Our next tour will be of Dr. Karla Kaun's lab at Brown University. The Kaun lab works on understanding how addiction works in the brain. What are the relevant genetic pathways that makes us crave an addictive substance? How are memories that lead to addictive behavior formed? Can we take advantage of some of these genetic pathways to develop new treatments for addiction and relapse? Work in the Kaun lab uses the fruit fly Drosophila melanogaster as a model organism. Fruit flies have the advantage hat their genome is well understood and there is an impressive array of experimental tools that can be used to manipulate gene expression in their tiny brains. So how does one study drug addiction in flies? Let Dr. Kaun tell us how:

Who are you?

I'm Karla Kaun and I'm an assistant professor of neuroscience at Brown University.

What Research Questions Do You Work On?

I'm interested in the neural and molecular mechanisms of addiction. Addiction is a really complex disorder and it’s composed of intoxication, bingeing, withdrawal, and craving of drugs and so one of the questions that I'm interested in understanding are what are some the genetic contributions to this because we know that there's about 50 percent of the likelihood to become addicted is due to your genetic makeup and the other percent is due to both psychological and social factors associated with drug intake.

In my lab, we're really interested in figuring out both what's going on in the brain and what's going on inside of the neurons, molecularly, to contribute towards addictive behaviors. We concentrate on addiction for alcohol in my lab. Alcohol is the most widely used and abused substance worldwide, but unlike other drugs of abuse like nicotine or cocaine, for example, the exact molecular targets for alcohol are really not very well characterized. We use the fruitfly, Drosophila melanogaster, to be able to understand this because the flies’ genes and neurons are quite easy to manipulate.

My name is Arjun and I’m a grad student in Karla’s lab and I work on associative memory in these flies. Right now I'm going to show you how I sort flies. Turn on the CO₂. This knocks the flies out and it's pretty simple; just use this scary looking thing to gas them. You can see them passing out there. Just maneuver them onto this pad were they get continual co2 and they'll stay out. So that’s it.

One of the reasons that Drosophila is so easy to use in the laboratories is because it's really easy to knock them out and then they're really obvious phenotypes associated with their mutations like eye color or the curliness of the wings or the size of the bristles, so we can sort different types of mutations very quickly. Fly biologists like Arjun we call "fly pushers" because they essentially spend half their days pushing around flies on the carbon dioxide pad. In order to understand how alcohol affects the brain, we have to dissect brains of flies and this is not always an easy task to accomplish but my students upon very low caffeine intake are able to extract the brains of flies and then we stain it with antibodies and fluorescent dyes to look at exactly what neurons we think are important for alcohol reward. Half of the student’s day is some times spent in front of this little scope here expecting out the brains of flies and then figuring out where they glow in the brain.

In my lab, I'm interested not so much in the acute intoxicating effective of alcohol, like what happens when you give flies and what happens when you give flies alcohol and watch them get excited. I'm interested in the memories that are associated for the intoxication experience and it’s these memories that we think are important for reducing cravings later on in addicted individuals.

So what we do is essentially manipulate specific genes and there's a couple molecular pathways I'm interested in and as well as very specific subsets of neurons inside the brain to figure out what molecules are acting inside of those neurons to create these really long lasting memories for alcohol intoxication.

What Techniques/Model Organisms Do You Use? What Do They Tell Us About Nervous System Function?

I use the fruit fly Drosophila melanogaster and this is an amazing animal to be able to understand behavior. Because, first they're really robust laboratory creature so it's really hard to kill them. We measure their behavior and have very sophisticated tracking devices to be able to do this. But they have tiny little brains and an amazing toolbox of neurogenetic tools to be able to manipulate individual subjects that neurons or almost any molecule that we want inside of those neurons. So what we're able to do essentially is manipulate almost any gene we want in almost any subset of cells inside the brain we want and record behavior in live behaving animals without any kind of external manipulations.

Fruit flies have been used as a genetic model organism from more than 100 years and that means we know an incredible amount of detail about most of the genes in the Drosophila genome. In addition, they've also been used to study behavior for over 50 years, so they're incredibly well characterized laboratory animal. We do something called mutagenesis by mail.

Because there are so many genetic tools available, different laboratories hold their own subsets of genetic tools and so sometimes all we have to do is send off an email or pick up the phone and say I want mutant XYZ and then they’ll send it by mail so one of the benefits to working on flies is that it's really easy to keep them in the laboratory. We keep them in vials or bottles like this and they eat a yeast-molasses-corn meal media basically and so every single one of these flies is a different mutant or transgenic strain so we have thousands upon that we keep inside the lab and flies have different developmental stages: they go from egg to larvae to pupae to adults and they do this within about two weeks so not only is it easy to keep a lot of different strains of flies in the lab but the experiments can be done very quickly because they develop very rapidly.

Okay so I there were some amazing tools that were made recently by Gerry Rubin’s lab at Janelia Farm and I worked with one postdoc in particular Yoshi Aso and what he did was he used intersectional genetics to be able to make tools where we can express and very select subsets of neurons in the fly brain so this is an area of the fly brain we call the mushroom body and it's known to be important for olfactory learning and memory which is what I study in my lab and what Yoshi did was he mapped all of the different types of neurons in this brain structure as well as all of the neurons, neuron by neuron, that provide information to this structure and this is some of these neurons look like for example the cell bodies are here and this neuron will give information in this section and it’ll take information from this section and this is a particular tool where we were able to see that those neurons which we thought was actually one neuron was really two neurons and so what we can do is we can either silence these neurons using thermo-genetics or we can activate these neurons. We can do that both using thermo-genetics or opto-genetics and then we can shift our flies to different temperatures and observe the role of those neurons in behavior and once we have that done we can create maps like this which show us all of the neurons that are important for whatever type of memory or whatever type of behavior we’re looking for.

How Does Your Research Relate to Human Disease?

Addiction is a very complex disorder and it's actually a huge burden on today's health society so the National Institute of Drug Abuse, which is a component to the US National Institutes of Health, estimate that addiction is probably the cause of spending of over $600 billion dollars annually and what's really alarming is an increased abuse and use of people with prescription and abuse drugs in teenagers.

This really substantiates the need to understand addiction at a neuronal and a molecular level and ultimately what we hope to be able to do is to develop both better behavioral and pharmacological therapies to help addicted individuals.

What Are Some of the Pitfalls You Have Encountered in Your Research?

Research is complicated and I think one of the hardest things it took me to learn was how to be patient. With the amount of time it took to get progress in your own research so in my lab we study behavior of flies and flies’ behavior is incredibly variable. We don't just study an innate behavior, we study learning and memory, so memory for drug reward, and this is often really tricky behavior to be able to reproduce or even to be able to see in a fly, so when I started working on addiction in flies, I was really determined to find a method to measure how rewarding the Flies found alcohol intoxication and this method which now takes about four hours in my lap to perform took me about six months to troubleshoot so I think from this lesson or from this pitfall is that I learned that sometimes it's not just the end result that's really important but it's the path that you take because through this six-month long troubleshooting journey I discovered how important it was to find a rewarding dose of alcohol—it’s extremely dose-dependent in almost every organism including flies-- as well as how complicated is to study memory any organism including the fly.

This is one of the apparatuses that we use to measure memory in a fly and what this basically is a chamber that's temperature and heat controlled and we have boxes here when we put perforated vials of flies in and then we'll stream in an odor along with vaporized alcohol so the way flies get drunk is to breathe in high concentrations of alcohol and humans can get drunk this way too actually so flies get drunk by breathing in their alcohol. And we associate that intoxicating experience with an odor and the type of odors I use are ones that flies will smell in nature in rotting fruit and then once the flies have been trained to associate an odor with alcohol, we test their preference and we do this by giving flies a choice between one odor and another odor and then tracking where they go so we use cameras to basically take really fast pictures of whether the flies like to go to the odor that was associated with alcohol or the other odor and that's how we tell how much they remembered of their intoxication experience and if they liked to go to the odor previously associated with alcohol they found that experience rewarding.

This is a new apparatus that we're developing in collaboration with Ulrike Heberlein’s lab and internal design and fabrication at Janelia Farm and what it is basically is a way to measure the motivational response that flies have in order to reach a reward at the end of the tunnel so what you do is you place flies in a little tunnel and then a gate drops and then the fly runs down the tunnel, another gate drops and then fly gets trapped in the end of the room at the tunnel and what we're measuring is basically the speed at which the fly likes to run down the tunnel if it runs much faster on the second or third run than they’re more motivated to get to the alcohol reward at the end of the tunnel and this is a really interesting apparatus because it's going to be fully automated so we track the flies and then the tracking data can inform the instrumentation basically how it should behave according to the position of the fly.

Why Did You Choose to Pursue a Career in Research?

I think really the reason why I was so drawn to research stems from my early childhood experiences. I grew up in a very remote northern community in Canada and I spent a lot of time outdoors, so I was exploring and sort of hiking, discovering the world around me and my parents really encouraged this. My mom herself would sometimes do these crazy do it yourself home kids’ science experiment in the kitchen with me and my brother and I think it was these early life experiences that really taught me how exciting and fun science was, but more importantly I think it taught me how accessible it was and how possible it was for anybody to do, even myself.

When I started university I was increasingly drawn to a more reductionist approach to behavior. I wasn't satisfied with just understanding what chunks of the brain were important. I wanted to know exactly what neuron, exactly what molecules in every single neuron were important and I was really fortunate to have a number of amazing mentors in my undergraduate, in my graduate, and in my post doc experiences that really taught me to appreciate this approach to understanding behavior and also taught me, I think, how to pose challenging questions, to be able to push the frontiers of my own field.

So this is what I tell everybody that shows any kind of interest in any kind of science at all. Science isn't easy but I think the most important thing is to be persistent and to be patient, right? And anytime in science sometimes you learn a lot more from your failures than you do from your actual successes and I think this is true for everything you do in life so the more thought that you put into what you're doing, the more time that you put into it, then I think the more reward you get out of it. Be patient and be persistent. Don't give up. That's the most important thing.

More Video!

Here are some outtakes, where various students in the Kaun Lab tell us about their projects.

Neuroscience in Action: Lab Tours - Kaun Students from Brown CE on Vimeo.

Links to the Kaun Lab

Kaun lab website

Instructions:

1. Answer the following questions for discussion:

What are the central research questions addressed in this lab? Why are they significant?

Why was the fruit fly Drosophila melanogaster chosen as a model organism for this research, what are some of the advantages and disadvantages?

What are some of the experimental techniques used in this research? How are these approaches used to study addiction?

If you worked in this lab as a student, what types of project/experimental question would you like to pursue?

Are there any questions you'd like to ask Dr. Kaun?

2. Click here and post your answers on the discussion board on the next page.