Department of Biological Sciences, Western Michigan University, Kalamazoo, MI, 49008, USA.
J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2021 Nov;207(6):715-727. doi: 10.1007/s00359-021-01508-z. Epub 2021 Sep 3.
How do animals use visual systems to extract specific features of a visual scene and respond appropriately? The medicinal leech, Hirudo verbana, is a predatory, quasi-amphibious annelid with a rich sensorium that is an excellent system in which to study how sensory cues are encoded, and how key features of visual images are mapped into the CNS. The leech visual system is broadly distributed over its entire body, consisting of five pairs of cephalic eyecups and seven segmentally iterated pairs of dermal sensilla in each mid-body segment. Leeches have been shown to respond behaviorally to both green and near ultraviolet light (UV, 365-375 nm). Here, we used electrophysiological techniques to show that spectral responses by dermal sensilla are mapped across the dorsal-ventral axis, such that the ventral sensilla respond strongly to UV light, while dorsal sensilla respond strongly to visible light, broadly tuned around green. These results establish how key features of visual information are initially encoded by spatial mapping of photo-response profiles of primary photoreceptors and provide insight into how these streams of information are presented to the CNS to inform behavioral responses.
动物如何利用视觉系统提取视觉场景的特定特征并做出适当反应？医用水蛭， Hirudo verbana，是一种具有丰富感觉器官的捕食性、准两栖环节动物，是研究感觉线索如何编码以及视觉图像的关键特征如何映射到中枢神经系统的绝佳系统。水蛭的视觉系统广泛分布在整个身体上，由五对头部眼杯和每个中体节的七个分段迭代的真皮感觉器对组成。已经证明，水蛭对绿光和近紫外线（UV，365-375nm）有行为反应。在这里，我们使用电生理技术表明，真皮感觉器的光谱反应是沿着背腹轴映射的，使得腹侧感觉器对紫外线光有强烈的反应，而背侧感觉器对可见光有强烈的反应，对绿光有广泛的调谐。这些结果确定了视觉信息的关键特征如何通过初级光感受器的光反应谱的空间映射进行初始编码，并提供了有关这些信息流如何呈现给中枢神经系统以告知行为反应的见解。
