Bulletin of the American Physical Society
APS March Meeting 2018
Volume 63, Number 1
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session X06: Physics of Behavior |
Hide Abstracts |
Sponsoring Units: DBIO Chair: Joshua Shaevitz, Princeton Univ Room: LACC 153A |
Friday, March 9, 2018 8:00AM - 8:12AM |
X06.00001: Modulation of the Navigational Strategy of Insects in Controlled Temperature Environments Joseph Shomar, Anggie Ferrer, Joshua Forer, Ben Kaminski, Juan Bohorquez, Nikolaos Polizos, Mason Klein With its small size and limited motor tool set, the Drosophila larva is a good system to study how animals alter specific elements of their behavior to search and reach optimal environmental conditions. We aim to understand the larva’s response to temperature across development, in sensory gradients, and to distinguish behavioral modulations based on physical changes from those due to sensory input. |
Friday, March 9, 2018 8:12AM - 8:24AM |
X06.00002: Keeping it together: How humans coordinate with little information Edward Lee, Itai Cohen Swing in a crew boat, a good jazz riff, an excellent conversation: these are all results of good coordination between individuals. To perform such tasks, we must extract and encode sensory information about how others flow in order to mimic and respond. Recently, commercial virtual reality and motion capture platforms have become available, allowing us to manipulate visual and auditory fields while recording motion. Using these platforms to create a virtual reality environment, we study how people mirror the motion of a human avatar under different conditions. We find that people can coordinate well when the avatars are fully visible. However, when we limit visual information by blinking the visibility of the avatar we observe poor coordination where all individuals exhibit jerky motion at the blinking frequency. We then describe whether or not parallel visual or auditory feedback mitigates this transition. Finally, we comment on how such studies might be used to enhance coordination between individuals. |
Friday, March 9, 2018 8:24AM - 8:36AM |
X06.00003: Density-functional fluctuation theory of crowds Yunus Kinkhabwala, Juan Mendez Valderrama, Tomas Arias, Itai Cohen In 2017, in at least 9 separate incidents large crowds transitioned to dangerous stampedes causing hundreds of injuries and 68 deaths. The ability to predict a crowd’s state and whether it is susceptible to such transitions could prevent such catastrophes. We developed, and confirmed in a model system of fruit flies, a quantitative method that uses observations of local density to predict how crowds distribute themselves spatially and simultaneously measure the crowd’s “mood”. Our data-driven approach, inspired by DFT and statistical physics methods, extracts two independent functions to describe the crowd’s behavior. These functions separate individuals’ interactions with each other from interactions with their environment. We use these functions to quantify distinguishable collective behaviors of fruit flies and predict how they will distribute themselves in new environments. We also quantify interactions in multi-component systems to measure the mixing preference between male and female flies. If such techniques extend to human crowds, then observations of sparse crowds could be used to better prepare for highly crowded events and alert when a transition to a stampede is imminent. |
Friday, March 9, 2018 8:36AM - 8:48AM |
X06.00004: Substructure in Insect Swarms Kasper van der Vaart, Michael Sinhuber, Nicholas Ouellette Among collectively behaving animal aggregates swarming insects stand out with respect to bird flocks or fish schools because they seemingly lack global order; insects appear to fly around randomly through the swarm with little alignment. Nonetheless, this out-of-equilibrium system exhibits various emergent properties, giving investigators a strong incentive to uncover underlying order or structure in an effort to explain the emergent behavior. Here we address this question and reveal that laboratory swarms of flying midges display spatially heterogeneous substructure. In previous lab and field studies, individual midges were assumed to explore the whole volume of the swarm as no evidence suggested otherwise. But by making use of improved tracking algorithms we were able to follow individuals in laboratory swarms for longer time scales and show that individual midges limit themselves to vertical subvolumes. This effect leads to a vertical stratification of trajectories, which may have biological consequences. |
Friday, March 9, 2018 8:48AM - 9:00AM |
X06.00005: Exploring a strongly non-Markovian behavior Vasyl Alba, Gordon Berman, Joshua Shaevitz, William Bialek Quantitative observations of a freely walking fly provide an opportunity to search for simplicity and universality underlying the complexity and diversity of animal behavior. Recent work shows that the walking fly visits roughly 100 stereotyped states in a strongly non-Markovian sequence. |
Friday, March 9, 2018 9:00AM - 9:12AM |
X06.00006: Modeling behavioral evolution in fruit flies through reconstructing ancestral states Catalina Rivera, Damian Hernandez Lahme, Baohua Zhou, Jessica Cande, David Stern, Gordon Berman Despite the variety of behaviors that even closely-related species of animals display, the field has made little progress in understanding the genetic basis underlying their evolution. One of the main difficulties is that, as opposed to morphological evolution, behavioral evolution cannot be explicitly measured in the fossil record. Furthermore, animal behavioral is controlled by many genes, and individual variability often conceals the differences between species. Here, we propose a new framework to identify the genetic loci of behavioral evolution in fruit flies through behavioral coarse-graining. First, behavioral repertoires for individuals from six species of fruit flies are measured in an unsupervised manner. In combination with the phylogeny of these species, we fit a maximum likelihood GLMM, from which we infer the behavioral maps of ancestral flies. We propose a method to identify possible groups of behaviors that could have evolved together through changes in upstream genes that regulate the performance of many actions. This contrasts current approaches, where the focus is on how often an animal performs one specific behavior. Our results point towards broader theories of behavioral evolution and suggests new methods for identifying the genetic basis of these changes. |
Friday, March 9, 2018 9:12AM - 9:24AM |
X06.00007: Quantifying Behavior and Interaction in Paired Fruit Flies Ugne Klibaite, Gordon Berman, Joshua Shaevitz Social behaviors are exhibited by a wide range of animals, and may be crucial not only to a specific animal’s survival, but the success of the species. These interactions vary across time scales, lengths scales, and sensory modalities, and are often difficult to characterize due to this complexity, in addition to problems posed by visual occlusion during interaction. We have recently introduced an unsupervised method for quantifying behaviors in pairs of interacting flies, and describe several interesting features of interaction that emerge in wild type Drosophila melanogaster. We find that behavioral densities between a given pairing exhibit distance-dependence, and mutual information reveals that interactions are enriched for similar simultaneous behaviors, regardless of pairing. Finally, we explore courtship bouts in opposite-sex pairings and show that prior to copulation attempts, females in successful and unsuccessful pairings display different behavioral phenotypes. |
Friday, March 9, 2018 9:24AM - 9:36AM |
X06.00008: Insects Change Locomotion Modes to Traverse 3-D Obstacles with Varied Potential Energy Barriers Ratan Sadanand Othayoth Mullankandy, Chen Li Our recent work showed that legged locomotion in complex 3-D terrain can be understood as a locomotor-terrain interaction system that explores a potential energy landscape, where kinetic energy fluctuations from intermittent body/leg-terrain interactions help the system explore the landscape to form locomotor transition pathways. Here, we study cockroaches traversing grass-like obstacles to understand how the relative size of potential energy barriers and kinetic energy fluctuations affect system behavior. We created a terrain with grass-like beams whose torsional stiffness is precisely controlled and systematically varied to change potential energy barriers of the terrain, relative to the animal’s kinetic energy fluctuations. We discovered that, as potential energy barriers increased with beam stiffness, the animal switched its dominant traversal mode from running over with high beam deflection (95 ± 5 %), to a low beam deflection, body roll maneuver (90 ± 6 %), with traversal time increasing from 1.1 ± 1.1 s to 2.7 ± 1.4 s (P < 0.001, ANOVA). Our locomotion energy landscape model revealed that as potential energy barriers increase, it takes longer for the system to find low barrier transition pathways; potential energy barriers that are too low do not affect system behavior. |
Friday, March 9, 2018 9:36AM - 9:48AM |
X06.00009: Inferring the role of internal dynamics in Drosophila aging Katherine Overman, Daniel Choi, Joshua Shaevitz, Gordon Berman
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Friday, March 9, 2018 9:48AM - 10:00AM |
X06.00010: A Novel 3-D Full Body Model of Snake Locomotion in Complex 3-D Terrain Thomas Mitchel, Qihan Xuan, Jin Seob Kim, Gregory Chirikjian, Chen Li Despite many studies of snake locomotion on 2-D surfaces, our understanding in 3-D terrains remains limited, due to the lack of a full body description of motion. Here we developed a novel model using variational calculus on Lie Groups to enable 3-D full body quantification of snake locomotion and understand body-terrain interaction. To our surprise, although the model simplified the composite, actuated snake body as an elastic rod, it well predicted the entire body form using only a small number of marker constraints (average error of 0.15 ± 0.05 body radius over entire body). Body acceleration and force estimates from an anisotropic friction model using our method showed that, because opposing forces almost always canceled out, the system behaved quasi-statically near equilibrium. For further validation, we performed experiments to measure elastic properties of snake bodies to improve the accuracy of input parameters. Finally, our model allowed us to apply a novel framework of locomotion energy landscapes to understand quasi-static and dynamic stability in complex 3-D terrains. Our model has a broader applicability to quantitatively measure and model 3-D locomotion and manipulation using continuum body or appendages, such as worms, bacteria flagella, and elephant trunks. |
Friday, March 9, 2018 10:00AM - 10:12AM |
X06.00011: Adaptive, Locally-Linear Models of Living Dynamics Antonio Costa, Tosif Ahamed, Greg Stephens The dynamics of living systems generally include high-dimensional, non-stationary and non-linear behavior, posing fundamental challenges to quantitative analysis. Even successful methods often employ complex representations which can obscure conceptual understanding. To address these difficulties we detail a new approach in which the dynamics are captured through local linear models within windows determined adaptively from the data. Within each window, the dynamics are simple, consisting of exponential decay, growth and oscillations, yet the collection of local parameters across all windows provides a principled and interpretable parameterization of the full time series. From a minimum length selected for a well-conditioned model, windows are expanded until the model likelihood with new parameters signals a better fit, at which point there is a break and the process repeats. We apply our analysis to the posture dynamics of C. elegans and show that coarse behavioral transitions correspond to bifurcations and that the dynamics are generically close to an instability boundary. |
Friday, March 9, 2018 10:12AM - 10:24AM |
X06.00012: Excitable gait control of microswimming Kirsty Wan, Raymond Goldstein Since the invention of the microscope, scientists have known that pond-dwelling algae can actually swim – powering their way through the fluid at several times their own body size per second using tiny limbs called cilia and flagella. Only recently has it become clear that these tiny structures are the very same cilia that fulfil many important physiological and developmental functions within the human body. Here, we report a novel, tripartite motility in an octoflagellate Prasinophyte alga, comprising a steady forward gait (run), a fast knee-jerk response with dramatic reversals in beat waveform (shock), and, remarkably, long quiescent periods (stop) within which the flagella continue to exhibit very small amplitude oscillations. Combining high-speed imaging with detailed tracking of the swimming dynamics, we estimate transition probabilities between these highly stereotypical states to reveal that gait control in these microorganisms exists far from equilibrium. Moreover, we will demonstrate that rapid bifurcations in locomotion behaviour can also be triggered by direct mechanical contact, and discuss possible implications of these findings for an early evolution of excitable signal transduction in a primitive species. |
Friday, March 9, 2018 10:24AM - 10:36AM |
X06.00013: Insect flight in the unsteady wakes of flowers – how unsteady environments impact maneuverability and leading-edge vortex stability Megan Matthews, Simon Sponberg Flying insects use unsteady aerodynamic mechanisms to achieve stable hovering flight. When maneuvering, they must manipulate these aerodynamics, yet the surrounding airflow is typically unsteady. How do animals control their movement in unsteady environments so they can maintain aerodynamic structures, like the bound leading-edge vortices (LEVs) that assist lift in insect wings? Hawkmoths, Manduca sexta, hover while feeding from flowers and can actively track flower motion up to 14 Hz during flight. Using a 3D-printed robotic flower in a wind tunnel, we study how the unsteady flower wake affects the animals’ ability to control maneuvers and aerodynamics. Moths in still and unsteady air exhibit near perfect tracking at low frequencies, but flower wake tracking shows larger overshoot at mid-range. Smoke visualization of the flower wake shows that the dominant vortex shedding matches the frequency band of increased overshoot. However, the LEV remains bound throughout the wingstroke. This suggests that maneuverability and LEV stability are not equally impacted by unsteady flow. Moths may encode coherent structures in airflow to sense and control aerodynamics during maneuvers. Future work will quantify the interaction between unsteady flow and the bound LEV with 3D tomographic PIV. |
Friday, March 9, 2018 10:36AM - 10:48AM |
X06.00014: Individual and Automatic Training and Assay of Learned Navigational Behaviors in Drosophila larva Amanda Lesar, Marc Gershow Previous studies of olfactory learning in Drosophila larva show larva can learn through classical conditioning. While behavioral responses of trained larva have been studied, neural responses of freely moving, trained larva are unexplored. Previous training experiments involve presenting larva with an odor and reinforcer in a small number of training trials, then allowing larva to make a decision in the presence of odor without reinforcer. We develop a training chamber which involves rigorous training. The larva is presented with an odor plus reinforcer in more trials over longer period of time, which could increase the output of correct decisions in trained larva. The Y maze training chamber allows larva to make a decision, turn around, and go back to Y intersection to quickly make another decision. This allows us to study large number of decisions in short times. We will study neural responses of trained versus untrained larva, while larva is making decisions, which can help us to connect stimulus, behavioral responses, and neural activity. We will present results which demonstrate the training chamber is unbiased when no stimuli are present, and initial results for olfactory training of individual larva. |
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