more understandable. Of course, this analogy is laughable given the relative understanding that scientists and engineers have about the brain versus computers.

Think of the 10 to 100 billion neurons (like transistors) with more than many trillions of connections in the human brain and it is hard to wrap your brain (pun intended) around any ability to understand human perception, awareness, memory and more. For many decades, neuroscientists had to concern themselves with inserting a single electrode into the one of 10 billion neurons and recording the electrical activity of that single cell. All the while, they had little or no clue as to what other neurons might be connected to, controlling or communicating with the neuron under observation. Imagine going into Shanghai, with several billion telephone subscribers, and being given access to one telephone, challenged to come up with the complete wiring diagram of the Shanghai telephone system and how it operates!

So what’s different about the current decade and the science behind understanding brain function? A whole lot, to be sure. The most amazing discoveries in how the brain operates have been enabled by technologies:

1. Manipulation of the genome: Scientists can now insert specific genes not only into brain cells, but into particular types of brain cells. These ‘inserts’ can encode for proteins that mimic human diseases like Alzheimer’s and Huntington’s diseases and many, many more;

2. Observing the activity of hundreds of neurons (and more): The green fluorescent protein, a protein found in jellyfish in the ocean off the coast of San Diego, emits green light whenever a particular neuron in question is active. Thanks to this technology, scientists can observe hundreds (or more) cells;

3. Stimulating nerve cells with light (optogenetics): Using genes that encode for proteins that absorb light and convert light to electrical signals (analogous to the photosensitive pigments found in our retinal cells), it is possible to stimulate one or many nerve cells selectively;

4. Identifying which neurons are connected to a particular nerve cell of interest: Using a technology developed at Salk by Ed Callaway and John Young, the rabies virus can be used (safely I might add) to outline which neurons are connecting to a specific neuron of interest;

5. Pluripotent stem cells used to study human neurons: The generation of pluripotent stem cells from patients with neuropsychiatric diseases allows scientists to study brain cells in the laboratory. This is a vehicle to better understand abnormalities in neuronal function;

6. Advanced microscopy: At the Waitt Advanced Biophotonics Center, Salk scientists are conceiving of powerful new microscopes that provide previously unheard of capability to carry out the actions outlined above.

With these new tools, scientists are pushing back the frontiers of Alzheimer’s, brain cancer, stroke, movement disorders (e.g., Parkinson’s), and many more areas, as well as increasing our basic understanding of brain function in health and disease. While I can be certain that the complexity of the brain will not be unraveled at Salk or elsewhere in the next ten years, I am also highly optimistic that the discoveries of the next decade will move the field of neuroscience forward farther and faster than perhaps in the previous 200 years.

It is truly a time of great renaissance for the study of the brain.