Welcome to the cockroach world!
My work for these five weeks was to develop a novel low-cost system to study the circadian rhythm of cockroaches. I’m working with my beautiful friends discoid cockroaches (B. discoidalis).
Circadian rhythms are physical, mental, and behavioral changes that follow a roughly 24-hour cycle, responding primarily to light and darkness in an organism’s environment. In the case of these nocturnal creatures the changes in locomotor activity (what I’m measuring) goes from sleeping during daylight, and activity during night. The sleep-wake cycle is generated by an internal clock that is synchronized to the light-dark cycle of the environment. Because they are nocturnal, light may directly inhibit locomotor activity.
We asked what would happen to the activity patterns of discoid roaches if they kept a normal 12 hour light/dark cycle for ten days and then switched to 24 hours of darkness for another ten days, and then with constant light. In the absence of external cues to tell the cockroach what time of day it is, our hypothesis is that we will see free-running, and a new activity cycle will develop based solely on the internal biological clock. To track this, we measure the activity of the cockroach with running-wheels throughout the day in free-running conditions (no external cues), along with sensors to track light and temperature. From this we hope to develop the cockroach wheel as a model for educating students about circadian rhythms, animal behavior, and neuroscience, and to provide a simple, low-cost, but flexible experimental system for research into the behavioral effects of various commonly consumed substances such as caffeine.
The rhythm in cockroaches is controlled by the sub-oesophageal ganglion. The photoreceptors on eyes detects light or darkness, transduce the signal, this signal goes through the optical nerve to the optic lobe (where is located the clock), this one receives the message and output the activity. I will control the external cue (light) that her brain used to output the activity that corresponds to the time.
Want to study with cockroaches?
When I came here 5 weeks ago I began with a microcontroller (BeagleBone Black), the green board with sensors, a wheel with some black,
and white stripes, a devilish code to run all of this, and knowing nothing about anything of the electrical and computer science work that I was needed to do.
As soon as possible I put everything to work. My older set-up looks like the photo at the right-it was in a box that I carried to my house several times in order to record data. I need them this way because the BeagleBone wasn’t, at the time programmed to access Internet through an ethernet cable, so I needed it, at all times, connected to my computer and my laptop turned on. The most difficult objective to complete was to have the code with all the commands in the correct way so it can collect good data. There seemed to always be a problem with missing, commented, uncommented, or extra lines that made this code a stressful thing to work with.
I now have five 3D printed running-wheels with plenty space for the cockroach and a good object sensor at the back, the light sensor to tell when the lights go on and off, and temperature sensors that showed the environment was constant. I attached these to the support of the wheel, all in a comfortable locker with soundproofing foam (to eliminate outside noise), and a device that control when the lights goes on and off. The board with these sensors is attached to the BeagleBone Black, and the BBB runs through Wi-Fi (no easy feat). Though not done yet, my code is getting better with the help of people like Stanislav our programmer, and Max and Nick-our resident super-engineers. Now the system is complete and beautiful:
Outlet Timer Wi-Fi adapter Research in Progress
Sensors at the back Object sensor with B/W Stripes Microcontroller with breadboard (red)
The Fantastic Five
Let there be (12 hour cycle) light! Cockroach Rave
Want to see cool cockroaches running on the wheel? Click here:
https://www.youtube.com/watch?v=jEmhrpX7Ntc
https://www.youtube.com/watch?v=SqUIjPRfMgk
The fastest one? Click here: https://www.youtube.com/watch?v=vdbTq0RI9MI
Environment for cockroaches
I put my cockroaches in a controlled environment with no external cues interfering, such as noise or light during night, that could let them know what time of day it is. We don’t want them to potentially associate other external cues to time because their rhythm will be based on other cues, and not on light cues which we control and provide. In order to achieve this I put them in a locker with soundproofing foam, a stripe of LED lights (sun light), and the green board that contains the sensors attached to the 3D printed running-wheel for a sexy and clean set-up.
Understanding the collected data
Now that we have all the set-up, let’s move to the best part-Science! In my data I have a range of arbitrary values that will represent whether the sensor received lots of infrared light back or not. That usually goes from 2500 to 4000-A value of 2500 means that the sensor was in front of a white stripe, and if in front of black stripe the value can go up to 4000. Every time the cockroach moves, the stripes do too, and so I can see in my data the movements in a wave that goes from white (2500) to black (4000).
How object sensor works
Set-up to collect data
First ever collection of complete 23.3 hours of data!
Cockroaches are nocturnal animals, that’s why light may directly inhibit locomotor activity in a them. I’m looking for a pattern of activity-once I have that, I will begin with the dark/dark cycle, and compare this data to the normal cycle they exhibit.
Actograms!
You’re seeing two circadian rhythms of two different cockroaches in the same environment. As you see, It showed a rhythmicity, although does not follow the light cycle. This may have been because the cockroaches were living in a dark room. A couple of weeks are needed for them to adjust to the light cycle.This is the most astounding data I ever saw. This is the first time data is collected and plotted in an actogram. Hope you enjoyed like I do.
Why study circadian rhythms
My main goal for this project is to prove the system is viable to study the circadian rhythms of cockroaches, and I did it. Research in this area can lead to knowledge about how the daily cycle in humans works, and what are the consequences of disruptions to it. It is known that disruptions to the circadian rhythms are highly related to cancer, obesity, mood disorders, stress, and other health issues.
You made it! Thanks for taking the time to read how it is going with my research.
Behind this project is
The Alpha Dog, also called Karina M. Matos Fernández. I study Psychology and Mental Health in the University of Puerto Rico in Ponce, and I’m a proudly intern in Backyard Brains. For this project I’m using papers such as Control of the circadian rhythm of activity in the cockroach by John Brady, along with Recording and Analysis of Circadian Rhythms in Running-wheel Activity in Rodents by Verwey, Robinson, and Amir.
I’ve never known anything about what a microcontroller is or could do, and this month I programed six of the most finicky kind-BeagleBones. That’s why I’m called The Alpha Dog. Also it never crossed my mind that I would be so close to a cockroach… And yet, now I love them. How could one not love these amazing creatures?
If you are wondering how I beat my fear of cockroaches, let me tell you that I’m still working on that. In case no one was available to grab them, I used a special mechanism I invented consisting of a cup and a lid: these two helped me to grab them. However, I still feel a special love for them.
I’ll be glad to know who you are, and what are your questions and comments. I hope that now you’re interested in making research with cool model systems such as this one. Whoever is out there, I want to know more about you. Keep in touch to know more about the progress of the project.
Contact: karina@backyardbrains.com
To be continued…
Katelyn Rowley put some scientific
photos in my post. Thanks!