Biological Physics (CPLC) Seminar: Mirna Mihovilovic Skanata

2/7/2020 11:30:44 AM

Mirna Mihovilovic Skanata New York University

Title: Cracking Neural Circuits of a Simple Brain

Abstract:   How do brains compute? The Drosophila (fruit fly) larva is a small, semi-transparent crawling organism with about 10,000 neurons, compared to 100 billion in humans and 100 million in mice. Despite this simplicity, the larva carries out information-processing tasks, including navigation – moving towards a favorable location based on information from its senses. A century of genetic work in Drosophila combined with recent innovations in protein engineering allow us to use light to directly activate specific neurons in the larva. For instance, we can engineer larvae with light-activable neurons in their “noses.” When presented with red light, these larvae perceive an odor and respond by attempting to find its source. Using sophisticated light patterns and analysis methods, we developed an assay that allowed us to quantify how the larva makes decisions based on multiple sources of sometimes conflicting information.
Advances similar to the ones that allow us to activate neurons using light allow us to measure thought patterns using light microscopes. Because the larva is almost clear, it has been a long-standing goal to use a microscope to “read the larva’s mind” as it navigates its surroundings. However, the 3D brain movements generated by the larva’s complicated locomotion have prevented optical recording of neural activity in behaving larvae. We developed a two-photon microscope capable of tracking single neurons moving rapidly in 3D while monitoring their activity in real time without motion artifacts. To record from many neurons we added a second beam that scans the volume around the tracked neuron to enable motion-corrected volumetric imaging in a freely-behaving animal. This allowed us to image correlated activity of motor and pre-motor neurons from a significant portion of larva’s “spine” in a completely unrestrained crawling animal. I will use these techniques to follow information flow through the larva’s circuits during sensory-motor transformations and achieve a neuron-level understanding of how a simple brain implements fairly complex calculations.

2/6/2014 11:00:00 AM Siv Schwink

Bryan Clark is a condensed matter theorist who specializes in the use and development of computational simulations and models to study the complexity of behaviors and interactions within many body and strongly correlated systems. In this work, Clark fully exploits today’s powerful supercomputing capabilities and he has written a wide range of highly efficient and massively parallel numerical codes, while developing novel numerical methods that improve the accuracy, parallelizability and efficiency of computing properties of many body systems. Clark was selected for an inaugural Blue Waters Professorship, which confers a significant commitment of Blue Waters computing resources, up to 240,000 node hours per year.

Clark’s broad research interests are reflected in his substantial list of publications and invited talks on a range subjects—supersolids, mesoscopic phases, water, the dynamics of cold atoms, and frustrated magnets.

Clark explains, “In this research area, there are no fast, exact methods, which is in some sense disappointing, because it’s hard to get answers. But in another sense, it’s exciting: it means the opportunity for fresh perspectives and for finding new methods is wide open. This is especially true with strongly correlated materials: in these systems, thinking about the behavior of individual electrons isn’t effective. If you take the material and parse it down to a simplified model, it’s still hard to solve. In my research, I apply computational tools to better understand how a material behaves and interacts, identify different phases of matter, and establish whether a material can be induced to exhibit interesting properties.”

At Illinois, Clark is looking forward to building a strong research group of graduate and undergraduate students interested in condensed matter, to explore superconducting systems, quantum dynamics, and frustrated magnetism.

“Having spent my graduate years at Illinois, I came to appreciate this department’s unique strength in condensed matter, its collegial atmosphere, and its driving passion for physics that permeates both faculty and students,” he comments. “This, along with strong peers on both the experimental and theoretical sides with whom to interact, makes me excited to return to Urbana.”

Clark joins the faculty as a member of the Institute of Condensed Matter Theory.

Clark received his bachelor’s degrees in physics and in computer science from Carnegie Mellon University in 2002. He received his doctoral degree in physics from the U. of I. in 2009, working under Professor David Ceperley.

Prior to joining the faculty at Illinois, Clark worked as a postdoctoral fellow at the Kavli Institute for Theoretical Physics in Santa Barbara, CA, (fall 2013) and before that at the Microsoft Research-Station Q in Santa Barbara, CA, (beginning in 2012). Prior to that, he worked as a postdoctoral fellow at the Princeton Center for Theoretical Science at Princeton University (2009–2012).