Neural mechanisms that detect defocus in the retina

项目摘要 清晰的视网膜图像对于准确编码视觉世界至关重要。焦 眼睛光学系统的长度可以在几分之一秒内调整， 兴趣转化为焦点，这个过程叫做“适应”。在更长的时间尺度上， 到几个月，当眼轴长度增长时， 以匹配光学器件的折射能力，这一过程称为“正视化”。为了 为了做出适当的反应，调节和正视需要视网膜 检测图像散焦的符号和大小。众所周知，少校 发出散焦信号的光学提示是纵向色差（LCA）。 LCA是由于短波长光的折射比长波长光强。的身份 视网膜中检测LCA信号的神经元，以及它们如何将信号传递到视网膜。 控制眼睛生长和调节的下游机制仍然是 感觉神经生物学中最大的难题这项建议旨在确定 对LCA有反应的视网膜神经元我们将使用多光子钙成像， 同时测量一个区域内数十到数百个神经元的反应。 明视适应水平下的视网膜。图案化的彩色图像将用于 识别候选散焦神经元。神经元的胞体将被靶向 单细胞全细胞记录，以详细测量感受野特性， 恢复形态。我们还将测量对自然场景的反应， 并且没有针对眼睛的光学计算的LCA。识别LCA敏感神经元 这将为未来的研究奠定基础，旨在确定这些视网膜 神经元最终控制调节和正视化。这些见解可能 也提供线索的起源神秘，持续增加的流行 近视，也许导致缓解策略的发展。

PROJECT SUMMARY A sharp retinal image is essential for accurately encoding the visual world. The focal length of the eyes' optics can be adjusted within a fraction of a second to bring object of interest into sharp focus, a process called “accommodation”. On longer timescales, hours to months, a sharp retinal image is made possible when the axial length of the eye grows to match the refractive power of the optics, a process called “emmetropization”. In order to respond appropriately, accommodation and emmetropization require the retina to detect the sign and magnitude of image defocus. It is well established that the major optical cue that signals the sign of defocus is longitudinal chromatic aberration (LCA). LCA is due to the stronger refraction of short than long wavelength light. The identity of the neurons in the retina that detect LCA signals, and how they relay the signals to the down-stream mechanisms that control eye growth and accommodation, remains one of the great outstanding puzzles in sensory neurobiology. This proposal aims to identify the retinal neurons that respond to LCA. We will use multi-photon calcium imaging to simultaneously measure responses from tens to hundreds of neurons within an area of retina under photopic adaptation levels. Patterned, chromatic images will be used to identify candidate defocus neurons. The somas of the neurons will then be targeted for single-cell whole-cell recordings to measure in detail the receptive field properties and to recover the morphology. We will also measure responses to natural scenes rendered with and without LCA calculated for the optics of the eye. Identification LCA-sensitive neurons will lay the groundwork for future studies aimed at determining how these retinal neurons ultimately control accommodation and emmetropization. These insights may also provide clues as to the origin of the mysterious, continuing increase in the prevalence of myopia and perhaps lead to development of mitigative strategies.