Chirp Chirp-Crickets Armed to the ears!
My name is Nick Weston and I am an intern in the summer program at Backyard Brains. I’m an an undergraduate student studying neuroscience at Michigan State University and during this internship I plan on trying to capture neuronal spiking activity from the internal organs of a crickets ear while also trying to record and distinguish between the cricket’s chirps and their relative frequencies.
Before giving you information on my project’s methods and goals, you might be interested in the fascinating way crickets ears have evolved. For starters their ears are actually located in their forelegs. Each pair of legs has one, not including the hind legs which are primarily used for jumping, which makes four in total. However only the front two legs contain ears and ganglia which receive and send neuronal signals to the rest of the body. These small ear structures are very similar to ours including a middle ear made up of fluid and an inner ear composed of air and their microscopic hearing organs. These organs receive sound vibrations from two different areas-small holes in the middle of their legs, similar to our outer ear, and chest hole cavities where a majority of sound input is taken up. The neuronal signal originates in the middle of their foreleg, so that is where my recordings will be taken from.
My project deals with utilizing the spikerbox to pick up these tiny neuron impulses, so a great deal of time has to be put into the preparation of the crickets.
The crickets first have to be stripped of all of the body parts that make them active, including the wings. Then they must be attached to a cross-like structure so their tiny forelegs can be accessed. If you can see in this picture, above left image, the legs are very small and the crickets aren’t the most receptive to wax sticking their arms to the cross. Using a dissecting microscope I can insert electrodes carefully into their delicate hearing organs and the overall plan is to be able to record neuron impulses from these organs. At this point in the project I am mainly concerned with the preparation and placement of the crickets and the electrodes. Most of the setbacks occur when the crickets wake up from the anesthesia of their ice bath and start thrashing around on their cross. This usually halts my progress with the insertion of recording electrodes. There have been a couple setbacks but practice makes perfect and soon the preparation for the experiment will be second nature, or so I’m told. Once I can easily place electrodes into the crickets forearm I can start gathering neuron data.
I am trying to recreate some data collected by Jennifer Hummel and her colleagues presented in the paper Sound-induced tympanal membrane motion in bushcrickets and its relationship to sensory output. Like them I will be using the typical bushcricket found in most pet stores, M. elongata. They were successfully able to record neuron spikes from the forelegs of these crickets, so I am trying to recreate and expand on this data. Hopefully during this 12 week period I can successfully perform these experiments and collect data that will further the knowledge of how these complex hearing organs in crickets function. If I can find an inexpensive way to record these neurons,then this information could be available to several different levels of education to help children explore the fascinating world of neuroscience. “To Infinity and Beyond!”