Male crickets produce a species specific song to attract females which in response move towards the sound source. This behaviour, termed phonotaxis, has been the subject of many morphological, neurophysiological and behavioural studies making it one of the most well studied examples of acoustic communication in the animal kingdom. Despite this fact, the precise leg movements during this behaviour is unknown. This is of specific interest as the cricket’s ears are located on their front legs, meaning that the perception of the sound input might change as the insect moves. This dissertation describes a methodology and an analysis that fills this knowledge gap. I developed a semi-automated tracking system for insect motion based on commercially available high-speed video cameras and freely available software. I used it to collect detailed three dimensional kinematic information from female crickets performing free walking phonotaxis towards a calling song stimulus. I marked the insect’s joints with small dots of paint and recorded the movements from underneath with a pair of cameras following the insect as it walks on the transparent floor of an arena. Tracking is done offline, utilizing a kinematic model to constrain the processing. I obtained, for the first time, the positions and angles of all joints of all legs and six additional body joints, synchronised with stance-swing transitions and the sound pattern, at a 300 Hz frame rate. I then analysed this data based on four categories: The single leg motion analysis revealed the importance of the thoraco-coxal (ThC) and body joints in the movement of the insect. Furthermore the inside middle leg’s tibio-tarsal (TiTa) joint was the centre of the rotation during turning. Certain joints appear to be the most crucial ones for the transition from straight walking to turning. The leg coordination analysis revealed the patterns followed during straight walking and turning. Furthermore, some leg combinations cannot be explained by current coordination rules. The angles relative to the active speaker revealed the deviation of the crickets as they followed a meandering course towards it. The estimation of ears’ input revealed the differences between the two sides as the insect performed phonotaxis by using a simple algorithm. In general, the results reveal both similarities and differences with other cricket studies and other insects such as cockroaches and stick insects. The work presented herein advances the current knowledge on cricket phonotactic behaviour and will be used in the further development of models of neural control of phonotaxis.

Superior swimming stamina in adult fish is presumably passed on to their offspring, but the ontogeny of the appearance of superior stamina and the requisite enhanced cardio-respiratory support for locomotion in larval fishes has not been determined. Is the expression of the suite of parental traits enabling superior swimming stamina in their offspring dependent upon their achieving juvenile/adult morphology, or does it appear earlier in their larvae? To answer this, adults were classified into three groups based on swimming stamina, followed by measurement of length, mass, and width. Larval offspring from the two parental groups -high stamina larvae (HSL) and low stamina larvae (LSL)- were reared at 27°C in aerated water (21% O2). Routine and active heart rate, routine and active mass specific oxygen consumption were recorded through 21dpf, and cost of transport (COT) and factorial aerobic scope were derived from oxygen consumption measurements. Routine heart rate at 2dpf of LSL was 164 ± 1 b·min-1, compared to only 125 ± 2 b·min-1 for HSL. Routine heart rate subsequently peaked at 203 ± 1 b·min-1 at 5dpf in the HSL group, compared to 207 ± 1 b·min-1, at 4dpf in the LSP larvae. Active heart rate at 5 dpf of LSL was 218 ± 2 b·min-1 compared to 216 ± 2 b·min-1 for HSL. Active heart rate increased slightly to 227 ± 2 b·min-1 for LSL before decreasing again, while active heart rate remained relatively constant for HSL. Routine O2 consumption at 2dpf of HSL was 0.09 μmol·mg-1·hr-1, compared to 0.03 μmol·mg-1·hr-1 in LSL. Routine O2 consumption subsequently peaked at 0.70 μmol·mg-1·hr-1 at 9dpf in the HSL, compared to 0.71 μmol·mg-1·hr-1, at 9dpf in the LSL. These values dramatically decreased before leveling off at around 0.20 μmol·mg-1·hr-1 and 0.15 μmol·mg-1·h-1, respectively. Active O2 consumption at 5dpf for HSL was 0.38 μmol·mg-1·hr-1, compared to 0.57 μmol·mg-1·hr-1 for LSL. Active O2 consumption subsequently peaked at 0.97 μmol·mg-1·hr-1 at 10dpf in HSL, compared to 1.19 μmol·mg-1·hr-1 at 7dpf in LSL. These values also dramatically decreased and leveled off. Significant differences (p < 0.05) in heart rate and oxygen consumption persisted through 21dpf. The onset of differences observed in routine and active heart rate in early larvae, correlated with parent stamina, show that juvenile or adult features are not required as a precondition for the emergence of phenotypic physiological differences.

<p>For primates, and other arboreal mammals, adopting suspensory locomotion represents one of the strategies an animal can use to prevent toppling off a thin support during arboreal movement and foraging. While numerous studies have reported the incidence of suspensory locomotion in a broad phylogenetic sample of mammals, little research has explored what mechanical transitions must occur in order for an animal to successfully adopt suspensory locomotion. Additionally, many primate species are capable of adopting a highly specialized form of suspensory locomotion referred to as arm-swinging, but few scenarios have been posited to explain how arm-swinging initially evolved. This study takes a comparative experimental approach to explore the mechanics of below branch quadrupedal locomotion in primates and other mammals to determine whether above and below branch quadrupedal locomotion represent neuromuscular mirrors of each other, and whether the patterns below branch quadrupedal locomotion are similar across taxa. Also, this study explores whether the nature of the flexible coupling between the forelimb and hindlimb observed in primates is a uniquely primate feature, and investigates the possibility that this mechanism could be responsible for the evolution of arm-swinging. </p><p> To address these research goals, kinetic, kinematic, and spatiotemporal gait variables were collected from five species of primate (Cebus capucinus, Daubentonia madagascariensis, Lemur catta, Propithecus coquereli, and Varecia variegata) walking quadrupedally above and below branches. Data from these primate species were compared to data collected from three species of non-primate mammals (Choloepus didactylus, Pteropus vampyrus, and Desmodus rotundus) and to three species of arm-swinging primate (Hylobates moloch, Ateles fusciceps, and Pygathrix nemaeus) to determine how varying forms of suspensory locomotion relate to each other and across taxa. </p><p> From the data collected in this study it is evident the specialized gait characteristics present during above branch quadrupedal locomotion in primates are not observed when walking below branches. Instead, gait mechanics closely replicate the characteristic walking patterns of non-primate mammals, with the exception that primates demonstrate an altered limb loading pattern during below branch quadrupedal locomotion, in which the forelimb becomes the primary propulsive and weight-bearing limb; a pattern similar to what is observed during arm-swinging. It is likely that below branch quadrupedal locomotion represents a “mechanical release” from the challenges of moving on top of thin arboreal supports. Additionally, it is possible, that arm-swinging could have evolved from an anatomically-generalized arboreal primate that began to forage and locomote below branches. During these suspensory bouts, weight would have been shifted away from the hindlimbs towards forelimbs, and as the frequency of these boats increased the reliance of the forelimb as the sole form of weight support would have also increased. This form of functional decoupling may have released the hindlimbs from their weight-bearing role during suspensory locomotion, and eventually arm-swinging would have replaced below branch quadrupedal locomotion as the primary mode of suspensory locomotion observed in some primate species. This study provides the first experimental evidence supporting the hypothetical link between below branch quadrupedal locomotion and arm-swinging in primates.</p> / Dissertation

La robotique humanoïde arrive a maturité avec des robots plus rapides et plus précis. Pour faire face à la complexité mécanique, la recherche a commencé à regarder au-delà du cadre habituel de la robotique, vers les sciences de la vie, afin de mieux organiser le contrôle du mouvement. Cette thèse explore le lien entre mouvement humain et le contrôle des systèmes anthropomorphes tels que les robots humanoïdes. Tout d’abord, en utilisant des méthodes classiques de la robotique, telles que l’optimisation, nous étudions les principes qui sont à la base de mouvements répétitifs humains, tels que ceux effectués lorsqu’on joue au yoyo. Nous nous concentrons ensuite sur la locomotion en nous inspirant de résultats en neurosciences qui mettent en évidence le rôle de la tête dans la marche humaine. En développant une interface permettant à un utilisateur de commander la tête du robot, nous proposons une méthode de contrôle du mouvement corps-complet d’un robot humanoïde, incluant la production de pas et permettant au corps de suivre le mouvement de la tête. Cette idée est poursuivie dans l’étude finale dans laquelle nous analysons la locomotion de sujets humains, dirigée vers une cible, afin d’extraire des caractéristiques du mouvement sous forme invariants. En faisant le lien entre la notion “d’invariant” en neurosciences et celle de “tâche cinématique” en robotique humanoïde, nous développons une méthode pour produire une locomotion réaliste pour d’autres systèmes anthropomorphes. Dans ce cas, les résultats sont illustrés sur le robot humanoïde HRP2 du LAAS-CNRS. La contribution générale de cette thèse est de montrer que, bien que la planification de mouvement pour les robots humanoïdes peut être traitée par des méthodes classiques de robotique, la production de mouvements réalistes nécessite de combiner ces méthodes à l’observation systématique et formelle du comportement humain. / Humanoid robotics is coming of age with faster and more agile robots. To compliment the physical complexity of humanoid robots, the robotics algorithms being developed to derive their motion have also become progressively complex. The work in this thesis spans across two research fields, human neuroscience and humanoid robotics, and brings some ideas from the former to aid the latter. By exploring the anthropological link between the structure of a human and that of a humanoid robot we aim to guide conventional robotics methods like local optimization and task-based inverse kinematics towards more realistic human-like solutions. First, we look at dynamic manipulation of human hand trajectories while playing with a yoyo. By recording human yoyo playing, we identify the control scheme used as well as a detailed dynamic model of the hand-yoyo system. Using optimization this model is then used to implement stable yoyo-playing within the kinematic and dynamic limits of the humanoid HRP-2. The thesis then extends its focus to human and humanoid locomotion. We take inspiration from human neuroscience research on the role of the head in human walking and implement a humanoid robotics analogy to this. By allowing a user to steer the head of a humanoid, we develop a control method to generate deliberative whole-body humanoid motion including stepping, purely as a consequence of the head movement. This idea of understanding locomotion as a consequence of reaching a goal is extended in the final study where we look at human motion in more detail. Here, we aim to draw to a link between “invariants” in neuroscience and “kinematic tasks” in humanoid robotics. We record and extract stereotypical characteristics of human movements during a walking and grasping task. These results are then normalized and generalized such that they can be regenerated for other anthropomorphic figures with different kinematic limits than that of humans. The final experiments show a generalized stack of tasks that can generate realistic walking and grasping motion for the humanoid HRP-2. The general contribution of this thesis is in showing that while motion planning for humanoid robots can be tackled by classical methods of robotics, the production of realistic movements necessitate the combination of these methods with the systematic and formal observation of human behavior.

Cette recherche propose d’étudier l’incidence de l’environnement urbain sur certains aspects du déplacement de la personne aveugle. Dans une approche écologique, nous prenons en considération plusieurs paramètres en étudiant, en situation réelle, la perception et le ressenti liés à l’environnement, la vitesse de marche, la représentation mentale et enfin le stress, vécu et objectivé. Nous faisons l’hypothèse que la structure urbaine a un effet notable sur l’ensemble de ces paramètres, affectant ou facilitant le déplacement. Notre protocole a mobilisé 27 personnes aveugles, utilisant une canne blanche ou un chien-guide sur un trajet urbain de 1 km, qui offre cinq scènes urbaines successives (« Ruelle A », « Place », « Berges », « Rue » et « Ruelle B »). La première session s’est faite au bras du chercheur afin d’étudier la perception et le ressenti liés à l’environnement, grâce à la technique des trajets commentés. La seconde session a été consacrée à la mémorisation du trajet. Enfin, la troisième session, intégralement enregistrée sur vidéo, a consisté en un déplacement autonome. Nous avons également enregistré l’activité électrodermale in situ, afin d’en saisir les variations au fur et à mesure du trajet. Nous avons, enfin, demandé aux participants de dessiner le trajet effectué (carte mentale).Les résultats indiquent que les différentes scènes présentent des ambiances vécues comme très différentes par les marcheurs aveugles. L’environnement influence le ressenti en termes de plaisir, de sentiment de sécurité et de stress. Il influence également la vitesse de marche, ainsi que la capacité à mener le trajet à son terme. Les « Ruelles » et la « Rue » sont les scènes les plus favorables au déplacement, alors que les espaces ouverts comme la « Place » et les « Berges » se sont avérés défavorables. L’analyse de l’activité électrodermale révèle également un effet de la scène. Elle nous a permis d’identifier des zones problématiques sur le trajet. Ces nœuds correspondent aux lieux où les marcheurs aveugles doivent prendre des décisions importantes (traverser la chaussée, choisir une orientation). Enfin, la représentation mentale semble être en rapport avec les aspects précédents et varie en fonction des scènes. Les lieux les plus sécurisants sont sous-représentés, alors que les lieux vécus comme les plus stressants sont surreprésentés dans les dessins. Ces résultats invitent à prendre en considération la perception incarnée et l’expérience que les personnes aveugles ont de leur environnement dans l’élaboration des aménagements de nos cités, pour permettre à tous une meilleure autonomie et liberté de déplacement. / This study investigates the influence of urban environment on some aspects of the mobility of blind people in the city. Using an ecological approach, we explore some mobility parameters in real conditions: environmental perception and feeling, walking speed, cognitive mapping and subjective and objective stress.Our hypothesis suggests that environmental setup and features have a significant effect on these parameters, affecting or facilitating mobility. Twenty-seven blind subjects were requested to perform a 1-kilometer journey consisting of five successive urban scenes in Lyon (“Street 1”, “Square”, “River-bank”, “Avenue”, “Street 2”). Subjects walked using a white cane or a guide dog. There were three sessions. During the first walking session, blind pedestrians were accompanied all along. We asked them to comment on their perception of and feeling about the surroundings as they walked. The second walking session was devoted to memorizing the route. Finally, we asked subjects to walk independently for the third and last session, which was integrally recorded on video. We also monitored electrodermal physiological signals with an ambulatory device. Once the journey was over, we asked subjects to make a line-drawing depicting the route (i.e. a map).Results suggest that blind pedestrian’s experience of the environment differs according to the urban scene. Environmental conditions affect enjoyment, safety and stress levels. They also affect walking speed and spatial skills. “Streets” and “Avenue” are the most favorable scenes for those mobility parameters, where wide open-spaces like “Square” and “River-bank” are unfriendly. The cognitive map seems to be related to these previous observations: its accuracy varies with environmental conditions. Analysis of the drawings indicates that the most secure scenes (i.e. “Avenue”) were under-represented while the most stressful scenes and least secure scenes were over-represented (i.e. “Square”). Electrodermal monitoring yielded the same scene-effect on the physiological signals, as well as the existence of high-activation areas in the journey, apparently corresponding to node-places requiring blind subjects to make important decisions (e.g. having to cross a road, or to choose a direction).These results invite us to consider the environment spectific-perception of the visually impaired persons in the development of accessibility aids, in order to offer a greater autonomy and freedom in mobility in our modern cities.

<p>U tezi je prikazan novi metod za sintezu i realizaciju dvonožnog<br />veštačkog hoda koji se zasniva na upotrebi jednostavnih pokreta čijim<br />je kombinovanjem moguće realizovati kompleksne pokrete kao što je<br />hod, a čiji se parametri mogu menjati tokom kretanja. Time je omogućeno<br />da se na osnovu informacija o nameravanom kretanju i stanja okoline<br />izvrši sinteza kretanja izborom i kombinacijom jednostavnih<br />bazičnih pokreta koje se nazivaju primitivi. Takođe je omogućeno da se,<br />tokom izvršavanja hoda bez njegovog prekida, menjaju parametri<br />kretanja kao što su brzina hoda, dužina koraka, pravac kretanja i<br />visina podizanja noge tokom prenosne faze. Potvrda je data kroz<br />eksperimentalne rezultate koji su sprovedeni simulacijom na<br />dinamičkom modelu humanoidnog robota.</p> / <p>This dissertation presents new method for the synthesis and realization of<br />biped artificial walk based on the use of simple movements that can be<br />combined in order to achieve complex movements such as walk, whereas it<br />is possible to change the motion parameters at any time. It means that,<br />based on the information about intended movement and current state of the<br />environment, it is possible to synthesize motion by selecting and tying simple<br />movements, i.e. motion primitives. It also enables the robot to change<br />walking parameters online such as walking speed, direction of walk, foot<br />length during swing phase and step length. Proof of this method is given by<br />experimental results obtained during the simulation on a dynamic model of<br />humanoid robot.</p>

Motility of flagellated bacteria has been a topic of increasing scientific interest over the past decades, attracting the attention of mathematicians, physicists, biologists and engineers alike. Bacteria and other micro-organisms cause substantial damage through biofilm growth on submerged interfaces in water cooling systems, ship hulls and medical implants. This gives social and economic motivations for learning about how micro-organisms swim and behave in different environments. Fluid flows on such small scales are dominated by viscosity and therefore behave differently from the inertia-dominated flows that we are more familiar with, making bacterial motility a physically intriguing phenomenon to study as well. We use the boundary element method (BEM) to simulate the motion of singly flagellated bacteria in a viscous, Newtonian fluid. One of our main objectives is to investigate the influence of external surfaces on swimming behaviour. We show that the precise shape of the cell body and flagellum can be important for determining boundary behaviour, in particular, whether bacteria are attracted or repelled from surfaces. Furthermore, we investigate the types of motion that may arise between two parallel plates and in rectangular channels of fluid and show how these relate to the plane boundary interactions. As an extension to original models of flagellar propulsion in bacteria that assume a rotation of the rigid helical flagellum about an axis fixed relative to the cell body, we consider flexibility of the bacterial hook connecting the aforementioned parts of the swimmer. This is motivated by evidence that the hook is much more flexible than the rest of the flagellum, which we therefore treat as a rigid structure. Elastic dynamics of the hook are modelled using the equations for a Kirchhoff rod. In some regimes, the dynamics are well described by a rigid hook model but we find the possibility of additional modes of behaviour.

In the spinal cord, an intricate neural network generates and coordinates the patterning of limb movements during locomotion. This network, known as the locomotor central pattern generator (CPG), comprises of various cell populations that together orchestrate the output of motor neurons. Identification of CPG neurons through their specific gene expression is a valuable tool that can provide considerable insight to the character, intrinsic properties and role of a population, which represents a step toward understanding locomotor circuit function and correlating neural activity to behaviour. We selectively targeted two inhibitory CPG populations to investigate their molecular characteristics, circuitry and functional role; Renshaw cells (RCs) marked by their specific expression of the cholinergic nicotinic receptor α2 (Chrna2) and a subset of the dI6 population derived by their selective expression of the Doublesex and mab-3 related transcription factor 3 (Dmrt3). We found that RCs have hyperpolarisation-activated cation (Ih) and small calcium-activated potassium (ISK) modulatory currents that differentially regulate their excitation and firing properties, which influence the instantaneous feedback to motor neurons through the recurrent inhibition circuit. Due to previous difficulties isolating RCs from the surrounding locomotor circuits, their functional role remains poorly defined. For the first time, we selectively silenced RC inhibition and found that all aspects of motor behaviour, including coordination and gait were normal. The deletion of RC signalling instead altered the electrical and synaptic properties of the recurrent inhibitory circuit, suggesting that developmental plasticity compensates for the loss of RC inhibition. We reveal Dmrt3 neurons comprise a population of glycinergic inhibitory, spike-frequency adapting commissural interneurons active during locomotion. Conditional silencing of the Dmrt3 population resulted in considerable gait abnormalities in the neonatal and adult mouse. This manifested as an uncoordinated CPG output in vitro, impaired limb coordination in pups and increased fore- and hindlimb synchrony in adults that was exacerbated at faster locomotor speeds. Dmrt3 mediated inhibition subsequently impacts locomotion and suggests the Dmrt3 population contribute to coordinating speed dependent left-right limb alternation. This thesis provides cellular, circuit and behavioural insights into the Renshaw cell and Dmrt3 populations and enhances our knowledge regarding their probable function within the locomotor CPG.

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

La respiration est une activité motrice autonome rythmique au cours de laquelle de nombreux muscles se contractent de manière coordonnée afin de produire des mouvements ventilatoires adaptés aux contraintes environnementales et aux exigences de l'organisme. Cette fonction vitale doit être fiable et adaptable à très court terme, c’est pourquoi elle est influencée, entre autres, par un grand nombre d’activités motrices. Par exemple, lors d’exercices physiques, le rythme respiratoire peut se coupler au rythme locomoteur. Les objectifs de ce travail doctoral sont centrés sur l’exploration des mécanismes neurogènes à la base du couplage entre ces deux fonctions motrices chez le rat nouveau-né. Pour une grande partie, cette étude a été réalisée sur préparation isolée in vitro de tronc cérébral-moelle épinière de rat nouveau-né (0 à 3 jours), ce modèle permettant de conserver dans leur intégrité les centres responsables des rythmes respiratoire et locomoteur. Compte tenu de l’accessibilité directe aux réseaux neuronaux, les mécanismes de couplage et d'entraînement respiratoire ont été abordés par des approches combinées électrophysiologique, neuroanatomique, pharmacologique et lésionnelle. Dans ce contexte, un des principaux résultats de ce travail doctoral est le rôle crucial joué par les informations sensorielles en provenance des membres antérieurs et postérieurs dans l'entraînement respiratoire observé lors de séquences locomotrices. Ainsi, les afférences proprioceptives spinales capables de réinitialiser et d'entraîner l’activité des centres respiratoires bulbaires via un relais pontique, établissent également des connexions sur l’ensemble des populations de motoneurones spinaux respiratoires phréniques, intercostaux et abdominaux. / Respiration is an autonomous rhythmic motor activity that requires the coordinated contractions of diverse muscles to produce ventilatory movements adapted to organismal needs. This crucial physiological function must be reliable and adaptable on a short-term basis, and requires coordianted movements with various other motor activities. For instance, respiratory rhythmicity becomes coupled to locomotion during physical exercise. My doctoral work aimed to explore the neurogenic mechanisms underlying the interactions between these two motor functions in the neonatal rat. This work was mainly conducted on isolated in vitro brain stem-spinal cord preparations of newborn rats (0-3 days), an experimental model that allows the maintenance of the still functional respiratory and locomotor CPGs in vitro. Due to the easy access to the neuronal networks in these preparations, locomotor-respiratory coupling and respiratory entrainment mechanisms were investigated by combined electrophysiological, neuroanatomical, pharmacological and lesional approaches. A major finding was the crucial played by sensory information from fore- and hindlimb in respiratory entrainment induced by locomotor rythmicity. Spinal sensory afferents can reset and entrain the activity of the medullary respiratory centres via a pontine relay, as well as making direct connections with the various spinal respiratory motoneuron (phrenic, intercostal and abdominal) populations.