Fig. 2

Deconstruction of astrocyte processes into representative vectors. a Binary representation of an 8-month DBA/2 J nerve with glial processes highlighted to indicate coverage (white; 19.35% of nerve area). Colored overlay demonstrates result of algorithm to calculate vectors, with degree of orientation along the vertical axis (V) indicated by red tint and degree of orientation along the horizontal axis (H) indicated with blue tint. Our algorithm excludes the outer 20% of nerve area to minimize edge effects and rotates the image to maximize orientation along the horizontal axis, shown by the inset magnified in panel b. c Inset from b in higher magnification shows glial processes in binary image. d Same glial processes skeletonized for assigning vectors to segments of constant orientation. e Representative resultant vectors for each segment calculated from skeletonized image overlaid on original binary representation of glial processes. The length of each vector represents the pixel distance of each segment between branch points in the skeletonized image. Side branches less than threshold length or width were excluded (see Materials and methods). Scale = 100 μm (a), 10 μm (b), 2 μm (c, d, e)