Reconstruction of firing rate changes across neuronal populations by temporally deconvolved Ca2+ imaging

Methods to record action potential (AP) firing in many individual neurons are essential to unravel the function of complex neuronal circuits in the brain. A promising approach is bolus loading of Ca2+ indicators combined with multiphoton microscopy. Currently, however, this technique lacks cell-type specificity, has low temporal resolution and cannot resolve complex temporal firing patterns. Here we present simple solutions to these problems. We identified neuron types by colocalizing Ca2+ signals of a red-fluorescing indicator with genetically encoded markers. We reconstructed firing rate changes from Ca2+ signals by temporal deconvolution. This technique is efficient, dramatically enhances temporal resolution, facilitates data interpretation and permits analysis of odor-response patterns across thousands of neurons in the zebrafish olfactory bulb. Hence, temporally deconvolved Ca2+ imaging (TDCa imaging) resolves limitations of current optical recording techniques and is likely to be widely applicable because of its simplicity, robustness and generic principle.