Motor patterns during active electrosensory acquisition

Hofmann V, Geurten B, Sanguinetti-Scheck JI, Gomez-Senna L, Engelmann J. Motor patterns during active electrosensory acquisition. Frontiers in Behavioral Neuroscience. 2014;8:186.Motor patterns displayed during active electrosensory acquisition of information seem to be an essential part of a sensory strategy by which weakly electric fish actively generate and shape sensory flow. These active sensing strategies are expected to adaptively optimize ongoing behavior with respect to either motor efficiency or sensory information gained. The tight link between the motor domain and sensory perception in active electrolocation make weakly electric fish like Gnathonemus petersii an ideal system for studying sensory-motor interactions in the form of active sensing strategies. Analyzing the movements and electric signals of solitary fish during unrestrained exploration of objects in the dark, we here present the first formal quantification of motor patterns used by fish during electrolocation. Based on a cluster analysis of the kinematic values we categorized the basic units of motion. These were then analyzed for their associative grouping to identify and extract short coherent chains of behavior. This enabled the description of sensory behavior on different levels of complexity: from single movements, over short behaviors to more complex behavioral sequences during which the kinematics alter between different behaviors. We present detailed data for three classified patterns and provide evidence that these can be considered as motor components of active sensing strategies. In accordance with the idea of active sensing strategies, we found categorical motor patterns to be modified by the sensory context. In addition these motor patterns were linked with changes in the temporal sampling in form of differing electric organ discharge frequencies and differing spatial distributions. The ability to detect such strategies quantitatively will allow future research to investigate the impact of such behaviors on sensing

Interdisciplinary design of a fish ramp using migration routes analysis

The study presents several steps of a fish ramp geometry optimization performed with a 3D numerical model DualSPHysics, which is based on the smoothed particle hydrodynamics (SPH) method. The optimization process led to the design of a bottom ramp that is capable of providing suitable conditions for the migration of target fish species (Salmo truta, Phoxinus phoxinus, Cottus gobio, and Eudontomyzon vladykovi). Migration routes were determined as complex 3D volumes of fluid according to the simulated velocity field in various steady flow conditions. Including three categories of potential migration zones (rest, effort, and limit zones), migration routes were quantified in high detail in terms of the size and position of each zone, and in terms of the distance from a given fluid part to the nearest rest zone. The interdisciplinary approach of this study also led to the development of new tools for the DualSPHysics model, specifically suited to improve functionality in eco-hydraulics research. Fishway Ramp River restoration Smoothed particle hydrodynamics DualSPHysicspublishedVersio

How worms move in 3D

Animals that live in the sky, underwater or underground display unique three dimensional behaviours made possible by their ability to generate movement in all directions. As animals explore their environment, they constantly adapt their locomotion strategies to balance factors such as distance travelled, speed, and energy expenditure. While exploration strategies have been widely studied across a variety of species, how animals explore 3D space remains an open problem. The nematode Caenorhabditis elegans presents an ideal candidate for the study of 3D exploration as it is naturally found in complex fluid and granular environments and is well sized (~1mm long) for the simultaneous capture of individual postures and long term trajectories using a fixed imaging setup. However, until recently C. elegans has been studied almost exclusively in planar environments and in 3D neither its modes of locomotion nor its exploration strategies are known. Here we present methods for reconstructing microscopic postures and tracking macroscopic trajectories from a large corpus of triaxial recordings of worms freely exploring complex gelatinous fluids. To account for the constantly changing optical properties of these gels we develop a novel differentiable renderer to construct images from 3D postures for direct comparison with the recorded images. The method is robust to interference such as air bubbles and dirt trapped in the gel, stays consistent through complex sequences of postures and recovers reliable estimates from low-resolution, blurry images. Using this approach we generate a large dataset of 3D exploratory trajectories (over 6 hours) and midline postures (over 4 hours). We find that C. elegans explore 3D space through the composition of quasi-planar regions separated by turns and variable-length runs. To achieve this, C. elegans use locomotion gaits and complex manoeuvres that differ from those previously observed on an agar surface. We show that the associated costs of locomotion increase with non-planarity and we develop a mathematical model to probe the implications of this connection. We find that quasi-planar strategies (such as we find in the data) yield the largest volumes explored as they provide a balance between 3D coverage and trajectory distance. Taken together, our results link locomotion primitives with exploration strategies in the context of short term volumetric foraging to provide a first integrated study into how worms move in 3D

Interactive advertising displays

Interactive public displays are the latest development in the field of out-of-home advertising. Throughout history characteristic shapes for billboards evolved such as flat rectangular displays, long displays or cylindrical advertising columns. This work presents novel interactive display designs that are based on these historical role models and allow passers-by to interact with them in a natural, touchless manner. It further pursues a vision where interactive public displays become more active themselves and actively influence passer-by behavior in order to increase their effectiveness, better attract attention and improve public interaction in front of them. First, to overcome the challenge that passers-by often do not expect public displays to be interactive and thus pay no attention to them, this work presents a solution called unaware initial interaction that surprises passers-by and communicates interactivity by giving visual feedback to their initial movements. To be effective, the visual feedback has to be designed considering the specific display shapes, their requirements to contents and the typical approaching trajectories. Second, to overcome the challenge that larger groups of passers-by often crowd together in front of wide public displays or do not take optimal positions for interaction, this work presents a solution to subtly and actively guide users by dynamic and interactive visual cues on the screen in order to better distribute them. To explore these concepts and following an initial analysis of the out-of-home domain and of typical display qualities, interactive counterparts to the classical display shapes are designed such as interactive advertising columns, long banner displays and life-size screens. Then interactive contents and visual feedbacks are designed which implement the presented interactivity concepts, and audience behavior around them is analyzed in several long-term field studies in public space. Finally the observed passer-by and user behavior and the effectiveness of the display and content designs are discussed and takeaways given that are useful for practitioners and researchers in the field of public interaction with out-of-home displays.Interaktive öffentliche Displays sind die neueste Entwicklung im Bereich der Außenwerbung. Im Laufe der Geschichte bildeten sich charakteristische Formen für Werbetafeln heraus wie flache rechteckige Displays, lange Displays oder zylindrische Werbesäulen. Die vorliegende Arbeit stellt neuartige Designs für Displays vor, die auf diesen historischen Vorbildern aufbauen und den Passanten erlauben, mit ihnen auf eine natürliche, berührungslose Art und Weise zu interagieren. Darüber hinaus verfolgt sie eine Vision, in der interaktive öffentliche Displays aktiver werden und entsprechend das Passantenverhalten beeinflussen, um ihre Wirksamkeit zu erhöhen, mehr Aufmerksamkeit auf sich zu ziehen und die öffentliche Interaktion mit ihnen zu verbessern. Zunächst stellt diese Arbeit eine als Unbewusste Initialinteraktion bezeichnete Lösung vor, welche die Passanten überrascht und mittels visuellem Feedback auf ihre anfänglichen Bewegungen Interaktivität übermittelt, um die Herausforderung zu bewältigen, dass Passanten oft nicht erwarten, dass öffentliche Displays interaktiv sind und sie ihnen somit keine Aufmerksamkeit schenken. Um effektiv zu sein, muss das visuelle Feedback dabei so gestaltet werden, dass es die spezifischen Displayformen, ihre Anforderungen an die dargestellten Inhalte und ihre typischen Annäherungswege berücksichtigt. Zweitens stellt sie eine Lösung vor, bei der die Nutzer auf subtile Weise und durch auf dem Bildschirm dargestellte dynamische und interaktive visuelle Reize aktiv geführt werden, um sie besser vor dem Display zu verteilen, um die Herausforderung zu bewältigen, dass größere Gruppen von Passanten sich oft vor breiten öffentlichen Displays zusammendrängen oder keine optimalen Positionen für die Interaktion einnehmen. Zur Erforschung dieser Konzepte werden im Anschluss an eine einführende Analyse von Außenwerbedisplays und ihrer typischen Eigenschaften interaktive Entsprechungen der klassischen Displayformen entwickelt wie interaktive Litfaßsäulen, lange Bannerdisplays und Life-size Screens. Weiter werden für diese Displays interaktive Inhalte und visuelle Feedbacks entwickelt, welche die vorgestellten Interaktivitätskonzepte umsetzen und das Verhalten des anwesenden Publikums in mehreren Langzeit-Feldstudien im öffentlichen Raum untersucht. Schließlich werden das beobachtete Passanten- und Nutzerverhalten und die Effektivität der entwickelten Display-Designs und Inhalte bewertet und nützliche Empfehlungen für Praktiker und Forscher auf dem Gebiet der öffentlichen Interaktion mit Außenwerbedisplays gegeben

Neural Circuit Dynamics and Ensemble Coding in the Locust and Fruit Fly Olfactory System

Raw sensory information is usually processed and reformatted by an organism’s brain to carry out tasks like identification, discrimination, tracking and storage. The work presented in this dissertation focuses on the processing strategies of neural circuits in the early olfactory system in two insects, the locust and the fruit fly. Projection neurons (PNs) in the antennal lobe (AL) respond to an odor presented to the locust’s antennae by firing in slow information-carrying temporal patterns, consistent across trials. Their downstream targets, the Kenyon cells (KCs) of the mushroom body (MB), receive input from large ensembles of transiently synchronous PNs at a time. The information arrives in slices of time corresponding to cycles of oscillatory activity originating in the AL. In the first part of the thesis, ensemble-level analysis techniques are used to understand how the AL-MB system deals with the problem of identifying odors across different concentrations. Individual PN odor responses can vary dramatically with concentration, but invariant patterns in PN ensemble responses are shown to allow odor identity to be extracted across a wide range of intensities by the KCs. Second, the sensitivity of the early olfactory system to stimulus history is examined. The PN ensemble and the KCs are found capable of tracking an odor in most conditions where it is pulsed or overlapping with another, but they occasionally fail (are masked) or reach intermediate states distinct from those seen for the odors presented alone or in a static mixture. The last part of the thesis focuses on the development of new recording techniques in the fruit fly, an organism with well-studied genetics and behavior. Genetically expressed fluorescent sensors of calcium offer the best available option to study ensemble activity in the fly. Here, simultaneous electrophysiology and two-photon imaging are used to estimate the correlation between G-CaMP, a popular genetically expressible calcium sensor, and electrical activity in PNs. The sensor is found to have poor temporal resolution and to miss significant spiking activity. More generally, this combination of electrophysiology and imaging enables explorations of functional connectivity and calibrated imaging of ensemble activity in the fruit fly.</p

Science-based restoration monitoring of coastal habitats, Volume Two: Tools for monitoring coastal habitats

Healthy coastal habitats are not only important ecologically; they also support healthy coastal communities and improve the quality of people’s lives. Despite their many benefits and values, coastal habitats have been systematically modified, degraded, and destroyed throughout the United States and its protectorates beginning with European colonization in the 1600’s (Dahl 1990). As a result, many coastal habitats around the United States are in desperate need of restoration. The monitoring of restoration projects, the focus of this document, is necessary to ensure that restoration efforts are successful, to further the science, and to increase the efficiency of future restoration efforts

NEUROMECHANICAL CONTROL OF LOCOMOTION IN INTACT AND INCOMPLETE SPINAL CORD INJURED RATS

Rodent models are being extensively used to investigate the effects of traumatic injuryand to develop and assess the mechanisms of repair and regeneration. We presentquantitative assessment of 2D kinematics of overground walking and for the first time3D joint angle kinematics of all four limbs during treadmill walking in the intact and inincomplete spinal cord contusion injured (iSCI) adult female Long Evans rats. Phaserelationship between joint angles on a cycle-by-cycle basis and interlimb footfalls areassessed using a simple technique. Electromyogram (EMG) data from major flexor andextensor muscles for each of the hindlimb joints and elbow extensor muscles of theforelimbs synchronized to the 3D kinematics is also obtained in intact rats. EMG activityindicates specific relationships of the neural activity to joint angle kinematics. We findthat the ankle flexors as well as the hip and elbow extensors maintain constant burstduration with changing cycle duration. Overground walking kinematics providesinformation on stance width (SW), stride length (SL) and hindfoot rotation (Rot). SW andRot increased in iSCI rats. Treadmill walking kinematics provides information on jointangle trajectories. In iSCI rats double burst pattern in ankle angle as seen in intact ratsis lost and knee extension and range are reduced. Intra and interlimb coordination isimpaired. Left-right interlimb coordination and forelimb kinematics are not alteredsignificantly. In iSCI rats, maximum flexion of the knee during swing occurs in phasewith the hip as opposed to knee flexion preceeding hip flexion in intact rats. A mildexercise regimen in intact rats over eight weeks does not alter the kinematics