Spatiotemporal perturbations in paced finger tapping suggest a common mechanism for the processing of time errors

Paced finger tapping is a sensorimotor synchronization task where a subject has to keep pace with a metronome while the time differences (asynchronies) between each stimulus and its response are recorded. A usual way to study the underlying error correction mechanism is to perform unexpected temporal perturbations to the stimuli sequence. An overlooked issue is that at the moment of a temporal perturbation two things change: the stimuli period (a parameter) and the asynchrony (a variable). In terms of experimental manipulation, it would be desirable to have separate, independent control of parameter and variable values. In this work we perform paced finger tapping experiments combining simple temporal perturbations (tempo step change) and spatial perturbations with temporal effect (raised or lowered point of contact). In this way we decouple the parameter-and-variable confounding, performing novel perturbations where either the parameter or the variable changes. Our results show nonlinear features like asymmetry and are compatible with a common error correction mechanism for all types of asynchronies. We suggest taking this confounding into account when analyzing perturbations of any kind in finger tapping tasks but also in other areas of sensorimotor synchronization, like music performance experiments and paced walking in gait coordination studies.Fil: Lopez, Sabrina Laura. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Laje, Rodrigo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Learning of Temporal Motor Patterns: An Analysis of Continuous Versus Reset Timing

Our ability to generate well-timed sequences of movements is critical to an array of behaviors, including the ability to play a musical instrument or a video game. Here we address two questions relating to timing with the goal of better understanding the neural mechanisms underlying temporal processing. First, how does accuracy and variance change over the course of learning of complex spatiotemporal patterns? Second, is the timing of sequential responses most consistent with starting and stopping an internal timer at each interval or with continuous timing? To address these questions we used a psychophysical task in which subjects learned to reproduce a sequence of finger taps in the correct order and at the correct times – much like playing a melody at the piano. This task allowed us to calculate the variance of the responses at different time points using data from the same trials. Our results show that while “standard” Weber’s law is clearly violated, variance does increase as a function of time squared, as expected according to the generalized form of Weber’s law – which separates the source of variance into time-dependent and time-independent components. Over the course of learning, both the time-independent variance and the coefficient of the time-dependent term decrease. Our analyses also suggest that timing of sequential events does not rely on the resetting of an internal timer at each event. We describe and interpret our results in the context of computer simulations that capture some of our psychophysical findings. Specifically, we show that continuous timing, as opposed to “reset” timing, is consistent with “population clock” models in which timing emerges from the internal dynamics of recurrent neural networks

Small perturbations in a finger-tapping task reveal inherent nonlinearities of the underlying error correction mechanism

Time estimation is critical for survival and control of a variety of behaviors, both in humans and other animals. Time processing in the few hundred milliseconds range, known as millisecond timing, is involved in motor control, speech generation and recognition, and sensorimotor synchronization like playing music or finger tapping to an external beat. In finger tapping, a mechanistic explanation in terms of neuronal activations of how the brain achieves average synchronization against inherent noise and perturbations in the stimulus sequence is still missing despite considerable research. In this work we show that nonlinear effects are important for the recovery of synchronization following a perturbation (a step change in stimulus period), even for perturbation magnitudes smaller than 10% of the period, which is well below the amount of perturbation needed to display other nonlinear effects like saturation. We build a mathematical model for the error correction mechanism and test its predictions, and further propose a framework that allows us to unify the description of the three common types of perturbations and all perturbation magnitudes with a single set of parameter values. While previous works have proposed that multiple mechanisms/strategies are used for correcting different perturbation conditions (based on fitting the model?s parameters separately to different perturbation types and sizes), our results suggest that the synchronization behavior can be interpreted as the outcome of a single mechanism/strategy, and call for a revision of the idea of multiple strategies.Fil: Bavassi, Mariana Luz. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnologia; Argentina;Fil: Tagliazucchi, Enzo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnologia; Argentina;Fil: Laje, Rodrigo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnologia; Argentina; University Of California; Estados Unidos de América

Response to perturbations as a built-in feature in a mathematical model for paced finger tapping

Paced finger tapping is one of the simplest tasks to study sensorimotor synchronization. The subject is instructed to tap in synchrony with a periodic sequence of brief tones, and the time difference (called asynchrony) between each response and the corresponding stimulus is recorded. Despite its simplicity, this task helps to unveil interesting features of the underlying neural system and the error correction mechanism responsible for synchronization. Perturbation experiments are usually performed to probe the subject's response, for example in the form of a "step change", i.e. an unexpected change in tempo. The asynchrony is the usual observable in such experiments and it is chosen as the main variable in many mathematical models that attempt to describe the phenomenon. In this work we show that although asynchrony can be perfectly described in operational terms, it is not well defined as a model variable when tempo perturbations are considered. We introduce an alternative variable and a mathematical model that intrinsically takes into account the perturbation, and make theoretical predictions about the response to novel perturbations based on the geometrical organization of the trajectories in phase space. Our proposal is relevant to understand interpersonal synchronization and the synchronization to non-periodic stimuli

Complexity without chaos: Plasticity within random recurrent networks generates robust timing and motor control

It is widely accepted that the complex dynamics characteristic of recurrent neural circuits contributes in a fundamental manner to brain function. Progress has been slow in understanding and exploiting the computational power of recurrent dynamics for two main reasons: nonlinear recurrent networks often exhibit chaotic behavior and most known learning rules do not work in robust fashion in recurrent networks. Here we address both these problems by demonstrating how random recurrent networks (RRN) that initially exhibit chaotic dynamics can be tuned through a supervised learning rule to generate locally stable neural patterns of activity that are both complex and robust to noise. The outcome is a novel neural network regime that exhibits both transiently stable and chaotic trajectories. We further show that the recurrent learning rule dramatically increases the ability of RRNs to generate complex spatiotemporal motor patterns, and accounts for recent experimental data showing a decrease in neural variability in response to stimulus onset

The Blursday database as a resource to study subjective temporalities during COVID-19

The COVID-19 pandemic and associated lockdowns triggered worldwide changes in the daily routines of human experience. The Blursday database provides repeated measures of subjective time and related processes from participants in nine countries tested on 14 questionnaires and 15 behavioural tasks during the COVID-19 pandemic. A total of 2,840 participants completed at least one task, and 439 participants completed all tasks in the first session. The database and all data collection tools are accessible to researchers for studying the effects of social isolation on temporal information processing, time perspective, decision-making, sleep, metacognition, attention, memory, self-perception and mindfulness. Blursday includes quantitative statistics such as sleep patterns, personality traits, psychological well-being and lockdown indices. The database provides quantitative insights on the effects of lockdown (stringency and mobility) and subjective confinement on time perception (duration, passage of time and temporal distances). Perceived isolation affects time perception, and we report an inter-individual central tendency effect in retrospective duration estimation

Clases de ciencia, herramientas mentales, mi abuela y una papa

Hay ya muchos trabajos de investigación que muestran repetidamente que las formas de enseñar basadas en la indagación y el aprendizaje activo, es decir las que tienen en cuenta aspectos más reales de cómo funciona la ciencia, son mucho más eficientes que las formas tradicionales. La sugerencia es modificar apenas un poco un par de clases en el año, en lo posible al comienzo, incorporando algunas de estas y otras sugerencias, para que la dinámica en el aula se dé vuelta y los chicos pasen a ser participantes activos. Hagamos que la ciencia escolar sea diferente, mostremos cómo son los vericuetos del pensamiento científico, qué significa saber algo en base a evidencia, cómo podemos hacer predicciones informadas, perdamos el miedo a lo que no sabemos y el respeto a lo que supuestamente sabemos. Esa ciencia será más real, más posible, más apasionante, más humana.Fil: Laje, Rodrigo. Universidad Nacional de Quilmes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

The physics of birdsong

Esta tesis está dedicada al análisis y modelado de los mecanismos físicos de la fonación en el órgano vocal de las aves canoras, la siringe. Algunas aves son popularmente conocidas por su capacidad de imitar sonidos. Se trata de todas las especies del suborden Oscinos (aves canoras), más los loros y los colibríes. Más allá del hecho curioso, la gran cantidad de similitudes entre la adquisición del habla en humanos y el aprendizaje del canto convierte a estas aves en un modelo invaluable para estudiar los mecanismos neuronales del habla en particular, y de aprendizaje y control motor de un comportamiento complejo en general. Entender cómo el cerebro del ave organiza las acciones motoras del canto es una motivación central en dicho programa. El vínculo entre actividad neuronal y comportamiento observado lo establece la siringe, el aparato vocal de las aves. La siringe en Oscinos produce sonido por vibración de los labia (tejidos móviles análogos a las cuerdas vocales humanas); es un dispositivo mecánico que muestra una riquísima variedad de soluciones oscilatorias. La comprensión de los mecanismos físicos de la fonación es de fundamental importancia para establecer el mapa de control motor y evaluar posibles restricciones a nivel periférico. En esta tesis presentamos un modelo matemático de fonación en aves canoras cuyos parámetros tienen estrecha relación con parámetros fisiológicos relevantes, como actividad muscular y presión del saco aéreo. Este modelo está basado en un detallado conocimiento de la función de diferentes estructuras en la siringe, gracias a recientes mediciones electrofisiológicas in vivo. Proponemos además que una gran variedad de vocalizaciones pueden interpretarse en términos de dos gestos motores cíclicos básicos: la presión del saco aéreo y la tensión de los labia. El parámetro clave para generar sílabas diversas es el desfasaje entre los gestos motores propuestos. El incipiente estudio de sonidos complejos en aves (frecuencias subarmónicas, espectros anarmónicos y saltos de frecuencia, por ejemplo) dió por tierra con la idea tácitamente aceptada de que hay una relación directa entre las instrucciones neuronales y las propiedades acústicas del sonido emitido. Los orígenes físicos de la complejidad, sin embargo, distan de ser entendidos completamente. Aquí presentamos un modelo que permite estudiar el acople acústico entre fuente sonora y tracto vocal, así como la interacción acústica entre las dos fuentes sonoras presentes en la siringe. Mostramos que el acople acústico y la realimentación acústica retrasada son posibles causas de sonidos complejos en un sonograma, y proponemos experimentos sencillos para evaluar los orígenes de la complejidad en el canto de algunas aves. Por último, la idea de los gestos motores nos da un marco para analizar el sorprendente canto a dúo del hornero. Más allá de la física del aparato fonador, la hipótesis de los gestos motores nos permite intuir comportamientos no lineales en los centros neuronales que controlan el canto. Este resultado es una de las pocas evidencias de sincronización de ritmos corporales en animales intactos.This thesis is dedicated to the analysis and modeling of the physical mechanisms of phonation in the avian vocal organ, the syrinx. Some birds are known due to their ability to imitate sounds. We are referring to songbirds (all species in suborder Oscines), together with parrots and hummingbirds. Beyond the simple curiosity, the large number of similarities between speech acquisition in humans and song learning in these birds makes them an invaluable model to study the neural mechanisms underlying speech and, more generally, learning and motor control of a complex behaviour. Understanding the mechanisms by which the bird brain organizes the song motor gestures is a central motivation in such a program. The link between neural activity and observed behaviour is established by the syrinx, the avian vocal organ. The syrinx in Oscines generates sound through vibration of the labia (mobile tissues analogous to the human vocal cords); it is a mechanical device displaying a rich variety of oscilatory solutions. The comprehension of the physical mechanisms playing at phonation is of fundamental importance in order to build the motor control map and evaluate possible peripheral constraints. In this thesis we present a mathematical model for the phonation in songbirds whose parameters are closely related to relevant physiological parameters such as muscular activity and air sac pressure. This model is based upon a detailed knowledge of the function of different structures in the syrinx, due to recent in vivo electrophysiological measurements. We propose in addition that a large number of different vocalizations can be interpreted in terms of two cyclic, basic motor gestures: air sac pressure and labia tension. The key parameter needed to generate a diversity of syllables is the phase difference between the proposed motor gestures. The incipient study of complex sounds in birds (subharmonic frequencies, anharmonic spectra and frequency jumps, for instance) abolished the unexpressed belief of a direct relationship between neural instructions and acoustic properties of the emitted sound. The physical origins of complexity, however, remain obscure. Here we present a model that allows us to study the acoustic coupling between sound source and vocal tract, as well as the acoustic interaction between the two sound sources in the syrinx. We show that acoustic coupling and delayed acoustic feedback are possible origins of complex sounds in a sonogram, and propose simple experiments to evaluate the source of complexity in the song of some birds. Last, the motor gestures hypothesis gives us a framework to study the surprising song of the duetting bird hornero. Beyond the physics of the vocal organ, we found a nonlinear behaviour that allows us to have an insight into the neural circuits driving the song. This result is one of the few evidences of synchronization of bodily rhythms in intact animals.Fil: Laje, Rodrigo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Time-oriented attention improves accuracy in a paced finger-tapping task

Finger tapping is a task widely used in a variety of experimental paradigms, in particular to understand sensorimotor synchronization and time processing in the range of hundreds of milliseconds (millisecond timing). Normally, subjects do not receive any instruction about what to attend to and the results are seldom interpreted taking into account the possible effects of attention. In this work we show that attention can be oriented to the purely temporal aspects of a paced finger-tapping task and that it affects performance. Specifically, time-oriented attention improves the accuracy in paced finger tapping and it also increases the resynchronization efficiency after a period perturbation. We use two markers of the attention level: auditory ERPs and subjective report of the mental workload. In addition, we propose a novel algorithm to separate the auditory, stimulus-related components from the somatosensory, response-related ones, which are naturally overlapped in the recorded EEG.Fil: Versaci, Leonardo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; ArgentinaFil: Laje, Rodrigo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentin