Using Running Subtraction to Detect the Wavefront of Cortical Spreading Depression

The purpose of this paper was to present a simple method for analyzing the optical images from cortical spreading depression (CSD). The experimental data was acquired by optical intrinsic signal imaging (OISI) in Sprague-Dawley rats. In order to characterize the spatiotemporal evolution of CSD, especially the wavefront, running subtraction and background subtraction were both applied to process the series of images. By comparing the output results of the two different methods, running subtraction was more sensitive to the first transient and small phase of CSD (i.e. wavefront), and the extracted spatial pattern of CSD showed less vascular artifacts. For these advantages, running subtraction proved to be an appropriate approach to detect the wavefront of CSD.