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Entrainment is the rhythmic coordination of movement with a signal or other person. Most studies on entrainment have looked at synchronization with auditory or visual signals, whereas much less is known about how entrainment emerges mutually between individuals, especially when they are in physical contact with one another. In this dissertation, I empirically explored dance partnering as an ecological model for understanding interpersonal entrainment through haptic interaction. I began by performing a statistical meta-analysis of functional neuroimaging articles devoted to the most common experimental paradigm for entrainment, namely externally-paced finger tapping to an acoustic rhythmic stimulus (Chapter 2). The results showed that the cerebellar vermis was a strong neural marker of entrainment, as it was more activated by externally-paced tapping than by self-paced tapping, whereas the basal ganglia was activated by both types of rhythmic movements. Next, I used functional magnetic resonance imaging (fMRI) with a group of participants trained at couple dancing in order to explore the neural basis of haptic mutual entrainment, with a focus on the dynamics of leading and following (Chapter 3). While mutual interaction overall engaged brain networks involved in somatosensation, internal-body sensation and social cognition, leading showed enhanced activity principally in areas for motor control and self-initiated action, whereas following showed enhanced activity mainly in sensory and social-cognition areas. Finally, I used 3D motion capture to explore multisensory coupling for mutual entrainment at the group level during folk dancing (Chapter 4). The results showed that dancers relied most extensively on haptic coupling to synchronize as a group, whereas auditory and visual coupling were dependent on the spatiotemporal context. These studies advance our understanding of the neural and behavioural mechanisms underlying joint actions in which entrainment emerges mutually through haptic interaction. / Thesis / Doctor of Philosophy (PhD) / Entrainment is the rhythmic coordination of movement with a signal or other person. Most studies on entrainment have looked at synchronization with auditory or visual signals, whereas much less is known about how entrainment emerges mutually between individuals, especially when they are in physical contact with one another. I began my research by performing a statistical analysis of the literature examining the brain basis of synchronization with auditory signals, identifying a key brain area for entrainment. Next, using a group of participants trained at couple dancing, I explored the brain areas engaged when two individuals in physical contact improvised movement together, focusing on who is leading or following the interaction. Finally, I explored how folk dancers use multiple sensory signals (auditory, visual and tactile) to synchronize as a group. These studies advance our understanding of the neural and behavioural mechanisms by which people mutually entrain through physical interaction.

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Les circuits neuronaux peuvent générer une panoplie de rythmes. Nous pouvons séparer les mécanismes de création de ces rythmes en deux grands types. Le premier consiste de circuits contrôlés par des cellules « pacemakers », ayant une activité rythmique intrinsèque, comme dans le ganglion stomatogastique des crustacés. Le deuxième consiste de circuits multi-neuronaux connectés par un réseau synaptique qui permet une activité rythmique sans la présence de neurones pacemakers, tel que démontré pour les circuits de la nage chez plusieurs vertébrés. Malgré nos connaissances des mécanismes de rhythmogénèse chez les vertébrés adultes, les mécanismes de la création et la maturation de ces circuits locomoteurs chez les embryons restent encore inconnus. Nous avons étudié cette question à l’aide du poisson-zébré où les embryons débutent leur activité motrice par des contractions spontanées alternantes à 17 heures post-fertilisation (hpf). Des études ont démontré que cette activité spontanée n’est pas sensible aux antagonistes de la transmission synaptique chimique et ne requiert pas le rhombencéphale. Après 28 hpf, les embryons commencent à nager et se propulser en réponse au toucher. Des études antérieures on démontré que l’apparition de la nage nécessite le rhombencéphale et la transmission synaptique chimique. Cette thèse explore la possibilité que ces changements comportementaux représentent la progression d’un circuit contrôle par un pacemaker à un circuit ou le rythme provient d’un circuit distribué. En mesurant le groupement des contractions de l’activité spontanée, plutôt que la fréquence moyenne, nous avons découvert une nouvelle forme d’activité spontanée qui débute à 22 hpf. Cette activité consiste de deux contractions alternantes à succession très rapide. Contrairement à l’activité spontanée présente dès 17 hpf cette nouvelle forme d’activité requiert le rhombencéphale et la transmission synaptique chimique, comme démontré pour la nage qui apparait à 28 hpf. Cette forme de comportement intermédiaire représente potentiellement une étape transitoire lors de la maturation des circuits moteurs. / Neuronal circuits are capable of generating diverse forms of rhythmic activity. Mechanisms underlying rhythmogenesis can be separated into two main groups. First, pacemaker central pattern generators (CPGs) are composed of neurons that have intrinsic oscillatory properties, such as the lobster stomatogastric ganglion. Second, CPGs driven by network-based dynamics rely on synapse-mediated cell properties, such as locomotion in aquatic vertebrates. Despite an existing wealth of knowledge obtained through studying frog and lamprey swimming CPGs, the means by which a locomotor CPG develops remains elusive. Here, we propose to address this question using the zebrafish embryo, for its rapid development, optical transparency and stereotyped behaviour. Motor activity in zebrafish embryos begins with spontaneous activity around 17 hours post-fertilization (hpf). Studies have shown that this activity is not sensitive to antagonists of chemical neurotransmission, and does not require the hindbrain. By 28 hpf, they become able to swim, and generate low-amplitude alternating contractions at a rate of 30 Hz. This study explores the developmental window between the onset of motility and the onset of a mature locomotor output, such as swimming, with the objective of uncovering key steps in motor network maturation. By measuring the grouping of contractions rather than overall frequency of spontaneous activity, we uncovered a novel form of spontaneous activity, starting around 22 hpf. This activity consists of two alternating contractions in rapid succession. In contrast to early spontaneous activity, this motor activity requires glutamatergic neurotransmission and input from the hindbrain, as previously shown for swimming at 28 hpf. This intermediate behavior may reveal an important step in the maturation of the motor network.

Nesta tese de doutorado abordamos modelos cognitivos de percepção da métrica musical e entrainment a partir de questões musicológicas, como a ambiguidade métrica decorrente de exemplos da literatura. Partindo de uma verificação do estado da arte em pesquisas rítmicas que envolvem o estudo de anacruses, realizamos um percurso experimental que investiga a efetividade da chamada percepção da acentuação subjetiva revelada por Povel e Okkerman (1981), por acreditarmos que o fenômeno da acentuação subjetiva esteja envolvido na desambiguação da percepção de referenciais métricos dúbios. Para tanto, desenvolvemos uma metodologia de quantificação das similaridades entre os padrões de acentuação coletados em grupo universitário da cidade de São Paulo e os padrões de referência da literatura, sobretudo de Povel e Essens (1985). Estes experimentos revelaram que há uma tendência significativa à percepção da acentuação subjetiva predominantemente em grupo sem estudo formal de música. Por outro lado, os estudantes de música revelaram uma tendência de acentuação mais relacionada à pulsação musical. / In this doctoral thesis we address cognitive models of perception of musical meter and entrainment from musicological issues, such as the metric ambiguity arising from examples of literature. Based on a state-of-the-art check on rhythmic researches involving the study of anacruses, we conducted an experimental study that investigates the effectiveness of the so-called subjective accent revealed by Povel and Okkerman (1981), because we believe that the phenomenon of subjective accent is Involved in the disambiguation of dubious beat references perception. Therefore, we developed a methodology to quantify the similarities between the accentuation patterns collected in university group of São Paulo and the literature reference standards, especially Povel and Essens (1985). These experiments revealed that there is a significant tendency to subjective perception of accent predominantly in people without formal music study. On the other hand, the students of music revealed a tendency of accentuation more related to the musical beat.

O objetivo desta pesquisa é o estudo da dinâmica climática e dos tipos de tempo responsáveis pela gênese de nevoeiro no aeródromo da Academia da Força Aérea - AFA, localizado na região de Pirassununga/SP, nas coordenadas 21º59\'07\'\' S, 47º20\'06\'\' O e altitude 600 m. Foi aplicada a metodologia de análise rítmica proposta por Monteiro (1971), ao período de maior ocorrência do fenômeno - abril, maio, junho e julho -, durante três anospadrão (habitual, excepcional de alta ocorrência e excepcional de baixa ocorrência). Na primeira parte deste trabalho foi realizada a estatística descritiva das ocorrências de nevoeiro e a caracterização de sua distribuição temporal durante de 20 anos (1989 a 2008). A escolha dos anos-padrão foi realizada por técnicas estatísticas aplicadas ao período de maior ocorrência do fenômeno. A segunda parte do trabalho consistiu na aplicação da análise rítmica aos anos escolhidos como padrão para o aeródromo - 2003 (habitual), 2008 (excepcional de alta ocorrência) e 2005 (excepcional de baixa ocorrência). Como resultado, constatou-se que os tipos de tempo geradores de nevoeiro ocorreram, preferencialmente, sob o domínio da Massa Polar Atlântica. Sequências de tipos de tempo desencadeadas após a passagem da Frente Polar Atlântica ou do domínio da Massa Polar Atlântica com Linha de Instabilidade contribuíram, também, para a gênese de nevoeiro no local. / The objective of this research is the study of climate dynamics of the weather types, responsible for the fog genesis at the Air Force Academy airfield- AFA-located in the region of Pirassununga at coordinates 21º59\'07\'\' S, 47º20\'06\'\' W and the altitude of 600 m . The rhythmic analysis methodology proposed by Monteiro (1971) was applied to the period of the highest occurrence of the phenomenon - April, May, June, July - during three standard years (usual, exceptionally high occurrence and exceptionally low occurrence). Descriptive statistics of the fog occurrences were held in the first part of this paper as well as the characterization of its temporal distribution over 20 years (1989 to 2008 ). The choice of standard years was made by statistical techniques applied to the period of highest occurrence of the phenomenon. The second part of this paper was based on the rhythmic analysis over the years chosen as the standard for the airfield 2003 (usual), 2008 (exceptionally high occurrence) and 2005 (exceptionally low occurrence). As a result it was found that types of fog generator weather occurred preferably under the influence of the Atlantic Polar Air Mass. Sequences of different types of weather triggered after the passage of the Atlantic Polar Air Front or the dominance of the Atlantic Polar Air Mass with squall lines also contributed to the genesis of fog occurrences at the local.

O presente trabalho tem por objetivo relacionar a ação das ondas incidentes no arco praial de Massaguaçú com a presença e o comportamento de feições morfológicas como as cúspides praiais. O conjunto de dados utilizados consiste em uma série de imagens provenientes do sistema Argus. Esse sistema utiliza cinco câmeras de alta resolução resultando em uma cobertura de 180° da zona costeira. A partir destas imagens realizou-se a digitalização das cúspides praiais encontrando-se duas linhas de cúspides, uma na face praial superior (CFS) e a outra na face praial inferior (CFI). Em conjunto com os dados de imagem foi analisado o clima de ondas atuantes durante o período. A presença de feições rítmicas foi alta no arco praial de Massaguaçú, sendo praticamente predominante na face praial superior. O espaçamento médio da CFS foi superior ao espaçamento da CFI e a alternância das condições atuantes foi determinante na redução do espaçamento assim como condições energéticas baixas. O aumento do espaçamento das cúspides ocorreu sob condições energéticas médias à altas e sob condições extremas observou tanto a destruição como o aumento das feições rítmicas. A interação entre o espraiamento e a morfologia existente, modulado pela variação do nível d\'água, foi um dos motores para a formação de cúspides em níveis inferiores enquanto que as condições extremas causaram sua destruição. / This study aims to relate the action of incident waves on Massaguaçú\'s beach with the presence and the behavior of morphological features such as beach cusps. The set of data used consists in a series of images from the Argus system. This system uses five high-resolution cameras resulting in a 180 ° coverage of the coastal zone. From these images, realize the presence of beach cusps lying in two rows on the beach face, one in the upper beach face (CFS) and the other in the lower beach face (CFI). At the same time with the image data the wave regime acting at Massaguaçú\'s beach was analyzed during the period. The presence of rhythmic features was almost constant Massaguaçú\'s beach face, nearly predominant on the upper beach face. The average spacing of CFS was greater than the spacing of the CFI and the interchange in active conditions was crucial in reducing the spacing as well as low energy conditions. The increased spacing of the cusps occurred under medium to high energy conditions and under extreme conditions both as increased and destruction of the rhythmic features were observed. The interaction between the swash motions and the existing morphology, modulated by varying the water level, was important for the formation of cusps at lower levels while the extreme conditions caused its destruction.