Losing the beat: brain and behavior basis of human rhythm

失去节拍：人类节奏的大脑和行为基础

• 批准号: RGPIN-2014-04068
• 负责人: Peretz, Isabelle
• 金额: $ 3.57万
• 依托单位: Université de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=587582
• 关键词: Losing; beat; brain; behavior; basis

A defining characteristic of our interactions with music is the ability to identify and move to the “beat”. This complex ability is universal and spontaneously acquired early in life. Yet, as we have recently shown, some individuals fail to find the beat in music and to synchronize with it, despite having normal hearing, normal motor and intellectual abilities. This disorder, to which we refer as beat deafness (a new form of congenital amusia), provides a natural experiment, a rare chance to examine how a selective cognitive deficit emerges and how it is expressed in the brain. The goal of this proposal is to characterize the functional and neural anomalies of beat deafness. To this aim, we will recruit and test groups of abnormal (beat deaf) and control adults. Beat-deaf adults will be selected according to the same criteria as those used to diagnose our first case. Its essential behavioral manifestation is poor synchronization of body movements to selections of dance music, as measured by motion capture. The disorder appears specific to rhythm because it spares melodic pitch processing. Hence beat deafness is distinct from the most common form of congenital amusia, pitch deafness that affects pitch processing. The comparison of beat-deaf and pitch-deaf performance will serve to fractionate beat-based entrainment while controlling for impoverished musical experience. In PART I of the proposal, we will examine how deficits in beat-tracking can shed light on characteristics of human beat-based entrainment. Typically, people tap in advance of the beat to eliminate the time lag introduced by sensorimotor reaction. Such anticipatory tendencies are considered to be unique to humans. We will test here whether beat-deaf individuals are more reactive or exhibit stronger influences of preferred endogenous rates in anticipatory tapping to metronome-like stimuli as compared to control and pitch-deaf performance. In PART II, we will test the music-specificity of entrainment mechanisms. We predict that normal participants should tap less variably and with fewer asynchronies to song than to regular speech. In contrast, beat deaf individuals should be equally poor whether they tap on natural, regular speech or songs, and pitch deaf performance will show the opposite pattern with best performance on regular speech since songs contain interfering pitch variations. In PART III, neural entrainment to music will be measured with a novel electrophysiological (EEG) technique that captures beat-related steady-state evoked potentials, following the idea that natural brain oscillations can entrain to the periodicities of the auditory stimulus. In the brains of beat deaf listeners, the evidence for the presence of an internal representation of the beat should be weak. An interesting alternative is that the EEG reveals normal neural entrainment in listening but not in tapping. Such a finding would suggest that the deficit is not perceptual but arises from poor auditory-motor coupling. Finally, in PART IV, we will search for brain anomalies with several Magnetic Resonance Imaging (MRI) techniques that have proven to be informative in pitch deafness. Beat deafness represents a rare chance to identify which parts of the neural network (from the basal ganglia to the dorsal premotor cortex) are essential for entrainment. By combining these diverse neuropsychological methods, this project should provide theoretical insight on the neurobiological basis of human rhythm.

我们与音乐互动的一个决定性特征是识别并跟随“节拍”的能力。这种复杂的能力是普遍存在的，并且是在生命早期自发获得的。 然而，正如我们最近所表明的那样，尽管有正常的听力、正常的运动和智力，有些人却无法找到音乐的节拍并与之同步。这种疾病，我们称之为节拍性耳聋（先天性失乐症的一种新形式），提供了一个自然实验，一个难得的机会来检查选择性认知缺陷如何出现以及它如何在大脑中表达。该提案的目标是描述搏动性耳聋的功能和神经异常特征。 为此，我们将招募并测试异常（失聪）和对照成年人组。将根据与诊断我们第一个病例相同的标准来选择失聪成年人。其基本的行为表现是身体动作与所选舞曲的同步性较差（通过动作捕捉测量）。这种紊乱似乎是节奏特有的，因为它不影响旋律音高处理。因此，节拍性耳聋不同于最常见的先天性失乐症，即影响音调处理的音调聋。节拍聋和音调聋表演的比较将有助于细分基于节拍的夹带，同时控制贫乏的音乐体验。 在该提案的第一部分中，我们将研究节拍跟踪的缺陷如何揭示人类基于节拍的夹带特征。通常，人们会提前敲击节拍，以消除感觉运动反应带来的时间滞后。这种预期倾向被认为是人类所独有的。我们将在这里测试与对照组和音调聋的表现相比，节拍聋的个体在对节拍器类刺激的预期敲击中是否更具反应性或表现出更强的首选内源速率影响。在第二部分中，我们将测试夹带机制的音乐特异性。我们预测，与常规语音相比，正常参与者对歌曲的敲击变化和不同步性应该更少。相比之下，失聪者无论是自然的、常规的语音还是歌曲，表现都应该同样差，并且音高聋的表现将显示出与常规语音的最佳表现相反的模式，因为歌曲包含干扰性的音调变化。在第三部分中，将采用一种新颖的电生理学 (EEG) 技术来测量音乐的神经夹带，该技术捕获与节拍相关的稳态诱发电位，遵循自然大脑振荡可以夹带听觉刺激的周期性的想法。在对节拍充耳不闻的听众的大脑中，节拍内部表征存在的证据应该很弱。一个有趣的替代方案是，脑电图显示了聆听时的正常神经夹带，但敲击时却没有。这一发现表明，缺陷不是知觉上的，而是由听觉-运动耦合不良引起的。最后，在第四部分中，我们将使用几种磁共振成像 (MRI) 技术来寻找大脑异常，这些技术已被证明可以为音调耳聋提供信息。节拍性耳聋代表了一个难得的机会来确定神经网络的哪些部分（从基底神经节到背侧前运动皮层）对于夹带至关重要。 通过结合这些不同的神经心理学方法，该项目应该为人类节律的神经生物学基础提供理论见解。