Centre for Brain and Mind, University of Western Ontario, Perth Drive, London, Ontario N6A 5B7, Canada.
Western Institute for Neuroscience, University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7, Canada.
Cereb Cortex. 2024 Oct 3;34(10). doi: 10.1093/cercor/bhae406.
Humans perceive a pulse, or beat, underlying musical rhythm. Beat strength correlates with activity in the basal ganglia and supplementary motor area, suggesting these regions support beat perception. However, the basal ganglia and supplementary motor area are part of a general rhythm and timing network (regardless of the beat) and may also represent basic rhythmic features (e.g. tempo, number of onsets). To characterize the encoding of beat-related and other basic rhythmic features, we used representational similarity analysis. During functional magnetic resonance imaging, participants heard 12 rhythms-4 strong-beat, 4 weak-beat, and 4 nonbeat. Multi-voxel activity patterns for each rhythm were tested to determine which brain areas were beat-sensitive: those in which activity patterns showed greater dissimilarities between rhythms of different beat strength than between rhythms of similar beat strength. Indeed, putamen and supplementary motor area activity patterns were significantly dissimilar for strong-beat and nonbeat conditions. Next, we tested whether basic rhythmic features or models of beat strength (counterevidence scores) predicted activity patterns. We found again that activity pattern dissimilarity in supplementary motor area and putamen correlated with beat strength models, not basic features. Beat strength models also correlated with activity pattern dissimilarities in the inferior frontal gyrus and inferior parietal lobe, though these regions encoded beat and rhythm simultaneously and were not driven by beat alone.
人类能感知到音乐节奏中的节拍。节拍的强度与基底神经节和辅助运动区的活动相关，这表明这些区域支持节拍感知。然而，基底神经节和辅助运动区是一般节奏和定时网络的一部分（与节拍无关），也可能代表基本的节奏特征（例如，节奏、起音数）。为了描述与节拍相关的和其他基本节奏特征的编码，我们使用了表示相似性分析。在功能磁共振成像期间，参与者听到 12 种节奏-4 种强节拍、4 种弱节拍和 4 种非节拍。测试了每种节奏的多体素活动模式，以确定哪些大脑区域对节拍敏感：即那些在不同节拍强度的节奏之间的活动模式差异大于相似节拍强度的节奏之间的活动模式差异的区域。事实上，壳核和辅助运动区的活动模式在强节拍和非节拍条件下差异显著。接下来，我们测试了基本节奏特征或节拍强度模型（反证分数）是否可以预测活动模式。我们再次发现，辅助运动区和壳核的活动模式差异与节拍强度模型相关，而与基本特征无关。节拍强度模型也与额下回和顶下小叶的活动模式差异相关，尽管这些区域同时编码节拍和节奏，并且不是由节拍单独驱动的。
