Backyard Brains is now in its second year of interns from the University of Santiago de Chile (affectionately called Usach). Last year we had a project recording the ganglia of snails – and this we will continue our voyage in the world of invertebrates with an old favorite and a new favorite. Cockroaches and Clams.
Hi, my name is Eduardo Isla, and I am in my final year as a student of biochemistry working at both USACH and UChile (Universidad de Chile). I am completing my undergraduate thesis right now as well as working for two months at the Backyard Brains Chile office. My thesis is in a quite different area (virology) working on epitranscriptomics of HIV-2. In my spare time I like to play MMORPG games as well as explore outdoor photography.
A lot of high school students like Backyard Brains’ Neuropharmacology experiment, as you can indirectly study synaptic activity in crickets, but it is time for an upgrade. First, a little bit about neurotransmitters
Did you know that neurotransmitters were discovered working on frog hearts? Everything began in 1921, when an Austrian scientist named Otto Loewi discovered the first neurotransmitter. In his experiment, he used two frog hearts. Heart 1 was still connected to the vagus nerve, and Heart 1 was placed in a chamber that was filled with Ringers solution. This chamber was connected to a second chamber that contained Heart 2. So, fluid from chamber 1 could flow into chamber 2. Electrical stimulation of the vagus nerve (which was attached to Heart 1) caused Heart 1 to slow down its heart rate. Loewi observed that after a delay, Heart 2 also slowed down. From this experiment, Loewi hypothesized that electrical stimulation of the vagus nerve released a chemical into the fluid of chamber 1 that flowed into chamber 2. He called this chemical “Vagusstoff”. We now know this chemical as the neurotransmitter called acetylcholine. It is also interesting to know English scientist Henry Hallet Dale had previously isolated acetylcholine. So, they both shared the Nobel Prize in Physiology or Medicine in 1936.
For the Backyard Brains neuropharmacology upgrade I will use some Clams, yes Clams. We eat them, but they are animals too, and believe or not they have a heart. So, I’m trying to adapt Loewi’s experiments into much simpler animals, easier to access/buy and less traumatic to work on. These experiments consist of using the Backyard Brains Heart and Brain SpikerBox to make recordings of electrocardiograms on clam hearts and the effects of different compounds. For this, first of all I need to record an electrocardiogram of the heart of clams. Afterwards, I will then treat them with various compounds to attempt to alter the heart rate. I also need to ensure that the record that we actually obtain is EKG and not movement of the electrodes. In these first few days I am trying to optimize the preparation, opening the clam while keeping the cardiovascular system intact.
The Quantified RoboRoach
Hi, my name is Claudio Moreno, and I am also in my final year working at USach in the lab of Neuroscience. I am doing my thesis in ion channel physiology, studying TRPM8 channels. TRP channels are the body’s temperature transducers, and TRPM8 is responsible for the feeling of coldness. In Chile we get cranky when the temperature gets below 40 degrees Fahrenheit (I know, nothing like Michigan), and we can thank our TRPM8 channels for that.
When not studying TRPM8 channels I enjoy going playing video games and guitar. I’ve being playing guitar for 13 years and it has been one of the best things I have done to get my mind distracted during moments of high stress. I also like to travel to different cities and countries. I have travelled to many cities here on Chile (my country), and it’s really beautiful, so if you have an opportunity to come here, trust me, you won’t regret it.
The RoboRoach is one of Backyard Brains’ original inventions where you can control cockroach locomotion by electrically stimulating the antenna, but, strangely, Backyard Brains has never systematically measured the adaptation rate. Until now. To do this experiment we are doing a bunch of RoboRoach surgeries, so we can have a high enough sample size to compare sensory adaptation rate.
Once a RoboRoach is recovered from the surgery, we can start to see if we can control our RoboRoach and measure turning responses with time! And for that we built a lego tower, which has a floating ball the cockroach walks on, along with an optical mouse to read the floating ball’s movements. When the antenna neurons are activated with electrical stimuli, they will send this electrical information (called spikes) to the cockroach brain, stimulating the neural-motor reactions. The cockroach will change direction, and we can measure this change.
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This contraption allows us to measure precisely the turning of the cockroach in response to stimulation of the antenna, so we can see how it adapts over time. Now it is time to collect the data and finally say with some degree of certainty the adaptation rates across cockroaches. Like all kinds of animals with a central neural system, you can expect that neurons can adapt to a stimulus (which Backyard Brains has anecdotally observed many times in the RoboRoach). Now it is time to quantify! I am starting to get skilled at the surgery, and below you can see my first successful antenna nerve recording!
Hi Everyone. Juan here! My two month tour with Backyard Brains has reached its end, and I’m really grateful to have had the opportunity to work on this project.
I had three activites during the “practica” here at Backyard Brains:
- Recording from the Ganglia of Snails
- Helping on the Anemone Project
- Assisting in Outreach.
The snail recording was my main project at 70% of my time, the anemona project occupied about 10% of my time, and the high school outreach was 20%.
Recording from Snails.
The original aim was to record the intracellular action potential of pacemaker-like cells from the parietal ganglia of Helix aspersa, using Backyard Brains hardware for the optics, acquisition and amplification. From the last blog post you can see that we had no problem with dissecting the ganglia or visualizing the neurons with hand pulled pipettes in the microscope, but we couldn’t get any recordings. Recording electrical activity from the leg of the cockroach is different from the ganglia of the snail. Because of the dry environment of the cockroach leg and the strong signal from the leg nerves, the cockroach leg nerve activity is very easy to record. Buuuuut with the snail, we have a really weak signal in a conductive aqueous salt solution, so we must take a different approach to the experiment, as repeated attempts at the BYB lab did not yield results.
Sooo we went to familiar ground (for me) and replicated the experiment with lab equipment from the Laboratorio de Neurociencias at the University of Santiago (Usach). We had divine intervention from Darwin Contreras, a PhD student who just that day had successfully defended his Ph.D. and happened to only be coming back to the lab to get his motorcycle helmet to go motor on home and relax with his growing family. Using a large Faraday cage, a dissection scope, and a high end manipulator (but yes, a Backyard Brains Neuron SpikerBox Pro), we carefully inserted an insulated blunt tip silver wire into the ganglia.
And we listened to the low background noise coming out from the speaker of the SpikerBox. But….Every now and then there was a rattle, sparse and random enough to not be an artifact, so we recorded it and to the surprise of everyone there it was, spontaneous, asynchronous action potentials. Success!
We witnessed high amplitude spiking (download the raw data if you like!).
And we also witnessed the rhythmic “neuron dying” response.
But this was only a partial success, as it was 1) our only successful recording, and 2) made extracellularly instead of intracellularly. We found a shorter electrode, to prevent the antenna effect, and a faraday cage minimized the noise profile, but we are still far away from the original goal, recording intracellularly from the large neurons in the parietal ganglion.
At the moment, we may seek another preparation for intracellular single unit recording, as the snail preparation is a bit tricky. We may go to the intracellular recordings of the muscles of the tail of the crayfish, or perhaps try another mollusk, say a “macha,” a type of clam very common along the Chilean and Peruvian coast, that we looooovvveeee to eat.
Recording from the Nervous System of Anemones
We continue in the long term project to record from sea anemones. We built a harpoon style electrode…
but the silver wire wasn’t strong enough to pierce the membrane of the oral disc of the anemone. We had heard that there are more neurons around the oral disc (which, in an anemone, serves as its mouth, anus, and reproductive orifice). We will try tungsten next, which is the classic, strong material for small metal electrodes.
But….we had the idea that maybe we could remove the tentacles, like we remove the leg of the cockroach, and attempt a recording in a more controlled environment under a microscope. To our surprise, the tentacles kept moving for an hour after we had cut them! We may be on to a new preparation, it is very fascinating to watch. Very primordial success, yet waiting, yet to come. See our video below.
We then inserted an insulated blunt tip silver wire into the open end of the tentacle and tried to see if we could measure spontaneous activity or evoked activity (when we touched the tentacle with a probe).
But….we did not get any successful neuron recordings. We are sure there is something here though, there have got to be neurons inside the tentacle. The tentacle is moving, and neurons must be talking to the muscles. The neurons in the anemone tentacle are arranged like sheets between rings of muscle, so it’s a matter of optimizing the preparation. We are always getting closer to the elusive anemone neurophysiology, stay tuned.
During the last part of May we taught the students how to build a two stage amplifier circuit from a breadboard, and the students can now recognize the logic of how to manage components like resistors, capacitors, and transistors.
During the last two classes I helped teach about the difference between reactions and reflexes using the knee and elbow.
For the last class, we did experiments measuring the difference between audio and visual reaction times. Data collected in a classroom can be noisy. Supposedly auditory reactions are faster than visual reaction times but we did not observe that difference in the students who had well tabulated data. But I always continue in my experiments. I always continue trying to have compelling data that tells an interesting story.
Bye Guys, Now I have to write my thesis! I’ll miss the late night pizza party experiment sessions with Florencia and Tim and the workshops in the Fablab at the high school Colegio Alberto Blest Gana. I will not miss the cardboard-tasting garlic bread (pizza delivery company to remain anonymous).
As part of our operations, we give talks to the public on weekly basis. We begin with neural signals from the legs of cockroaches, display of which carries low risk as the legs can grow back and cockroach leg neural signals are not covered under United States Privacy laws.
But, as we have been expanding our electrophysiology offerings to our fellow humans of this Earth, we find ourselves travelling into the internal you. We first started with muscle recordings, typically from your arms. We then went further into the body, now regularly showing the electrical signals of the hearts of the audience.
But as we entered the final domain and began demonstrating the electrical waves of the cerebral cortex, we began to feel a slight discomfort.
We realized Pablo’s brain is exposed to all the world. Furthermore, once shared on social media, his brain waves are no longer his property. This must be stopped. Given the rash of recent hacks on sensitive websites, Backyard Brains is preemptively offering a “Brain Privacy Mode” on its Spike Recorder software
Your brain is now safe. You now have the discretion to reveal your cerebral cortex only to those intimate to you.