Author Archives: Jenna White

Constructing Electronic Devices for Recording Cell-Specific Neural Signaling

Jenna White

Mentors: Isaac Weaver, Sasha Burwell, Michael Tadross, PhD.

Department of Biomedical Engineering

Neurological diseases such as Parkinson’s have been found to alter electrical and chemical signaling in the brain, but it is unknown how these diseases affect neural signaling due to insufficient technologies for neural recording. It is hypothesized that if the fabrication of devices featuring transparent electrodes with appropriate dimensions is feasible, these devices would allow for recordings of individual neurons. This project involves the creation of devices using glass wafers layered with a conductor, utilizing the method of photolithography (exposing the wafers to UV light) for patterning electrodes on the conductor and patterning a layer of insulator added on top of the conductor. These wafers were then diced into separate devices, and wells for holding neurons were added onto each device. Despite errors in constructing these devices, over half of the devices created yielded well-aligned electrodes with a diameter similar to that of a neuronal soma. This suggests that the dimensions of each electrode allow for the isolation of signals from a single cultured neuron in vitro. The fabrication of these devices has shown feasibility, and with future improvements such as increased mechanical stability, these devices show potential for cell-specific neural recording.

Biodiversity in Watersheds

Throughout my experience in B-SURF prior to this week, I have been immersed in engineering approaches to various biological issues. However, this week, I was exposed to multiple different topics through the Chalk Talks, and I was amazed by how wide the scope of the study of biology really is. I was especially interested by Lali’s presentation, as her research is so different from mine and serves such an important purpose.

Lali’s research looks into the impact of urban development on the biodiversity of aquatic insects. Her lab focuses on the the watersheds of two creeks in the Durham area: Ellerbe Creek, which has a lot of urban development, and New Hope Creek, which has much less development. She is taking samples from two points on Ellerbe Creek with 90% urban development and 75% development, as well as one point on New Hope Creek  with 9% urban development. She is using sticky traps to gather bugs and count the amount and type of bugs at each point and then comparing them. Her hypothesis is that Ellerbe Creek will have less biodiversity and more resilient insects than New Hope Creek, as when it rains, the water in Ellerbe Creek rises much more and causes sand to form , resulting in there being no rocks for the insects to hold on in turn making it more likely for them to die. New Hope Creek rises much less following rain due to less development, resulting in there being more rocks for the insects to hold on to.

I loved Lali’s talk because even without being an expert in biodiversity, I feel like I very clearly understand the methods and purpose of this research. I also enjoyed how she talked about the way in which this research could be used to apply to humans and our everyday lives. I found it cool how this research could be used to look into socioeconomic inequities in resources used to improve the environment and how its results could have effects on the Raleigh population, as this population drinks water that comes from Ellerbe Creek.

I’m happy that I was able to learn a lot from all of the Chalk Talks, and I feel that I learned a lot from Lali’s in particular.

Carrying Mice and Building Electrodes: Days in the Tadross Lab

Due to having two mentors, my days in the Tadross lab vary quite a bit. I work with one mentor typically observing the behavior of mice after they have been injected with drugs into the brain 2-3 days a week, and I work with another mentor building electrodes that will eventually be used to observe electrical activity in neurons for the other 2-3 days.

When working with one of my mentors, Sasha, I show up and greet the fellow members of the lab around 11 am. When I’m working with her, I either observe her slicing the brains of mice for imaging and doing histology, or I perform behavior tests (aka open field tests) with the mice. These behavior tests analyze the impact of drugs that attach to dopamine neurons on the movement of the mice. After the drugs are injected into the mice by Sasha, I put the mice into boxes and video their movement around the box for an hour. This video is then analyzed using software that detects regular and irregular movements of the mice.

On a typical day of doing behavior tests, I take the cages into the room where we perform the open field test, which we call the “behavior room, ” and put on gloves and a lab coat. To set up the experiment , I take the mice out of the cages by picking them up by the tail and put them into the boxes (one mouse per box). I then spend the next hour in the dark behavior room (the lights need to be off in order to not distract the mice) doing miscellaneous work like reading papers and filling out forms while periodically looking at the computer screen to make sure nothing irregular happens to the mice (basically ensuring sure that they don’t die). Then, after the hour is done, I stop the video, save the files, take the mice out of the boxes and put them back into the cages, and clean off any excrement that the mice released while in the boxes.

When working with my other mentor, Zack, I typically meet him or a recent graduate now working as a research tech named Austin around 11. We then head to the cleanroom, a place in the Fitzpatrick Center where products can be manufactured. It is called a cleanroom because there is filtration that constantly removes dust and other debris from getting on the devices being built. The biggest source of contamination in the cleanroom is humans, so when we enter the cleanroom, we have to put on a suit including a hood, a jumpsuit, cloth boots (which I still haven’t figured out how to properly secure so they don’t fall to my ankles), gloves, and goggles. We then head to the lockers in the cleanroom and get our materials, including the glass disks on which we build the microelectrodes and the instructions for building the electrodes (printed on a special type of paper that does not shed particles like regular white paper). Each disk has four devices containing electrodes, and we typically work with 3-5  disks per batch. We then follow the instructions, spending 2-3 hours working on different sections of manufacturing the device a day. It typically takes around a week to get a whole batch of devices completely finished. We just completed the first batch of these devices, and I mainly observed Zack and Austin build the electrodes while taking notes. Next week, I will start making my first batch of the devices by myself!

Overall, I’ve loved how different each day working in the Tadross lab has been different. I learn something new every single day.

Showing There’s More than One Path to Success

The PI in the lab that I am working in this summer, Dr. Michael Tadross, has had a bit of an unorthodox experience in academia. His PhD in BME took an extra three years due to a failed experiment. Then, following this, he made his greatest invention, DART (Drugs Acutely Restricted by Tethering) without having his own lab. Today, he has been able to establish a lab focusing on creating tools to target specific parts of the brain in order to monitor their functions and activities. After having a good discussion with him earlier this week, I’ve learned more about his life and the lessons that he has learned throughout it.

I first asked about his academic background and if he was always interested in what he studies now.  He told me that he had developed an interest in discovering more about brains while in undergrad. In addition,  he began with a background in electrical engineering before graduate school, and was originally interested in developing brain-computer interfaces. However, as time progressed, he came to the conclusion that in order to truly study functions of the brain, one should have knowledge and skills in biological, chemical, and electrical processes. As a result, the Tadross lab features projects studying the biological effects of drugs on behavior, the chemical components best suited for particular drugs, the electrical response of neurons targeted by certain drugs, and more. Also, due to his background in electrical engineering, he was able to look at the brain as a circuit. This has allowed him to obtain a better understanding of the mechanisms of the brain.

However, he told me that he hit some trials along the way. In graduate school at Johns Hopkins, he joined a lab whose topic of study he was not interested in because he had in his own words “a crazy idea” and needed to find a lab that would give his resources, so he made a deal with the PI that he would be able to create his own project for his PhD as long as he helped with projects that the lab was currently working on on the side. Unfortunately, after three years, this project did  not succeed, so he had to start all over with a new project that the lab was working on. This project ended up being very successful. After this, he worked in a prefaculty position known as a fellow in which he was able to do research but with limited resources. After around five years, he was able to come up with a method of delivering drugs to specific areas in the brain (DART) and publish a paper on it, and this really helped him become a faculty member at Duke. Since then, he has been working on new ways to improve DART and using this method to see how different drugs and conditions affect different parts of the brain.

From my talk with Dr. Tadross, I have learned that interests change over time, and though success does not always come easy, hard work is worth it if you are truly passionate about what you are doing. Dr. Tadross used lessons that he learned from his failed experiment in order to create DART, and he still loves doing research more than he loves doing anything else. Above all, I have learned that I should never be afraid to be creative. He told me that there is still so much to learn about the brain, so I should never doubt my ability to come up with something new. Overall, I’m very happy that I got to speak with him, as he has helped me see that I should keep my options open and not doubt my abilities.

Creating and Using Tools to Discover More About the Brain

The possibilities in neuroscience research and neural engineering are endless, as there is still so much about the brain that we do not know. Tools can be created to help make amazing discoveries about the brain. For example, the Tadross lab created DART (drugs actively restricted by tethering) in order to deliver drugs to specific cells in the brain in order to discover new things about the function of specific neurons in the brain. This is accomplished by injecting a virus into an animal such as a mouse, waiting a few weeks to let the virus select cells of interest, and then injecting drugs that will only be able to be captured by the selected cells of interests. The use of DARTs in research can be helpful in the study of particular cells that are affected by neurological diseases such as Parkinson’s.

I am working on two projects in the Tadross lab. The first project involves seeing how dopamine affects movement. This project involves injecting mice with various DARTs that each target dopamine receptors (each mouse receiving one DART), then using open field tests in which the mice are put into a box and their movement/behavior is observed for an hour. This is done in 3 trials for each mouse: 3 hours after the injection, 6 hours after the injection, and 24 hours after the injection. The movement will then be tracked using software and compared to a control in order to see if there is any abnormal movement and in turn if the drug actually affected the dopamine receptors and how its effect on the dopamine receptors change movement. Along with the trials, we will check to see if the neurons that were being targeted actually captured the drugs in order to assess if the drugs truly affected the mice’s movement. In this case, the effect of the DARTs will be able to mimic the effects of certain diseases on the brain, potentially giving new information for what exactly in the brain changes behavior. 

The second project that I am working on is building electrodes that can be used to measure the electrical activity of neurons in order to see how the electrical activity of neurons changes after they have been manipulated by DARTs. This will involve constructing the electrodes in a cleanroom, putting cultured mouse cells on the electrode, and using software to stimulate the neurons and view the intensity/frequency of the action potentials that occur as a result. This project will assess both the ability of the electrodes to properly measure electrical activity and the DART’s ability to alter the neurons. This could be used to see how the electrical activity changes due to neurological diseases, giving greater hints at what treatments may be most effective.

I’m grateful for being able to work on projects both testing the efficiency of a tool that has been created and creating a new tool. I’m very excited for what is to come!

Mice and Cool Suits

The brain is an amazing enigma. We as humans use the brain to do everything, but we are unaware of how it controls much of the body. This summer, I am working in Dr. Tadross’ lab, which studies the connection between the activity of specific cell types of the brain and various behaviors. Through working in this lab, I have the great opportunity to work with two mentors, one specializing in biomedical engineering and one specializing in neurobiology. Through this, I envision myself learning more about how to build tools that detect the activity of specific cell types and use these tools in order to make discoveries about the functions of these cell types.

This past week, I was faced with a lot of different trainings focusing on topics from general lab safety and chemical safety to animal handling. My mentor focusing in neurobiology, Sasha, is working with mice to see how dopamine affects movement and learning, so I needed to learn how to properly handle these mice in order to use them in experiments. On my first day, she led me to a room full of mice in cages. Throughout the day, she would carry them out of the cages, at times perching them on her arm, and she told me that I would be doing the same sometime soon. I’ve never worked with animals. In fact, I’ve never even had a pet, so I have no experience actually taking care of animals. I expect to become a lot more comfortable with working with animals and hopefully become less scared to hold them. My other mentor, Zack, is creating a product that can measure the electrical activity of cells in the brain, and in order to build and test this product, I will need to learn how to use equipment in a cleanroom. As a part of my training, I watched a video detailing how to put on a cleanroom suit. The suit looks somewhat like the suits you see in movies when people are handling radioactive materials. I will not lie, I am very intimidated, but I anticipate eventually mastering the use of the equipment and gaining more experience with actually building a medical device (which I really haven’t done much in my classes, I will add).

Overall, I expect to learn a lot about the brain and the functions of different parts of the brain. I’ve known that I have been interested in the brain for about a year now, but I had never taken an actual class focusing solely on neuroscience, so I believe that this hands-on  experience will help me further look into my interests. In addition, I anticipate developing a great relationship with Dr. Tadross and my bench mentors Sasha and Zack. They all seem to be very kind so far, and they show that they believe that there is no such thing as a dumb question and greatly encourage me to ask questions and research what I am not familiar with. I hope that I can adopt this mindset and use this mindset to become a better scientist by becoming more comfortable with exploring and investigating new topics and new research questions. Furthermore, I anticipate making some mistakes. I am sure that I will not do everything perfectly the first time, and it may take a few attempts to effectively understand what I need to do. I am prepared for this, and I hope that this experience will further help me understand that success does not equal perfection.

Also, to be completely honest, I hope this summer can help me figure out what biomedical engineering (and engineering in general) is, as I just declared it as a major and I still don’t really know.