MICHEL MARTIN, HOST:
More than 30,000 brain scientists are in Washington, D.C., this week attending the Society for Neuroscience meeting. One of the hot topics this year is mental disorders such as depression and schizophrenia and autism. NPR science correspondent Jon Hamilton has just come from the meeting to talk about some of what he's been seeing and hearing. Hi, John. Thanks for coming.
JON HAMILTON, BYLINE: Hi.
MARTIN: So how does this work contribute to understanding mental disorders in people?
HAMILTON: Twenty years ago, I'd say it didn't contribute much, but things are really changing. And I was really surprised. I was going through the abstracts to this year's meeting, and there were nearly a thousand papers that mentioned depression. There were 500 that mentioned schizophrenia or autism. And just this morning, there was this study on how - looking at the brain tissue of people with obsessive compulsive disorder and how it's different.
So the fields of brain science and mental health are converging. And I think the reason is that brain scientists are finally beginning to figure out how the biology works, the biology that underlies mental health problems. So I was talking to a scientist at the meeting. His name is Robby Greene. He's a psychiatrist, but he's also a lab scientist at UT Southwestern in Dallas. And he was telling me that neuroscience is now at a point where it can help psychiatrists and psychologists understand all of those things that are happening in the brain that we're not conscious of. Here's what he told me.
ROBBY GREEN: Now we're starting to actually understand this unconscious activity in terms of how the neurons are working, firing, talking to each other in ways that produce the behavior, the feelings, things like that that we actually see.
MARTIN: So has something changed to let scientists understand so much more about what's going on in the brain?
HAMILTON: A lot of things that changed, but one of the big things is the ability to reproduce aspects of human mental disorders in animals. And you do this using genetic engineering. So, for example, there's a technique called optogenetics. And what it lets scientists do is use light to switch on and off specific circuits in the brain of an animal, not a person. Here's how Robby Green described what it can do.
GREEN: You shine this light on a specific area of the brain and activate those neurons. And all of a sudden, the mouse changes his behavior. And you say, oh, here's a circuit that's controlling whether an animal, let's say, avoids something or it goes towards something.
HAMILTON: I should say science has been using this technique to induce things like depression and anxiety. So you turn the switch on, a mouse gets depressed - you turn it off, they feel better. And it gives you a way to identify the circuits that are involved in depression. It also gives you a way to see how the rest of the brain is reacting to depression.
MARTIN: But that's still in animals. So how do we know things work the same way in humans?
HAMILTON: Well, because there are now ways to actually watch the human brain as it's working. And probably one that people know best is called functional magnetic resonance imaging - FMRI. It has limitations. It cannot look at individual brain cells, but it can tell you when certain areas of the brain become active and when two areas of the brain are communicating. And that means scientists have a way to see whether something they noticed in a mouse brain seems to be the same in a human brain.
MARTIN: So I think the question that a lot of people would have is, is all of this leading to any new treatments for mental disorders?
HAMILTON: Yeah, of course. It is beginning to. All this stuff about brain circuits we've been talking about, it turns out to be really important for using treatments like brain stimulation. So most people know about brain stimulation because it's a way to reduce tremors in people who have Parkinson's disease. But it turns out, there's more and more evidence that you can treat other diseases by stimulating different brain areas.
So, for example, if you stimulate one area of the brain, it can relieve some of the symptoms of depression. If you stimulate a different area, it seems to relieve some of the symptoms of obsessive compulsive disorder. And doctors would not have known which areas of the brain to stimulate if it hadn't been for all the basic research that comes out of places like the Society for Neuroscience meeting.
MARTIN: That's NPR's science correspondent Jon Hamilton. Jon, thanks so much.
HAMILTON: You're welcome. Transcript provided by NPR, Copyright NPR.