Working Together to Understand How the Brain Sees the World

November 11, 2021

Looking at the world around us, we rarely stop to wonder how what our eyes see is reflected in the complex circuitry of our brain. But that is exactly the question that a group of researchers in MPFI’s Fitzpatrick Lab, led by Dr. Madineh Sedigh-Sarvestani, set out to discover. Their findings were recently published in the journal Neuron.

As project lead, Madineh started where many daunting research undertakings begin- with a strong group of collaborators. Scientific teams are often made up of researchers with different expertise and in many different stages of their careers, and this one was no different.

“Having a diverse team is important because people with different backgrounds and skillsets will often see the same problem from varying perspectives and offer different solutions,” Madineh said.

Madineh initiated this project with Kuo-Sheng Lee, then a graduate student in the lab who shared an interest in exploring uncharted regions in visual regions of the tree shrew brain. They expanded the team to include Juliane Jaepel, a postdoctoral fellow who was following a similar line of inquiry in ferrets and whose perspective allowed the team to better understand their observations in the tree shrew. As the data became more complex, certain components didn’t make sense, as if there were multiple puzzle pieces that didn’t fit together. To better understand the data, new approaches and teammates were recruited. Rachel Satterfield, a research assistant, shared her expertise in viral vector tools and played a major role in the collection and analysis of structural brain data. Nicole, the lab manager, and histology coordinator, also contributed to histological data analysis. In addition, she was vital to establishing an organization and communication infrastructure that enabled the team to conduct their study in the most efficient way.

“We were a predominantly woman-driven team, and it was refreshing to witness the drive, determination, and willing­­ness to learn from each other,” Nicole shared. “The in-depth discussions we collectively had as a group was enlightening, as each of us provided valuable insight, and by utilizing individual skillsets, we were able to ultimately rethink how maps of visual space are formed.”

Throughout the project, the team received guidance and mentorship from principal investigator David Fitzpatrick, CEO and scientific director of Max Planck Florida.

“At every step, from the inception of the question and hypothesis to the final writing of the report, David challenged us to provide stronger evidence for the patterns we found in the data, why our findings mattered and what new questions they brought up, and how to communicate all this to the rest of the scientific community,” said Madineh.

The Fitzpatrick lab is one of a handful of labs in the United States that works with tree shrews, small animals closely related to primates. Tree shrews are the natural prey of large birds, but predators to insects, so they need to move quickly and see with high acuity. Other animals with different habitats or movement abilities have different needs from their visual system and therefore exhibit correspondingly different visual acuity and abilities. However, the basic structure of the visual system of many mammals contains common elements. One of the questions that defined this project was whether a particular area in the visual cortex of tree shrews processed visual information in the same way as the corresponding area in primates and ferrets. If so, this would suggest that this area served some basic visual need that was similarly useful to these animals, even though each animal has distinct visual demands.

Because so few labs are skilled at working with tree shrews, there is not a lot of documentation on how the tree shrew brain is structured, adding an additional risk, and potential reward, for the researchers. To help facilitate future discoveries in tree shrews, several members of the team are involved in efforts to organize and grow the community of neuroscientists who use tree shrews as their model organism. “This whole project was a creative challenge in that we discovered a new explanation for data that had been previously observed in other animals,” Madineh explained. “One of the first Eureka moments was when I realized that the structural connectivity between brain regions, measured using histological data from brain tissue, could easily explain the neural response data I had collected in the living brain.”

As Madineh looks ahead to her own career as an independent investigator, the tools and approaches she developed during this project will serve as a foundation for her research program devoted to understanding how the visual system of different animals reflects their behavioral needs. “In my (future) lab, I’ll study how brain circuits are optimized to an animal’s specific visual needs, determined by many forces including how the animal moves to explore its environment and the statistics of that environment. This will help us form a new understanding of the visual system that is more in line with our experience as moving animals. Ultimately, this missing knowledge will help us understand why sensory-motor deficits occur with disease and age, and how to slow or prevent these deficits so that the brain and body jointly function in an optimal manner.”

Read more about “A sinusoidal transformation of the visual field is the basis for periodic maps in area V2”  by Madineh Sedigh-Sarvestani, Kuo-Sheng Lee, Juliane Jaepel, Rachel Satterfield, Nicole Shultz, David Fitzpatrick (2021).The full paper is available in Neuron, online now.