Mechanisms of rhythm perception

随着音乐节拍移动是依赖于规律的无数人类行为之一(例如，走路、说话、转弯)，但我们对规律节拍的敏感性背后的机制仍然是一个谜。当我们听有节奏的时间间隔序列时，节拍感觉会自发地发生，不费力气。现有的时间感知模型无法解释节拍感知的许多特征，行为证据表明，人类可能有一种独特的基于节拍的计时系统。我的研究试图描述这个系统的特点。到目前为止，我的研究表明了节拍感知和运动之间的联系：当我们听到节奏时，控制运动的大脑区域被激活，某些运动区在节拍感知时做出特定的反应，即使在没有动作的情况下也是如此。我的目标是：i)开发独立于节拍产生来评估节拍感知的工具，ii)表征运动系统在节拍感知中所扮演的角色的时序性，以及iii)结合脑刺激和成像方法来了解特定运动区域在节奏和节拍感知中的因果作用。*在第一个研究项目中，我和我的受训人员将验证一个新的范式来评估节拍感知。这一范式使我们能够确定节拍感应的时间进程(在有节奏的序列中找到规则的节拍)，并研究这种时间进程如何以及为什么在不同的个体之间存在差异。在第二个项目中，我们将使用经颅磁刺激(TMS)来测量搏动感觉过程中运动系统的兴奋性。运动兴奋性的时间进程(例如，它是在对每一个即将到来的节拍的预期中波动，还是在对节拍的反应中波动)将告诉我们运动系统在节拍诱导和节拍感知中的作用。此外，我们将研究音乐经验和个人节律能力的差异是否反映在运动兴奋性变化的程度或潜伏期上。第三个项目将研究在节奏和节拍感知过程中做出反应的单个运动区所起的因果作用。一些角色可能是所有类型的节拍的通用角色，而其他角色可能特定于基于节拍的节拍。为了研究这一点，我们将应用非侵入性大脑刺激来暂时扰乱和增强个别运动区的功能，测量每个区域如何支持计时和节拍感知。*了解节拍和节奏感知机制对于建立人类复杂计时行为的准确模型至关重要，但也对音乐以外的许多领域产生影响。时间感知是我们整合来自不同感官的信息、协调运动和感知世界关系的能力的基础。在临床上，节拍感知预测语言和听力技能，并构成基于音乐的步态干预的基础。

Moving to a musical beat is one of myriad human behaviours that rely on regularity (e.g., walking, talking, turn-taking), but the mechanisms underlying our sensitivity to a regular beat are still a mystery. Beat perception occurs spontaneously, without effort, when we listen to rhythmic sequences of time intervals. Existing models of time perception cannot account for many features of beat perception, and behavioural evidence suggests that humans may have a unique beat-based timing system. My research seeks to characterize this system. Thus far, my research indicates a link between beat perception and movement: brain areas that control movement are activated when we hear rhythm, and certain motor areas respond specifically during beat perception, even when no movement is made. I aim to: i) develop tools to assess beat perception independently from beat production, ii) characterize the timecourse of the motor system's role in beat perception, and iii) combine brain stimulation and imaging methods to understand the causal roles of specific motor areas in rhythm and beat perception.***In the first research project, my trainees and I will validate a novel paradigm to assess beat perception. The paradigm enables us to determine the timecourse of beat induction' (finding the regular beat in a rhythmic sequence), and to examine how and why this timecourse varies across individuals. In the second project, we will use transcranial magnetic stimulation (TMS) to measure motor system excitability during beat perception. The timecourse of motor excitability (e.g., does it fluctuate in anticipation of each upcoming beat, or in reaction to the beat) will inform us about the role of the motor system during beat induction and beat perception. Further, we will examine whether musical experience and individual differences in rhythmic ability are reflected in the degree or latency of motor excitability changes. The third project will examine the causal roles played by individual motor areas that respond during rhythm and beat perception. Some roles may be general to all types of timing, whereas others may be specific to timing based on the beat. To investigate this, we will apply noninvasive brain stimulation to transiently disrupt, as well as enhance, functioning in individual motor areas, measuring how each supports timing and beat perception. ***Understanding the mechanisms of beat and rhythm perception will be crucial to creating accurate models of humans' complex timing behaviour, but also has implications for many domains beyond music. Temporal perception underlies our capacity to integrate information from different senses, coordinate movement, and perceive relationships in the world. Clinically, beat perception predicts language and hearing skills, and forms the basis of music-based gait interventions.