Image Processing Approximately 300 images could be acquired at each of up to 50 locations, making up to 15,000 images per experiment. We developed an algorithm in MATLAB (MathWorks, Natick, MA) to determine the movement of somas after injury. The algorithm has two parts: detection and tracking. Somas were detected using the process depicted in Fig. 7 in order to identify the positions of each cell in all image frames. The standard deviation of the intensity in square matrices of 90 pixels (Fig. 7A) was thresholded and a binary image obtained (Fig. 7B). A mask was computed by closing and filling (Fig.7C), and finally eroding (Fig. 7D) the binary image. The centroids of all objects obtained in the resultant mask were used to assign a position to the somas present in each frame (see Fig. 6 for an example). The positions obtained were then processed with a single particle-tracking algorithm to calculate the cell trajectories [35] (See supplemental material File S1 for the complete code). 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