Over a dozen busy bees, 5 research projects, 4 hot weeks of July, countless data, iterations and coffee cups, one book of experiments to soak it all up and present to the wider audience — and the Backyard Brains 2023 US-Serbian Summer Research Fellowship rounds off. The result will hit the shelves this fall, with the new, Serbian edition of our book “How Your Brain Works” containing brand new experiments that our team started working on.
But if you expect to see a bunch of cockroaches, worms, moths and bees and other invertebrates buzzing around Belgrade’s Center for Promotion of Science lab makerspace where we spent the month, you’re in for a surprise. This time, we ventured into two completely different, even opposite realms, hoping to eventually tie them together. One is the realm of single-celled creatures who don’t seem to be hindered or bothered by their lack of brain. The other lies behind our all-powerful brain and borders on philosophy of awareness. What is consciousness and attention? How do we think what reality is — and how do we share it with others? Finally, is there a way for these two realms to inform and complement each other?
This year’s cohort was small but diverse, composed of three undergrads who flew in from the University of Michigan and four Serbian undergrads from the Universities of Belgrade and Novi Sad. One of the greatest values was the wide variety of backgrounds that came together: from neuroscience to electrical engineering, psychology, molecular biology and computer science.
Well we made it! We’re at the final week of the BYB Fellowship! We faced many challenges throughout this project and had to pivot in order to get results, but we are happy where it ended.
To give updates on our progress, let’s first start where we left off 3 weeks ago. Using a blue light, we took one picture of the slime mold every minute over 24 hours. This allowed us to string the pictures together and make some great time lapse videos! After this, we were able to analyze the videos using a program in Python and create a special kind of video which converts yellow slime branches into lines of directed growth – skeletonized growth video. This was really helpful for understanding how the slime mold grows, explores new areas, and creates a network. But we also think that there’s more to it, and that behavioral analysis opens a lot of questions in the field of biophysics and is a project for itself.
We were very excited to get this imaging. However, we then made the decision to keep the rest of our experiments in the dark and in that manner reduce the amount of imaging done. Slime mold prefers to grow in the dark, and we wanted to make sure light wasn’t inhibiting growth in our experiments.
This means we were more focused on quantifying decision making rather than behavior. We set up a series of three types of experiments and ran many, many tests. (The order of explaining them isn’t coordinated with the chronological order of our work, but makes more sense this way!)
1. Solving Mazes
We wanted to test the ability of slime molds to choose a path that leads them to food, so we set up the easiest of mazes – a Y maze where there was food on one side of the Y and nothing on the other side of the Y (see photo above). Slime molds showed us that they have no intentions of staying hungry and that they’re doing just fine when it comes to finding the food source.
Then we wanted to make things more complicated for them, so we constructed a specific T maze – one side of the letter T was longer and had a food source, and the other was a lot shorter and had an object as a mechanical stimulus (we’ll get more into the mechanical stimulation in a bit). The idea was to check if they can see the difference between the food and something that isn’t food and if they are gonna choose the shorter path towards the no-food region. So, we tried to confuse them, but failed at it – they knew where the food was and grew in that direction almost every time!
Considering the slime craze of 2016, we’re pretty sure we have all played with slime – or at least know what it is. Have you ever heard of slime molds though? Slime molds, scientifically referred to as Physarum polycephalum, are a type of single-celled protist that is aneural (lacks a brain)! They move through shifting their cytoplasm back and forth in a movement known as “shuttle streaming”. In just 24 hours, we can observe the slime mold go from a single dot to a yellow slime spread throughout an agar dish!
Slime molds have been a subject of interest to neuroscientists because of their ability to perform behaviors, move through mazes, and preferentially move towards food sources. This means we can change conditions slime molds grow in to test for the decision (or lack of decisions) they makes. This research could eventually lead to insights about human behavior and cognition and lead us to have a better understanding of decision making.
What Our Project is About
One week in, our project is going pretty well! Our first step was to start growing the slime mold on an agar plate from a dormant phase it was transferred here in. Slime molds prefer to grow in warmer, humid temperatures (summer in Belgrade was perfect for this) and in the dark. They eat nutrients on oats. Pictured below is the first plate of slime molds we grew!
We’re right at the stage where we’re starting to collect our data.
Using a camera that takes a photo every minute, we are hoping to create a time lapse of slime mold growth towards an object – specifically, towards 3D printed cubes representing the mechanical stimulus.
Since they cannot grow in light, and we had to make our molds visible in photos, we made an installation using LED blue lights. This allows us to see the molds, hopefully without interfering with their growth. To check and rule out that possibility, we set the three Petri dishes in the dark, where they should grow just fine.
In our setup under the blue light, we also have some control dishes. One is just mold growing with nutrients to allow for positive control for the blue light. The second is mold growing without nutrients or mechanical stimuli to test if there is a directed movement that isn’t an answer to stimulus.
Finally, the third dish contains just 3D printed cubes with no molds. Its purpose is sterilization control – if we get a contamination, this dish shows us if we got it from the cubes.