Merrill Julia, Bangert Marc, Sammler Daniela, Friederici Angela D
a Department of Neuropsychology , Max Planck Institute for Human Cognitive and Brain Sciences , Leipzig , Germany.
b Music Department , Max Planck Institute for Empirical Aesthetics , Frankfurt , Germany.
Neurocase. 2016 Dec;22(6):496-504. doi: 10.1080/13554794.2016.1237660. Epub 2016 Oct 11.
Song and speech represent two auditory categories the brain usually classifies fairly easily. Functionally, this classification ability may depend to a great extent on characteristic features of pitch patterns present in song melody and speech prosody. Anatomically, the temporal lobe (TL) has been discussed as playing a prominent role in the processing of both. Here we tested individuals with congenital amusia and patients with unilateral left and right TL lesions in their ability to categorize song and speech. In a forced-choice paradigm, specifically designed auditory stimuli representing sung, spoken and "ambiguous" stimuli (being perceived as "halfway between" song and speech), had to be classified as either "song" or "speech". Congenital amusics and TL patients, contrary to controls, exhibited a surprising bias to classifying the ambiguous stimuli as "song" despite their apparent deficit to correctly process features typical for song. This response bias possibly reflects a strategy where, based on available context information (here: forced choice for either speech or song), classification of non-processable items may be achieved through elimination of processable classes. This speech-based strategy masks the pitch processing deficit in congenital amusics and TL lesion patients.
歌曲和言语代表了大脑通常能够相当容易进行分类的两种听觉类别。在功能上，这种分类能力可能在很大程度上取决于歌曲旋律和言语韵律中存在的音高模式的特征。在解剖学上，颞叶（TL）在这两者的处理过程中都被认为起着重要作用。在这里，我们测试了患有先天性失歌症的个体以及患有左侧和右侧颞叶单侧病变的患者对歌曲和言语进行分类的能力。在一个强制选择范式中，专门设计的代表演唱、说话和“模糊”刺激（被感知为处于歌曲和言语“中间状态”）的听觉刺激必须被分类为“歌曲”或“言语”。与对照组不同，先天性失歌症患者和颞叶病变患者表现出一种令人惊讶的倾向，即尽管他们明显难以正确处理歌曲特有的特征，但仍将模糊刺激分类为“歌曲”。这种反应偏差可能反映了一种策略，即基于可用的上下文信息（这里：对言语或歌曲进行强制选择），通过排除可处理的类别来实现对不可处理项目的分类。这种基于言语的策略掩盖了先天性失歌症患者和颞叶病变患者的音高处理缺陷。
