Estimation of neuronal activity based on voltage-sensitive dye imaging in a moving preparation

Voltage-sensitive dye imaging allows simultaneous recording of graded voltage changes of multiple neurons. While this experimental technique is a great tool to study neuronal network activity in neuroscience, the optical recording suffers from artifacts. In particular, bleaching of the dye and cell movement impede the analysis and interpretation of imaging results. In this paper, we present methods to tackle these two main artifacts. Cell movement during the experiment is corrected by an optical flow method. Bleaching decay is estimated based on a line fit of recordings without stimulus, which is subtracted from the rest of the recordings in the same experiment. Here, we use a leech ganglion as an example tissue to evaluate these processing procedures. This preparation allows simultaneous voltage-sensitive dye imaging of the entire neuronal network and intracellular recording of one cell´s membrane voltage. Using the intracellularly recorded voltage as the ground truth reference, we show that our processing methods for the VSD imaging signal clearly improve the correlation between the real and the estimated voltage. Since other imaging techniques (e.g., calcium imaging) suffer from the same type of artifacts as voltage-sensitive dye imaging, our processing method might be useful for a wide range of biomedical imaging studies.