Diabetes can damage both the peripheral sensory organs, causing retinopathy, as well as the central visual system, leading to contrast sensitivity and impaired color vision in patients without retinopathy. Orientation discrimination is important for shape recognition by the visual system. Our psychophysical findings in this study show diminished orientation discrimination in diabetic patients without retinopathy. To reveal the underlying mechanism, we established a diabetic mouse model and recorded in vivo electrophysiological data in the dorsal lateral geniculate nucleus (dLGN) and primary visual cortex (V1). Reduced orientation selectivity was observed in both individual and populations of neurons in V1 and dLGN, which increased in severity with disease duration. This diabetes-associated neuronal dysfunction appeared earlier in the V1 than dLGN. Additionally, neuronal activity and signal-to-noise ratio is reduced in V1 neurons of diabetic mice, leading to a decreased capacity for information processing by V1 neurons. Notably, the V1 in diabetic mice exhibits reduced excitatory neuronal activity and lower levels of phosphorylated mammalian target of rapamycin (mTOR). Our findings show that altered responses of both populations and single V1 neurons may impair fine vision, thus expanding our understanding of the underlying causes of diabetes-related impairment of the central nervous system.

中文翻译：

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糖尿病中枢神经系统损伤的新证据：精细视觉辨别力受损

糖尿病会损害周围感觉器官，导致视网膜病变，以及中枢视觉系统，导致没有视网膜病变的患者对比敏感度和色觉受损。方向辨别对于视觉系统的形状识别很重要。我们在这项研究中的心理物理学发现表明，没有视网膜病变的糖尿病患者的方向歧视减少。为了揭示潜在机制，我们建立了糖尿病小鼠模型并记录了背外侧膝状体核（dLGN）和初级视觉皮层（V1）的体内电生理数据。在 V1 和 dLGN 中的个体和神经元群体中都观察到定向选择性降低，其严重程度随着疾病持续时间而增加。这种与糖尿病相关的神经元功能障碍在 V1 中比 dLGN 出现得更早。此外，糖尿病小鼠 V1 神经元的神经元活动和信噪比降低，导致 V1 神经元处理信息的能力下降。值得注意的是，糖尿病小鼠中的 V1 表现出兴奋性神经元活性降低和雷帕霉素磷酸化哺乳动物靶标 (mTOR) 水平降低。我们的研究结果表明，群体和单个 V1 神经元的反应改变可能会损害良好的视力，从而扩大我们对糖尿病相关中枢神经系统损害的根本原因的理解。糖尿病小鼠的 V1 表现出兴奋性神经元活性降低和雷帕霉素磷酸化哺乳动物靶标 (mTOR) 水平降低。我们的研究结果表明，群体和单个 V1 神经元的反应改变可能会损害良好的视力，从而扩大我们对糖尿病相关中枢神经系统损害的根本原因的理解。糖尿病小鼠的 V1 表现出兴奋性神经元活性降低和雷帕霉素磷酸化哺乳动物靶标 (mTOR) 水平降低。我们的研究结果表明，群体和单个 V1 神经元的反应改变可能会损害良好的视力，从而扩大我们对糖尿病相关中枢神经系统损害的根本原因的理解。