This is the third and final installment of our guest blog by Kevin Wolfe, a PhD student at TAMUCC
How marine science benefits by studying a simple brain
The biomedical benefits of studying Aplysia are fairly obvious; learning about the human brain is easy using a simpler analogue. Parkinson’s disease, post-traumatic stress disorder, and Alzheimer’s disease research are currently underway using Aplysia. Though not as intuitive, the ecological benefits of studying Aplysia are still numerous. To keep this section succinct, I’ll discuss my own research a bit.
Fear is an important ecological driver. Animals that are afraid will modify their behaviors in ways that may carry consequences on an environmental scale. For example, removing wolves from Yellowstone caused elk to forage in more open patches containing different plant species. As the elk grazed these species down, the system more or less came crashing with it. Re-introducing wolves to the park caused elk to fear open spaces, allowing many grazed sites to recover and become more biodiverse.
Many studies suggest that the fear of being eaten is more ecologically important than being eaten, mostly because one predator can scare a much greater number of prey than it can consume. This assumes prey are able to detect when predators are present and change their behavior in response. In the oceans, most organisms use smell as their primary sense, thus prey cue into predator smells to decide when to respond. A large number of studies show this pattern time and time again; introduce predator smells to prey, and prey immediately alter their behavior.
But what about long-term behavioral changes? Ideally, how long should a prey change its behavior when it smells a predator? If a prey doesn’t respond to a predator or the response isn’t long enough, it exposes itself to higher predatory risk. On the other hand, being afraid of predators can cause animals to skip a meal or miss an opportunity to mate. Thus, animals have to balance these costs and respond accordingly. This is an important question because it allows us to determine the potential effects a single predator can have on the health and stability of marine ecosystems.
As important as this behavioral trade-off is, not much consideration has been given to the memory of fear. Studying Aplysia is hugely beneficial for questions like these because we can reliably observe traces of fear in behaviors and in the brain. In Aplysia, we know where to look and how to find where the memory of fear is stored, and we have methods of determining how long these anti-predatory behaviors can persist without perturbation. In essence, this is my project: determine how chemical cues are converted to memory, where these memories are stored, and figure out how the persistence of these memories can be manipulated by the type or number of predatory cues. I have some very interesting data on this that I’m currently writing up for publication, but I’ll save that to avoid spoiling anything for you all.
What other uses can Aplysia yield? One very interesting question arises when prey don’t respond to predators: is the animal not detecting the presence of the predator, or is it choosing not to respond? My advisors and I are altering an established (and really cool) protocol to test this question directly by turning a living animal into an electrical nose. Electrodes can be implanted into live Aplysia by hooking and gluing wire underneath one or several nerves. This essentially turns an animal into a piece of lab equipment that can sense and convert chemical cues into legible electrical outputs on our lab computer. Based on the activity of the nerve, we can determine if the animal is detecting a smell and how these impulses can activate the circuits of the brain that cause the animal to respond.
Much of what I’ve elaborated upon applies to my own research interests, namely understanding more about fear and the brain and how they relate to natural predator-prey interactions. But imagine the potential for these types of neuroscience approaches for other scientific questions. For example, do you study plants and not animals? No problem! You could use Aplysia to study plant chemical defenses and understand how herbivores use them to establish diet preferences (an idea I plan to pursue after grad school. Please don’t steal it). If you’re into animal behavior, you could also uncover how the brain responds to mating pheromones, lack of sleep or rest, or how specific behaviors change with environmental factors like elevated temperature or pH. The possibilities are aplenty!
Other than talking about a cool snail, my point is this: it’s important to understand that marine science is evolving into an interdisciplinary field, involving efforts from differently-minded individuals studying the same problem from different angles. I challenge all of you, graduate student or not, to try to add something new to your lives. Experiment out of your comfort zone. Build new experiences and acquire new skills. Form new friendships. Diversify yourself.
You never know, you may just find yourself writing for a blog across the country about a snail.
Like what you read? Check out some of my other articles at chargedmagazine.org!
Also, head to youtube.com/user/scienceisfunnyfilms for short videos made by marine biology grad students at TAMUCC!!
Sources for further reading (hyperlinks included in the text):