Laboratory of Retinal Neurochemistry and Experimental Ophthalmology, School of Science/IQUIBICEN, University of Buenos Aires/CONICET, Buenos Aires, Argentina.
Department of Neurobiology, Northwestern University, Evanston, IL, USA.
Sci Rep. 2024 May 31;14(1):12499. doi: 10.1038/s41598-024-63458-1.
In the animal kingdom, threat information is perceived mainly through vision. The subcortical visual pathway plays a critical role in the rapid processing of visual information-induced fear, and triggers a response. Looming-evoked behavior in rodents, mimicking response to aerial predators, allowed identify the neural circuitry underlying instinctive defensive behaviors; however, the influence of disk/background contrast on the looming-induced behavioral response has not been examined, either in rats or mice. We studied the influence of the dark disk/gray background contrast in the type of rat and mouse defensive behavior in the looming arena, and we showed that rat and mouse response as a function of disk/background contrast adjusted to a sigmoid-like relationship. Both sex and age biased the contrast-dependent response, which was dampened in rats submitted to retinal unilateral or bilateral ischemia. Moreover, using genetically manipulated mice, we showed that the three type of photoresponsive retinal cells (i.e., cones, rods, and intrinsically photoresponsive retinal ganglion cells (ipRGCs)), participate in the contrast-dependent response, following this hierarchy: cones > > rods > > > ipRGCs. The cone and rod involvement was confirmed using a mouse model of unilateral non-exudative age-related macular degeneration, which only damages canonical photoreceptors and significantly decreased the contrast sensitivity in the looming arena.
在动物王国中，威胁信息主要通过视觉感知。皮层下视觉通路在快速处理视觉信息引起的恐惧方面起着至关重要的作用，并引发反应。啮齿动物的逼近诱发行为，模仿对空中捕食者的反应，有助于确定本能防御行为的神经回路；然而，无论是在大鼠还是小鼠中，盘/背景对比度对逼近诱发行为反应的影响尚未被研究。我们研究了在逼近竞技场中，大鼠和小鼠防御行为的黑盘/灰背景对比度的影响，结果表明，大鼠和小鼠的反应随盘/背景对比度的变化而调整为类 S 型关系。性别和年龄都影响了对比度依赖的反应，而单侧或双侧视网膜缺血的大鼠的反应则减弱。此外，使用基因操作的小鼠，我们表明三种光反应性视网膜细胞（即视锥细胞、视杆细胞和内在光反应性视网膜神经节细胞（ipRGCs））参与了对比度依赖的反应，其参与程度如下：视锥细胞 > 视杆细胞 > ipRGCs。通过单侧非渗出性年龄相关性黄斑变性的小鼠模型证实了视锥细胞和视杆细胞的参与，该模型仅损伤经典光感受器，并显著降低了在逼近竞技场中的对比度敏感性。
