Faculty of Medicine, Lithuanian University of Health Sciences, Kaunas, 50161, Lithuania.
Neurophysiology laboratory, Neuroscience Institute, Lithuanian University of Health Sciences, Kaunas, 50161, Lithuania.
Sci Rep. 2018 Jun 12;8(1):8942. doi: 10.1038/s41598-018-27331-2.
Adaptation of visual responses enhances visual information processing mainly by preserving the full dynamic range of neuronal responses during changing light conditions and is found throughout the whole visual system. Although adaptation in the primate superior colliculus neurons has received much attention little is known about quantitative properties of such adaptation in rodents, an increasingly important model in vision research. By employing single unit recordings, we demonstrate that in the rat collicular neurons visual responses are shaped by at least two forms of adaptation. When visual stimuli were repeatedly presented in the same location, visual responses were reduced in the majority of single units. However, when the adaptor stimulus was outside a small diameter receptive field (RF), responses to stimulus onset but not offset were enhanced in the majority of units. Responses to stimulus offset were reduced less and recovered faster than responses to stimulus onset and the effect was limited to a fraction of RF area. Simulations showed that such adaptation acted as a powerful spatiotemporal filter and could explain several tuning properties of collicular neurons. These results demonstrate that in rodents the adaption of visual responses has a complex spatiotemporal structure and can profoundly shape visual information processing.
视觉响应的适应主要通过在光照条件变化时保持神经元响应的全动态范围来增强视觉信息处理，并且在整个视觉系统中都有发现。尽管灵长类动物上丘神经元的适应已经受到了广泛关注，但在作为视觉研究中越来越重要的模型的啮齿动物中，这种适应的定量特性却知之甚少。通过采用单细胞记录，我们证明了在大鼠丘脑中，视觉响应至少受到两种形式的适应的影响。当视觉刺激在同一位置重复呈现时，大多数单个单元中的视觉响应会减小。然而，当适应刺激位于小直径感受野 (RF) 之外时，大多数单元对刺激起始而不是结束的响应会增强。刺激结束时的响应减少较少且恢复较快，比刺激起始时的响应更快，并且该效果仅限于 RF 区域的一小部分。模拟表明，这种适应作用是一种强大的时空滤波器，可以解释丘脑中神经元的几个调谐特性。这些结果表明，在啮齿动物中，视觉响应的适应具有复杂的时空结构，可以深刻地塑造视觉信息处理。
