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.

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.