Matheson Andrew M M, Sakata Jon T
Department of Biology, McGill University, Montreal, Quebec, Canada.
PLoS One. 2015 Dec 9;10(12):e0143203. doi: 10.1371/journal.pone.0143203. eCollection 2015.
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.
精确协调运动手势的顺序和时间对于执行复杂且与进化相关的行为至关重要。然而，运动顺序和时间之间的关联程度在很大程度上仍不为人知。鸟鸣是一种交流行为，由离散的发声运动元素（“音节”）组成，这些音节以精确的方式进行排序和计时。为了揭示音节排序和时间之间的关系，我们分析了成年 Bengalese 雀鸟鸣声中分支点（即不同演唱版本中具有可变排序的歌曲节点）处音节转换概率的变化与音节转换之间无声间隙持续时间（“间隙持续时间”）的变化之间的相关性。我们观察到转换概率与间隙持续时间之间存在显著的负相关关系：转换概率越高，间隙持续时间越短。然后，我们评估了音节排序和时间的长期年龄依赖性变化以及急性情境依赖性变化在多大程度上遵循这种反比关系。音节排序和时间的年龄依赖性变化（而非情境依赖性变化）呈反比关系。平均而言，分支点处的间隙持续时间随年龄增长而缩短，且这种缩短的幅度在转换概率增加的情况下比在转换概率降低的情况下更大。相比之下，音节排序和时间的急性情境依赖性变化之间没有系统的关系。与发出无特定指向的歌声时相比，当鸟类发出针对雌性的求偶歌声时，分支点处的间隙持续时间会缩短，且这种缩短的幅度与转换概率变化的方向和幅度无关。这些分析表明，调节音节排序的神经机制可能同样控制音节时间，但也突出了能够独立调节音节排序和时间的机制。
