Laboratorio de Sistemas Dinámicos, Departamento de Física, FCEyN, Universidad de Buenos Aires, Buenos Aires, Argentina.
PLoS Comput Biol. 2012;8(6):e1002546. doi: 10.1371/journal.pcbi.1002546. Epub 2012 Jun 28.
Because of the parallels found with human language production and acquisition, birdsong is an ideal animal model to study general mechanisms underlying complex, learned motor behavior. The rich and diverse vocalizations of songbirds emerge as a result of the interaction between a pattern generator in the brain and a highly nontrivial nonlinear periphery. Much of the complexity of this vocal behavior has been understood by studying the physics of the avian vocal organ, particularly the syrinx. A mathematical model describing the complex periphery as a nonlinear dynamical system leads to the conclusion that nontrivial behavior emerges even when the organ is commanded by simple motor instructions: smooth paths in a low dimensional parameter space. An analysis of the model provides insight into which parameters are responsible for generating a rich variety of diverse vocalizations, and what the physiological meaning of these parameters is. By recording the physiological motor instructions elicited by a spontaneously singing muted bird and computing the model on a Digital Signal Processor in real-time, we produce realistic synthetic vocalizations that replace the bird's own auditory feedback. In this way, we build a bio-prosthetic avian vocal organ driven by a freely behaving bird via its physiologically coded motor commands. Since it is based on a low-dimensional nonlinear mathematical model of the peripheral effector, the emulation of the motor behavior requires light computation, in such a way that our bio-prosthetic device can be implemented on a portable platform.
由于鸟类歌唱的产生和习得与人类语言有相似之处，因此鸟类歌唱是研究复杂的、后天习得的运动行为的一般机制的理想动物模型。鸣禽丰富多样的叫声是大脑中的模式发生器与高度非线性的外围相互作用的结果。通过研究鸟类发声器官，特别是鸣管的物理学特性，人们已经理解了这种复杂发声行为的很大一部分复杂性。描述复杂外围的数学模型将非线性动力系统的结论表明，即使器官受到简单的运动指令的控制，也会出现非平凡的行为：在低维参数空间中平滑的路径。对模型的分析提供了深入了解哪些参数负责产生丰富多样的不同发声，以及这些参数的生理意义是什么。通过记录自发歌唱的静音鸟引起的生理运动指令，并在实时数字信号处理器上计算模型，我们产生逼真的合成发声，以替代鸟类自己的听觉反馈。通过这种方式，我们通过鸟类生理编码的运动指令来驱动一个生物仿生的鸟类发声器官。由于它是基于外围效应器的低维非线性数学模型，因此运动行为的仿真需要轻量级的计算，以便我们的生物仿生设备可以在便携式平台上实现。
