Krause Martin, Distler Claudia, Hoffmann Klaus-Peter
Allgemeine Zoologie & Neurobiologie, Ruhr-University Bochum, Bochum, Germany.
Eur J Neurosci. 2014 Jul;40(1):2274-82. doi: 10.1111/ejn.12572. Epub 2014 Apr 3.
The optokinetic deficits in albinotic rats and ferrets are caused by the loss of direction selectivity in the accessory optic system (AOS). However, the underlying mechanisms for this loss are still not clear. Here we tested the hypothesis that, in albino rats, the retinal input to the AOS lacks direction selectivity and, as a consequence, neurons in the AOS are direction non-selective. We investigated ON-center direction-selective retinal ganglion cells, the major input to the AOS, in pigmented Long Evans and albino Wistar rats using extracellular in vitro patch-clamp techniques. To visualise putative AOS-projecting direction-selective ganglion cells, we retrogradely labeled them by injection of the infrared-sensitive dye indocyanine green into the medial terminal nucleus of the AOS. The present study is the first to present physiological evidence for retinal ON-center direction-selective ganglion cells in rat. Our results show that, in albinotic and pigmented rats, ON-center retinal ganglion cells projecting to the AOS are similarly direction-selective, suggesting that the optokinetic deficit must be caused by the abolition of direction selectivity in the AOS itself.
白化大鼠和雪貂的视动缺陷是由附属视觉系统（AOS）中方向选择性的丧失引起的。然而，这种丧失的潜在机制仍不清楚。在这里，我们检验了一个假设，即在白化大鼠中，视网膜向AOS的输入缺乏方向选择性，因此，AOS中的神经元是方向非选择性的。我们使用细胞外体外膜片钳技术，研究了有色长 Evans 大鼠和白化 Wistar 大鼠中作为AOS主要输入的ON中心方向选择性视网膜神经节细胞。为了可视化假定的投射到AOS的方向选择性神经节细胞，我们通过将红外敏感染料吲哚菁绿注入AOS的内侧终核来对它们进行逆行标记。本研究首次提供了大鼠视网膜ON中心方向选择性神经节细胞的生理学证据。我们的结果表明，在白化和有色大鼠中，投射到AOS的ON中心视网膜神经节细胞同样具有方向选择性，这表明视动缺陷一定是由AOS自身方向选择性的丧失所导致的。
