Elemental gesture dynamics are encoded by song premotor cortical neurons

摘要

Quantitative biomechanical models can identify control parameters that are used during movements, and movement parameters that are encoded by premotor neurons. We fit a mathematical dynamical systems model including subsyringeal pressure, syringeal biomechanics and upper-vocal-tract filtering to the songs of zebra finches. This reduces the dimensionality of singing dynamics, described as trajectories (motor 'gestures') in a space of syringeal pressure and tension. Here we assess model performance by characterizing the auditory response 'replay' of song premotor HVC neurons to the presentation of song variants in sleeping birds, and by examining HVC activity in singing birds. HVC projection neurons were excited and interneurons were suppressed within a few milliseconds of the extreme time points of the gesture trajectories. Thus, the HVC precisely encodes vocal motor output through activity at the times of extreme points of movement trajectories. We propose that the sequential activity of HVC neurons is used as a 'forward' model, representing the sequence of gestures in song to make predictions on expected behaviour and evaluate feedback.%“斑胸草雀”等乌儿发出的复杂叫声需要精rn确计时的声音控制。关于怎样实现这种计时rn的一个理论是，HVC(对于鸟叫声的学习和rn产生来说必不可少的脑区域)中的神经元产rn生一个“时钟”信号来确定音节长短。Daniel rnMargoliash及其同事提出了支持另一模型的证rn据：通过将对禽鸣管进行生物物理模拟与对rn睡着的和清醒的鸟儿进行录音的方法相结合，rn他们发现，HVC活动与鸟儿歌唱是精确同步rn的。这说明，这些神经元不是编码时间，而是rn采用一个预测性的、“前瞻性”的“感觉运动”rn(sensorimotor)唱歌(鸣叫)模式。