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Intracellular recording in Snails Midterm Update – Juan Ferrada

Hi! Juan Ferrada here from the University of Santiago again to give you an update on my project with Backyard Brains.

Main Project – Single unit recording from Snail Neurons

First mission – Isolate the Neurons

As we spoke of a month ago, we are trying to record the individual neurons of the giant pacemaker cells of the parietal ganglia of the common garden snail Helix aspersa. Our first step is to isolate this ganglia so we can visualize the famously large F1 neurons, that can reach up to a crazy big 200 um in diameter. After anesthetizing the snail with magnesium chloride, we began the preparation.

Here we can see the exposed cerebral ganglion and parietal ganglion. They are the highly white structures around the yellowish-white esophagus.

We removed the ganglion, and you can see it is surrounded by connective tissue. Using fine #5 forceps, we slowly picked away the tissue…

until, looking at the sample below a RoachScope at high mag, we see what appear to be a cluster of spheres. These, my friends, are the neurons we are looking for.

Second mission – Get an electrode close to the neurons

Now that we have the neurons in our sights, we have to get an electrode near it, not so easy when the sample is under our microscope. Luckily, we used the Backyard Brains Manipulator to move a glass pipette that we made just by holding a hollow borosilicate glass tube (part number 615000 – 1.0 mm x 0.75 mm) over a lighter and pulling it apart in the flame to make a very fine tip. Using the manipulator holding the electrode, we have just enough clearance to move between the sample and the microscope.

We can easily see the pipette tip on our smartphone looking through the RoachScope lens, and we can manipulate the electrode to come close to our neurons, attempting to insert them into the neurons. You can see a brief video of electrode movement below.

Third mission – Get a recording

We have the neurons, we have the electrode, we have the microscope, we have the manipulator. Now it is time to do the recording. This is my trial by fire, the hardest part of the whole experiment. The plan is to stab the cell with a high resistance glass electrode, then listen and record the spontaneous action potentials. Unfortunately, so far we are only getting noise, but we are slowly improving the amplifier setup, experimenting with electrode styles, reducing 50/60 Hz noise, and chasing the dragon of weak signals. We keep trying to catch it. Stay tuned!

Side-Project – Recording from Sea Anemone Tentacles
Since we are dealing with glass microelectrodes and amplifying signal in a noisy watery environment, I have also been working with the Backyard Brains team on a project they have had in mind for a long time – extracellular recordings from the tentacles of sea anemones. The lab has been caring for 9 anemones (taken from the intertidal zone near Algarrobo, Chile, an understudied organism called Anemonia alicemartinae). Over the past four months, the Backyard Brains team has been learning how to maintain a prosperous anemone colony. Since these are Humboldt current creatures, they like their water cold. So we have a trick to keep the aquarium under 20 degrees Celcius by having a fan always blowing air over the water. To further keep the anemones healthy we feed them surf clam meat every day, and clean the tank entirely, replacing and remixing the salt water, every 4-6 weeks.

We were originally using long silver wire (32 gauge) inside our pipette but it turned out to be brittle and the insulation susceptible to breaks and shorts, causing a lot of noise. We switched to flexible 30 gauge copper Minatronics wire that we threaded into a glass pipette, sucked up a tentacle, and recorded….nothing. To try to evoke a response, we touched the anemone trunk with a glass probe, but we did not register any electric activity in the tentacles.

Our next step is to try to insert an electrode near the oral disc, where we have read that more neurons are present.


Any Backyard Brains internship has an outreach component, and I have been helping Backyard Brains teach classes in Colegio Alberto Blest Gana in San Ramón, Santiago. In the past few weeks we have been teaching the students, ranging from 11-17, how to read circuit diagrams and use broadboards. We are building electromyogram amplifiers from scratch. I have learned more about electronics in 1 month than all the combined previous months of my life!

Now we are deep in the experiments, and we will update you at the end of May. 

Intracellular recording in Snails – Juan Ferrada

About me

Hi! I am Juan Ferrada, a biochemistry student at the lovely Universidad de Santiago in Chile. That’s me below with my girlfriend Rocia on campus. She is an important part of my project.

At the university I work with Dr. Patricio’s Rojas, a longtime colleague of Backyard Brains. Thanks to Patricio, Backyard Brains’ equipment has been to Antarctica!

In his lab, I study the temperature dependence of ion channels. I am in my last semester of studies, and in Chile every student has to do a “práctica” which is doing an internship for a clinical lab, company, or non-university research lab. Since Backyard Brains is in a sweet spot between company product development and neuroscience research, it makes doing a project with them an exciting, novel, and unorthodox práctica.

About my project

Backyard Brains started out studying neurons in cockroaches, then expanded to muscles in humans (EMG), than hearts (EKG), then brains (EEG), and then eyes (EOG). Now we return come back to the first love and dedication, the neuron, in search of the the most iconic symbol – the intracellularly recording action potential, Hodgkin-Huxley style. Teachers all the time ask Backyard Brains how to replicate, in a certain form, the famous Hodgkin Huxley intracellularly recorded action potential, and I am here to help! To begin, we will go to our backyard. Or, well, my girlfriend’s backyard (I told you Rocia would appear again).

Rocia has a garden, full of exotic and indigenous plants, from rosales to venus flytraps, but there are other things besides plants in the garden. There are things that eat my girlfriend’s plants:












Specifically, The scourge of my girlfriend is named Helix aspersa, also known as the pond snail. They like green leaves, but are especially of eating the tomato plant entirely, fruit and all. In France and Spain, these are the same snails that are cooked and served as elegant dishes (escargot).










These snails are interesting because they have very large pacemaker cells (which fire spontaneous action potentials like the ones you can see in your heart) located in the parietal ganglia (PG) involved in the chemo-mechanical sensation. Most classical intracellular recording techniques involve electrically stimulating the neuron, which can result in artifact, requires multiple electrodes, etc… Given that we will record from cells that are constantly firing spikes, we should be able to record spontaneous action potentials without the need for electrical stimulation. We want to make the preparation as simple as we can, BYB style.

Beginning the Project

To begin, we have to get the snails, which I collected during Easter Weekend. Check.














Now we will do some exploratory surgeries to extract the PG and try to isolate the neurons. To do this, we will anesthetize the snails with a Magnesium Chloride solution. Once we have the neurons, we will build a DIY glass electrode, mated with the original Neuron SpikerBox, to try to record the elusive intracellular action potential. Stay tuned as we begin this project. Saludos desde el Sur!

Fun facts

Chile has some a famous squid called  Dosidicus gigas. With a mantle of 4.9 ft and 60 lbs it’s one of the largest of its kind. Experiments using the giant axon of this squid kickstarted the field of biophysics in Chile.

Due to Chile’s isolation, surrounded by the Andes Mountains, the Atacama desert, and the Pacific ocean, we have a very diverse unique fauna, indigenous to the country, and we have an even greater marine fauna thanks to the Humboldt current. But, we don’t have many mammals (around 150) for a country of such North-South extent. But… we do have the smallest wild cat in the americas, Leopardus guigna.


Tiwari SK, Woodruff ML.Helix aspersa neurons maintain vigorous electrical activity when co-cultured with intact H. aspersa ganglia. Comp Biochem Physiol C. 1992;101(1):163-74.

Backyard Brains visits China

This past August, we were graciously invited by ZAST (Zhejiang Association for Science and Technology) to come to China to give a series of workshops and talks in Hangzhou, Ningbo, and Shanghai at the various impressive science museums there. Similarly to the United States, Neural Engineering is a relatively new discipline for the public, and there was enormous interest in the topic.

We were honored. In early August, Tim flew to Hangzhou and began the Sino-Backyard Brains adventures. At the beginning of the trip, we gave a “deep workshop” where the staff of the Zhejiang Museum of Science and Technology (ZMST), affiliated to ZAST, received 6 hours of training on interactive experiments, ranging from our cockroach work, to our earthworm conduction velocity experiments, to our new human interfaces, and even our (then just prototyped) EEG experiments.

Hangzhou is famous for its West Lake, and it was quite beautiful walking around the city and visiting the nearby Dragonwell (Longjing) tea farms, all the while planning the subsequent science talks with Bing, who was the organizer of the visit.

One of the highlights was to give an ASTalk at the ZMST. The audience consisted of a mix of students from local high schools, universities, and the public. They were treated to the first demos of our robot hand interface, a Chilean-USA collaboration between Backyard Brains and the Chilean Startup “HackerHand.”


This was followed by a organized field trip to the Zhuxiang National Park with grammar school students, the ZAST’s museum staff, and an entomologist. The objective was to try the RoboRoach preparation on a Chinese Beetle (unidentified, perhaps a dung beetle). Zhuxiang is known for being one of the best examples of a bamboo forest.

We searched for our elusive beetle in the Chinese scenery borne of dreams.

The beetles were found on a distinctive tree that was co-localized with a type of plentiful brown butterfly easy to spot. Both are fond ofthe sap the tree emits. You look for the butterfly, then look for the tree the Butterfly always flies to, and you find your beetle.

We collected about 10 of these beetles, and implanted 3 of them with RoboRoach electrodes. These beetles have an impressively strong exoskeleton, making the surgery a bit of a challenge, but we achieved it.

However, the wires did not hold up to the Beetles’ jaws. The next morning, when we tried to test the RoboRoach circuit, the beetle had cut the wires. The surgical preparation needs a little bit more adaptation to work on this creature, but we left the RoboRoach kit with ZAST…maybe an adventurous Chinese student will continue the work to study the adaptation and motor response properties of this beetle!

We gave many talks to the public, who were very gracious, and we must thank Phyllis, Bing, and our talk translators for doing the challenging job of learning so many new biological terms. Our favorite was- “ulnar nerve” – chî gû shén jin.

The translators taught us two words for the cockroach. There is the formal name “cockroach” which sounds like zháng láng

But there is also an informal word used that translates into “little strong” because, of course, a cockroach is a quite durable creature– which sounds like xiâo qiáng.

The world is full of enthusiastic students and minds who live to unravel the mechanisms of the brain, and we were delighted to meet some of the curious future Neural Engineers in China. The Staff of ZAST, when we parted ways in Shanghia, gave a gift all engineers would treasure – an abacus. The Abacus is now part of our office in the Santiago MakerSpace in Chile, in our growing ganglious network of inventors and scientists spread around the world.