Université Claude Bernard Lyon 1, CNRS, INSERM, Centre de Recherche en Neurosciences de Lyon CRNL U1028 UMR5292, F-69500, Bron, France.
École Normale Supérieure, PSL University, CNRS, Paris, France.
J Cogn Neurosci. 2023 May 1;35(5):765-780. doi: 10.1162/jocn_a_01973.
Congenital amusia is a neurodevelopmental disorder characterized by difficulties in the perception and production of music, including the perception of consonance and dissonance, or the judgment of certain combinations of pitches as more pleasant than others. Two perceptual cues for dissonance are inharmonicity (the lack of a common fundamental frequency between components) and beating (amplitude fluctuations produced by close, interacting frequency components). Amusic individuals have previously been reported to be insensitive to inharmonicity, but to exhibit normal sensitivity to beats. In the present study, we measured adaptive discrimination thresholds in amusic participants and found elevated thresholds for both cues. We recorded EEG and measured the MMN in evoked potentials to consonance and dissonance deviants in an oddball paradigm. The amplitude of the MMN response was similar overall for amusic and control participants; however, in controls, there was a tendency toward larger MMNs for inharmonicity than for beating cues, whereas the opposite tendency was observed for the amusic participants. These findings suggest that initial encoding of consonance cues may be intact in amusia despite impaired behavioral performance, but that the relative weight of nonspectral (beating) cues may be increased for amusic individuals.
先天性失歌症是一种神经发育障碍，其特征是在感知和产生音乐方面存在困难，包括对协和与不协和的感知，或对某些音高组合的判断，认为它们比其他音高组合更悦耳。不和谐的两个感知线索是不谐和（组件之间缺乏共同的基频）和拍频（由接近的、相互作用的频率分量产生的幅度波动）。先前有报道称，失歌症患者对不谐和不敏感，但对拍频表现出正常的敏感性。在本研究中，我们测量了失歌症参与者的自适应辨别阈值，发现两种线索的阈值都升高了。我们在一个奇特的范式中记录了脑电图，并测量了对协和和不协和偏差的诱发电位中的 MMN。失歌症和对照组参与者的 MMN 反应幅度总体上相似；然而，在对照组中，不谐和线索的 MMN 倾向于比拍频线索更大，而失歌症参与者则相反。这些发现表明，尽管行为表现受损，但在先天性失歌症中，对协和线索的初始编码可能是完整的，而对于失歌症个体来说，非频谱（拍频）线索的相对权重可能会增加。
