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Humans must process fleeting auditory information in real time, such as speech and music. The amplitude modulation of the acoustic waveforms of speech and music is rhythmically organized in time, following, for example, the beats of music or the syllables of speech, and this property enables temporal prediction and proactive perceptual optimization. At the neural level, external rhythmic sensory input entrains internal neural oscillatory activities, including low-frequency (e.g., delta, 1-4 Hz) phase, high-frequency (e.g., beta, 15-25 Hz) power, and their phase-amplitude coupling. These neural entrainment activities represent internal temporal prediction and proactive perceptual optimization. The present thesis investigated two critical but previously unsolved questions. First, do these multiple entrainment mechanisms for tracking auditory rhythm have distinct but coordinated perceptual functions? Second, does regularity in the temporal (when) domain associate with prediction and perception in the orthogonal spectral (what) domain of audition? This thesis addressed these topics by combining electroencephalography (EEG), psychophysics, and statistical modeling approaches. Chapter II shows that beta power entrainment reflects both rhythmic temporal prediction (when events are expected) and violation of spectral information prediction (what events are expected). Chapter III further demonstrates that degree of beta power entrainment prior to a pitch change reflects how well an upcoming pitch change will be predicted. Chapter IV reveals that rhythmic organization of sensory input proactively facilitates pitch perception. Trial-by-trial behavioural-neural associations suggested that delta phase entrainment reflects temporal expectation, beta power entrainment reflects temporal attention, and their phase-amplitude coupling reflects the alignment of these two perceptual mechanisms and is associated with auditory-motor communication. Together, this thesis advanced our understanding of how neural entrainment mechanisms relate to perceptual functions for tracking auditory events in time, which are essential for perceiving speech and music. / Thesis / Doctor of Science (PhD) / Perceiving speech and musical sounds in real time is challenging, because they occur in rapid succession and each sound masks the previous one. Rhythmic timing regularities (e.g., musical beats, speech syllable onsets) may greatly aid in overcoming this challenge, because timing regularity enables the brain to make temporal predictions and, thereby, anticipatorily prepare for perceiving upcoming sounds. This thesis investigated the perceptual and neural mechanisms for tracking auditory rhythm and enhancing perception. Perceptually, rhythmic regularity in streams of tones facilitates pitch perception. Neurally, multiple neural oscillatory activities (high-frequency power, low-frequency phase, and their coupling) track auditory inputs, and they are associated with distinct perceptual mechanisms (enhancing sensitivity or decreasing reaction time), and these mechanisms are coordinated to proactively track rhythmic regularity and enhance audition. The findings start the discussion of answering how the human brain is able to process and understand the information in rapid speech and musical streams.

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This study creates and analyzes a model of the Hypothalamus-Pituitary-Adrenal axis to better understand cortisol rhythmicity perpetuated by circadian inputs, system dynamics and feedback inherent within the system. Differential equations are created to model human physiology with cortisol and precursor hormone outputs fit to physiologic data. The model is created with an input of circadian cues from the hypothalamus which are designed to create a more realistic stimulation of the cortisol cascade over predecessors. The study also incorporates additional signaling pathways unique to this model. The project explores the properties of the model under mathematical analysis; then, the simulation of known medical pathologies is used to analyze the model's predictive ability. It is found that incorporating the additional signaling pathway of Arginine Vasopressin increases the model's predictive capability in certain pathological conditions over predecessor models. Additionally, the origination of ultradian rhythm is explored through simulation and two possible explanations are found. First, pulsatile release of Adrenocorticotropic Hormone combined with negative feedback into the system from glucocorticoid receptors elicits the observed ultradian oscillations in humans. Additionally, simulations of increased hypothalamic monitoring and control of cortisol concentrations create a natural oscillation within the desired period. Results from numerical perturbation simulations and dynamic sensitivity analysis are employed to offer justification for known pathological conditions developing from circadian dysregulation. / Master of Science / This study aims to better understand the body's natural cortisol rhythm by creating a mathematical model of the Hypothalamus-Pituitary-Adrenal axis. The model uses differential equations to simulate human physiology and includes circadian cues from the suprachiasmatic nucleus to create a more accurate representation of how cortisol is released in the body. The study also incorporates additional signaling pathways and interactions unique to this model. By analyzing the model and simulating known medical conditions, it was found found that incorporating these additional signaling pathways improved the model's predictive ability in certain situations. Then, numerical simulations were used to investigate how circadian dysregulation can lead to pathological conditions.The study also explored the origin of ultradian rhythm, or short-term fluctuations in cortisol levels, and found two possible explanations. One explanation is the pulsatile release of Adrenocorticotropic Hormone combined with negative feedback from glucocorticoid receptors. Another explanation is increased hypothalamic control of cortisol concentrations. Overall, this study provides insights into the complex dynamics of the Hypothalamus-Pituitary-Adrenal axis and the origination of pathology in the system.

Muitos trabalhos sobre comportamento consideram que os ritmos observados são simplesmente uma resposta aos estímulos ambientais. No entanto, desde o século XVIII, sabe-se que a temporização é real e muitos organismos exibem ritmos endógenos que são arrastados por zeitgebers ou \"doadores de tempo\". Para a grande maioria dos seres vivos, o principal zeitgeber é o ciclo claro/escuro (CE). No entanto, para os organismos das zonas entremarés, o ciclo das marés é tão importante quanto o ciclo de luz. A maré e seus componentes agindo como zeitgeber têm sido estudados com invertebrados e pouca atenção tem sido dada aos peixes que vivem nas zonas entremarés. Uma das espécies mais comuns destes ambientes é o Bathygobius soporator, conhecido como amborê, e o presente trabalho teve como objetivo verificar a presença de ritmicidade em sua atividade locomotora, avaliando as contribuições endógenas e exógenas dos ciclos de luminosidade, da variação da coluna d\'água e da turbulência da água sobre este ritmo. Para isso, os amborês foram mantidos em aquários individuais onde as condições abióticas puderam ser controladas de acordo com os experimentos em andamento. A atividade locomotora foi registrada com câmeras de segurança e fontes de luz infravermelha acopladas a um vídeo \"time-lapse\" que fez o registro de um quadro a cada trinta segundos. As distâncias percorridas a cada trinta segundos foram categorizadas em quatro classes discretas, e esses valores foram agrupados a cada trinta minutos, compondo 48 pontos a cada 24 horas. A análise das séries temporais foi feita através do programa \"El Temps\" que gerou actogramas e periodogramas de Lomb-Scargle, que permitem identificar ritmos com períodos significativos. Diante dos resultados obtidos, pôde-se concluir que o ciclo CE e de variação na coluna d\'água são zeitgebers, enquanto a turbulência é um agente mascarador para a ritmicidade locomotora dos amborês. Concluiu-se, também, que os relógios biológicos nos amborês não são rígidos e possuem acoplamento extremamente frágil, gerando uma alta plasticidade na expressão dos ritmos endógenos e exógenos, o que está de acordo com o modo de vida dos amborês observados no ambiente natural. / Many organisms\' rhythms are considered to be simple reactions to the cyclical changes in the environment. However, the endogenous rhythms entrained by zeitgebers are well known and have been described for many organisms since the 18th century. Although the light/dark cycle (LD) is the main zeitgeber for most living beings, the tidal cycles are as important for the intertidal organisms. It has been studied as a zeitgeber mainly for invertebrates, and little attention has been given to the intertidal fish. Bathygobius soporator, also known as frillfin goby, is one of the most abundant species in the tropical intertidal zone, and this project was designed to verify the rhythmicity in its locomotor activity, and measure how the LD cycle, the cyclical change in water level, and the turbulence cycle affect the endogenous and/or exogenous aspects of this rhythm. The gobies were kept in individual aquariums where all abiotic conditions were controlled according to the requirements of each experiment. The locomotor activity was recorded with security cameras and infrared light bulbs connected to a time-lapse video recorder that taped one frame every thirty seconds. The distance moved by each fish every thirty seconds was categorized into four discrete classes. The values assigned to these classes of movements were added into thirty minutes blocks, thus giving 48 numbers for every 24 hours. The collected data was analyzed by the \"El Temps\" software that provided actograms and Lomb-Scargle periodograms which allowed the detection of rhythms and significant periods. The results led us to conclude that LD cycle and the cyclical change in water level are zeitgebers to locomotor activity of B. soporator, and that the turbulence is a masking agent. We could also affirm that the frillfin gobies\' biological clocks are weak and have a very fragile coupling, giving the fish a malleable expression of their endogenous and exogenous rhythms. This concurs with the natural history of B. soporator.

The purpose of the study were / to compare the effects of tennis specific and general rhythm training on the forehand consistency performance, rhythmic competence, tennis playing level and agility performance, and to examine the effects of different tempos on rhythmic competence of tennis players. 30 university students whose mean score of International Tennis Number (ITN) was 7.3 (SD=0.9) were divided randomly into three sub-groups: tennis group (TG), general rhythm training group (GRTG), and tennis-specific rhythm training group (TRTG). Measurement instruments were ITN, Agility Test, Rhythmic Competence Analysis Test (RCAT), and Untimed Consecutive Rally Test (UCRT). A Kruskal-Wallis Test was conducted to calculate possible differences between initial scores and to compare improvement scores of groups. A Mann-Whitney U Test was conducted to determine pairwise comparisons of groups for improvement scores and to analyze RCAT scores for different tempos. Results revealed that participants in both rhythm training groups (GRTG and TRTG) improved their forehand consistency performance and rhythmic competence significantly after training period. Results for the improvement scores indicated that there was significant difference in UCRT (3m) between TRTG and TG and in RCAT (50) between both rhythm training groups and TG. On the other hand, participation to additional rhythm trainings was unable to differentiate tennis playing level and agility performance of groups. There was no significant difference between rhythm training groups for all parameters tested. Results also revealed that synchronization of participants&rsquo / movements with the external stimulus was more precise at fast tempo than at slow tempo.

Šiame bakalauro darbe siekiama atskleisti ritmo apraiškas audio ir vizualiniuose menuose. Ritmas – viena esminių žmogaus gyvenimo palydovų. Jo esmė – pasikartojimai, kuriais paremta ir visatos, ir žmogaus gyvenimo tvarka. Nukrypimo nuo įprasto ritmo pasekmė – žmogaus vidinis diskomfortas, kurį siekiama kuo greičiau atitaisyti. Kadangi menas yra žmogaus emocinės išraiškos priemonė, jame taip pat atsispindi vidinis kūrėjo ritmas. Siekdamas žiūrovui padaryti įspūdį savo kūriniu, menininkas ritmą gali panaudoti ir panaudoja kaip vieną iš poveikio sustiprinimo priemonių. Darbe atskleidžiamos ritmo vizualiniuose menuose – dailėje, architektūroje, audio mene – muzikoje bei audiovizualiniuose menuose – kine ir videomene apraiškos bei jų poveikis žmogui. Kūrybiniame video darbe „Gyvenimo ritmas“ siekiama ritmą atskleisti kaip vidinio žmogaus pasaulio darną užtikrinantį veiksnį bei pavaizduoti, kaip bendrą kūrinio ritminę struktūrą gali suardyti vaizdinio ir muzikinio ritmo nesinchroniškumas. / In this bachelor paper it is striven to reveal the rhythm manifestations in audio and visual arts. The rhythm is one of the most essential guides in human life. Its essence includes repetitions on which the life order of man and universe are based. Consequence of deviation from usual rhythm is man’s inner discomfort which he strives to immediately rectify. Since art is the means of human emotional expression, it also reflects the inner rhythm of a creator. When striving to make impression to a spectator with its piece of art, an artist may use the rhythm as one of the measures for increasing of effect. The paper reveals manifestations of the rhythm in visual arts, namely art, architecture, audio art – music and in audiovisual arts, namely cinema and video art along with their impact on man. In creative video piece “Life Rhythm” it is striven to reveal the rhythm as the factor ensuring inner harmony of man’s world as well as to depict how general rhythmic structure of a piece of art may be destroyed by non-synchronicity of visual and musical rhythm.

Thesis (Ph. D.)--University of Virginia, 2008. / Includes bibliographical references. Also available online through Digital Dissertations.

Introdução: Interações sociais podem afetar diretamente ritmos biológicos, independente de seu papel na organização do zeitgeber fótico. A força do zeitgeber social refere-se ao padrão rítmico das interações sociais e pode ser quantificada através da escala de ritmo social. Objetivos: Principais: 1. Adequar o instrumento de avaliação do ritmo social ao contexto de pesquisa. 2. Estudar o ritmo social em humanos. Secundários: 1. Estabecer uma versão abreviada da Escala de Ritmo Social com vistas à aplicação em pesquisa. 2. Estabelecer uma versão da Escala de Ritmo Social de 17 itens para o português angolano, para estudos transculturais. 3. Investigar a correlação entre ritmo social, fase do sono e sintomas psiquiátricos menores em trabalhadores saudáveis. Métodos: Na primeira parte do trabalho a Escala de Ritmo Social (ERS-17) foi submetida a um processo de adequação a dois contextos de pesquisa diferentes. Na segunda parte, a escala foi utilizada em um estudo clínico para avaliar a correlação entre sintomatologia psiquiátrica menor e a variável ritmo social em uma amostra saudável. Tomando como padrão-ouro a ERS-17, foram comparados escores de regularidade e quantidade de atividades de 167 sujeitos saudáveis, 25 portadores de epilepsia mioclônica juvenil e 16 portadores de transtorno depressivo, para o estabelecimento da Versão Breve. No estudo transcultural, a versão brasileira da Escala de Ritmo Social foi submetida à avaliação de 10 estudantes universitários angolanos, que analisaram o grau de clareza de cada uma das 15 sentenças do instrumento por meio da Escala Analógico-Visual de 10 cm e propuseram modificações na escala. Foi realizada revisão dos resultados para a elaboração da versão final, bem como prova de leitura e relatório final. No estudo clínico, transversal, foram avaliados 143 trabalhadores saudáveis do HCPA. Sintomas psiquiátricos menores foram avaliados pelo Self-Repport Questionnaire (SRQ-20), e ritmo social foi avaliado pela ERS-17. Exposição à luz e variáveis do sono foram avaliadas pelo Munich Choronotype Questionnaire (MCTQ). Resultados: Foi estabelecida uma versão breve de 6 itens com boa concordância com relação ao padrão-ouro k=0,51; p<0,001 e significativa correlação entre ambas: (r=0,87; p<0,001). No estudo transcultural foi estabelecida uma versão angolana que manteve uma equivalência de itens com relação à versão em português brasileiro e grau satisfatório de clareza e equivalência semântica. No estudo clínico, Quantidade de atividades correlacionou com escolaridade e tempo médio do sono e, inversamente, com (Ponto Médio do Sono) MSF e SRQ-20. Regularidade correlacionou com idade, SRQ-20 e número de dias trabalhados. SRQ-20 correlacionou inversamente com regularidade e quantidade de atividades. Conclusões: No estabelecimento da versão breve, concluiu-se que a simplificação da escala diminui a porcentagem de itens não preenchidos, o custo em material impresso e facilita a padronização. O estudo transcultural demonstrou que apesar de ser o Português o idioma oficial nos dois países, há diferenças culturais significativas que podem influenciar os resultados caso sejam ignoradas. O estudo clínico demonstrou que variáveis de ritmo social tiveram correlação inversa com sintomas psiquiátricos menores, que foram mais explicados por baixos níveis de atividade do que por baixos níveis de regularidade. / Background: Social rhythms can directly affect biological rhythms, independent of its role in organizing the photic zeitgeber. The strength of the social zeitgeber refers to the rhythmic pattern of social interactions and can be measured by Social Rhythm Metric. Objectives: Main Objectives: 1. To match the assessment tool of social rhythm to the research context. 2. To Study the social rhythm in humans. Secondary Objectives: 1. Establish an abbreviated version of the Social Rhythm Metric-17 for use in research. 2. Establish a version of the SRM-17 for the Angolan Portuguese, for cross-cultural studies. 3. To investigate the correlation between social rhythm, sleep phase and minor psychiatric symptoms in healthy workers. Methods: In the first part of this work, the Social Rhythm Metric (SRM-17) was submitted to a process of adaptation to two different research contexts. In the second part, the scale was used in a clinical study to evaluate the correlation between minor psychiatric symptomatology and the variable social rhythm in a healthy sample. Taking as gold standard SRM-17, were compared scores of regularity and amount of activities of 167 healthy subjects, 25 patients with juvenile myoclonic epilepsy and 16 patients with major depressive disorder, for establishing the Brief Version. In the cross-cultural study, the Brazilian version of the of SRM-17 was submitted to evaluation of 10 college students Angolans, who analyzed the clarity of each of the 15 sentences of the instrument through the Visual Analog Scale-10 cm and proposed modifications. Review of the results was performed for the final version, as well as proof reading and final report. In the clinical study, cross-sectional, were evaluated 143 healthy workers from HCPA. Minor psychiatric symptoms were assessed by the Self-Repport Questionnaire (SRQ-20) and social rhythm was assessed by SRM-17. Light exposure and Sleep variables wereassessed by MCTQ. Results: Was established brief version of 6 items with good agreement with respect to the gold standard (k = 0.51, p <0.001) and significant correlation between the two: (r = 0.87, p <0.001). In the transcultural study was established an angolan version that kept an equivalence of items with respect to Brazilian Portuguese version of SRM-17 and satisfactory degree of clarity and semantic equivalence. In the clinical study, number of activities correlated with schooling and average sleep time and inversely, with Midpoint of sleep (MSF) and SRQ score. Regularity correlated with age, SRQ score and number of days worked. SRQ score correlated inversely with regularity and amount of activities. Conclusions: When establishing of the short version, it was concluded that the simplification of the scale decreases the percentage of unanswered questions, the print cost, and facilitates the standardization. The transcultural study showed that, in spite of the common language in both countries, there are significant cultural differences which can inffluence the results when ignored. The clinical study showed that social rhythm variables were inversely correlated with minor psychiatric symptoms, which were explained more by lower activity levels than low levels of regularity.