Neurobiology and Cognitive Interaction Technology Center of Excellence (CITEC), Bielefeld University, Bielefeld, Germany.
J Neurophysiol. 2011 Apr;105(4):1825-34. doi: 10.1152/jn.00359.2010. Epub 2011 Feb 9.
It is still unclear how sensory systems efficiently encode signals with statistics as experienced by animals in the real world and what role adaptation plays during normal behavior. Therefore, we studied the performance of visual motion-sensitive neurons of blowflies, the horizontal system neurons, with optic flow that was reconstructed from the head trajectories of semi-free-flying flies. To test how motion adaptation is affected by optic flow dynamics, we manipulated the seminatural optic flow by targeted modifications of the flight trajectories and assessed to what extent neuronal responses to an object located close to the flight trajectory depend on adaptation dynamics. For all types of adapting optic flow object-induced response increments were stronger in the adapted compared with the nonadapted state. Adaptation with optic flow characterized by the typical alternation between translational and rotational segments produced this effect but also adaptation with optic flow that lacked these distinguishing features and even pure rotation at a constant angular velocity. The enhancement of object-induced response increments had a direction-selective component because preferred-direction rotation and natural optic flow were more efficient adaptors than null-direction rotation. These results indicate that natural dynamics of optic flow is not a basic requirement to adapt neurons in a specific, presumably functionally beneficial way. Our findings are discussed in the light of adaptation mechanisms proposed on the basis of experiments previously done with conventional experimenter-defined stimuli.
目前尚不清楚感觉系统如何有效地对动物在现实世界中体验到的具有统计学特征的信号进行编码，以及适应在正常行为过程中扮演什么角色。因此，我们研究了复眼蝇的水平系统神经元对视觉运动敏感神经元的表现，这些神经元的光流是根据半自由飞行苍蝇的头部轨迹重建的。为了测试运动适应如何受到光流动力学的影响，我们通过有针对性地修改飞行轨迹来人为地改变半自然光流，并评估了神经元对靠近飞行轨迹的物体的反应在多大程度上取决于适应动力学。对于所有类型的适应光流，与非适应状态相比，适应状态下物体诱导的反应增量更强。具有平移和旋转段典型交替特征的光流适应产生了这种效果，但也包括缺乏这些特征的光流适应，甚至是恒定角速度的纯旋转。物体诱导的反应增量增强具有方向选择性成分，因为与零方向旋转相比，优选方向旋转和自然光流是更有效的适应器。这些结果表明，光流的自然动态并不是以特定的、可能具有功能益处的方式来适应神经元的基本要求。我们的发现是基于以前用传统实验者定义的刺激进行的实验提出的适应机制的基础上进行讨论的。
