Pfäffle Clara, Spahr Hendrik, Gercke Katharina, Puyo Léo, Höhl Svea, Melenberg David, Miura Yoko, Hüttmann Gereon, Hillmann Dierck
Institute of Biomedical Optic, University of Lübeck, Lübeck, Germany.
Medical Laser Center Lübeck GmbH, Lübeck, Germany.
Front Med (Lausanne). 2022 Jun 1;9:885187. doi: 10.3389/fmed.2022.885187. eCollection 2022.
Non-invasive spatially resolved functional imaging in the human retina has recently attracted considerable attention. Particularly functional imaging of bipolar and ganglion cells could aid in studying neuronal activity in humans, including an investigation of processes of the central nervous system. Recently, we imaged the activity of the inner neuronal layers by measuring nanometer-size changes of the cells within the inner plexiform layer (IPL) using phase-sensitive optical coherence tomography (OCT). In the IPL, there are connections between the neuronal cells that are dedicated to the processing of different aspects of the visual information, such as edges in the image or temporal changes. Still, so far, it was not possible to assign functional changes to single cells or cell classes in living humans, which is essential for studying the vision process. One characteristic of signal processing in the IPL is that different aspects of the visual impression are only processed in specific sub-layers (strata). Here, we present an investigation of these functional signals for three different sub-layers in the IPL with the aim to separate different properties of the visual signal processing. Whereas the inner depth-layer, closest to the ganglion cells, exhibits an increase in the optical path length, the outer depth-layer, closest to the bipolar cell layer, exhibits a decrease in the optical path length. Additionally, we found that the central depth is sensitive to temporal changes, showing a maximum response at a stimulation frequency of around 12.5 Hz. The results demonstrate that the signals from different cell types can be distinguished by phase-sensitive OCT.
非侵入性的人类视网膜空间分辨功能成像最近引起了广泛关注。特别是双极细胞和神经节细胞的功能成像有助于研究人类的神经元活动，包括对中枢神经系统过程的研究。最近，我们使用相敏光学相干断层扫描（OCT）通过测量内网状层（IPL）内细胞的纳米级变化来成像内层神经元的活动。在IPL中，神经元细胞之间存在连接，这些连接专门用于处理视觉信息的不同方面，如图像中的边缘或时间变化。然而，到目前为止，还无法将功能变化归因于活体人类中的单个细胞或细胞类别，而这对于研究视觉过程至关重要。IPL中信号处理的一个特点是视觉印象的不同方面仅在特定的子层（层）中进行处理。在这里，我们对IPL中的三个不同子层的这些功能信号进行了研究，目的是分离视觉信号处理的不同特性。最靠近神经节细胞的内深层的光程长度增加，而最靠近双极细胞层的外深层的光程长度减少。此外，我们发现中央深度对时间变化敏感，在约12.5Hz的刺激频率下显示出最大响应。结果表明，相敏OCT可以区分来自不同细胞类型的信号。
