Ryan Post, a Cornell PhD student, studies the brain—looking for ways to modulate behaviors such as lack of motivation, by changing the activities of neuromodulators. (PC: Dave Burbank)

Exploring the Brain, Changing Behaviors

by Molly Karr

Ryan Post, a fourth-year PhD student studying neurobiology and behavior, initially wanted to be a teacher, but he felt pulled to pursuing a doctoral degree. He also wanted to study how the brain works and why anhedonia — the inability to feel pleasure — occurs.

After completing dual degrees in biology and psychology at Providence College, Post was torn between graduate and medical school. His passion for designing and running experiments and the extensive opportunities to do so at Cornell, however, led him to his current research position in the Melissa Warden lab.

“I’m interested in animals’ behavior in new environments — why some animals will choose to explore their surroundings, and others stay in a corner and play it safe,” says Post.

PC: Dave Burbank

Evolutionary Behavior and Neuromodulators in the Brain

According to Post, this behavioral choice occurs in neutral, positive, and slightly negative environments. How brain cells work in these different states and how this activity in the brain contributes to behavior have deep implications for human depression and the lack of motivation to do things.

Post’s focus is the prefrontal cortex, which he calls the executive control center. While it is one of the most evolutionarily recent parts of the brain, it sends its projections to some of the oldest evolutionary regions, where serotonin and dopamine are produced. “These neuromodulators are interesting. They can really change and modulate behavior over large scales of time in organisms from worms to humans. I explore how to change the activity of these modulators, which respond to the more raw, emotional instincts,” says Post.

Optogenetics for Investigating the Brain

Post uses a technique called optogenetics to study how a brain works in varied environments. In the past, labs were limited by technology that only allowed for examining one portion of the brain such as the frontal cortex. Creating lesions on the cell body in those tissues would not account for axons, the tails of the cell body, which extend and react in other areas of the brain. “Optogenetics looks at not just one region but the projections as well. We can control the activity of neurons, using light, and we can inject a viral vector in a given region of the brain, which will express light-sensitive proteins,” says Post.

In the lab, Post takes freely behaving organisms and expresses proteins in the prefrontal cortex by implanting a very thin fiber optic. Through it, Post can shine light over axons of the prefrontal cortex cells. When the light is turned off, the organism model goes back to its perfectly normal behavior.

“Not all of the prefrontal cortex is activated. It is just the parts that send projections to the ventral tegmental area in the midbrain — the area with dopamine. We’re activating these neurons during behavior. There are certain actions that these are important for and some that are not,” explains Post. The light activates the projection from the prefrontal cortex to the ventral tegmental area that leads to exploration.

“These neuromodulators are interesting. They can really change and modulate behavior over large scales of time in organisms from worms to humans.”

“My research has found that motivation can be separated into different aspects. The prefrontal projection that I’m investigating controls movement, exploring surroundings, and trying to find ways out of slightly aversive situations but doesn’t have any effect on reward. In the past, these were thought of as one aspect,” says Post. Post’s results have shown that there was no influence on anhedonia, so he is now looking at a decreased willingness to explore an environment.

Research, For the Love of Exploring

Post’s favorite aspect of his research is observing, firsthand, that the very slight changes he makes in organisms’ neuropsychology cause obvious behavioral changes for the duration of the testing. Yet, his work in the lab has many challenges. One of the most difficult and intriguing parts of his research occurs when an experiment is run with predicted results, and said results violate the original hypothesis.

PC: Dave Burbank

“Getting those types of results will lead us to new interpretations and more interesting questions, which is amazing, but one has to be extremely careful. You have to ask if the test was run properly. You have to be absolutely sure the fiber optic was in the right place and that the protein was expressing correctly,” says Post.

All of Post’s meticulous work and diligence pay off, however. “Just to be able to get there and talk about the new ideas and my findings, and listen to other lab member’s interpretations of my results, is really rewarding,” says Post.

Cornell — Generous Resources and Support

Cornell has greatly helped guide Post down his academic path with its generous and accessible resources, such as expansive physical space and cutting-edge microscopes at the imaging facility in the Biotechnology Resource Center.

Post also enjoys the small size of his department, which created a built-in support network for questions and tips. “Everyone knows what everyone else is doing (at the Warden lab), and everyone is really helpful. That speaks to the great faculty in my department,” says Post.

Post claims that while he did experience a learning curve when he began at the lab, it didn’t stop him from pursuing his passion for the study of behavior, and he encourages others to have the same mentality.

“One should never consider letting their lack of technical or biological knowledge hinder them from exploring research. You don’t know nearly as much as you should before beginning at a lab. I think people should realize that everyone starts like that. You shouldn’t be afraid of science. You learn hands-on, and people are super supportive. Always seek out your interests,” says Post.

When not working at the Warden lab, Post enjoys nature runs around campus and hiking at nearby state parks. He also participates in an outreach science program for local schools. Post is also the co-president for GRASSHOPR.

“GRASSHOPR allows graduate students like me to design mini courses for K-12 at a level that students can understand and be integrated into the curriculum. Some students don’t always have all the educational resources, so getting kids excited about science and realizing it can be fun is extremely rewarding,” says Post, whose future career dream is to work at a liberal arts college and run a small lab.

Post is also a Mong Junior Cornell Neurotech Fellow — a program of Cornell Neurotech for exceptionally talented graduate students who are pursuing potentially transformative brain research.

Originally published on the Cornell Research website. All rights are reserved in the images. If you’d like to reproduce the text for noncommercial purposes, please contact us.

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