Name: Katelyn Rowley
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.
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).
…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:
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.
This is where I will begin, and I will be sure to update this blog as I continue my summer.
Thanks for reading!