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Galvanometer-the Retro SpikerBox

Name: Katelyn Rowley

Pic of me (1)

School: University of Michigan (Go Blue!)

Major: Biomedical Engineering

Hobbies: Running (I’ve run a half marathon and I hope to run a full one someday!), journaling, trying new restaurants in Ann Arbor, being outdoors, finding new music to listen to (Florence and the Machines, Bon Iver, classic rock, you name it)

What’s up interwebz? When I think of things that terrify me here is a brief list of things that come to mind: White Walkers (shout out to Game of Thrones fans), the killer bunny rabbit from Monty Python and the Holy Grail, Physics 240 (electricity and magnetism), liking Kayne West’s music, history classes, and a Moose Tracks ice cream cone melting all over my hand before I can enjoy it. Digressing, this summer I get to face two of my fears and get a good understanding of the electricity, magnetism, and the history of neuroscience.

The origins of my project began with a paper describing the life of Julius Bernstein (1839–1917) and his process of developing Membrane Theory—the prediction that the concentrations and charge of electrolytes (charged atoms) inside and outside of a nerve cell is responsible for a nerve firing and thus pretty much the ability to move, sense, feel, and survive. The differing concentrations of charged particles, such as K+ (potassium), is obtained through the cells selecting which particles are allowed inside and outside of the cell, thus creating an electrical potential across the membrane, as described by the Nernst equation below.


Nerst Eq (1)

This equation tells us that the greater the temperature and the bigger the concentration difference, the more electrical potential a cell has. As the difference in concentration between inside and outside of the cell increases, the more the thermodynamic system craves to return everything to a perfect balance and expel the consequent stored electrical energy used to invoke motion or transmit signals.

To develop this Membrane Theory, he had spent time developing what became known as a time slicer to measure the current our bodies use to signal muscles and adjacent cells. It had been shown by this time that jolts of electricity can be conducted and cause a muscle to spasm (first shown by a frog leg twitching when an electrical charge touched its nerve by Galvani), but Bernstein took it upon himself to assign a speed and direction of this supposed current that could exist while being entrapped inside of the human body. Thus, from the depths of his scientific and electrical genius, he made the time slicer (below).

Time Slicer (1)

…I was confused at first, too. Bernstein’s original paper was in German so that also made it difficult to find anything more in depth about the mysterious time slicer.

After many hours of research and study, I eventually learned what all of these parts were. Basically speaking, this wheel spins and alternates between stimulating the muscle/nerve (left half of wheel) and recording the current from this stimulation (right half of wheel). By changing positions of the different circuits, Bernstein was able to measure the current precisely at differing parts in time…hence the imposed name, time slicer. He eventually collected enough information about the currents at different parts in time and produced this:

Negative Variation (1)

Which, remarkably, shows that the current is negative. This publication was the first accurate description of the action potential in the nerve.

Further, my job this summer is to recreate this machine that sliced through current and time (which makes me sound more like a supervillain than an intern) and defined a key moment in the development of what we know about neuroscience today. If we think about my project in two key parts, it involves the wheel pictured above to manipulate the different circuits and the device called a galvanometer to measure the currents at different points in time. And so, my journey into science begins by recreating the ancient galvanometer to measure these small currents. A galvanometer I would like to redesign is pictured below.

Mirror Galvanometer (2)

This is where I will begin, and I will be sure to update this blog as I continue my summer.

Thanks for reading!

Mothman Spotted in Ann Arbor

Hey! What’s up? My name is Trevor Smith, currently a senior at the fabulous Michigan State University, and I am lucky enough to be participating in an internship at Backyard Brains this summer. I am currently working on pheromone detection in moth antennae, specifically how sensitive male moths antennae are to the female pheromone used in locating a mate. Moths are renowned for their bushy antennae, which look much like combs. I have chosen to study the silkmoth (Bombyx Mori) as my test subject. They are very well studied, as their pupae are used for silk production. What’s novel about these moths is that the males can detect the female pheromone (Bombykol) from up to 11 km away! This is incredible as the pheromone is released and stays in the air for only a short time. The males sense the bombykol from great distances and travel to the secreting female to mate. It is very important that the male can detect the bombykol because once hatched from their cocoon they only have 5-10 days to mate before they die-try that one as a pickup line!


My task this summer will be to track the unique spikes from the antennae, and show just how sensitive the antennae are to this compared to other stimulation. It is my primitive hypothesis that the spikes from the pheromone will be easy to elicit upon first contact, and will linger for a short time after exposure. Silkmoths lifespans are very short and seasonal due to the metamorphic process they undergo, so although I am working with moths this summer, I am currently waiting for my moths to reveal themselves from their cocoons.


In the mean time I have been working with the main specimen of Backyard Brains, the beloved cockroach. As we all know from the remarkable SpikerBoxes BYB has created, we are now very easily and in a cost effective way able to track spikes off cockroach legs. (Thanks Trevor, your check’s in the mail-editor)  In preparation for my work with the moths I have been attempting to track spikes from cockroach antennae. Through the method known as an electroantennogram (EAG), in which you isolate the antennae and place two electrodes on both ends, I have been able to record spikes from these antennae.


Along the way I have encountered several hiccups, along with a learning curve to understand the basics of how these pheromone work in specific receptors in the antennae. From the simple problems, such as putting the wrong end of the aux cord into the Spikerbox, to figuring out how to properly use a Faraday cage to isolate the specimen I have been able to expand my knowledge on to properly conduct scientific methods and procedures. I am far from mastering this craft, but as Greg, a founder of BYB, has explained to us: Most people will quit after a few failures on the bench, it’s not until you use these failures to learn, that you will truly succeed. It is my full intention to continue upon my failures and strive to progress everyday on my project, and make meaningful goals each day.

Currently I am working on a new set-up based on an existing method to deliver olfactory stimulus to a cockroach antennae. In order to deliver a specific smell to an antenna you need a couple things. First you need constant airflow over the antennae to ensure you are not tracking the spikes from initial air stimulus. Second you need a way to deliver the stimulus under controlled setting, and third you need a way to combine the constant airflow and stimulus and be able to turn the stimulus on and off. Using an air mattress pumps, a series of clear tubing and a few self fabricated boxes I am reconstructing a way to deliver a stimulus to the antennae. I am currently still working on some of the kinks, but hope to soon track spikes specifically from an olfactory stimulus soon!

Air Pumps