Probing retinal and neural mechanisms of vision by hyperacute optical stimulation of single photoreceptor cells

视觉功能通常是通过测量观察者的视觉灵敏度来评估的，也就是说，最小的视型——通常是字母——仅仅是可识别的。这一过程受到眼睛的光学质量和采集视网膜图像的神经结构的限制。然而，存在另一类视觉分辨率——超敏锐——超过传统的敏锐度，从而表明视觉能力受到视网膜回路和大脑神经元机制的强烈影响。超敏锐感知的测量提供了一些优于视觉分辨率的经典测试，因为它主要解决了观察者视觉能力的神经部分。虽然游标敏锐度在神经科学中得到了很好的研究，但超敏锐知觉背后的确切视网膜和神经机制尚不清楚。在光学刺激和视网膜成像方面的最新进展使得在活体人眼的视锥目标视网膜位置传递视觉刺激成为可能。在此，我建议在单个视网膜感光器的水平上研究超敏锐知觉的机制，以揭示空间视觉任务背后的离散视网膜线路。为了区分纯视网膜和超敏性中枢方面，所有实验也将在弱视受试者中进行，即神经视力下降的受试者。最后，程序将被设计，以促进超急性测量在标准眼科检查中的使用。超视力测试可能提供鉴别诊断早期神经性视力丧失的可能性，这是传统视力测试无法做到的。

Visual function is most frequently assessed by measuring the observer’s visual acuity, i.e. the smallest optotypes – usually letters – that are just identifiable. This process is limited by the optical quality of the eye and the neural structures that sample the retinal image. However, another class of visual resolution – hyperacuity – exists that surpass conventional acuity, thereby demonstrating that visual capabilities are strongly influenced by retinal circuitry and the neuronal machinery of the brain. The measurement of hyperacute perception offers a few advantageous over classical tests of visual resolution, since it primarily addresses the neural fraction of the observer’s visual capabilities. Although vernier acuity is well-studied within the neurosciences, the exact retinal and neural mechanisms underlying hyperacute perception are unknown. Recent advances in optical stimulation and retinal imaging makes it now possible to deliver visual stimuli at cone-targeted retinal locations in the living human eye. I here propose to study the mechanisms of hyperacute perception at the level of single retinal photoreceptors to uncover the discrete retinal wiring underlying spatial vision tasks. To distinguish pure retinal from central aspects of hyperacute sensitivity, all experiments will also be carried out with amblyopic subjects, i.e. subjects who suffer from decreased neural visual acuity. Finally, procedures will be engineered that promote the use of a hyperacute measurement in standard ophthalmic examination. Hyperacuity tests may offer the possibility to differentially diagnose early neural vision loss, a feat that is not possible with conventional acuity testing.