What investigating neural pathways can reveal about mental health | Kay M. Tye
Neuroscientist Kay M. Tye investigates how your brain gives rise to complex emotional states like depression, anxiety or loneliness. From the cutting edge of science, she shares her latest findings -- including the development of a tool that uses light to activate specific neurons and create dramatic behavioral changes in mice. Learn how these discoveries could change the way you think about your mind -- and possibly uncover effective treatments for mental disorders.
this Ted talk features neuroscientist K Ty recorded live at Ted. It s 2019. Ted talks daily is supported by BB and T. Now, truest BB and T sees all sides of you beyond just your financial side. They see your personal side You're strong and confident side your silly side your vulnerable side your loving side because when they focus on you they strive to be the best bank for you That they can be at BB and t always see is you tow Learn more visit bea bea t dot com slash checking
I'm gonna start by saying something you think you know to be true.
Your brain creates all facets of your mind.
So then why do we treat mental and physical illnesses so differently if we think we know that the mind comes from the brain?
As a neuroscientist,
I'm often told that I'm not allowed to study how internal states like anxiety or craving or loneliness are represented by the brain.
And so I decided to set out and do exactly that.
My research program is designed to understand the mind by investigating brain circuits.
how does our brain give rise to emotion It's really hard to study feelings and emotions because you can't measure them.
Behavior is still the best and on Lee window into the emotional experience of another for both animals and people.
self report is a behavioral output.
Motivated behaviors fall into two general classes,
seeking pleasure and avoiding pain.
The ability to approach things that are good for you and avoid things that are bad for you is fundamental to survival.
And in our modern day society,
trouble telling the difference can be labeled as a mental illness.
If I was having car trouble and I took my car to the mechanic, the first thing they do is look under the hood. But with mental health research, you can't just pop open the hood with the press of a button. So this is why we do experiments on animals specifically in my lab. Nice toe. Understand the brain? Well, we need to study brains, and for the first time, we actually can. We can pop up in the hood. We can look inside and do an experiment and see what comes out. Technology has opened new windows into the black box. That is our minds. The development of opted genetic tools has allowed us unprecedented control over specific neurons in the brain and how they talk to each other by firing electrical signals.
Weaken genetically engineer neurons to be light sensitive and then use light to control how neurons fire. This can change an animal's behavior, giving us insight into what that neural circuit can. D'oh! I want to know how scientists figure this out. Scientists developed opera genetic tools by borrowing knowledge from other basic science fields. Algae are single celled organisms that have evolved to swim towards light. And when blue light shines onto the ice spot of analogy, sell ah channel open, sending electrical signal that makes little flag L. A flap and propels the algae towards sunlight. If we clone this light sensitive part of the algae and then added two neurons through genetic modification, we could make neurons light sensitive, too, except with neurons. When we shine light down an optical fiber deep into the brain,
we change how they send electrical signals to other neurons in the brain and thus change the animal's behavior. With the help of my colleagues, I pioneered the use of opera genetic tools to selectively target neurons that are living in point A. Sending messages down wires aimed at point B leaving neighboring neurons going, other places unaffected. This approach allowed us to test the function off each wire within the tangled mess that is our brain. A brain region called the amygdala has long been thought to be important for emotion, and my laboratory discovered that thehe middle of resembles a fork in the road were activating. One path can drive positive emotion and approach and active ng. Another path could drive negative emotion and avoidance. I'm gonna show you a couple of examples a taste of raw data of how we can use opted genetics to target specific neurons in the brain and get very specific changes in behavior. Anxiety patients have abnormal communication between two parts of the amygdala, but in people it's hard to know if this abnormality is cause or effect of the disease. We can use opera genetics to target the same pathway in a mouse and see what happens. So this is the elevated plus maze. It's a widely used anxiety test that measures the amount of time that the mouth spends in the safety of the closed arms relative to exploring the open arms.
Mice have evolved to prefer enclosed spaces like the safety of their burrows. But to find food water mates, they need to go out into the open, where they're more vulnerable to predatory threats. And now, when I felt the switch and turn a light on, you can see the mouse begins to explore the open arms of the maze more. And in contrast to drug treatments for anxiety. There's no sedation, no local motor impairment, just coordinated natural looking exploration. So not only is the fact almost immediate, but there are no detectable side effects. Now when I flip the switch off the mouse goes back to its normal brain function and back to its corner. When I was in the lab and I was taking these data, I was all by myself,
and I was so excited. I was so excited to one these quiet screens. Why was I so excited? I mean, yeah, theoretically, I knew that the brain control the mind, but flip the switch with my hand and see the mouse change its behavioral state so rapidly and so reversible. E. It was really the first time that I truly believed it. Since that first breakthrough, there have been a number of other discoveries finding specific neural circuits that can elicit dramatic changes in animal behavior. Here's another example. Compulsive overeating. We can eat for two reasons. Seeking pleasure,
like tasty food or avoiding pain like being hungry. How can we find a treatment for compulsive overeating without messing up the hunger driven feeding that we need to survive? The first step is to understand how the brain gives rise to feeding behavior. This fully fed mouse is just exploring a stays completely devoid of any food. Here we're using up the genetics to target neurons living in the hypothalamus, sending messages down wires aimed at the mid brain. When I turned the light on, you could see that the mouse immediately begins licking the floor. This seemingly frenzy behavior is about to escalate into something I find really incredible. It's kind of trippy, actually. See, he picks up his hands as if he is eating a piece of food, But there's nothing. There is a whole anything. So this circuit is sufficient to drive feeding behavior in the absence of hunger.
Even in the absence of food, I can't know for sure how this mouse is feeling. But I speculate these neurons, Dr Craving, based on the behaviors we elicit when we target this pathway, turn the light back off animals back to normal. When we silenced this pathway, we can suppress reduced compulsive overeating without altering hunger driven feeding. What did you take away from these two videos that I just showed you that making a very specific change to neural circuits in the brain. Caf specific changes to behavior that every conscious experience that we have is governed by cells in her brain. I am the daughter of a physicist and a biologist who literally met on the boat coming to America in pursuit of an education. So naturally, since there was no pressure to be a scientist as a college student, I had to decide whether I wanted to focus on psychology, the study of the mind or neuroscience, the study of the brain.
And I chose neuroscience because I wanted to understand how the mind is born out of biological tissue. But really, I've come full circle to do both. And now my research program bridges the gap between the mind and the brain research for my laboratory suggests that we can begin to tie specific neural circuits to emotional states, and we have found a number of circuits that control anxiety related behavior, compulsive overeating, social interaction, avoidance and many other types of motivated beavers that may reflect internal emotional states. We used to think of functions of the mind as being defined by brain regions. But my work shows that within a given brain region there are many different Iran's doing different things, and these functions are partly defined by the path they take. Here's a metaphor to help illustrate how these discoveries change the way that we think about the brain. Let's say that the brain is analogous to the world and that neurons are analogous to people, and we want to understand how information is transmitted across the planet. Sure, it's useful to know where given person is located when recording what they're saying.
But I would argue that it's equally important to know who this person is talking to, who is listening and how the people listening respond to the information that they receive. The current state of mental health treatment is essentially a strategy of trial and error and it is not working. The development of new drug therapies for mental health disorders has hit a brick wall with scarcely any real progress since the 19 fifties. So what does the future hold in the near future? I expect to see a mental health treatment revolution where we focus on specific neural circuits in the brain. Diagnoses will be made based on both behavioral symptoms and measurable brain activity further in the future, by combining our ability to make a cute changes to the brain and get the cute changes to behavior with our knowledge of synaptic plasticity to make more permanent changes, we could push the brain into a state of fixing itself by reprogramming neural circuits exposure therapy at the circuit level. Once we switch the brain into a state of self healing, this could potentially have long lasting effects with no side effects. I could envision a future where neural circuit reprogramming represents, ah, potential cure. Not just a treatment. Okay,
but what about right now, If from this very moment forward, each and every one of you left this talk and truly believed that the mind comes entirely from cells in your brain, then we could immediately get rid of negative perceptions and stigmas that prevent so many people from getting the mental health support that they need. Mental health professionals. We're always thinking about what's the next new treatment. But before we could apply new treatments, we need people to feel comfortable seeking them. Imagine how dramatically we could reduce the rates of suicides and school shootings if everyone who needed mental health support actually got it. When we truly understand exactly how the mind comes from the rain, we will improve the lives of everyone who will have a mental illness in their lifetime half the population as well as everyone else with whom they share the world. Thank you,
P. R X.