Extracting nectar from flowers that may be dancing in the wind requires precise, millisecond timing between the brain and muscles.
By capturing and analyzing nearly all of the brain signals sent to the wing muscles of hawk moths (Manduca sexta), which feed on such nectar, researchers have shown that precise timing within rapid sequences of neural signal spikes is essential to controlling the flight muscles necessary for the moths to eat.
The research shows that millisecond changes in timing of the action potential spikes, rather than the number or amplitude of the spikes, conveys the majority of information the moths use to coordinate the five muscles in each of their wings. The importance of precise spike timing had been known for certain specific muscles in vertebrates, but the new work shows the general nature of the connection.
“We were able to record simultaneously nearly every signal the moth’s brain uses to control its wings, which gives us an unprecedented and complete window into how the brain is conducting these agile and graceful maneuvers,” said Simon Sponberg, Dunn Family Professor in the School of Physics at the Georgia Institute of Technology. “These muscles are coordinated by subtle shifts in the timing at the millisecond scale rather than by just turning a knob to create more activity. It’s a more subtle story than we might have expected, and there are hints that this may apply more generally.”
The research was reported Dec. 16 in the journal Proceedings of the National Academy of Sciences. The work was supported by the National Science Foundation, the Esther A. & Joseph Klingenstein Fund, and the Simons Foundation.
Researchers Joy Putney, Rachel Conn and Sponberg set out to study how the brain coordinates agile activities such as running or flying that require compensating for perturbations in the air or variations on the ground. While the size of the signals could account for gross control of the behavior, the fine points of choreographing the tasks had to come from elsewhere, they reasoned.
Recording motor control signals in humans and other vertebrates would be a daunting task because so many neurons are used to control so many muscles in even simple behaviors. Fortunately, the researchers knew about the hawk moth, whose flight muscles are each controlled by a single or very few motor neurons. That allowed the researchers to study neural signals by measuring the activity of the corresponding muscles, using tiny wires inserted through the insect’s exoskeleton.
Putney and Conn determined the location of each wing muscle inside the moth exoskeleton, and learned where to create tiny holes for the wires — two for each muscle — that capture the signals. After inserting the wires in the anesthetized moths, the graduate students closed the holes with superglue to hold the wires in place. Connections to a computer system allowed recording and analysis.
“The first time I did the surgery by myself, it took six hours,” said Putney. “Now I can do it in under an hour.”
While connected to the computer, the moths were able to fly on a tether as they viewed a moving 3D-printed plastic flower. To measure the torque forces the moths created as they attempted to track the flower, the wired-up moths were suspended from an accelerometer.
The torque information was then correlated with the spiking signals recorded from each wing muscle.
The importance of the work relates to the completeness of the signal measurement, which brought out the importance of the timing codes to what the moth was doing, Putney said.
“People have recorded lots of muscles together before, but what we have shown is that all of these muscles are using timing codes,” she said. “The way they are using these codes is consistent, regardless of the size of the muscle and how it is attached to the body.”
Indeed, researchers have seen hints about the importance of precision timing in higher animals, and Sponberg believes the hawk moth research should encourage more study into the role of timing. The importance and prevalence of timing across the moth’s motor program also raises questions about how nervous systems in general create precise and coordinated motor commands.
“We think this raises a question that can’t be ignored any longer — whether or not this timing could be the real way that the brain is orchestrating movement,” Sponberg said. “When we look at specific signals in vertebrates, even up to humans, there are hints that this timing could be there.”
The study could also lead to new research on how the brain produces the agile motor control needed for agile movement.
“Now that we know that the motor control is really precise, we can start trying to understand how the brain integrates precise sensory information to do motor control,” Sponberg said. “We want to really understand not only how the brain sets up signals, but also how the biophysics of muscles enables the precise timing that the brain uses.”
This material is based upon work supported by National Science Foundation Graduate Research Fellowships DGE-1650044 and DGE-1444932, an NSF CAREER award (1554790), and a Klingenstein-Simons Fellowship Award in the Neurosciences. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the sponsoring organization.
CITATION: Joy Putney, Rachel Conn, and Simon Sponberg, “Precise timing is ubiquitous, consistent and coordinated across a comprehensive, spike-resolved flight motor program.” (Proceedings of the National Academy of Sciences, 2019.) https://www.pnas.org/content/early/2019/12/11/1907513116
Research News
Georgia Institute of Technology
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Media Relations Contact: John Toon (404-894-6986) (jtoon@gatech.edu)
Writer: John Toon
Silvia Salinas Blemker, Ph.D.
Professor
Biomedical Engineering, Mechanical & Aerospace Engineering, Ophthalmology, and Orthopaedic Surgery
University of Virginia
Abstract
Skeletal muscles are extraordinarily adapted motors that enable us to perform many important functions, from walking to sight to speech. From a basic science perspective, we have a sophisticated understanding of the fundamental biology and mechanics of skeletal muscle. However, how these fundamentals relate to in vivo function is complex and remains poorly understood, which limits the translation of this basic biology understanding to medicine. The goal of the Multi-Scale Muscle Mechanophysiology (“M3”) Lab’s research is to develop and experimentally validate multi-scale computational models of skeletal muscle that allow us to relate structure, biology, and function across a range of muscles. We aim apply these models to answering questions related to the role of complex muscle biology and mechanics in a variety of clinical problems. In this presentation, I will describe these approaches and present some recent examples of how computational models of muscle have led to clinically relevant insights.
Speaker Bio
Silvia Salinas Blemker is a Professor of Biomedical Engineering, with joint appointments in Mechanical & Aerospace Engineering, Ophthalmology, and Orthopaedic Surgery, at the University of Virginia in Charlottesville, VA, USA. She obtained her B.S. and M.S. degrees in Biomedical Engineering from Northwestern University and her Ph.D. degree in Mechanical Engineering from Stanford University. Before joining the faculty at UVa in 2006, Silvia worked as a post-doctoral Research Associate at Stanford University’s National Center for Biomedical Computation. At UVA, she leads the Multi-scale Muscle Mechanophysiology Lab (“M3 Lab”).
The M3 lab group develops advanced multi-scale computational and experimental techniques to study skeletal muscle biomechanics and physiology, and they are currently applying these techniques to variety of areas, including speech disorders, movement disorders, vision impairments, muscle atrophy, aging, and muscular dystrophies. While the work is grounded in biomechanics, it strongly draws from many other fields, including biology, muscle physiology, biomedical computation, continuum mechanics, imaging, and a variety of clinical fields. The M3 lab is enthusiastic to take part in outreach activities, including having active participation of K-12 teachers in the lab and hosting an annual National Biomechanics Day event locally. The M3 lab’s research has been funded by several institutes at the National Institutes of Health (NIAMS, NIBIB, NIA, and NIDCD), NASA, the NSF, the Department of Defense, The Hartwell Foundation, the UVA-Coulter Translational Research Partnership, in addition to industry partnerships. Dr. Blemker has multiple patents pending and recently co-founded Springbok, Inc, a company focused on image-based muscle analytics for a variety of applications from sports medicine to neuromuscular disorders.
Host: Gregory Sawicki
Event Details
The ExplOrigins group is hosting the 3rd annual Exploration and Origins Colloquium on January 27th and 28th, in another example of Georgia Tech’s thriving collaboration between the astrobiology and space science communities.The program kicks off with a poster session on Monday, Jan. 27, and continues with plenary lectures, contributed talks, and a networking session on Tuesday, Jan. 28.
The interdisciplinary colloquium will highlight space exploration science, as well as biological, geological, and astronomical origins research in the Georgia Institute of Technology and neighboring universities. The colloquium aims to forge relationships among diverse individuals, encourage collaboration and interdisciplinary understanding, and kick-start fundable projects requiring the skills and expertise of multilab teams.
The colloquium will begin with a poster session on the evening of the 27th where attendees will show off their latest work in an environment conducive to interdisciplinary collaboration. Activities on the 28th include a day-long seminar with twelve contributed talks, and highlighted keynote addresses by: Mariel Borowitz of Georgia Tech’s Sam Nunn School of International Affairs, and Christopher Carr of MIT and Massachusetts General Hospital. This colloquium takes place in the context of a burgeoning astrobiology community at Georgia Tech, with the Institute having recently hosted the Astrobiology Graduate Conference in 2018 and announced the host of Astrobiology Science Conference in 2021.
Register here.
Check here for schedule.
Event Details
The 2020 Frontiers Lecture with Moon Duchin, originally scheduled for March 26, 2020, has been postponed. Please visit cos.gatech.edu for further updates.
A Frontiers in Science Lecture and the 2020 Karlovitz Lecture by Moon Duchin, Tufts University
The theory of random walks has found a fruitful application in electoral redistricting, by allowing us to sample from the partitions of a state into districts. By comparing a plan to neutral alternatives, we can measure the extent of gerrymandering—when one party takes advantage of the authority to draw the lines. Moon Duchin will discuss some surprisingly simple questions about graphs and geometry that can help us make advances in policy and civil rights.
About the Speaker
Moon Duchin is an Associate Professor of Mathematics and Senior Fellow in the Jonathan M. Tisch College of Civic Life at Tufts University. Her research in pure mathematics focuses on geometric group theory, low-dimensional topology, and dynamics. She is also interested in the social studies of science, particularly the role of expertise, authority, intuition, and proof.
She founded the Metric Geometry and Gerrymandering Group to use geometry and computation to study gerrymandering, believing it to be a fundamental threat to democracy. The redistricting lab uses tools from math, geography, and computing to study politics and policy.
She is a Fellow of the American Mathematical Society. In 2018, she was awarded a Guggenheim fellowship.
Duchin’s Frontiers in Science Lecture is co-sponsored by the 14th Biennial Gathering for Gardener Conference.
About the Karlovitz Lecture Series
The lecture is made possible by an endowment in memory of College of Sciences Dean Les Karlovitz, who served as dean from 1982 until 1989. Seeking to broaden intellectual discourse on campus, the series focuses on speakers whose work has led them to stretch across disciplinary boundaries.
About the Frontiers in Science Lecture Series
Lectures in this series are intended to inform, engage, and inspire students, faculty, staff, and the public on developments, breakthroughs, and topics of general interest in the sciences and mathematics. Lecturers tailor their talks for nonexpert audiences.
Event Details
While it’s largely business as usual in Cobb’s cities following Tuesday’s municipal elections, Smyrna’s government faces significant change....It would also mean newcomer Lewis Wheaton, a 42-year-old Georgia Tech professor who won 57% of the preliminary vote in the Ward 7 race, would be the only person of color on the council.
At Georgia Tech, members and trainees of the Center for Microbial Dynamics and Infection discuss the identification of pathogen essential genes during coinfections, and how coral management can improve coral defenses against pathogens. Guests were Marvin Whiteley, Gina Lewin, Deanna Beatty, Mark Hay, and Frank Stewart.
Fire ants build living rafts to survive floods and rainy seasons. Georgia Tech scientists are studying if a fire ant colony’s ability to respond to changes in their environment during a flood is an instinctual behavior and how fluid forces make them respond. Hungtang Ko and David Hu will present the science behind this insect behavior, focusing their discussion on how the living raft changes size under various environmental conditions at the American Physical Society’s Division of Fluid Dynamics 72nd Annual Meeting on Nov. 26.
By A. Maureen Rouhi
Examine your hands. The right is a mirror image of the left. They look very similar, but you know they’re not when you try to put your left hand inside a right glove.
The molecules of life have a similar handedness. Proteins for example are like your left hand, made up of amino acids that are all left-handed. This phenomenon is called chirality. How chiral systems emerged is one of the key questions of origins-of-life research.
Many explanations have been proposed. Now a Georgia Tech team examining the problem suggests that stability is what drove the emergence of chiral systems. Led by Jeffrey Skolnick, a professor in the School of Biological Sciences, the team includes research scientists Hongyi Zhou and Mu Gao. The work was supported in part by the Division of General Medical Sciences of the National Institutes of Health (NIH Grant R35-118039) and published on Dec. 10, 2019, in PNAS.
They reached their conclusion from computer simulations examining the stability and properties of a prepared protein library made up of
- nonchiral proteins, containing a 1:1 ratio of right- (D) and left-handed (L) amino acids, also called demi-chiral;
- nonchiral proteins containing 3:1 and 1:3 of D and L amino acids; and
- chiral proteins containing all D and all L amino acids.
Their simulations showed that nonchiral proteins, even the demi-chiral ones, have many properties of chiral proteins. They fold and form cavities just like ordinary proteins. They could have performed many of the biochemical functions of ordinary proteins, especially the most ancient and essential ones. These nonchiral proteins also can adopt the structures of contemporary proteins including ribosomal proteins, necessary for protein transcription.
“This ability of nonchiral proteins to fold and function might have been an essential prerequisite for the life on Earth,” says Eugene Koonin, a senior investigator at the National Center for Biotechnology Information, in the National Institutes of Health. “If so, this result is a truly fundamental finding that contributes to our understanding of the origins of life.”
However, nonchiral proteins have fewer hydrogen bonds than those made of all D or all L amino acids. The demi-chiral ones have the fewest. Thus chiral proteins are much more stable than demi-chiral ones. “The biochemistry of life as we know it likely results from stability driven by hydrogen bonds,” says Skolnick, who is a member of the Parker H. Petit Institute of Bioengineering and Bioscience.
The PNAS study examines the properties of proteins from the point of view of physics alone, without the intervention of evolution, Skolnick says. “It explains how the chemistry of life emerged from basic physical principles. It also strongly suggests that simple life might be quite ubiquitous throughout the universe.”
“I wish to understand how life emerged and to know its design principles,” Skolnick says. “On the most academic level, I wish to explain the origin of life based on physics with well-defined testable ideas.”
The newly published “work offers a non-intelligent-design perspective as to how the biochemistry of life might have gotten started,” Skolnick says. “It shifts the emphasis from evolution to the inherent physical properties of proteins. It removes that chicken-and-egg quandary that chiral RNA is required to produce chiral proteins. Rather, such excess chirality is shown to emerge naturally from a nonchiral system.”
What the work does not address is why L-amino acids and L-proteins emerged dominant on Earth. It is know that some meteorites have an excess of L-amino acids. “If one assumes that many primordial amino acids were seeded by meteorites, many of them have an excess of L over D amino acids,” Skolnick says. “All it would take is just a little bias to get the whole process started.”
Skolnick says the next step is to test the computer simulations by studying the emergent chemistry of nonchiral proteins. A key unanswered question is how did replication emerge? “We can explain life’s biochemistry and many of the parts associated with replication from this study, but not replication itself,” he says. “If we can do this, then we have all of life’s components. If this works, ultimately I want to recreate what could be the early living systems in a test tube.”
A Frontiers in Science Lecture by Elizabeth Loftus, University of California, Irvine
For several decades, Elizabeth Loftus has been manufacturing memories in unsuspecting minds. Sometimes these techniques change details of events that someone actually experienced. Other times, the techniques create entire memories of events that never happened: they create “rich false memories.” Collectively, this work shows people can be led to believe they did things that would have been rather implausible. They can be led to falsely believe they had experiences that would have been emotional or traumatic had they actually happened.
False memories, like true ones, also have consequences for people—affecting their later thoughts, intentions, and behaviors. Can we tell true memories from false ones? In several studies, Loftus created false memories in the minds of people, compared them to true memories, and discovered that once planted, those false memories look very much like true memories: they have similar behavioral characteristics, emotionality, and neural signatures.
Considered as a whole, these findings raise important questions: If false memories can be so readily planted in the mind, do we need to think about “regulating” this mind technology? And what do these pseudomemories say about the nature of memory itself?
About the Speaker
Elizabeth Loftus is Distinguished Professor at the University of California, Irvine. She holds positions in the Departments of Psychological Science, and Criminology, Law & Society. And she is Professor of Law.
She also has a faculty appointment in the Department of Cognitive Sciences and is a Fellow of the Center for the Neurobiology of Learning and Memory, and was the Founding Director of the Center for Psychology and Law.
Loftus received her undergraduate degree in Mathematics and Psychology from the University of California, Los Angeles, and her Ph.D. in Psychology from Stanford University. Since then, she has published 23 books and over 500 scientific articles. Her fourth book, "Eyewitness Testimony," won a National Media Award (Distinguished Contribution) from the American Psychological Foundation. Her books have been translated into Dutch, French, German, Japanese, Chinese, and other languages.
Loftus has been an expert witness or consultant in hundreds of cases, including the McMartin PreSchool Molestation case, the Hillside Strangler, the Abscam cases, the trial of Oliver North, the trial of the officers accused in the Rodney King beating, the Menendez brothers, the Bosnian War trials in the Hague, the Oklahoma Bombing case, and litigation involving Michael Jackson, Martha Stewart, Scooter Libby, and the Duke University Lacrosse players.
Loftus's research has focused on human memory, eyewitness testimony, and also on courtroom procedure. Her work has been funded by the National Institute of Mental Health and the National Science Foundation.
She was elected president of the Association for Psychological Science (APS), the Western Psychological Association (twice), the American Psychology-Law Society, and the Experimental Psychology division of the American Psychological Association (APA).
Loftus studies human memory. Her experiments reveal how memories can be changed by things that we are told. Facts, ideas, suggestions and other post-event information can modify our memories. The legal field, so reliant on memories, has been a significant application of the memory research. Loftus is also interested in psychology and law, more generally.
About Frontiers in Science Lectures
Lectures in this series are intended to inform, engage, and inspire students, faculty, staff, and the public on developments, breakthroughs, and topics of general interest in the sciences and mathematics. Lecturers tailor their talks for nonexpert audiences.
Event Details
The Georgia Tech Urban Honey Bee project will be celebrating the end of the semester and showcasing student projects (and new digs) on Tuesday, December 10 from 11am-1pm in room 280 of the Kendeda Building for Innovative Sustainable Design.
Please drop in for snacks, tours, and to browse student posters.
A limited number of holiday gift bags will also be available for purchase for $15 and support the urban honey bee project. Bags include a small jar of honey, beeswax lip balm, and a "slumgum" firestarter for all your winter campfire and fireplace needs.
Hope to see you there!
Event Details
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