[Summer’16 Internship] Neuroscience of Grasshopper Jumps: Experimental Setup & Data Collection Begins!
Materials: check. Grasshoppers: Check. Protocol: Check, and please do check the instructions on the main project profile for the protocol of this experiment. Next step: Setting up the experiment and take off!
This is how the grasshopper spends an hour of its time for science:
The iPad screen is placed on the side contralateral (opposite) to where I place the electrode on the grasshopper’s neck. Here, the electrode is on the grasshopper’s right side, so the iPad is on the left. In the blurry background, you might see a white RadioShack mini speaker, which amplifies the signal sounds and helps me identify neural spikes the DCMD neurons generate during the experiment. Electrophysiology is half seeing the spikes on the oscilloscope (or in this case, the iPad app that can do it all) and hearing them. And the spikes are distinctive! Here, see and listen to my initial test of the setup. In this test, the ball’s radius is 6cm (0.06m) approaching at 3m/s.
Do you hear it? As the black ball gets closer and closer, at a certain size of the ball, there’s a swoosh or krrrrr (or whatever you heard) sound that stands out from the base noise of the recordings. That’s the DMCD spiking! In the screenshot of the recordings above, the spikes standing tall and distinctive are marked by the red dots. In the field, the grasshopper would probably jump away when the neurons fire, to avoid colliding with whatever object that’s coming toward it. In my Backyard Brains lab, by cooperating and responding to the simulated ball, the grasshopper is greatly contributing to vision neuroscience at large and my experience with insect electrophysiology and neuroscience in particular. So, thank you, little grasshopper.
After I tested the setup and heard those exciting initial spikes, I added a few more finishing details to the setup. As of now, the grasshopper will get a room of its own whenever the experiment is conducted. The lights will be off, so there is sufficient intensity of contrast of the black ball against a white background of the iPad. (Perhaps as followup questions and studies, I can test whether grasshoppers can identify approaching objects in a cluttered background, or what colors can these bugs see.) Noise from other electronic equipment and devices will need to be minimized and thus those devices will be turned off, for optimal signal:noise ratio.
Thus, the experiment is conducted in darkness like this:
I will collect data from now on. Stay tuned for an update on the data!
By Dieu My Nguyen