Previous physiological work has established that factors such as power and status modulate the motor resonance system. Motor resonance is classified as motor activity that occurs during action observation in the absence of action execution. However, no previous work has explored whether these factors have downstream behavioural effects on automatic imitation using a community sample (as opposed to a university student sample). In addition, no prior work has examined whether online social hierarchies (as opposed to real-world social hierarchies) also modulate this system. As such, this dissertation aims to corroborate and extend on previous physiological work in the field and explore whether online status has similar downstream effects on motor resonance compared to previously documented effects of offline (real-world) status using behavioural and physiological methods. In chapters 2-3, I provide evidence from community-based behavioural studies that suggest high socioeconomic status (SES) and high power individuals are less susceptible to automatically imitating “other-oriented” social stimuli compared to their low SES and low power counterparts. In chapters 4-5, I show that Instagram followers exhibit significantly greater motor cortical output (via transcranial magnetic stimulation induced motor-evoked potentials) during action observation compared to Instagram leaders. I also show that this effect can be extended behaviourally using the automatic imitation task, whereby Instagram leaders are less susceptible to automatically imitating “other-oriented” social stimuli compared to Instagram followers. In chapter 6, I begin to explore the effect of online status on behavioural mimicry. I show that Instagram leaders exhibit reduced behavioural mimicry during an online interaction compared to Instagram followers. In the final chapter of this dissertation, I summarize the contributions and limitations of each chapter and recommend future avenues of research. Overall, this dissertation furthers our understanding on how online and offline social hierarchies modulate the motor resonance system using behavioural and physiological methods. / Dissertation / Doctor of Philosophy (PhD)

Embodied Cognition accounts propose that motor activation contributes to semantic representations in action language (Fischer & Zwaan, 2008). However, the nature of this activation remains largely unspecified: in particular, which processes result in relevant activation? Long-term motor experience (e.g., the comprehender’s dominant hand), short-term motor experience (e.g., the hand the comprehender has recently used), and action planning (e.g., the hand the comprehender is planning to use) are all potential candidates. This thesis uses a range of psycholinguistic methods (e.g., timed sentence-picture matching, two-alternative forced-choice sentence-picture matching, spoken sensibility judgements) to distinguish between these possibilities. A first set of experiments investigated how comprehenders’ handedness affects their interpretation of sentences describing manual actions (e.g., I am slicing the tomato). Participants matched sentences of actions to pictures of that action. The Body-Specificity Hypothesis (Casasanto, 2009; Willems, Hagoort, & Casasanto, 2010) predicts that right-handed and left-handed comprehenders will interpret manual action sentences differently, according to whether they would perform that action with their right or their left hand. However, we found that comprehenders appear to interpret manual action sentences according to the hand they use to respond to the task, and not the hand they would typically use to perform manual actions. In addition, this effect was stronger for first-person than third-person sentences, implying that the effect of motor activation is moderated by linguistic context. A second set of experiments used the same paradigm but manipulated at what point comprehenders knew which hand they would use to respond to the sentences: during sentence processing, or after sentence processing was complete. We replicated the finding that comprehenders interpret manual action sentences according to their response hand, and that this effect was stronger for first- than for third-person sentences; but only when comprehenders knew their response hand during sentence processing. In both sets of experiments, there was no effect of whether the picture of the action was presented from an egocentric or allocentric perspective, implying that action sentences are encoded for what effector (in this case, hand) will be used in the action, but not necessarily from what perspective the action will occur. A third set of experiments investigated the existence of a causal role of action planning-based activation on sentence processing. Many studies have shown an effect of language processing on action execution (e.g., Glenberg & Kaschak, 2002; Glenberg et al., 2008), but a fully embodied theory of language also predicts an effect of motor activation on language processing. Here, right-handed participants made spoken judgements about sentences while planning an action with their right or left hand that matched or did not match the action described in the sentence. An effect of response hand on accuracy was found when the task required participants to explicitly judge the congruency of sentence and the action they were preparing, but not otherwise. These results corroborate recent research suggesting that activation of embodied lexical representations may be goal-driven rather than an automatic aspect of language processing (Hoedemaker & Gordon, 2013). Overall, the experiments presented in this thesis suggest a possible role for planning-based motor activation in sentence processing, in line with embodied approaches; however, the results challenge strong accounts of embodiment by suggesting that the effect of planning-based activation is not automatic, and is moderated by linguistic context and task demands.

The aim of the present thesis was to investigate the relationship between individuals' allocation of overt visual attention during action observation and their consequent pickup of information. Four interrelated studies were conducted to achieve this. In Study 1 we examined the effects of visual guidance - colour highlighting of relevant aspects of the action - on observational learning of the golf swing. The results showed that the visual guides facilitated novices' intake of information pertaining to the model's posture, which was reflected in faster learning. In the remaining studies, transcranial magnetic stimulation and eye tracking data were acquired concurrently to measure the interaction between gaze behaviour and motor resonance - a neurophysiological index of the motor system's engagement with a viewed action, and thus a correlate of information extraction. In Study 2, we directed observers' gaze to distinct locations of the display while they viewed thumb adduction/abduction movements. The results showed that, by directing gaze to a location that maximised the amount of thumb motion across the fovea, motor resonance was maximised relative to a free viewing condition. In Study 3 we examined the link between gaze and motor resonance during the observation of transitive actions. Participants viewed reach-to-grasp actions with natural gaze, or while looking at a target- or an effector- based visual guide. The results showed that the effector-based guide disrupted natural gaze behaviour, and this was associated with a reversal of the motor resonance response. In Study 4 we showed novice and skilled golfers videos of the golf swing and of a reach-grasp-lift action. The results revealed that, for both actions, the extent of motor resonance was related to the location of participants' fixations. The present work provides the first evidence of a relationship between gaze and motor resonance and highlights the importance of appropriate gaze behaviour for observational learning.

Le concept de "cognition incarnée" considère que le schéma classique Perception-Cognition-Action proposant un flux séquentiel de traitement de l’information n'est pas approprié pour comprendre l'effet comportemental des troubles neurodégénératifs et trouver des solutions thérapeutiques innovantes. La découverte des neurones miroirs (NM) a donné un substrat biologique à cette théorie: on pense maintenant que les NM relient les connaissances sur les actions et les perceptions non seulement pour intégrer la perception dans la planification et l'exécution, mais aussi pour soutenir un large éventail de fonctions cognitives, par ex. empathie et langage. En même temps, il est maintenant clair que dans chaque maladie neurodégénérative les symptômes cognitifs et moteurs sont représentés le long d'un continuum. Les maladies neurodégénératives liées au vieillissement, comme la maladie d'Alzheimer (MA), la forme la plus courante de démence, sont devenues un enjeu social très important. Comme il n'y a pas de remède pour la MA, les études se concentrent sur la prévention. Une catégorie qui représente maintenant une cible privilégiée est le trouble cognitif léger (TCL), considéré comme une étape intermédiaire entre le vieillissement normal et la MA. Même si MA et TCL ont été caractérisées comme des maladies «cognitives» jusqu'à présent, un lien entre la fonction motrice et le risque de développer la MA a été reconnu.Le but principal de cette recherche est d'étudier l'intégrité du réseau NM dans la MA, le TCL et le vieillissement normal. La caractérisation de son fonctionnement dans les maladies neurodégénératives serait utile pour une meilleure compréhension de leurs mécanismes fonctionnels et manifestations cliniques. Cela permettrait également d’exploiter le NM dans la réhabilitation des symptômes.La thèse comprend deux parties : la première inclue une vaste recherche bibliographique destinée à décrire le cadre scientifique qui justifie une telle recherche.Nous avons d'abord passé en revue les preuves sur l'existence d'un système NM chez les singes et les humains, et ses multiples rôles possibles et après brièvement décrit le tableau clinique des principaux troubles neurodégénératifs, en montrant comment les symptômes cognitifs et moteurs s’entrecroisent. Ensuite, nous avons détaillé les résultats de la recherche documentaire sur les maladies neurodégénératives, NM et cognition incarnée, en les commentant à la lumière de cette théorie.La deuxième partie de la thèse décrit la procédure expérimentale qui a été réalisée dans le but de la recherche.Trois groupes appariés de 16 sujets chacun (CA-contrôles âgées, TCL amnésique avec atrophie hippocampique et MA) ont été évalués avec une batterie neuropsychologique centrée sur les fonctions liées au système NM, et une tâche IRMf spécifiquement créée pour tester les NM: celle- ci était constituée d'une tache d’observation, où aux sujets ont été montrés des vidéos d'une main droite saisissant différents objets, et d'une tache motrice où les sujets ont observé des images d'objets orientés pour être saisis avec la main droite, et ont fait le geste correspondant.Chez les CA, l'analyse de conjonction (comparant l'activation de l'IRMf pendant l'observation et l'exécution) a indiqué l'activation d'un réseau bilatéral fronto-pariétal dans les zones NM « classiques» et du gyrus temporal supérieur (STG), entrée visuelle corticale aux NM. Le groupe TCL a montré une activation similaire, cependant, les zones pariétales ont été moins activées et le STG n'a pas été activé, tandis que l'inverse était vrai pour la zone de Broca droite. Nous n'avons observé aucune activation du réseau fronto-pariétal chez le groupe MA. Dans tous les tests neuropsychologiques (y compris les tests de fonctions attribuées à NM), les sujets MA ont été plus mauvais que les CA, alors que les sujets TCL montraient seulement des troubles de mémoire épisodique et fluidité sémantique (...). / The concept of “embodied cognition” considers that the classical Perception-Cognition-Action architecture proposing a sequential flow of processing with clean cuts between all modules is not appropriate to understand the behavioral effect of neurodegenerative disorders and to find innovative therapeutic solutions. In the last decades, the discovery of the mirror neurons (MN) has given a biological substrate to this theoretical perspective: the MN are now thought linking together knowledge about actions and perceptions not only to integrate perception in action planning and execution but also as a neural mechanism supporting a wide range of cognitive functions, e.g. empathy and language. At the same time, it is now clear that in each neurodegenerative disease both cognitive and motor symptoms are represented along a continuum. In the current demographic context, neurodegenerative diseases linked to aging have become a very important social issue. Alzheimer Disease (AD), the most common form of dementia, is a neurodegenerative disease strictly linked to aging. As actually there is no cure, several studies are focusing on prevention. A category which now represents a preferential target of intervention is Mild Cognitive Impairment (MCI), considered as an intermediate stage between normal aging and AD. Even if AD and MCI have been characterized as “cognitive” diseases until now, a link between motor function and the risk of developing AD has been recognized.The main purpose of this research is to investigate the integrity of the MN network in AD, MCI and normal aging. Characterizing the functioning of the MN network in neurodegenerative diseases would be useful to better understand functional mechanisms and their clinical manifestations. It would also allow to capitalize on these kinds of neurons in the rehabilitation of motor and cognitive symptoms.The thesis consists of two parts: the first part includes an extensive bibliographic research intended to describe the scientific frame which justifies such a research.We first reviewed the evidence about the existence of a MN system in monkeys and humans, and its multiple possible roles in humans.We then briefly reviewed the clinical picture of the main neurodegenerative disorders, showing how cognitive and motor symptoms intersect in all of them.Next, we detailed the results of literature searching on neurodegenerative diseases, MN, and embodied cognition, commenting them at the light of this hypothesis.The second part of the thesis describe the experimental procedure which has been performed to evaluate the integrity of the MN network in normal elderly and people with AD and MCI, and its results.Three matched groups of 16 subjects each (normal elderly-NE, amnesic MCI with hippocampal atrophy and AD) were evaluated with a neuropsychological battery centered on functions thought to be linked to the MN system, and a fMRI task specifically created to test MN: that comprised of an observation run, where subjects were shown videos of a right hand grasping different objects, and of a motor run, where subjects observed visual pictures of objects oriented to be grasped with the right hand, and made the corresponding gesture.In NE subjects, the conjunction analysis (comparing fMRI activation during observation and execution), indicated the activation of a bilateral fronto-parietal network in “classical” MN areas, and of the superior temporal gyrus (STG), an area thought to provide the cortical visual input to the MN. The MCI group showed the activation of areas belonging to the same network, however, parietal areas were activated to a lesser extent and the STG was not activated, while the opposite was true for the right Broca’s area. We did not observe any activation of the fronto-parietal network in AD participants (...).

Le but de ce travail de thèse était de contribuer à une meilleure compréhension des mécanismes par lesquels nous nous représentons nos propres actions et celles d'autrui. En nous situant notamment dans la perspective de la théorie idéomotrice, nous avons examiné ces questions tout d'abord dans le cadre de l'imitation. Nos résultats indiquent un effet de l'apprentissage idéomoteur sur l'imitation intentionnelle (Etude 1), confirmant la flexibilité des liens perception-action, et démontrant le rôle des associations réponse-effet dans l'imitation. Toutefois, les performances à une tâche d'imitation automatique n'étaient pas influencées par un tel type d'apprentissage (Etude 2), possiblement en raison de processus différents n'ayant pas la même sensibilité à l'apprentissage idéomoteur. Nous avons ensuite étendu nos recherches au cadre des tâches conjointes (Etude 3). Nous montrons qu'une expérience idéomotrice corrélant l'exécution d'une action avec celle d'un agent non-humain conduit à la co-représentation de l'action de cet agent (présence d'un effet Simon social). Ainsi, l'expérience idéomotrice pourrait également permettre de modifier la co-représentation de l'action d'autrui en situation de tâche partagée. Ce travail confirme donc l'approche idéomotrice de la perception et de la représentation des actions d'autrui. / The aim of present work was to better understand the mechanisms by which we represent our own actions and those of others. Within the frame of the ideomotor theory, we first examined these questions in relation to imitation. Our results indicated an effect of ideomotor learning on intentional imitation (Study 1), confirming the flexibility of perception-action links, and demonstrating the role of action-effect associations in imitation. However, automatic imitation was not influenced by this type of learning (Study 2), which may suggest different processes with less sensitivity to learning ideomotor learning. We then extended our research to joint-action tasks (Study 3). We showed that an ideomotor experience, where action execution triggered actions of a non-human agent, induced a subsequent co-representation of this agent's actions (as indexed by social Simon effect). Ideomotor experience therefore seems to influence also the way we represent the actions of others in task-sharing. This work confirms the ideomotor approach to perception and representation of others' actions.

Voltage source inverter (VSI) fed induction motors are increasingly used in industrial and transportation applications as variable speed drives. However, VSIs generate non-sinusoidal voltages and hence result in harmonic distortion in motor current, motor heating, torque pulsations and increased acoustic noise. Most of these undesirable effects can be reduced by increasing the switching frequency of the inverter. This is not necessarily true for acoustic noise. Acoustic noise does not decrease monotonically with increase in switching frequency since the noise emitted depends on the proximity of harmonic frequencies to the motor resonant frequencies. Also there are practical limitations on the inverter switching frequency on account of device rating and losses. The switching frequency of many inverters often falls in the range 2 kHz - 6 kHz where the human ear is highly sensitive. Hence, the acoustic noise emission from the motor drive is of utmost important. Further, the acoustic noise emitted by the motor drive is known to depend on the waveform quality of the voltage applied. Hence, the acoustic performance varies with the pulse width modulation (PWM) technique used to modulate the inverter, even at the same modulation index. Therefore a comprehensive study on the acoustic noise aspects of induction motor drive is required. The acoustic noise study of the motor drive poses multifaceted challenges. A simple motor model is sufficient for calculation of total harmonic distortion (THD). A more detailed model is required for torque pulsation studies. But the motor acoustic noise is affected by many other factors such as stator winding distribution, space harmonics, geometry of stator and rotor slots, motor irregularities, structural issues controlling the resonant frequency and environmental factors. Hence an accurate model for acoustic noise would have to be very detailed and would span different domains such as electromagnetic fields, structural engineering, vibration and acoustics. Motor designers employ such detailed models along with details of the materials used and geometry to predict the acoustic noise that would be emitted by a motor and also to design a low-noise motor. However such detailed motor model for acoustic noise purposes and the necessary material and constructional details of the motor are usually not available to the user. Also, certain factors influencing the acoustic noise change due to wear and tear during the operational life of the motor. Hence this thesis takes up an experimental approach to study the acoustic noise performance of an inverter-fed induction motor at any stage of its operating life. A 10 kVA insulated gate bipolar transistor (IGBT) based inverter is built to feed the induction motor; a 6 kW and 2.3 kW induction motors are used as experimental motors. A low-cost acoustic noise measurement system is also developed as per relevant standards for measurement and spectral analysis of the acoustic noise emitted. For each PWM scheme, the current and acoustic noise measurements are carried out extensively at different carrier frequencies over a range of fundamental frequencies. The main cause of acoustic noise of electromagnetic origin is the stator core vibration, which is caused by the interaction of air-gap fluxes produced by fundamental current and harmonic currents. In this thesis, an experimental procedure is suggested for the acoustic noise characterization of an induction motor inclusive of determination of resonant frequencies. Further, based on current and acoustic noise measurements, a vibration model is proposed for the stator structure. This model is used to predict the acoustic noise pertaining to time harmonic currents with reasonable accuracy. Literature on motor acoustic noise mainly focuses on sinusoidal PWM (SPWM), conventional space vector PWM (CSVPWM) and random PWM (RPWM). In this thesis, acoustic noise pertaining to two bus-clamping PWM (BCPWM) schemes and an advanced bus-clamping PWM (ABCPWM) scheme is investigated. BCPWM schemes are mainly used to reduce the switching loss of the inverter by clamping any of the three phases to DC rail for 120◦ duration of the fundamental cycle. Experimental results show that these BCPWM schemes reduce the amplitude of the tonal component of noise at the carrier frequency, compared to CSVPWM. Experimental results with ABCPWM show that the overall acoustic noise produced by the motor drive is reduced at low and medium speeds if the switching frequency is above 3 kHz. Certain spread in the frequency spectrum of noise is also seen with both BCPWM and ABCPWM. To spread the acoustic noise spectrum further, many variable-frequency PWM schemes have been suggested by researchers. But these schemes, by and large, increase the current total harmonic distortion (THD) compared to CSVPWM. Thus, a novel variable-frequency PWM (VFPWM) method is proposed, which offers reduced current THD in addition to uniformly spread noise spectrum. Experimental results also show spread in the acoustic noise spectrum and reduction in the dominant noise components with the proposed VFPWM. Also, the current THD is reduced at high speeds of the motor drive with the proposed method.

La musique et le mouvement sont inséparables. Les mouvements produits spontanément lors de l'écoute musicale seraient le reflet d'un lien étroit entre le système perceptif et moteur. Ce lien est l'objet d'étude de cette thèse. Une première approche concernait l'impact des mouvements induits par la musique sur la cognition musicale. Dans deux études, nous montrons que bouger en rythme sur la musique n'améliore ni la rétention de nouveaux morceaux de musique (Etude 1) ni la rétention d'informations contextuelles relatives à leur encodage (Etude 2). Les résultats des ces deux études suggèrent la superficialité du traitement inhérent à l'expression des affordances musicales nécessaire à la production de mouvements induits par la musique dans la tâche motrice ainsi qu'un traitement moteur automatique de la musique indépendamment de la tâche. L'importance du groove musical a également été mise en évidence. Une deuxième approche concernait l'influence de la perception de rythmes musicaux sur la production de mouvements rythmiques. Notre troisième étude testait l'hypothèse selon laquelle les membres du corps seraient influencés de manière différente en fonction du tempo musical. Les résultats montrent que la tâche de tapping était la plus influencée par la perception de rythmes musicaux. Ceci serait dû à la nature similaire de la pulsation musicale et des mécanismes de timing impliqués dans le tapping ainsi qu'à des phénomènes de résonance motrice. Nous avons également observé la mise en place de certaines stratégies face à la tâche. L'ensemble de ces résultats est discuté à la lumière du lien entre perception et action, de la cognition musicale incarnée et des affordances musicales. / Music and movement are inseparable. The movements that are spontaneously procuded when listening to music are thought to be related to the close relationship between the perceptual and motor system in listeners. This particular link is the main topic of this thesis. A first approach was focused on the impact of music-induced movements on music cognition. In two studies, we show that moving along to music neither enhances the retention of new musical pieces (Study 1) nor the retention of the contextual information related to their encoding (Study 2). These results suggest a shallow processing inherent to the expression of musical affordances required for the production of music-induced movements in the motor task. Moreover, they suggest that music is automatically processed in a motoric fashion independantly of the task. Our results also brought forward the importance of the musical groove. A second approach focused on the influence of the perception of musical rhythms on the production of rythmic movements. Our third study tested the hypothesis that different limbs would be differentially influenced depending on the musical tempo. Results show that the tapping taks was the most influenced by the perception of musical rhythms. We argued that this would come from the similar nature of the musical pulse and the timing mecanisms involved in the tapping task and motor resonance phenomena. We also observed different strategies put in place to cope with the task. All these results are discussed in light of the link between perception and action, embodied musical cognition and musical affordances.