Centre for Systems, Dynamics and Control, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF, UK.
Exp Brain Res. 2012 Aug;220(3-4):213-21. doi: 10.1007/s00221-012-3130-8. Epub 2012 May 29.
Congenital nystagmus is an involuntary bilateral horizontal oscillation of the eyes that develops soon after birth. In this study, the time constants of each of the components of the neural signal underlying congenital nystagmus were obtained by time series analysis and interpreted by comparison with those of the normal oculomotor system. In the neighbourhood of the fixation position, the system generating the neural signal is approximately linear with 3 degrees of freedom. The shortest time constant was in the range of 7-9 ms and corresponds to a normal saccadic burst signal. The other stable time constant was in the range of 22-70 ms and corresponds to the slide signal. The final time constant characterises the unidentified neural mechanism underlying the unstable drift component of the oscillation cycle and ranges between 31 and 32 ms across waveforms. The characterisation of this unstable time constant poses a challenge for the modelling of both the normal and abnormal oculomotor control system. We tentatively identify the unstable component with the eye position signal supplied to the superior colliculus in the normal eye movement system and explore some of the implications of this hypothesis.
先天性眼球震颤是一种出生后不久即出现的不自觉的双侧水平眼球摆动。在这项研究中，通过时间序列分析获得了先天性眼球震颤神经信号各组成部分的时间常数，并通过与正常眼动系统的时间常数进行比较来解释。在注视位置附近，产生神经信号的系统具有大约 3 个自由度的近似线性特性。最短的时间常数在 7-9ms 范围内，对应于正常的扫视突发信号。另一个稳定的时间常数在 22-70ms 范围内，对应于滑动信号。最后一个时间常数表征了眼球震颤周期中不稳定漂移分量的未识别神经机制，在不同的波形中范围在 31 到 32ms 之间。该不稳定时间常数的特征对正常和异常眼动控制系统的建模提出了挑战。我们初步将不稳定分量与正常眼动系统中供给上丘的眼位信号联系起来，并探讨了这一假设的一些含义。
