Over 11 sunny Ann Arbor weeks, our research fellows worked hard to answer their research questions. They developed novel methodologies, programmed complex computer vision and data processing systems, and compiled their experimental data for poster, and perhaps even journal, publication. But, alas and alack… all good things must come to an end. Fortunately, in research, the end of one project is often the beginning of the next!
Some of the fellows intend to continue working with on the research they began here while they’re away and many of these projects will be continued next summer! Definitely expect to hear updates from Nathan’s EEG Visual Decoding project and Joud’s Sleep Memory project. Additionally, two of the projects will continue throughout the next few months: Zach’s Songbird Identification and Shreya’s Electric Fish Detector projects will continue through to December!
Meet the Fellows, See the Projects
The fellows are off to a great start! Check out their blog posts introducing their projects:
The team has been working hard to bring their projects to life. Check out these blog posts on their rig construction and data collection efforts!
Our fellows experience the peaks and valleys of research this summer, but they all came out on top! Check out their final posts for their results, posters, and other details!
A few of our fellows are staying on throughout this next semester for longer term development projects! Zach is going to be back to working with his team on the Songbird Identification Device project, and Shreya will be working through to December on the Electric Fish Detector project. Expect updates on their progress from them soon!
Hey everyone! My summer of research in Ann Arbor has come to an end and it’s been an awesome experience. It’s been a busy 10 weeks of making daily improvements to my rig, resoldering the flyPAD, collecting data, and presenting what I found to others. The original goal of this project was to see if altering taste perception was possible by activating taste neurons with light – a new technique called optogenetics. To test this I stimulated channelrhodopsin in the neurons of fruit flies’ which give them a sweet taste response.
If you missed it, my first post: Optogenetics with the flyPAD, and my second post: The Taste Preferences of Fruit Flies
The FlyPAD setup in its full glory
Naturally, fruit flies prefer eating sugary as opposed to unsweet foods, similar to humans. This was the case when I offered them banana, a sweet fruit, and avocado, broccoli, and brussels sprouts, the unsweet alternatives. The flies always preferred banana over anything else. However, when Arduinos were programmed to pulse red light at the flies the same instant they sipped the unsweet foods, their gr5a neurons were activated, tricking them into thinking that what they were eating was sweet. The data is shown below, as bar graphs of the average number of sips and of sip % to see how food choice preference changed.
As we see here, the flies naturally prefer banana over avocado
But this preference switched when stimulation of channelrhodopsin activated their sweet tasting (gr5a) neuron
Flies, naturally, REALLY prefer banana over broccoli
The star preference we saw earlier disappeared, and the flies ate some of both foods: more of the newly sweet tasting broccoli and less of the banana.
Again, we see that banana wins the prize naturally.
And again, with stimulation, we see the sweet and the non-sweet options begin to level out
So, changing the subjective perception of taste is possible, as we could make a fly’s least preferred food become their absolute favorite! These findings show that subjective perception is alterable, but also that optogenetics is a neuroscience technique which can be done with little, affordable equipment.
If I end up continuing work on this project, I am interested to see how long the altered preference of the flies can persist. Anecdotally, I’ve seen that when the LED lights stop working there are some flies which continue to visit the unsweet food which they were tricked into tasting sweet. This wasn’t within the scope of my summer research, but I suspect that doing experiments on this would be interesting as it could reveal how powerful optogenetics is by creating a change in food choice preference that persists once stimulation trials have stopped.
After finding these results I compiled them into a poster which I recently presented at an UROP (undergraduate research opportunity program) symposium at the University of Michigan. It was fun explaining my summer’s work to the public and other researchers. Got a ribbon for it too!
Call me “Blue Ribbon”
A close up of my poster!
Aside from collecting data in the lab, I also had the chance to showcase my project with TED for their upcoming series of episodes focussed on the Backyard Brains’ research fellows’ projects. I was able to conduct experiments for them and give step by step walkthroughs of how they are carried out. Stay tuned on their posts coming around this fall to catch our episodes!
Huge thanks to Greg for mentoring me this summer and introducing me to the world of Neuroscience research in the coolest way possible with BYB.
Thank you so much to Backyard Brains for giving me this amazing opportunity and to all the research fellows who made it a really fun summer!
Hello everyone! It’s a been over a month since my project began on studying the diet and attempting taste manipulation of the Drosophila melanogaster.
Before my experiments could begin I faced many software and hardware issues. The flyPAD itself is an extremely thin 0.6mm PCB board so every slight bend of it can result in a breaking of the soldered connections with each channel’s circuits.
I transfer flies by sucking them up…don’t worry there’s a cotton stopper. Human Sips.
In order to change my flies’ taste perception, the light-sensitive proteins which were inserted into their ‘sweet’ tasting neurons had to be stimulated by an intense red light. For a proper response, this light stimulation has to happen almost exactly when the flies take sips of the target food. To make this happen, a code was programmed into Bonsai so that an LED is turned on nearly instantaneously to when food is touched by a fly, triggered by a change in capacitance between the electrodes. This is how the flies’ taste neurons are activated at the same instant they sip certain foods to influence their food choice preference.
The instant the fly’s proboscis (mouth) touches food, intense red light shines
To get to the finalized rig I use today, I experienced firsthand just how much debugging and problem-solving is involved in research. Below is a pictorial formula of how I got to my final experimental setup:
Got my flyPAD
Integrate circuit and solder under a microscope… this is what was breaking every time the .6mm boar bent… whch was all the time
Creating circuit and code for LEDs to sink up with each channel
I soldered a shield for easy LED plugin
LEDs set up with flyPAD
soldered LEDs to their drivers, which increase the light intensity
Another arduino programmed to pulse 100 Hz light to give flies recovery time of 900 ms
Painted acrylic to avoid unwanted light penetration of neighboring LEDs
The bonsai workflow for LED stimulation
Over many hours of adjusting my setup and learning how to insert the food, I finally got everything working so that experiments could get underway.
To see if the flies’ taste can be changed, I had to determine what their natural food preference was. I chose banana and avocado to compare. The cumulative number of sips showed banana was preferred over avocado, as avocados have almost no sugar in them.
To see if food choice preference can be altered, LEDs were activated upon contact with avocado. This fired the gr5a sweet neurons in the flies.
As predicted, the light stimulation successfully activated the flies’ sweet neurons to alter what they perceive as sweet tasting.
To verify these results, I ran a positive and negative control. The positive, showing the desired effect which is expected from the independent variable, was the proboscis extension (seen with the green arrow) from a gr5a fly upon stimulation from the 625nm red LED light.
As for the negative control, which does not produce the desired outcome of the experiment, I put gr5a flies that had not been feeding on all trans-retinal, under the same LED treatment targeted on avocado. All trans-retinal must be ingested to activate the proteins in the flies’ neurons, otherwise light stimulation will not fire the neurons. As expected, these flies still preferred the more sugary banana over the bland avocado.
Now that I know that the alteration of Drosophila taste preference is possible, I plan to study the nutrients within the flies’ diet.
It’s easy to eat sugar, but when offered your favourite sweet snack and a healthy food, it’s hard to eat what you know is better for you. I will create this scenario for my flies. Specifically, I am interested to see if the flies will eat protein after being deprived of it, even when a tasty, sugary apple is also up for grabs.
When deprived of protein, it has been found in the past that females will eat more protein when offered it again as opposed to males since they have to produce eggs. I want to see if this is still the case with natural foods rich in protein. I hypothesize that the flies will still prefer to eat a more sugary food as opposed to the nutrient they are deprived of. If this is the case, I will use optogenetics once again to see if I can make them eat the food they require the most. Are flies’ instincts to eat the nutrients they require stronger than their pickiness of taste? This is an interesting comparison to humans – as so many of us are more than willing to indulge in decadent desserts rather than eating our veggies any day of the week. Will optogenetics one day make its way into the human realm to revolutionize eating and health forever?
Thank you for taking a look at my post! I can’t wait to see what response I get out of my flies in the near future.