Muir Gillian D, Gowri K S V
Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada.
J Neurophysiol. 2005 Dec;94(6):3691-7. doi: 10.1152/jn.01121.2004. Epub 2005 Aug 10.
The purpose of this research was to investigate the role of motor and visual experience during the development of locomotion in chicks. We have previously demonstrated that when locomotor activity is restricted immediately posthatching, chicks walk with shorter stride lengths and attenuated head bobbing movements. Head bobbing is an optokinetic response in birds, driven by the movement of the visual world across the retina (i.e., optic flow). During locomotion, optic flow is generated by forward translation, and we have shown that the magnitude of head bobbing movements and stride lengths are moderately correlated in walking chicks. In the present study, we investigated this relationship more closely by examining whether imposed changes in stride length could affect head excursions during head bobbing. We manipulated stride length by hobbling chicks immediately after hatching and subsequently quantified kinematic parameters, including step timing and head excursions, during walking. Imposition of shorter stride lengths induced chicks to take more frequent steps, spend less time in contact with the ground, and shortened head excursions during head bobbing. Nevertheless, the developmental changes in head excursions were not fully accounted for by altered stride lengths, so in a separate experiment, we investigated whether the development of head bobbing relies on the normal experience of optic flow. We raised chicks under stroboscopic illumination to eliminate chicks' experience of optic flow but found that this did not significantly alter head bobbing. These results are discussed along with related findings in other species and the possible neural and biomechanical constraints underlying development of walking and head bobbing in birds.
本研究的目的是探究运动和视觉体验在雏鸡运动发育过程中的作用。我们之前已经证明，在雏鸡孵化后立即限制其运动活动，雏鸡行走时的步长会变短，头部摆动动作也会减弱。头部摆动是鸟类的一种视动反应，由视觉世界在视网膜上的移动（即光流）驱动。在运动过程中，光流由向前平移产生，并且我们已经表明，行走雏鸡的头部摆动动作幅度和步长呈中度相关。在本研究中，我们通过检查施加的步长变化是否会影响头部摆动时的头部偏移，来更深入地研究这种关系。我们在雏鸡孵化后立即束缚其腿部来控制步长，随后在行走过程中对包括步时和头部偏移在内的运动学参数进行量化。施加较短步长会导致雏鸡更频繁地迈步，与地面接触的时间减少，并且在头部摆动时头部偏移缩短。然而，头部偏移的发育变化并不能完全由改变的步长来解释，因此在另一个实验中，我们研究了头部摆动的发育是否依赖于正常的光流体验。我们在频闪照明下饲养雏鸡以消除雏鸡的光流体验，但发现这并没有显著改变头部摆动。我们将结合其他物种的相关研究结果以及鸟类行走和头部摆动发育背后可能的神经和生物力学限制来讨论这些结果。
