Read the full transcript of behavioral neuroscientist Dr. Kelly Lambert’s talk titled “Improving Our Neuroplasticity” at TEDxBermuda 2020 conference.
Listen to the audio version here:
TRANSCRIPT:
The Neuroplasticity Mystery: Depression in Modern Times
DR. KELLY LAMBERT: Such a wonderful experience to be here in beautiful Bermuda. Thanks for coming out today. Like most of you, we don’t get a lot of downtime, but when I get some downtime, I really love to read a mystery. It seems that our brains, our human brains with all of our complex circuits, are uniquely designed to put the pieces of the puzzle together and to solve mysteries. But one mystery that’s really been troubling me lately is the mystery of why in the midst of a multi-billion dollar antidepressant industry, depression rates continue to go up. About 300 million people across the world today experience depression. This isn’t good. We need to do better. It’s unacceptable.
It makes us think that maybe there are some other suspects, some other clues where we can get some information about how to come to the solution and solve this mystery of depression. Well, one area where we spend a lot of time looking for clues is neurochemistry. And this makes perfect sense because our brains are swimming in neurochemicals, dopamine, serotonin, acetylcholine, glutamate. And they have a huge impact on our behaviors, our emotions, our thoughts. So it makes perfect sense to think that we could take a pill that could change our neurochemistry in ways that would make us feel better, to be emotionally resilient.
But there are challenges with this because it’s hard to mimic nature in that if there is an imbalance that’s associated with something like depression, how do we make it take a pill and change the neurochemistry in these natural ways? So it’s not very precise. And unfortunately, it doesn’t help, reliably help, everyone who needs to, who has depression. So it makes us think that there are some other clues and suspects out there.
The Brain’s Movement Connection
So being a neuroscientist, when I go back to the drawing board, that drawing board is a brain. And I wanted to be, as I tell my students, let’s be brain whisperers of a sort and see what is important to the brain. And what really stands out to me is how our brains seem to be designed and evolved to move our bodies around. We like to think that our brains are about thinking, but movement is an incredibly important behavior. If we think about the cerebellum hanging off the back of our brains, it contains about 80% of our brain’s neurons, 80%. And what does the cerebellum do? Well, it does a lot of things, but it’s most noted for its role in controlling our motor coordination.
The areas that’s around the center of the brain called the striatum, also involved in coordinating and facilitating our movement. And in fact, individuals who have Parkinson’s disease or Huntington’s disease have some impairment of the system. And then going from the middle of our brain down to our ear is the motor cortex. And it’s involved in moving the specific muscles that are important for us to initiate and carry out that behavior that we want to carry out.
If you look at the proportion of that motor cortex and what muscles, the muscles that it’s coordinating and controlling, it’s the area that controls the hand is disproportionately large. It seems like nature is telling us movement is incredibly important. And movement of our hands is also very important. And if that’s true, what would happen if, say, we decided that we weren’t going to move around as much? Maybe we’re going to spend a lot of time sitting down in front of screens. Would that have some impact on our brains? Maybe so.
A Century of Lifestyle Changes
And it’s interesting to think over the past century just how much our lifestyle has changed. It’s about 100 years ago, but it’s hard to believe that just in 1939, the New York Times ran an article about this invention that was revealed at the World’s Fair. It was called the television. It was really a neat thing, they said. But they said it will never be more popular than the radio because what family has time to sit in front of a TV in the evenings and not use their hands to do work? Wow, things have really changed over the last century and past generations.
When I think about my own childhood, going back, driving back to Talladega, Alabama to see my grandparents, I have vivid memories of how busy, especially my grandmother, was. After working in the factory, her downtime was spent shelling peas or shucking corn or snapping green beans on that front porch, only to be followed by freezing and canning and preparing that food so that in the winter when she would bring that food out and prepare these wonderful Sunday dinners, I saw the pride on her face because now thinking back, she had to bring up these memories of how the role she played in providing that food for her family.
And it really made me see this pride. And if someone was sick in her community, I remember her saying, I’m from Alabama, bless her heart, she couldn’t have her own garden, so I’m going to take her these vegetables so at least she can prepare them for the winter. Wow, how things have changed. I’m beginning to think that maybe when we traded in our spears and our clubs for selfie sticks that maybe we’ve traded in something really important for our brain.
And what if our cultural contemporary ideas of prosperity in which we work really hard to make enough money to pay people to do the things our grandparents and ancestors used to do very well for themselves, maybe that doesn’t match our brain’s idea of prosperity. And maybe that mismatch could lead to some contribution of psychiatric illness, these high rates that we’re seeing today.
In fact, our ancestors’ dependence on their hands and interacting with the environment to provide the resources just to live for that day might have been the original Prozac, the prehistoric Prozac that perhaps we need to remember.
Behavioral Regulation of Emotions: Historical Examples
But this idea isn’t new. Charles Darwin, who was the great naturalist, wrote that he had a lot of angst when he was dealing and writing and musing about this idea of natural selection and how controversial it was and the impact it would have on his family and friends and ideas about religion and the origin of our species. And he said that when he would walk around his property, and there was a path called the thinking path, that it would calm his nerves.
And he would put a rock at the gate, and he would have his walking stick, and when he would walk around that path, he would knock that rock off to signify the effort that he had made. And if it was an especially stressful day, he’d put two rocks. And even more, he might have a three-rock walk, and he’d have to walk three times and knock that stone over. Well, he wasn’t just realizing that his behavior was important in regulating his emotions, but he was even dosing himself in whether or not he was going to have a one-walk, two-walk, or three-walk day.
So this idea of behavior was incredible, he saw that it was important for regulating his mental health. And in the days when cake mixes came out, mostly women making the cakes those days, the first cake mixes had everything you needed to make the cake. You just needed to pour the batter in the pan. But some very smart manufacturers noticed that women didn’t take as much pride in their cakes if they didn’t have a little skin in the game. So then they took, they didn’t have to, but they took the egg and the water. So you’d have to add the egg and the water, give you a little bit more effort, and people were more proud of the cake.
Behavior-ceuticals: A New Approach
So thinking that behavior is important for our mental health, and we can change our behavior and change our neurochemistry through behavior, as our ancestors have, it caused me to think about a new word, a word I just made up, behavior-ceuticals. So we can change our neurochemistry by taking a pill that will alter our neurochemistry, or maybe we can change our neurochemistry strategically by engaging in smart behaviors that will change it in more healthy ways.
Well, I was reading that about a hundred years ago, doctors used to prescribe knitting to women in those days that they described as overwrought with anxiety. They didn’t know why, but they saw that it calmed their nerves, kind of like Darwin. So now that we know about neuroscience, this makes perfect sense. Serotonin is increased when we are engaged in repetitive behavior, and the knits, knitting and making the stitches is an example of repetitive behavior. As the knitter is thinking about that beautiful scarf or hat that she…
As someone makes stitches while knitting, it increases dopamine. It’s known as the pleasure neurochemical of the brain, but it’s mostly involved with anticipation, looking forward to something. As you think about the stitches instead of the worries of the day, that probably calms and reduces stress hormones. If there was one neurochemical that probably is a culprit, a suspect in a lot of the mysteries related to mental health, it’s these stress hormones, cortisol, for example. About 50% of everyone diagnosed with depression has high cortisol levels. So anything we can do to depress or decrease the stress hormones is an important endeavor.
If we’re knitting in the company of friends, then that may increase oxytocin, and oxytocin is known as the cuddle chemical, but it’s important in fostering positive relationships and also probably reduces stress. So here you go, a behavior pseudical with one activity of knitting. It may be cooking or woodworking or gardening, but something that’s reminding you that your physical effort is the result of that is some reward.
I’m a neuroscientist, so we want to go back to the brain. I can remember the drawing board here. I was fascinated to see that the area of the brain that is involved in reward, that is impacted in depression, lack of feeling that reward, is the nucleus accumbens, kind of lower in the brain. It has rich connections to that area of the brain involved in movement called the striatum. Those areas have indirect and direct connections to the frontal cortex that’s involved in decision making and planning.
The more that we engage in behaviors where we can see the result of our effort, those circuits are consolidating so that as we go forward for the next challenge in our life, we have a little experiential capital to bring with us to remind us that what we do can make a difference. We did produce that scarf. We made that cake. We walked around the thinking path.
Rat Research: Evidence of Effort-Based Rewards
I work with rats for a living. These are my colleagues. And they outsmart me all the time. As a scientist, we need evidence. So all of that theorizing about our ancient humans and ideas about depression, it started to make sense. But I wanted to take this to the lab.
A lot of friends and people who find out what I do, they ask, but what can you learn about our brains, our fancy smancy brains, by looking at this very simplistic brain? Well, it is true that it’s small. It’s two grams compared to our about 1,400 gram brain. But it has all the same parts, all the same neurochemicals. If I showed you a neuron, that individual cell in a human brain versus a rat brain, you wouldn’t be able to tell the difference. So it’s a wonderful model to start with. I realize that a rat is not a little human, and we’re not a big rat. But it’s a good model.
When I was thinking about this, I wanted to put these rats to work. I’m thinking about this idea about work and producing products that we’re proud of. I needed something that the rats would work for, and our rats love Froot Loops. So we had to get them addicted to Froot Loops, and then I needed a task. I thought back to my grandmother’s garden, and I wanted them to harvest something. So we came up with a task where they would harvest Froot Loops, not fruit or vegetables, but they would dig up Froot Loops.
They have this arena, and we move around these mounds of bedding, and they were trained so when you see a mound, you go and you just gently dig, and voila, there’s a Froot Loop. They had an opportunity to get four of those every day. So it’s not intensive training. It’s about five or ten minutes a day for about six weeks. But they’re building those connections between the reward areas of the brain and the motor movement areas of the brain to produce effort-based rewards.
Well, for proper science, you need a control group to compare to this experimental group. So our control group was a group that we put in the same arena, and we gave them their Froot Loops regardless of what they did. So my students like to call the experimental group where their effort was contingent upon their behavior, or their rewards were contingent upon their behavior, the Worker Rats, and the rats that got the reward no matter what, there wasn’t a contingency there, the Trust Fund Rats.
Testing Resilience and Neuroplasticity
We’ve done several studies where we wanted to put our Worker Rats to the test to see if this effort-based reward training generalized to other things. So we like to expose them to new challenges like swimming. They’ve been in the lab. They’ve never been in water. Well, the effort-based reward Worker Rats, they’re more likely to dive down like little rat scuba divers to explore the environment. And they showed more evidence of effective coping.
When we look at their brains, I think brains are gorgeous, they show more evidence of neuroplasticity, that fertilizer, brain-derived neurotrophic factor, more complex connections with the neurons. So we see this neuroplasticity. For the interventions and therapeutic approaches that we have currently for depression, most of those directly or indirectly increase neuroplasticity. But here we’re doing it naturally.
But that was with training. We wanted another way to stimulate effort-based rewards that was more spontaneous. So we’ve known for a while that if you put a rat in an exciting, engaging world, something we call an enriched environment, kind of a Disneyland of sorts, they’re busier and they have more neuroplasticity. And it seems to be great for their brains.
We also look at artificial kind of manufactured stimuli and more natural stimuli. So we have our country rats and our city rats. They seem to be equally smart, but our country rats seem to have an edge on emotional resilience. So they’re more like those effort-based reward rats that’ll go out, the bold ones. Also with our effort-based reward rats, we see lower stress hormones and higher hormones of resilience. And remember we said that was important for mental health.
Social Connection and Natural Environments
Interestingly also, we found that when we have a group of rats in the enriched environment and a group of rats in just a standard environment, they do things more together. Not only in engaging with their environment, but through cooperation. We’ve actually shown that their oxytocin that we talked about increases when they’re engaged in these natural and enriched environments doing things together. And that’s important for our behavior suitable cocktail.
This doesn’t surprise me because recently in Denmark they showed that humans, they followed about a million, who grew up with, and their childhood household had more green around it, shrubs, trees, they were up to 55% less likely to experience depression in their life. If we could bottle that, whoa, that would be amazing.
So where does that leave us? We’re not going to go back to the cave. We’re not going to go back to being hunters and gatherers. We’re here in this advanced technologically rich world and we benefit in many ways from that. But looking back at what we know about our ancestors and the brain and my wise rats, I think it reminds us that we need to remember our evolutionary roots as we go forward in this world of technology and have a little bit of those effort-based rewards, especially if it’s related to nature in some way, to help us in our mental health.
Driving Rats: An Unexpected Experiment
I had an experience where I got to put this to the test to see if an engaged, enriched environment would allow the rats to show more healthier brains. I had a colleague who asked me, “Kelly, can you teach a rat to drive a car?” And I thought, well, why would I want to do that? That’s not natural and it goes against everything I thought, but we drive cars.
Before I knew it, we were talking about how you would get a rat to drive a car and how you would shape it to go in. And we decided it would grab the little copper bars and, of course, it would be driving to a Froot Loop tree. That’s their drive-in. And if you’ve ever wondered if you could teach a rat to drive a car, yes, you can. Not only can they drive, but they can steer. They’re auto-correcting.
And this blew my mind. But more relevant for this story is when we looked at rats that were in the enriched environment versus the standard environment, the rats in the enriched environment, when we took them through the ropes of driving to see how long it would take them to learn to drive the criterion for robust driving, they learned in 22 trials. The standard rats, it took, well, we don’t know how long it would take. They never really learned to drive. This blew our minds that the enriched environment made our rats better learners of technology. So we think that our driving, our enriched rats would get their driver’s license, but not so much for the rodents. They would be denied.
Neuroplasticity Through Experience
So as we think about our brains and what they evolved to do, the idea of taking a single pill and being able to replicate what goes on in our brains naturally seems just about as unreasonable as thinking that we could take a pill to be a better parent. You just can’t do that. You have to go through the ropes. You have to have those experiences to go forward. You have to have the behavior that leads to behavior suitables to change the neurochemistry in healthy ways.
Conclusion
So I started with a mystery. What’s going on with our brains? Why are these rates increasing? And looking back and thinking about how our behavior can change not only our neurochemistry but our neuroanatomy, I think that the solution and clues may have been in our hands all along. Thank you.
