It's not all black and white: visual scene parameters influence optokinetic reflex performance in Xenopus laevis tadpoles
It's not all black and white: visual scene parameters influence optokinetic reflex performance in Xenopus laevis tadpoles
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DOI：
10.1242/jeb.167700
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发表时间：
2017-11-15
影响因子：
2.8
通讯作者：
Straka, Hans
中科院分区：
文献类型：
--
作者：
Gravot, Celine M.;Knorr, Alexander G.;Straka, Hans
在主动和被动身体运动过程中，通过旨在最大限度地减少视网膜图像滑移的凝视稳定反射来确保视力的保持。对于视动反射(OKR)来说，周围的大视野视觉运动形成了激活眼球运动的基本刺激。运动视觉世界的特性影响认知运动知觉和视觉图像速度的估计。因此，脑干介导的视觉运动行为的表现也可能取决于图像场景特征。采用非洲爪哇蝌蚪中期幼虫的半完整标本，研究了对比度、强度、轮廓形状和不同的运动刺激方式对大视野视觉场景运动时OKR和多单位视神经放电的影响。在高对比度下，与负对比度的视觉场景相比，对比度为正的视觉场景(暗背景上的亮点)的OKR幅度明显更大。这一效应在亮度匹配的刺激对中持续存在，并且与轮廓形状无关。OKR表现的相对偏差以及反应与轮廓形状的独立性与相同视觉刺激诱发的视神经放电密切匹配。然而，视网膜神经节细胞对单个移动的小的垂直边缘的多单位活动反应强烈地受到垂直邻域的光照强度的影响。这表明，与对比极性相关的OKR偏差的潜在机制直接来自视网膜电路的视觉运动处理特性。
The maintenance of visual acuity during active and passive body motion is ensured by gaze-stabilizing reflexes that aim at minimizing retinal image slip. For the optokinetic reflex (OKR), large-field visual motion of the surround forms the essential stimulus that activates eye movements. Properties of the moving visual world influence cognitive motion perception and the estimation of visual image velocity. Therefore, the performance of brainstem-mediated visuo-motor behaviors might also depend on image scene characteristics. Employing semi-intact preparations of mid-larval stages of Xenopus laevis tadpoles, we studied the influence of contrast polarity, intensity, contour shape and different motion stimulus patterns on the performance of the OKR and multi-unit optic nerve discharge during motion of a large-field visual scene. At high contrast intensities, the OKR amplitude was significantly larger for visual scenes with a positive contrast (bright dots on a dark background) compared with those with a negative contrast. This effect persisted for luminance-matched pairs of stimuli, and was independent of contour shape. The relative biases of OKR performance along with the independence of the responses from contour shape were closely matched by the optic nerve discharge evoked by the same visual stimuli. However, the multi-unit activity of retinal ganglion cells in response to a small single moving vertical edge was strongly influenced by the light intensity in the vertical neighborhood. This suggests that the underlying mechanism of OKR biases related to contrast polarity directly derives from visual motion-processing properties of the retinal circuitry.