Combining electrophysiological recording and imaging in investigations of the rod pathway of the retina

The retina serves as an ideal model system for investigations that aim to bridge the gap between systems level descriptions and underlying mechanisms at cellular and molecular levels. The principal objective is to understand, at a molecular and microphysi ological level, the integrative dynamics of a neuronal network that plays a pivotal role for vision under dark-adapted conditions. While patch-clamp recording remains unchallenged with respect to sensitivity and temporal resolution, the morphological comp lexity of nervous tissue ideally requires experimental techniques that also have high spatial resolution. Multi-electrode recording, recording from thin neuronal processes, and combining electrophysiology with imaging microscopy aim to increase the spatia l resolution. Here, we will employ all these approaches to investigate the dynamics of specific cellular interactions in the rod pathway. Specifically, we want to establish a setup that incorporates a new microscope (movable objective microscope) that all ows for exceptional flexibility and easy switching between conventional transmitted light microscopy with optical contrast enhancement, wide-field fluorescence microscopy and multi-photon excitation (MPE) microscopy. The microscope also accommodates addit ional optical pathways for projection of visual stimuli onto the retina. First, we will use patch-clamp recording assisted by wide-field fluorescence microscopy to record from thin dendritic processes of rod amacrine cells in retinal slices to investigate their functional properties. Next, we will use MPE microscopy to investigate the calcium dynamics of the same dendrites and the influence of visual stimulation. Finally, we will use MPE-assisted targeted, multi-electrode patch-clamp recordings from rod b ipolar cells in wholemounts to investigate the functional role of a presynaptic transporter on these cells and the extent of glutamate spillover between axon terminals of rod bipolar cells in the intact retina.