Gollisch Tim
University Medical Center Göttingen, Department of Ophthalmology, Waldweg 33, 37073 Göttingen, Germany.
J Physiol Paris. 2013 Nov;107(5):338-48. doi: 10.1016/j.jphysparis.2012.12.001. Epub 2012 Dec 20.
Ganglion cells in the vertebrate retina integrate visual information over their receptive fields. They do so by pooling presynaptic excitatory inputs from typically many bipolar cells, which themselves collect inputs from several photoreceptors. In addition, inhibitory interactions mediated by horizontal cells and amacrine cells modulate the structure of the receptive field. In many models, this spatial integration is assumed to occur in a linear fashion. Yet, it has long been known that spatial integration by retinal ganglion cells also incurs nonlinear phenomena. Moreover, several recent examples have shown that nonlinear spatial integration is tightly connected to specific visual functions performed by different types of retinal ganglion cells. This work discusses these advances in understanding the role of nonlinear spatial integration and reviews recent efforts to quantitatively study the nature and mechanisms underlying spatial nonlinearities. These new insights point towards a critical role of nonlinearities within ganglion cell receptive fields for capturing responses of the cells to natural and behaviorally relevant visual stimuli. In the long run, nonlinear phenomena of spatial integration may also prove important for implementing the actual neural code of retinal neurons when designing visual prostheses for the eye.
脊椎动物视网膜中的神经节细胞在其感受野上整合视觉信息。它们通过汇聚通常来自许多双极细胞的突触前兴奋性输入来做到这一点，而这些双极细胞本身又从多个光感受器收集输入。此外，由水平细胞和无长突细胞介导的抑制性相互作用会调节感受野的结构。在许多模型中，这种空间整合被假定以线性方式发生。然而，长期以来人们就知道视网膜神经节细胞的空间整合也会产生非线性现象。此外，最近的几个例子表明，非线性空间整合与不同类型视网膜神经节细胞执行的特定视觉功能紧密相关。这项工作讨论了在理解非线性空间整合作用方面的这些进展，并回顾了最近定量研究空间非线性本质和机制的努力。这些新见解表明，神经节细胞感受野内的非线性对于捕捉细胞对自然和行为相关视觉刺激的反应起着关键作用。从长远来看，在为眼睛设计视觉假体时，空间整合的非线性现象对于实现视网膜神经元的实际神经编码可能也很重要。
