Williams Carrie A, DeWeerth Stephen P
The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.
Biol Cybern. 2007 Jun;96(6):603-14. doi: 10.1007/s00422-007-0150-8. Epub 2007 Apr 3.
We used a computational model of rhythmic movement to analyze how the connectivity of sensory feedback affects the tuning of a closed-loop neuromechanical system to the mechanical resonant frequency (omega(r)). Our model includes a Matsuoka half-center oscillator for a central pattern generator (CPG) and a linear, one-degree-of-freedom system for a mechanical component. Using both an open-loop frequency response analysis and closed-loop simulations, we compared resonance tuning with four different feedback configurations as the mechanical resonant frequency, feedback gain, and mechanical damping varied. The feedback configurations consisted of two negative and two positive feedback connectivity schemes. We found that with negative feedback, resonance tuning predominantly occurred when omega(r) was higher than the CPG's endogenous frequency (omega(CPG)). In contrast, with the two positive feedback configurations, resonance tuning only occurred if omega(r) was lower than omega(CPG). Moreover, the differences in resonance tuning between the two positive (negative) feedback configurations increased with increasing feedback gain and with decreasing mechanical damping. Our results indicate that resonance tuning can be achieved with positive feedback. Furthermore, we have shown that the feedback configuration affects the parameter space over which the endogenous frequency of the CPG or resonant frequency the mechanical dynamics dominates the frequency of a rhythmic movement.
我们使用了一个节律性运动的计算模型，来分析感觉反馈的连通性如何影响闭环神经机械系统对机械共振频率（ω(r)）的调谐。我们的模型包括一个用于中央模式发生器（CPG）的松冈半中心振荡器和一个用于机械部件的线性单自由度系统。通过开环频率响应分析和闭环模拟，我们比较了在机械共振频率、反馈增益和机械阻尼变化时，四种不同反馈配置下的共振调谐情况。反馈配置包括两种负反馈和两种正反馈连通性方案。我们发现，对于负反馈，当ω(r)高于CPG的内源频率（ω(CPG)）时，主要发生共振调谐。相反，对于两种正反馈配置，只有当ω(r)低于ω(CPG)时才会发生共振调谐。此外，两种正（负）反馈配置之间的共振调谐差异随着反馈增益的增加和机械阻尼的减小而增大。我们的结果表明，正反馈可以实现共振调谐。此外，我们还表明，反馈配置会影响参数空间，在该参数空间中，CPG的内源频率或共振频率（机械动力学主导节律性运动的频率）。
