June 21, 2013
I’d like to tell you a little bit about why I’m a neuroscientist, but I’m not really sure where to start. Not because I don’t know the reason, but because I know so many reasons why I do what I do. I guess they’re really all just different facets of the same single reason: that the more I learn about how the brain works, about how beautifully complex it is, the more I’m filled with wonder.
As our laboratories make new advances and discover new properties of the brain, we are continuously confronted by endless new questions about how our brains work. Let me give you some examples.
Did you ever read that humans share 98 percent of their DNA with chimpanzees? Did it blow your mind? How can such similar genetic information give rise to such different organisms? Let’s take a step back. Humans have about 20,000 genes. Some species of rice can have more than 50,000 genes! Aren’t you more complex than a rice plant? Shouldn’t you have more genes to encode that complexity? As we sequence the genomes of more and more organisms, we’re finding out that the number and complexity of the genes does not directly correlate with the complexity of the organism.
And think about your personal genetics. Unless you’re a twin, you have a genomic sequence that makes you unique, a DNA code in every cell in your body that makes you different from every other human, and all other organisms. But that DNA code is the same in all your cells. So, what makes a brain cell a brain cell, and a liver cell a liver cell? How do all the cells in your body have vastly different, but highly organized forms, yet have all the same genes with the same DNA code?
It turns out that all of these questions are related, and we’re beginning to answer them by exploring the idea that genes are “turned on” or “turned off.” It turns out that the main difference between the cells in your liver and those in your brain is the pattern of gene activation: though the cells have identical DNA, the regions of that DNA that are active, the parts of the code being read, are vastly different.
Maybe the rice plant has more genes than you do, but you have a much more complicated and regulated pattern for the activation of those genes throughout your body than does the plant. Maybe we share 98 percent of our DNA code with chimps, but our patterns of gene activation differ substantially, making us very distinct organisms.
The new science of studying patterns and mechanisms of gene activation is called epigenetics, and it’s not just important for differentiating your brain from your liver, or you from a plant. It turns out that lots of things can influence the epigenetic state of your cells, and that this can affect your health, your lifespan, and even your mood and behavior. My laboratory studies how exposure to drugs affects the patterns of gene activation in the brain, and it’s our hope that understanding these epigenetic effects could lead to new treatments for drug addiction.
Each of my days in the laboratory holds the possibility of a new discovery, a new piece of data that will deepen our understanding of how genes in the brain control behavior. But at the same time, every advance I make opens the door to a new mystery, and leads to new questions that keep me fascinated and make my job continuously new, and endlessly rewarding. Understanding the epigenetics of drug addiction is why I’m a neuroscientist today, but who knows why I’ll be a neuroscientist tomorrow?