249 research outputs found

    Cortico-muscular coherence in sensorimotor synchronisation

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    This thesis sets out to investigate the neuro-muscular control mechanisms underlying the ubiquitous phenomenon of sensorimotor synchronisation (SMS). SMS is the coordination of movement to external rhythms, and is commonly observed in everyday life. A large body of research addresses the processes underlying SMS at the levels of behaviour and brain. Comparatively, little is known about the coupling between neural and behavioural processes, i.e. neuro-muscular processes. Here, the neuro-muscular processes underlying SMS were investigated in the form of cortico-muscular coherence measured based on Electroencephalography (EEG) and Electromyography (EMG) recorded in human healthy participants. These neuro-muscular processes were investigated at three levels of engagement: passive listening and observation of rhythms in the environment, imagined SMS, and executed SMS, which resulted in the testing of three hypotheses: (i) Rhythms in the environment, such as music, spontaneously modulate cortico-muscular coupling, (ii) Movement intention modulates cortico-muscular coupling, and (iii) Cortico-muscular coupling is dynamically modulated during SMS time-locked to the stimulus rhythm. These three hypotheses were tested through two studies that used Electroencephalography (EEG) and Electromyography (EMG) recordings to measure Cortico-muscular coherence (CMC). First, CMC was tested during passive music listening, to test whether temporal and spectral properties of music stimuli known to induce groove, i.e., the subjective experience of wanting to move, can spontaneously modulate the overall strength of the communication between the brain and the muscles. Second, imagined and executed movement synchronisation was used to investigate the role of movement intention and dynamics on CMC. The two studies indicate that both top-down, and somatosensory and/or proprioceptive processes modulate CMC during SMS tasks. Although CMC dynamics might be linked to movement dynamics, no direct correlation between movement performance and CMC was found. Furthermore, purely passive auditory or visual rhythmic stimulation did not affect CMC. Together, these findings thus indicate that movement intention and active engagement with rhythms in the environment might be critical in modulating CMC. Further investigations of the mechanisms and function of CMC are necessary, as they could have important implications for clinical and elderly populations, as well as athletes, where optimisation of motor control is necessary to compensate for impaired movement or to achieve elite performance

    Effects of sensory feedback on duration reproduction

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    Most studies, investigating human time perception, have demonstrated a difference between subjective and objective timing. Very common are, for example, results showing that visual intervals are judged shorter than physically equivalent auditory intervals. Recent studies have also found differences between motor and perceptual timing. Considering those perceived differences, the idea has been proposed that the brain might employ distributed (modality- specific) timing mechanisms rather than one amodal timing mechanism. Distributed timing mechanisms and therefore independent temporal estimates would be convenient in the computation for reliability-based multisensory or sensorimotor integration, as predicted by Bayesian inference. Several studies have shown that multisensory temporal estimates can be predicted by reliability-based integration models, as for example the Maximum Likelihood Estimation (MLE) model. Reliability-based integration studies in time research are still fairly rare and discussed controversially, and especially studies investigating sensorimotor integration are mostly missing. The aim of this cumulative thesis was to investigate sensorimotor temporal reproduction with a focus on the influence of sensory (mainly auditory) feedback on motor timing. Here fore, in all studies a sensorimotor temporal reproduction paradigm was employed, and sensory and motor estimates were treated as different/independent estimates. First, we investigated the effect of onset and offset delayed sensory feedback on temporal reproduction (Chapter 2.1). Second, perceptual and motor timing were compared explicitly and then a reliability-based model was used to predict the observed sensorimotor reproduction times (Chapter 2.2). In a third study, we manipulated the prior representation of the standard duration, using different adaptation conditions (Chapter 2.3). The findings showed that if the onset of a feedback stimulus was delayed in relation to an action (in contrast to when the feedback signal was started before the action), reproduced durations increased immediately, as soon as a delay is introduced. Offset-delayed sensory feedback, on the other hand, only induced a minor decrease in reproduction times and this effect could only be observed with auditory feedback. In comparison to auditory comparison estimates, which were shown to be fairly precise, pure motor reproduction as well as auditory reproduction was found to be consistently overestimated. The observed overestimation bias in auditory reproduction was reduced, compared to pure motor reproduction. This pattern of result could be shown for various standard durations and different signal-to-noise ratios (SNR) in the compared/reproduced tones. Further, a reliability-based model 4 predicted observed auditory reproduction biases successfully. In the third study, we could show that shifting the temporal range of accuracy feedback, manipulating the SNR of the reproduced tone, as well as introducing a manipulation of the reproduced tone onset, led to significant changes in the prior representation of the standard duration. Only manipulating the reproduced tone onset during the adaptation phase induced a reduction of auditory weights, which could be observed during the test phase. Additional trial-wise analysis confirmed that the adapted prior representation is shifted back to normal dynamically over time, once no accuracy feedback is provided anymore. The differences between observed sensory and motor estimates of time are discussed. We concluded that the finding that onset and offset delay influenced reproduction performance differentially implies that participants rather rely on the sensory feedback as a start- timing signal (at least if a causal relationship between action and sensory feedback can be established), while the motor stop is used as primary stop-timing signal. Observed sensorimotor reproduction biases and variability could be described as the weighted integration of the auditory estimate and the motor estimate. The integration reflects the brain combines multiple timing signals to improve overall performance. The prior knowledge of the standard duration in the reference memory is updated dynamically in that current sensorimotor estimates are constantly integrated with the history of duration estimates. In the end, overall implications of all the results for time perception, as well as sensory integration research are discussed. In summary, this thesis helps to improve our knowledge about sensorimotor temporal integration in a sensorimotor reproduction task on the basis of behavioral findings as well as probabilistic modeling

    The influence of external and internal motor processes on human auditory rhythm perception

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    Musical rhythm is composed of organized temporal patterns, and the processes underlying rhythm perception are found to engage both auditory and motor systems. Despite behavioral and neuroscience evidence converging to this audio-motor interaction, relatively little is known about the effect of specific motor processes on auditory rhythm perception. This doctoral thesis was devoted to investigating the influence of both external and internal motor processes on the way we perceive an auditory rhythm. The first half of the thesis intended to establish whether overt body movement had a facilitatory effect on our ability to perceive the auditory rhythmic structure, and whether this effect was modulated by musical training. To this end, musicians and non-musicians performed a pulse-finding task either using natural body movement or through listening only, and produced their identified pulse by finger tapping. The results showed that overt movement benefited rhythm (pulse) perception especially for non-musicians, confirming the facilitatory role of external motor activities in hearing the rhythm, as well as its interaction with musical training. The second half of the thesis tested the idea that indirect, covert motor input, such as that transformed from the visual stimuli, could influence our perceived structure of an auditory rhythm. Three experiments examined the subjectively perceived tempo of an auditory sequence under different visual motion stimulations, while the auditory and visual streams were presented independently of each other. The results revealed that the perceived auditory tempo was accordingly influenced by the concurrent visual motion conditions, and the effect was related to the increment or decrement of visual motion speed. This supported the hypothesis that the internal motor information extracted from the visuomotor stimulation could be incorporated into the percept of an auditory rhythm. Taken together, the present thesis concludes that, rather than as a mere reaction to the given auditory input, our motor system plays an important role in contributing to the perceptual process of the auditory rhythm. This can occur via both external and internal motor activities, and may not only influence how we hear a rhythm but also under some circumstances improve our ability to hear the rhythm.Musikalische Rhythmen bestehen aus zeitlich strukturierten Mustern akustischer Stimuli. Es konnte gezeigt werden, dass die Prozesse, welche der Rhythmuswahrnehmung zugrunde liegen, sowohl motorische als auch auditive Systeme nutzen. Obwohl sich fĂŒr diese auditiv-motorischen Interaktionen sowohl in den Verhaltenswissenschaften als auch Neurowissenschaften ĂŒbereinstimmende Belege finden, weiß man bislang relativ wenig ĂŒber die Auswirkungen spezifischer motorischer Prozesse auf die auditive Rhythmuswahrnehmung. Diese Doktorarbeit untersucht den Einfluss externaler und internaler motorischer Prozesse auf die Art und Weise, wie auditive Rhythmen wahrgenommen werden. Der erste Teil der Arbeit diente dem Ziel herauszufinden, ob körperliche Bewegungen es dem Gehirn erleichtern können, die Struktur von auditiven Rhythmen zu erkennen, und, wenn ja, ob dieser Effekt durch ein musikalisches Training beeinflusst wird. Um dies herauszufinden wurde Musikern und Nichtmusikern die Aufgabe gegeben, innerhalb von prĂ€sentierten auditiven Stimuli den Puls zu finden, wobei ein Teil der Probanden wĂ€hrenddessen Körperbewegungen ausfĂŒhren sollte und der andere Teil nur zuhören sollte. Anschließend sollten die Probanden den gefundenen Puls durch Finger-Tapping ausfĂŒhren, wobei die Reizgaben sowie die Reaktionen mittels eines computerisierten Systems kontrolliert wurden. Die Ergebnisse zeigen, dass offen ausgefĂŒhrte Bewegungen die Wahrnehmung des Pulses vor allem bei Nichtmusikern verbesserten. Diese Ergebnisse bestĂ€tigen, dass Bewegungen beim Hören von Rhythmen unterstĂŒtzend wirken. Außerdem zeigte sich, dass hier eine Wechselwirkung mit dem musikalischen Training besteht. Der zweite Teil der Doktorarbeit ĂŒberprĂŒfte die Idee, dass indirekte, verdeckte Bewegungsinformationen, wie sie z.B. in visuellen Stimuli enthalten sind, die wahrgenommene Struktur von auditiven Rhythmen beeinflussen können. Drei Experimente untersuchten, inwiefern das subjektiv wahrgenommene Tempo einer akustischen Sequenz durch die PrĂ€sentation unterschiedlicher visueller Bewegungsreize beeinflusst wird, wobei die akustischen und optischen Stimuli unabhĂ€ngig voneinander prĂ€sentiert wurden. Die Ergebnisse zeigten, dass das wahrgenommene auditive Tempo durch die visuellen Bewegungsinformationen beeinflusst wird, und dass der Effekt in Verbindung mit der Zunahme oder Abnahme der visuellen Geschwindigkeit steht. Dies unterstĂŒtzt die Hypothese, dass internale Bewegungsinformationen, welche aus visuomotorischen Reizen extrahiert werden, in die Wahrnehmung eines auditiven Rhythmus integriert werden können. Zusammen genommen, 5 zeigt die vorgestellte Arbeit, dass unser motorisches System eine wichtige Rolle im Wahrnehmungsprozess von auditiven Rhythmen spielt. Dies kann sowohl durch Ă€ußere als auch durch internale motorische AktivitĂ€ten geschehen, und beeinflusst nicht nur die Art, wie wir Rhythmen hören, sondern verbessert unter bestimmten Bedingungen auch unsere FĂ€higkeit Rhythmen zu identifizieren

    Experiments in time:exploring the components of motor timing behaviour in dyslexia

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    This investigation aimed to pinpoint the elements of motor timing control that are responsible for the increased variability commonly found in children with developmental dyslexia on paced or unpaced motor timing tasks (Chapter 3). Such temporal processing abilities are thought to be important for developing the appropriate phonological representations required for the development of literacy skills. Similar temporal processing difficulties arise in other developmental disorders such as Attention Deficit Hyperactivity Disorder (ADHD). Motor timing behaviour in developmental populations was examined in the context of models of typical human timing behaviour, in particular the Wing-Kristofferson model, allowing estimation of the contribution of different timing control systems, namely timekeeper and implementation systems (Chapter 2 and Methods Chapters 4 and 5). Research examining timing in populations with dyslexia and ADHD has been inconsistent in the application of stimulus parameters and so the first investigation compared motor timing behaviour across different stimulus conditions (Chapter 6). The results question the suitability of visual timing tasks which produced greater performance variability than auditory or bimodal tasks. Following an examination of the validity of the Wing-Kristofferson model (Chapter 7) the model was applied to time series data from an auditory timing task completed by children with reading difficulties and matched control groups (Chapter 8). Expected group differences in timing performance were not found, however, associations between performance and measures of literacy and attention were present. Results also indicated that measures of attention and literacy dissociated in their relationships with components of timing, with literacy ability being correlated with timekeeper variance and attentional control with implementation variance. It is proposed that these timing deficits associated with reading difficulties are attributable to central timekeeping processes and so the contribution of error correction to timing performance was also investigated (Chapter 9). Children with lower scores on measures of literacy and attention were found to have a slower or failed correction response to phase errors in timing behaviour. Results from the series of studies suggest that the motor timing difficulty in poor reading children may stem from failures in the judgement of synchrony due to greater tolerance of uncertainty in the temporal processing system

    ON THE REPRESENTATION OF SPATIAL AND TEMPORAL STRUCTURES: EFFECTS IN HUMAN VISUOSPATIAL WORKING MEMORY

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    In a diverse range of environments, each replete with unique physical phenomena, humans are capable of acting and achieving with volition. To do so we capitalize upon structures that exist in the physical world, rapidly drawing associations and forming conceptual relationships between items and occurrences. In this dissertation work, I examine how structures in the domains of space and time impact the representations of information that we form and hold in working memory, in the service of goal-driven behavior. Three key findings arise from the studies I present herein. First, representation of spatial structures in working memory is supported by oscillatory neural activity that differs between individuals based upon biological sex. The peak of posterior alpha frequency oscillatory activity is modulated in support of visuospatial representation maintenance more so in females than males. Among males but not females, successful representation of relative spatial structure is positively tied to an individual’s peak frequency of alpha oscillatory activity. Second, the interaction of spatial and temporal structures across perceptual modalities impacts representation in working memory. Shared temporal structure between a stream of visual targets and a stream of sounds promotes representation of the spatial structure of those sounds. This integration of perceptual information occurs whether helpful or harmful, differentially impacting performance. Third, the representation of spatial information in working memory is impacted by a particular form of temporal structure — rhythm. The presence of rhythmic versus arrhythmic temporal structure within a visuospatial stream does not increase the precision of working memory representation, but rather increases the speed with which representations may be formed. Rhythmic structure spontaneously and consistently facilitates working memory performance. Arrhythmic structure may hinder temporal processing but can be behaviorally compensated for with the application of controlled attention to the temporal domain. A novel paradigm, designed and utilized to study effects of rhythmic temporal structure upon visuospatial working memory is described

    Timing and Time Perception: Procedures, Measures, and Applications

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    Timing and Time Perception: Procedures, Measures, and Applications is a one-of-a-kind, collective effort to present the most utilized and known methods on timing and time perception. Specifically, it covers methods and analysis on circadian timing, synchrony perception, reaction/response time, time estimation, and alternative methods for clinical/developmental research. The book includes experimental protocols, programming code, and sample results and the content ranges from very introductory to more advanced so as to cover the needs of both junior and senior researchers. We hope that this will be the first step in future efforts to document experimental methods and analysis both in a theoretical and in a practical manner

    Temporal mechanisms of multimodal binding

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    Musical Meter: Examining Hierarchical Temporal Perception in Complex Musical Stimuli Across Human Development, Sensory Modalities, and Expertise

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    Performing, listening, and moving to music are universal human behaviors. Most music in the world is organized temporally with faster periodicities nested within slower periodicities, creating a perceptual hierarchy of repeating stronger (downbeat) and weaker (upbeat) events. This perceptual organization is theorized to aid our abilities to synchronize our behaviors with music and other individuals, but there is scant empirical evidence that listeners actively perceive these multiple levels of temporal periodicities simultaneously. Furthermore, there is conflicting evidence about when, and how, the ability to perceive the beat in music emerges during development. It is also unclear if this hierarchical organization of musical time is unique to – or heavily reliant upon – the precise timing capabilities of the auditory system, or if it is found in other sensory systems. Across three series of experiments, I investigated whether listeners perceive multiple levels of structure simultaneously, how experience and expertise influence this ability, the emergence of meter perception in development, and how strong the auditory advantage for beat and meter perception is over visual meter perception. In Chapter 1, I demonstrated that older, but not younger, infants showed evidence of the beginnings of beat perception in their ability to distinguish between synchronous and asynchronous audiovisual displays of dancers moving to music. In Chapter 2, I demonstrated that adults, but not children, showed evidence of perceiving multiple levels of metrical structure simultaneously in complex, human-performed music, and this ability was not greatly dependent upon formal musical training. Older children were more sensitive to beat than younger children, suggesting beat and meter perception develops gradually throughout childhood into adolescence. However, perception of multiple levels of meter was not evident in younger children, and likely does not emerge until late adolescence. Formal musical training was associated with enhanced meter perception in adults and beat perception in children. In Chapter 3, both adults and children demonstrated an auditory advantage for beat perception over visual. However, adults did not show an auditory advantage for the perception of slower beat levels (measure) or the perception of multiple beat levels simultaneously. Children did not show evidence of measure-level perception in either modality, but their ability to perceive the beat in both auditory and visual metronomes improved with age. Overall, the results of the three series of experiments demonstrate that beat and meter perception develop quite gradually throughout childhood, rely on lifelong acquisition of musical knowledge, and that there is a distinct auditory advantage for the perception of beat
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