Data from: Relationship between the sequencing and timing of vocal motor elements in birdsong

Accurate coordination of the sequencing and timing of motor gestures is important for the performance of complex and evolutionarily relevant behaviors. However, the degree to which motor sequencing and timing are related remains largely unknown. Birdsong is a communicative behavior that consists of discrete vocal motor elements (‘syllables’) that are sequenced and timed in a precise manner. To reveal the relationship between syllable sequencing and timing, we analyzed how variation in the probability of syllable transitions at branch points, nodes in song with variable sequencing across renditions, correlated with variation in the duration of silent gaps between syllable transitions (‘gap durations’) for adult Bengalese finch song. We observed a significant negative relationship between transition probability and gap duration: more prevalent transitions were produced with shorter gap durations. We then assessed the degree to which long-term age-dependent changes and acute context-dependent changes to syllable sequencing and timing followed this inverse relationship. Age- but not context-dependent changes to syllable sequencing and timing were inversely related. On average, gap durations at branch points decreased with age, and the magnitude of this decrease was greater for transitions that increased in prevalence than for transitions that decreased in prevalence. In contrast, there was no systematic relationship between acute context-dependent changes to syllable sequencing and timing. Gap durations at branch points decreased when birds produced female-directed courtship song compared to when they produced undirected song, and the magnitude of this decrease was not related to the direction and magnitude of changes to transition probabilities. These analyses suggest that neural mechanisms that regulate syllable sequencing could similarly control syllable timing but also highlight mechanisms that can independently regulate syllable sequencing and timing.

运动动作的序列与时序精准协调，对于复杂且具有进化意义的行为表现至关重要。然而，运动序列与时序的关联程度目前仍未得到充分阐明。鸟鸣是一种通讯行为，由离散的发声运动单元——鸣啭音节（syllables）——以精准的序列与时序组合而成。为揭示鸣啭音节序列与时序间的关联，我们针对成年白腰文鸟的鸣啭展开分析，探究其分支点（即歌声中不同演绎版本间序列存在差异的节点）处的音节转换概率变异，与音节转换间静默间隔的间隙时长（gap durations）变异之间的相关性。我们观察到，音节转换概率与间隙时长之间存在显著的负相关关系：出现频率更高的转换，其对应的间隙时长更短。随后，我们评估了鸣啭音节序列与时序的长期年龄依赖性变化、急性情境依赖性变化，在多大程度上符合这一负相关关系。鸣啭序列与时序的年龄依赖性变化呈现负相关，而情境依赖性变化则无此关联。平均而言，分支点处的间隙时长随年龄增长而缩短；且相较于转换频率下降的情况，转换频率上升时的间隙时长缩短幅度更大。与之相反，鸣啭序列与时序的急性情境依赖性变化则未表现出系统性关联。相较于无指向性鸣啭，白腰文鸟在向雌性发出求偶鸣啭时，分支点处的间隙时长会缩短；且此类缩短幅度与转换概率变化的方向及幅度均无关联。本研究的分析结果表明，调控鸣啭音节序列的神经机制或许可同时管控音节时序，但同时也凸显了能够独立调控音节序列与时序的神经机制的存在。