Are you fast enough to catch a grasshopper with your bare hands? Might be tricky, because grasshoppers are quick to react to potential threats! This reaction time is thanks to a very specific, visual neural circuit in the grasshopper. By recording from this circuit in a living grasshopper prep, we can record the spikes that are actuated by visual stimulus! Move a piece of paper back and forth in front of the grasshopper’s eyes and you get spikes! But so much more can be done to study this fascinating, hardwired reaction.
Dieu My worked on this exact prep last summer! And we are excited to announce that she recently had her paper published in June’s edition of JUNE (Journal of Undergraduate Neuroscience Education)! Her paper, titled “Grasshopper DCMD: An Undergraduate Electrophysiology Lab for Investigating Single-Unit Responses to Behaviorally-Relevant Stimuli,” featured in this journal’s titular month, details her summer research in Grasshopper Vision and Educational Methodology. It takes a lot of work to bring a research project to publication, and we’re proud and excited for Dieu My’s accomplishment!
See the Publication
To coincide with her publication, we are pleased to also introduce to you the resulting Backyard Brains experiment!
https://backyardbrains.com/experiments/grasshoppervision
Here’s a brief sample from the experiment’s introduction:
“It’s easy to observe that grasshoppers are able to quickly hop away to escape potential predators or quickly incoming danger, but learning just how the grasshopper can react so quickly is a research question that has interested neuroscientists for years.
In 1992, researchers Simmons and Rind helped identify a specific neural circuit in the grasshopper that is responsible for reacting to movement, called the descending contralateral movement detector (DCMD). Certain movement patterns activate the grasshopper’s DCMD, sending an alert down to its legs telling it to jump away. The DCMD underlies the grasshoppers’ ability to visually detect, discriminate, and react to an approaching object.”
This experiment guides you through the methodology that Dieu My created to take recordings from a Grasshopper’s DCMD (Descending Contralateral Motion Detecting Neurons). Also, along with the methodology, Dieu My came up with a few experiments that could be performed to test the Grasshopper’s vision. One of the experiments has you compare different stimulation intervals, while the other has you adjust stimulus variables to see what triggers the DCMD.
The experiment does require some Backyard Brains tools and software, so check out the store for the Completo and SpikeRecorder.
The paper also details a pilot lab where this experiment was performed by a group of students during a 2-hour lab!
The evaluation of the lab’s effect on student engagement with neuroscience revealed that at least 60% of the students ‘strongly agreed’ or ‘agreed’ that the lab increased their interest in studying neuroscience and animal behavior, that the lab encouraged them to generate and test their own hypotheses, and increased their interest in becoming a neuroscientist. Overall, 16 out of the 18 students rated the lab 7 or higher out of 10, with 10 being ‘Excellent.’
The results were positive, with most students reporting tha
Let us know what experiments you come up with and please do share your results with us!
Update June, 2017: My paper was published! Check it out here in JUNE (Journal of Undergraduate Neuroscience Education).
…
Why are grasshoppers so hard to catch?!
I aim to study the neuroscience behind this question by replicating past studies on grasshopper vision. Grasshoppers can sense an approaching object and quickly hop away to avoid collision with the object because their visual system includes a type of neurons (descending contralateral movement detector, DCMD) that underlies the animal’s visual and motor sensitivity to approaching objects, such as predators. I use Backyard Brains’ open source SpikerBox and the SpikeRecorder iPad app to record and visualize the activity of the DCMDs in the form of electrochemical action potentials, or spikes.
Throughout this project, I aim to bring neuroscience research out of the far, far away university labs and design and perform a low-cost and reproducible project using open source and DIY tools, to explore and learn from the neural basis of the grasshopper’s escape mechanism.
Somewhere in Portland, there’s a restaurant that serves grasshopper sushi rolls. Is it safe? Is it good? I don’t know!
Because I am a grasshopper researcher this summer in Ann Arbor, Michigan, I have other questions in mind: How do people catch these bugs? If you’ve ever tried to catch one, you know that it is nearly uncatchable when its skeletal muscles get to work as you approach with silent steps, trying to capture it for an afternoon snack.
Catching grasshoppers in Ann Arbor is my exciting challenge this summer. Finding out why they are hard to catch is my neuroscience project.
Background:
Why are they hard to catch? Because they can quickly jump away when a person or another insect or object approaches it. How are they able to quickly hop away to escape a potential predator or avoid collision with an object? To address this specific question, I will look into the movement detector neurons in the grasshopper’s brain—the organ that fascinates me.
Just as I can see it with my eyes, the grasshopper can see me if I come to it. Or if I show it scenes from Star Wars when spaceships are flying toward the viewer, the grasshopper can see them too and would hop, hop away. That is what researchers Rind and Simmons found in 1992 in their research on the vision of the locust, or a kind of grasshoppers that form swarms. The grasshopper’s nervous system includes a type of visual neurons, called descending contralateral movement detector (DCMD), that receives visual info from the eyes and sends that info to the legs, and underlies the grasshoppers’ ability to visually detect and react to an approaching object, be it a spider looking for a crunch or an astronomically speedy spaceship.
In human language, the brains of these bugs are capable of serious mathematics. In a paper published in 1995, researcher Hatsopoulos and colleagues came up with an equation that describe how the DCMD neurons sense and respond to approaching and receding objects: velocity, or speed, of the approaching image:
multiplied by an exponential function of size of object’s image on the retina: 
On a high-level consideration of the computational way the brain of the grasshopper functions, the activity of the DCMD neuron is related to how fast the image is coming toward the eye of the grasshopper and the image size on the eye that changes with decreasing distance between object and the eye. The peak in firing is reached before the collision of the object and the grasshopper, and the bug can leap away using their legs to avoid being hit or eaten.
My goals:
In the world of scientific research, disagreements founded upon experimental evidence and thoughtful arguments give rise to scientific progress. In the two above-cited papers, I see several discrepancies between the two groups of researchers. While Rind and Simmons concluded that there was good correlation between the neuron’s activity and the object’s acceleration during the exposure of the grasshopper to approaching objects, Hatsopoulos and colleagues used both their computation and experiment to conclude that the correlation was poor. The two papers generally agree that the DCMD neuron’s responses depend on the size and speed of the object. Keeping these ideas in mind, I will see what results my project will yield and I look forward to contributing to the discussion.
Art by Tanner @ All Hands Active, Ann Arbor, MI
I hope to demonstrate that a fun and educational neuroscience project can be done outside of the far far away university labs! I use Backyard Brains’ Neuron SpikerBox that amplifies and visualizes the activity of the DCMDs in the form of electrochemical action potentials, or spikes. I also have an iPad with the SpikeRecorder app, which provides visual stimuli (growing or receding black dots on a white background) in front of the grasshopper’s eye as well as records the DCMD activity.
Hop, hop away. This is how the grasshopper stays alive. This is how it continues to exist and eats plants and destroys our crops. But it is also our food and art and stories. And it is my friend (euphemism for “study organism”) this summer. Please check out how I chase, catch, maybe eat, and perform electrophysiology on the grasshoppers to record the activity of the DCMD neurons in an open-source and DIY style.
Below are the complete instructions for this experiment, if you want to see the whole process (every step and attempt to achieve this project) you can check out the following logs:
For this experiment you will need:
- Grasshoppers: FREE – As many as you can catch!
|
- iPad: ~$400 or if already have – As screen for visual stimuli and recording and visualizing spikes, in a cumulative SpikeRecorder app
|
- Microscope: $200 or ask around or use a phone app! – 20X magnification is sufficient; For surgery on grasshopper and electrode placement
|
- Magnetic stirrer: $100 or be creative! -To heat, melt and mix the wax and rosin mixture
|
- RadioShack mini speaker/amplifier: $15 – To hear the spikes when the grasshopper sees the balls being thrown at it
|
- Backyard Brains Neuron SpikerBox: $100 or DIY – A bioamplifier that allows us to hear and see spikes in living neurons; has cork board piece on top for mounting animal
|
- Backyard Brains Micromanipulator: $100 or DIY – For precise placement of electrodes
|
- 1-Channel Electrodes: Reference and Recordingincluded with manipulator or DIY – Hook electrode around neck connective of grasshopper and reference electrode in abdomen, both connected to SpikerBox
|
- Painter’s Tape$2 – To restrain grasshopper and tape it down to corkboard piece on the SpikerBox
|
- Thread: $2 – To pull grasshopper’s neck up to expose neck where recording electrode is placed
|
- Wax and violin rosin mixture: $6 – Heated to be mixed together; for placing on thread around grasshopper’s neck to keep it in place
|
-
Build the SpikerBox, micromanipulator, and electrodes. Build instructions for these items are in the files section! Gather the materials:
-
Anesthetize the grasshopper by placing it in a plastic container (also its home in the lab) and keeping in the fridge (not freezer) for 15-20 minutes or until it is inactive. This keeps the animal still and painless (if insects indeed feel pain) during the upcoming surgery. (Dragonflies are also our faves.)
-
After anesthesia, tape the grasshopper belly up on the cork board piece on the BYB SpikerBox. Tape all the legs and the abdomen. Leave the head and a little of the thorax exposed—these areas are where electrodes will be placed. (I find masking/painter’s tape to be the easiest to work with.)
-
Then, use a piece of black thread to pull the head back until the neck connectives (two white strips under the neck skin) are visible. This step is tricky, so be patient. Also, the thread must not block the eye opposite of the side of the neck that the recording electrode will be placed. In the picture above, I plan to put the recording hook electrode (where needle is pointing in photo) around the left neck connective of the grasshopper. So the right side of the grasshopper (our left) must not be blocked by anything.
-
Create a 50/50 mixture of rosin and bee wax in a glass petri dish. Put the dish on magnetic stirrer, on very low heat (I’ve broken several dishes due to ignorance of kitchen basics). After a few minutes, the solid mixture is melted into a liquid.
-
Use a needle to pick up the warm rosin-wax liquid and place it around the thread holding back the head of the grasshopper. When the liquid cools and molds into a wax texture, the thread is secured to the neck of the grasshopper.
-
Now, another step as tricky as pulling back the grasshopper’s head: Placing the hook silver wire electrode around the neck connective to pick up the activity of the DCMD neurons. The BYB manipulator electrode comes as a simple straight wire. For this experiment, I modify it by using tweezers to bend the tip into a small hook, to place around the connective.
-
Then, under the microscope, use a tiny needle to pierce a hole on the left side of the grasshopper’s neck, next to the connective. Then, carefully place the hook electrode into the hole and use the BYB Micromanipulator to adjust so the electrode is deep enough to hook around the connective.
Depending on the grasshopper and the spot in the neck where the hole is made, there might be green blood oozing out from the hole (top photo). If there is no blood coming out, I immediately put a drop of Vaseline on the recording electrode and nerve cords to isolate them from the rest of the body and keep the pierced hole from drying out (which would otherwise happen within minutes).
Connect the BYB manipulator electrodes to the SpikerBox. Then, place the reference electrode (needle) either on the mid-thorax or abdomen. I find that the reference electrode grounded in the thorax yields better signals.
The prep is now finished! It looks something like this:
-
Almost done! On the iPad SpikeRecorder app, set the parameters for a new experiment. Here, I am testing the response of the DCMD neurons to an approaching black ball on a white screen. The balls of different sizes will approach the grasshopper’s eye at different speeds. Between each trial (each trial is a pair of an approach velocity and an object size) is an intertrial interval of 45 seconds for the neuron to fire again, based on literature and my own experiments.
The black balls originate from the center of the iPad screen and fill up the screen to simulate approach and collision with the grasshopper’s eye.
-
After the iPad is ready, tape it upright to the wall so the angle between the center of the screen/ball and the center of the grasshopper’s eye is minimal. Use a level and ruler to measure. Then, connect the iPad to the SpikerBox (green cable) and also connect a RadioShack mini speaker to the SpikerBox (blue cable) to hear the spikes. Then, turn off the lights and close the doors to the experimental room for good contrast of the black ball on the white screen.
Otherwise, make a portable experimental room! I use a card board box from the recycle bin of a restaurant. I turn on the iPad and close the flaps, and the ball begins to come at the grasshopper’s eye. And the grasshopper’s DCMD neuron will activate. And I will get experimental data!
Note: You might know that electrophysiology recording is troubled by lots of noise,including body and other electronic sources. Choose a spot without many electronics being used, and minimize body movement. I stay at least 5 feet away and sit as still as possible while the experiment is going on.
-
Finally, when the experiment is over, thank the grasshopper. Unhook the electrodes, untape it from the cork board, and bring it back to the field where it can feel most at home.
By Dieu My Nguyen
With the ideal ITI determined, I can move on to the set of core experiments: testing to see how the DCMD neuron behaves when simulated black balls of different sizes and velocities approach the grasshopper’s exposed eye. So my little friends spend about 2 hours on top of the SpikerBox for these experiments.
I continue to process the data in MatLab for better visualization. Here are the results for balls approaching from a constant initial distant of 10cm, 6cm in size, and with various velocities (-2, -4, -6, -8m/s).
Perievent histogram: showing DCMD firing frequency 2s before and 2s after the simulated collision between the eye and the object:
Raster plot: showing DCMD spiking pattern across each pair of S and v over time. DCMD firing peaks around collision for objects approaching at -2m/s, and after collision for objects approaching faster:
By Dieu My Nguyen
